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llvm / llvm-project / llvm / refs/heads/main / . / lib / Target / Hexagon / HexagonFrameLowering.cpp
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//===- HexagonFrameLowering.cpp - Define frame lowering -------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//
//===----------------------------------------------------------------------===//
#include "HexagonFrameLowering.h"
#include "HexagonBlockRanges.h"
#include "HexagonInstrInfo.h"
#include "HexagonMachineFunctionInfo.h"
#include "HexagonRegisterInfo.h"
#include "HexagonSubtarget.h"
#include "HexagonTargetMachine.h"
#include "MCTargetDesc/HexagonBaseInfo.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/LivePhysRegs.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <limits>
#include <map>
#include <optional>
#include <utility>
#include <vector>
#define DEBUG_TYPE "hexagon-pei"
// Hexagon stack frame layout as defined by the ABI:
//
// Incoming arguments
// passed via stack
// |
// |
// SP during function's FP during function's |
// +-- runtime (top of stack) runtime (bottom) --+ |
// | | |
// --++---------------------+------------------+-----------------++-+-------
// | parameter area for | variable-size | fixed-size |LR| arg
// | called functions | local objects | local objects |FP|
// --+----------------------+------------------+-----------------+--+-------
// <- size known -> <- size unknown -> <- size known ->
//
// Low address High address
//
// <--- stack growth
//
//
// - In any circumstances, the outgoing function arguments are always accessi-
// ble using the SP, and the incoming arguments are accessible using the FP.
// - If the local objects are not aligned, they can always be accessed using
// the FP.
// - If there are no variable-sized objects, the local objects can always be
// accessed using the SP, regardless whether they are aligned or not. (The
// alignment padding will be at the bottom of the stack (highest address),
// and so the offset with respect to the SP will be known at the compile-
// -time.)
//
// The only complication occurs if there are both, local aligned objects, and
// dynamically allocated (variable-sized) objects. The alignment pad will be
// placed between the FP and the local objects, thus preventing the use of the
// FP to access the local objects. At the same time, the variable-sized objects
// will be between the SP and the local objects, thus introducing an unknown
// distance from the SP to the locals.
//
// To avoid this problem, a new register is created that holds the aligned
// address of the bottom of the stack, referred in the sources as AP (aligned
// pointer). The AP will be equal to "FP-p", where "p" is the smallest pad
// that aligns AP to the required boundary (a maximum of the alignments of
// all stack objects, fixed- and variable-sized). All local objects[1] will
// then use AP as the base pointer.
// [1] The exception is with "fixed" stack objects. "Fixed" stack objects get
// their name from being allocated at fixed locations on the stack, relative
// to the FP. In the presence of dynamic allocation and local alignment, such
// objects can only be accessed through the FP.
//
// Illustration of the AP:
// FP --+
// |
// ---------------+---------------------+-----+-----------------------++-+--
// Rest of the | Local stack objects | Pad | Fixed stack objects |LR|
// stack frame | (aligned) | | (CSR, spills, etc.) |FP|
// ---------------+---------------------+-----+-----------------+-----+--+--
// |<-- Multiple of the -->|
// stack alignment +-- AP
//
// The AP is set up at the beginning of the function. Since it is not a dedi-
// cated (reserved) register, it needs to be kept live throughout the function
// to be available as the base register for local object accesses.
// Normally, an address of a stack objects is obtained by a pseudo-instruction
// PS_fi. To access local objects with the AP register present, a different
// pseudo-instruction needs to be used: PS_fia. The PS_fia takes one extra
// argument compared to PS_fi: the first input register is the AP register.
// This keeps the register live between its definition and its uses.
// The AP register is originally set up using pseudo-instruction PS_aligna:
// AP = PS_aligna A
// where
// A - required stack alignment
// The alignment value must be the maximum of all alignments required by
// any stack object.
// The dynamic allocation uses a pseudo-instruction PS_alloca:
// Rd = PS_alloca Rs, A
// where
// Rd - address of the allocated space
// Rs - minimum size (the actual allocated can be larger to accommodate
// alignment)
// A - required alignment
using namespace llvm;
static cl::opt<bool> DisableDeallocRet("disable-hexagon-dealloc-ret",
cl::Hidden, cl::desc("Disable Dealloc Return for Hexagon target"));
static cl::opt<unsigned>
NumberScavengerSlots("number-scavenger-slots", cl::Hidden,
cl::desc("Set the number of scavenger slots"),
cl::init(2));
static cl::opt<int>
SpillFuncThreshold("spill-func-threshold", cl::Hidden,
cl::desc("Specify O2(not Os) spill func threshold"),
cl::init(6));
static cl::opt<int>
SpillFuncThresholdOs("spill-func-threshold-Os", cl::Hidden,
cl::desc("Specify Os spill func threshold"),
cl::init(1));
static cl::opt<bool> EnableStackOVFSanitizer(
"enable-stackovf-sanitizer", cl::Hidden,
cl::desc("Enable runtime checks for stack overflow."), cl::init(false));
static cl::opt<bool>
EnableShrinkWrapping("hexagon-shrink-frame", cl::init(true), cl::Hidden,
cl::desc("Enable stack frame shrink wrapping"));
static cl::opt<unsigned>
ShrinkLimit("shrink-frame-limit",
cl::init(std::numeric_limits<unsigned>::max()), cl::Hidden,
cl::desc("Max count of stack frame shrink-wraps"));
static cl::opt<bool>
EnableSaveRestoreLong("enable-save-restore-long", cl::Hidden,
cl::desc("Enable long calls for save-restore stubs."),
cl::init(false));
static cl::opt<bool> EliminateFramePointer("hexagon-fp-elim", cl::init(true),
cl::Hidden, cl::desc("Refrain from using FP whenever possible"));
static cl::opt<bool> OptimizeSpillSlots("hexagon-opt-spill", cl::Hidden,
cl::init(true), cl::desc("Optimize spill slots"));
#ifndef NDEBUG
static cl::opt<unsigned> SpillOptMax("spill-opt-max", cl::Hidden,
cl::init(std::numeric_limits<unsigned>::max()));
static unsigned SpillOptCount = 0;
#endif
namespace {
class HexagonCallFrameInformation : public MachineFunctionPass {
public:
static char ID;
HexagonCallFrameInformation() : MachineFunctionPass(ID) {}
bool runOnMachineFunction(MachineFunction &MF) override;
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().setNoVRegs();
}
};
char HexagonCallFrameInformation::ID = 0;
} // end anonymous namespace
bool HexagonCallFrameInformation::runOnMachineFunction(MachineFunction &MF) {
auto &HFI = *MF.getSubtarget<HexagonSubtarget>().getFrameLowering();
bool NeedCFI = MF.needsFrameMoves();
if (!NeedCFI)
return false;
HFI.insertCFIInstructions(MF);
return true;
}
INITIALIZE_PASS(HexagonCallFrameInformation, "hexagon-cfi",
"Hexagon call frame information", false, false)
FunctionPass *llvm::createHexagonCallFrameInformation() {
return new HexagonCallFrameInformation();
}
/// Map a register pair Reg to the subregister that has the greater "number",
/// i.e. D3 (aka R7:6) will be mapped to R7, etc.
static Register getMax32BitSubRegister(Register Reg,
const TargetRegisterInfo &TRI,
bool hireg = true) {
if (Reg < Hexagon::D0 || Reg > Hexagon::D15)
return Reg;
Register RegNo = 0;
for (MCPhysReg SubReg : TRI.subregs(Reg)) {
if (hireg) {
if (SubReg > RegNo)
RegNo = SubReg;
} else {
if (!RegNo || SubReg < RegNo)
RegNo = SubReg;
}
}
return RegNo;
}
/// Returns the callee saved register with the largest id in the vector.
static Register getMaxCalleeSavedReg(ArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo &TRI) {
static_assert(Hexagon::R1 > 0,
"Assume physical registers are encoded as positive integers");
if (CSI.empty())
return 0;
Register Max = getMax32BitSubRegister(CSI[0].getReg(), TRI);
for (unsigned I = 1, E = CSI.size(); I < E; ++I) {
Register Reg = getMax32BitSubRegister(CSI[I].getReg(), TRI);
if (Reg > Max)
Max = Reg;
}
return Max;
}
/// Checks if the basic block contains any instruction that needs a stack
/// frame to be already in place.
static bool needsStackFrame(const MachineBasicBlock &MBB, const BitVector &CSR,
const HexagonRegisterInfo &HRI) {
for (const MachineInstr &MI : MBB) {
if (MI.isCall())
return true;
unsigned Opc = MI.getOpcode();
switch (Opc) {
case Hexagon::PS_alloca:
case Hexagon::PS_aligna:
return true;
default:
break;
}
// Check individual operands.
for (const MachineOperand &MO : MI.operands()) {
// While the presence of a frame index does not prove that a stack
// frame will be required, all frame indexes should be within alloc-
// frame/deallocframe. Otherwise, the code that translates a frame
// index into an offset would have to be aware of the placement of
// the frame creation/destruction instructions.
if (MO.isFI())
return true;
if (MO.isReg()) {
Register R = MO.getReg();
// Debug instructions may refer to $noreg.
if (!R)
continue;
// Virtual registers will need scavenging, which then may require
// a stack slot.
if (R.isVirtual())
return true;
for (MCPhysReg S : HRI.subregs_inclusive(R))
if (CSR[S])
return true;
continue;
}
if (MO.isRegMask()) {
// A regmask would normally have all callee-saved registers marked
// as preserved, so this check would not be needed, but in case of
// ever having other regmasks (for other calling conventions),
// make sure they would be processed correctly.
const uint32_t *BM = MO.getRegMask();
for (int x = CSR.find_first(); x >= 0; x = CSR.find_next(x)) {
unsigned R = x;
// If this regmask does not preserve a CSR, a frame will be needed.
if (!(BM[R/32] & (1u << (R%32))))
return true;
}
}
}
}
return false;
}
/// Returns true if MBB has a machine instructions that indicates a tail call
/// in the block.
static bool hasTailCall(const MachineBasicBlock &MBB) {
MachineBasicBlock::const_iterator I = MBB.getLastNonDebugInstr();
if (I == MBB.end())
return false;
unsigned RetOpc = I->getOpcode();
return RetOpc == Hexagon::PS_tailcall_i || RetOpc == Hexagon::PS_tailcall_r;
}
/// Returns true if MBB contains an instruction that returns.
static bool hasReturn(const MachineBasicBlock &MBB) {
for (const MachineInstr &MI : MBB.terminators())
if (MI.isReturn())
return true;
return false;
}
/// Returns the "return" instruction from this block, or nullptr if there
/// isn't any.
static MachineInstr *getReturn(MachineBasicBlock &MBB) {
for (auto &I : MBB)
if (I.isReturn())
return &I;
return nullptr;
}
static bool isRestoreCall(unsigned Opc) {
switch (Opc) {
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT:
case Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4:
case Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC:
return true;
}
return false;
}
static inline bool isOptNone(const MachineFunction &MF) {
return MF.getFunction().hasOptNone() ||
MF.getTarget().getOptLevel() == CodeGenOptLevel::None;
}
static inline bool isOptSize(const MachineFunction &MF) {
const Function &F = MF.getFunction();
return F.hasOptSize() && !F.hasMinSize();
}
static inline bool isMinSize(const MachineFunction &MF) {
return MF.getFunction().hasMinSize();
}
/// Implements shrink-wrapping of the stack frame. By default, stack frame
/// is created in the function entry block, and is cleaned up in every block
/// that returns. This function finds alternate blocks: one for the frame
/// setup (prolog) and one for the cleanup (epilog).
void HexagonFrameLowering::findShrunkPrologEpilog(MachineFunction &MF,
MachineBasicBlock *&PrologB, MachineBasicBlock *&EpilogB) const {
static unsigned ShrinkCounter = 0;
if (MF.getSubtarget<HexagonSubtarget>().isEnvironmentMusl() &&
MF.getFunction().isVarArg())
return;
if (ShrinkLimit.getPosition()) {
if (ShrinkCounter >= ShrinkLimit)
return;
ShrinkCounter++;
}
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineDominatorTree MDT;
MDT.recalculate(MF);
MachinePostDominatorTree MPT;
MPT.recalculate(MF);
using UnsignedMap = DenseMap<unsigned, unsigned>;
using RPOTType = ReversePostOrderTraversal<const MachineFunction *>;
UnsignedMap RPO;
RPOTType RPOT(&MF);
unsigned RPON = 0;
for (auto &I : RPOT)
RPO[I->getNumber()] = RPON++;
// Don't process functions that have loops, at least for now. Placement
// of prolog and epilog must take loop structure into account. For simpli-
// city don't do it right now.
for (auto &I : MF) {
unsigned BN = RPO[I.getNumber()];
for (MachineBasicBlock *Succ : I.successors())
// If found a back-edge, return.
if (RPO[Succ->getNumber()] <= BN)
return;
}
// Collect the set of blocks that need a stack frame to execute. Scan
// each block for uses/defs of callee-saved registers, calls, etc.
SmallVector<MachineBasicBlock*,16> SFBlocks;
BitVector CSR(Hexagon::NUM_TARGET_REGS);
for (const MCPhysReg *P = HRI.getCalleeSavedRegs(&MF); *P; ++P)
for (MCPhysReg S : HRI.subregs_inclusive(*P))
CSR[S] = true;
for (auto &I : MF)
if (needsStackFrame(I, CSR, HRI))
SFBlocks.push_back(&I);
LLVM_DEBUG({
dbgs() << "Blocks needing SF: {";
for (auto &B : SFBlocks)
dbgs() << " " << printMBBReference(*B);
dbgs() << " }\n";
});
// No frame needed?
if (SFBlocks.empty())
return;
// Pick a common dominator and a common post-dominator.
MachineBasicBlock *DomB = SFBlocks[0];
for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
DomB = MDT.findNearestCommonDominator(DomB, SFBlocks[i]);
if (!DomB)
break;
}
MachineBasicBlock *PDomB = SFBlocks[0];
for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
PDomB = MPT.findNearestCommonDominator(PDomB, SFBlocks[i]);
if (!PDomB)
break;
}
LLVM_DEBUG({
dbgs() << "Computed dom block: ";
if (DomB)
dbgs() << printMBBReference(*DomB);
else
dbgs() << "<null>";
dbgs() << ", computed pdom block: ";
if (PDomB)
dbgs() << printMBBReference(*PDomB);
else
dbgs() << "<null>";
dbgs() << "\n";
});
if (!DomB || !PDomB)
return;
// Make sure that DomB dominates PDomB and PDomB post-dominates DomB.
if (!MDT.dominates(DomB, PDomB)) {
LLVM_DEBUG(dbgs() << "Dom block does not dominate pdom block\n");
return;
}
if (!MPT.dominates(PDomB, DomB)) {
LLVM_DEBUG(dbgs() << "PDom block does not post-dominate dom block\n");
return;
}
// Finally, everything seems right.
PrologB = DomB;
EpilogB = PDomB;
}
/// Perform most of the PEI work here:
/// - saving/restoring of the callee-saved registers,
/// - stack frame creation and destruction.
/// Normally, this work is distributed among various functions, but doing it
/// in one place allows shrink-wrapping of the stack frame.
void HexagonFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineFrameInfo &MFI = MF.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
MachineBasicBlock *PrologB = &MF.front(), *EpilogB = nullptr;
if (EnableShrinkWrapping)
findShrunkPrologEpilog(MF, PrologB, EpilogB);
bool PrologueStubs = false;
insertCSRSpillsInBlock(*PrologB, CSI, HRI, PrologueStubs);
insertPrologueInBlock(*PrologB, PrologueStubs);
updateEntryPaths(MF, *PrologB);
if (EpilogB) {
insertCSRRestoresInBlock(*EpilogB, CSI, HRI);
insertEpilogueInBlock(*EpilogB);
} else {
for (auto &B : MF)
if (B.isReturnBlock())
insertCSRRestoresInBlock(B, CSI, HRI);
for (auto &B : MF)
if (B.isReturnBlock())
insertEpilogueInBlock(B);
for (auto &B : MF) {
if (B.empty())
continue;
MachineInstr *RetI = getReturn(B);
if (!RetI || isRestoreCall(RetI->getOpcode()))
continue;
for (auto &R : CSI)
RetI->addOperand(MachineOperand::CreateReg(R.getReg(), false, true));
}
}
if (EpilogB) {
// If there is an epilog block, it may not have a return instruction.
// In such case, we need to add the callee-saved registers as live-ins
// in all blocks on all paths from the epilog to any return block.
unsigned MaxBN = MF.getNumBlockIDs();
BitVector DoneT(MaxBN+1), DoneF(MaxBN+1), Path(MaxBN+1);
updateExitPaths(*EpilogB, *EpilogB, DoneT, DoneF, Path);
}
}
/// Returns true if the target can safely skip saving callee-saved registers
/// for noreturn nounwind functions.
bool HexagonFrameLowering::enableCalleeSaveSkip(
const MachineFunction &MF) const {
const auto &F = MF.getFunction();
assert(F.hasFnAttribute(Attribute::NoReturn) &&
F.getFunction().hasFnAttribute(Attribute::NoUnwind) &&
!F.getFunction().hasFnAttribute(Attribute::UWTable));
(void)F;
// No need to save callee saved registers if the function does not return.
return MF.getSubtarget<HexagonSubtarget>().noreturnStackElim();
}
// Helper function used to determine when to eliminate the stack frame for
// functions marked as noreturn and when the noreturn-stack-elim options are
// specified. When both these conditions are true, then a FP may not be needed
// if the function makes a call. It is very similar to enableCalleeSaveSkip,
// but it used to check if the allocframe can be eliminated as well.
static bool enableAllocFrameElim(const MachineFunction &MF) {
const auto &F = MF.getFunction();
const auto &MFI = MF.getFrameInfo();
const auto &HST = MF.getSubtarget<HexagonSubtarget>();
assert(!MFI.hasVarSizedObjects() &&
!HST.getRegisterInfo()->hasStackRealignment(MF));
return F.hasFnAttribute(Attribute::NoReturn) &&
F.hasFnAttribute(Attribute::NoUnwind) &&
!F.hasFnAttribute(Attribute::UWTable) && HST.noreturnStackElim() &&
MFI.getStackSize() == 0;
}
void HexagonFrameLowering::insertPrologueInBlock(MachineBasicBlock &MBB,
bool PrologueStubs) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
Align MaxAlign = std::max(MFI.getMaxAlign(), getStackAlign());
// Calculate the total stack frame size.
// Get the number of bytes to allocate from the FrameInfo.
unsigned FrameSize = MFI.getStackSize();
// Round up the max call frame size to the max alignment on the stack.
unsigned MaxCFA = alignTo(MFI.getMaxCallFrameSize(), MaxAlign);
MFI.setMaxCallFrameSize(MaxCFA);
FrameSize = MaxCFA + alignTo(FrameSize, MaxAlign);
MFI.setStackSize(FrameSize);
bool AlignStack = (MaxAlign > getStackAlign());
// Get the number of bytes to allocate from the FrameInfo.
unsigned NumBytes = MFI.getStackSize();
Register SP = HRI.getStackRegister();
unsigned MaxCF = MFI.getMaxCallFrameSize();
MachineBasicBlock::iterator InsertPt = MBB.begin();
SmallVector<MachineInstr *, 4> AdjustRegs;
for (auto &MBB : MF)
for (auto &MI : MBB)
if (MI.getOpcode() == Hexagon::PS_alloca)
AdjustRegs.push_back(&MI);
for (auto *MI : AdjustRegs) {
assert((MI->getOpcode() == Hexagon::PS_alloca) && "Expected alloca");
expandAlloca(MI, HII, SP, MaxCF);
MI->eraseFromParent();
}
DebugLoc dl = MBB.findDebugLoc(InsertPt);
if (MF.getFunction().isVarArg() &&
MF.getSubtarget<HexagonSubtarget>().isEnvironmentMusl()) {
// Calculate the size of register saved area.
int NumVarArgRegs = 6 - FirstVarArgSavedReg;
int RegisterSavedAreaSizePlusPadding = (NumVarArgRegs % 2 == 0)
? NumVarArgRegs * 4
: NumVarArgRegs * 4 + 4;
if (RegisterSavedAreaSizePlusPadding > 0) {
// Decrement the stack pointer by size of register saved area plus
// padding if any.
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(-RegisterSavedAreaSizePlusPadding)
.setMIFlag(MachineInstr::FrameSetup);
int NumBytes = 0;
// Copy all the named arguments below register saved area.
auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
for (int i = HMFI.getFirstNamedArgFrameIndex(),
e = HMFI.getLastNamedArgFrameIndex(); i >= e; --i) {
uint64_t ObjSize = MFI.getObjectSize(i);
Align ObjAlign = MFI.getObjectAlign(i);
// Determine the kind of load/store that should be used.
unsigned LDOpc, STOpc;
uint64_t OpcodeChecker = ObjAlign.value();
// Handle cases where alignment of an object is > its size.
if (ObjAlign > ObjSize) {
if (ObjSize <= 1)
OpcodeChecker = 1;
else if (ObjSize <= 2)
OpcodeChecker = 2;
else if (ObjSize <= 4)
OpcodeChecker = 4;
else if (ObjSize > 4)
OpcodeChecker = 8;
}
switch (OpcodeChecker) {
case 1:
LDOpc = Hexagon::L2_loadrb_io;
STOpc = Hexagon::S2_storerb_io;
break;
case 2:
LDOpc = Hexagon::L2_loadrh_io;
STOpc = Hexagon::S2_storerh_io;
break;
case 4:
LDOpc = Hexagon::L2_loadri_io;
STOpc = Hexagon::S2_storeri_io;
break;
case 8:
default:
LDOpc = Hexagon::L2_loadrd_io;
STOpc = Hexagon::S2_storerd_io;
break;
}
Register RegUsed = LDOpc == Hexagon::L2_loadrd_io ? Hexagon::D3
: Hexagon::R6;
int LoadStoreCount = ObjSize / OpcodeChecker;
if (ObjSize % OpcodeChecker)
++LoadStoreCount;
// Get the start location of the load. NumBytes is basically the
// offset from the stack pointer of previous function, which would be
// the caller in this case, as this function has variable argument
// list.
if (NumBytes != 0)
NumBytes = alignTo(NumBytes, ObjAlign);
int Count = 0;
while (Count < LoadStoreCount) {
// Load the value of the named argument on stack.
BuildMI(MBB, InsertPt, dl, HII.get(LDOpc), RegUsed)
.addReg(SP)
.addImm(RegisterSavedAreaSizePlusPadding +
ObjAlign.value() * Count + NumBytes)
.setMIFlag(MachineInstr::FrameSetup);
// Store it below the register saved area plus padding.
BuildMI(MBB, InsertPt, dl, HII.get(STOpc))
.addReg(SP)
.addImm(ObjAlign.value() * Count + NumBytes)
.addReg(RegUsed)
.setMIFlag(MachineInstr::FrameSetup);
Count++;
}
NumBytes += MFI.getObjectSize(i);
}
// Make NumBytes 8 byte aligned
NumBytes = alignTo(NumBytes, 8);
// If the number of registers having variable arguments is odd,
// leave 4 bytes of padding to get to the location where first
// variable argument which was passed through register was copied.
NumBytes = (NumVarArgRegs % 2 == 0) ? NumBytes : NumBytes + 4;
for (int j = FirstVarArgSavedReg, i = 0; j < 6; ++j, ++i) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_storeri_io))
.addReg(SP)
.addImm(NumBytes + 4 * i)
.addReg(Hexagon::R0 + j)
.setMIFlag(MachineInstr::FrameSetup);
}
}
}
if (hasFP(MF)) {
insertAllocframe(MBB, InsertPt, NumBytes);
if (AlignStack) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_andir), SP)
.addReg(SP)
.addImm(-int64_t(MaxAlign.value()));
}
// If the stack-checking is enabled, and we spilled the callee-saved
// registers inline (i.e. did not use a spill function), then call
// the stack checker directly.
if (EnableStackOVFSanitizer && !PrologueStubs)
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::PS_call_stk))
.addExternalSymbol("__runtime_stack_check");
} else if (NumBytes > 0) {
assert(alignTo(NumBytes, 8) == NumBytes);
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(-int(NumBytes));
}
}
void HexagonFrameLowering::insertEpilogueInBlock(MachineBasicBlock &MBB) const {
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
Register SP = HRI.getStackRegister();
MachineBasicBlock::iterator InsertPt = MBB.getFirstTerminator();
DebugLoc dl = MBB.findDebugLoc(InsertPt);
if (!hasFP(MF)) {
MachineFrameInfo &MFI = MF.getFrameInfo();
unsigned NumBytes = MFI.getStackSize();
if (MF.getFunction().isVarArg() &&
MF.getSubtarget<HexagonSubtarget>().isEnvironmentMusl()) {
// On Hexagon Linux, deallocate the stack for the register saved area.
int NumVarArgRegs = 6 - FirstVarArgSavedReg;
int RegisterSavedAreaSizePlusPadding = (NumVarArgRegs % 2 == 0) ?
(NumVarArgRegs * 4) : (NumVarArgRegs * 4 + 4);
NumBytes += RegisterSavedAreaSizePlusPadding;
}
if (NumBytes) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(NumBytes);
}
return;
}
MachineInstr *RetI = getReturn(MBB);
unsigned RetOpc = RetI ? RetI->getOpcode() : 0;
// Handle EH_RETURN.
if (RetOpc == Hexagon::EH_RETURN_JMPR) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::L2_deallocframe))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_add), SP)
.addReg(SP)
.addReg(Hexagon::R28);
return;
}
// Check for RESTORE_DEALLOC_RET* tail call. Don't emit an extra dealloc-
// frame instruction if we encounter it.
if (RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4 ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT ||
RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC) {
MachineBasicBlock::iterator It = RetI;
++It;
// Delete all instructions after the RESTORE (except labels).
while (It != MBB.end()) {
if (!It->isLabel())
It = MBB.erase(It);
else
++It;
}
return;
}
// It is possible that the restoring code is a call to a library function.
// All of the restore* functions include "deallocframe", so we need to make
// sure that we don't add an extra one.
bool NeedsDeallocframe = true;
if (!MBB.empty() && InsertPt != MBB.begin()) {
MachineBasicBlock::iterator PrevIt = std::prev(InsertPt);
unsigned COpc = PrevIt->getOpcode();
if (COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4 ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT ||
COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC ||
COpc == Hexagon::PS_call_nr || COpc == Hexagon::PS_callr_nr)
NeedsDeallocframe = false;
}
if (!MF.getSubtarget<HexagonSubtarget>().isEnvironmentMusl() ||
!MF.getFunction().isVarArg()) {
if (!NeedsDeallocframe)
return;
// If the returning instruction is PS_jmpret, replace it with
// dealloc_return, otherwise just add deallocframe. The function
// could be returning via a tail call.
if (RetOpc != Hexagon::PS_jmpret || DisableDeallocRet) {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::L2_deallocframe))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
return;
}
unsigned NewOpc = Hexagon::L4_return;
MachineInstr *NewI = BuildMI(MBB, RetI, dl, HII.get(NewOpc))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
// Transfer the function live-out registers.
NewI->copyImplicitOps(MF, *RetI);
MBB.erase(RetI);
} else {
// L2_deallocframe instruction after it.
// Calculate the size of register saved area.
int NumVarArgRegs = 6 - FirstVarArgSavedReg;
int RegisterSavedAreaSizePlusPadding = (NumVarArgRegs % 2 == 0) ?
(NumVarArgRegs * 4) : (NumVarArgRegs * 4 + 4);
MachineBasicBlock::iterator Term = MBB.getFirstTerminator();
MachineBasicBlock::iterator I = (Term == MBB.begin()) ? MBB.end()
: std::prev(Term);
if (I == MBB.end() ||
(I->getOpcode() != Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT &&
I->getOpcode() != Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC &&
I->getOpcode() != Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4 &&
I->getOpcode() != Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC))
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::L2_deallocframe))
.addDef(Hexagon::D15)
.addReg(Hexagon::R30);
if (RegisterSavedAreaSizePlusPadding != 0)
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(RegisterSavedAreaSizePlusPadding);
}
}
void HexagonFrameLowering::insertAllocframe(MachineBasicBlock &MBB,
MachineBasicBlock::iterator InsertPt, unsigned NumBytes) const {
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
// Check for overflow.
// Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
const unsigned int ALLOCFRAME_MAX = 16384;
// Create a dummy memory operand to avoid allocframe from being treated as
// a volatile memory reference.
auto *MMO = MF.getMachineMemOperand(MachinePointerInfo::getStack(MF, 0),
MachineMemOperand::MOStore, 4, Align(4));
DebugLoc dl = MBB.findDebugLoc(InsertPt);
Register SP = HRI.getStackRegister();
if (NumBytes >= ALLOCFRAME_MAX) {
// Emit allocframe(#0).
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
.addDef(SP)
.addReg(SP)
.addImm(0)
.addMemOperand(MMO)
.setMIFlag(MachineInstr::FrameSetup);
// Subtract the size from the stack pointer.
Register SP = HRI.getStackRegister();
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_addi), SP)
.addReg(SP)
.addImm(-int(NumBytes))
.setMIFlag(MachineInstr::FrameSetup);
} else {
BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
.addDef(SP)
.addReg(SP)
.addImm(NumBytes)
.addMemOperand(MMO)
.setMIFlag(MachineInstr::FrameSetup);
}
}
void HexagonFrameLowering::updateEntryPaths(MachineFunction &MF,
MachineBasicBlock &SaveB) const {
SetVector<unsigned> Worklist;
MachineBasicBlock &EntryB = MF.front();
Worklist.insert(EntryB.getNumber());
unsigned SaveN = SaveB.getNumber();
auto &CSI = MF.getFrameInfo().getCalleeSavedInfo();
for (unsigned i = 0; i < Worklist.size(); ++i) {
unsigned BN = Worklist[i];
MachineBasicBlock &MBB = *MF.getBlockNumbered(BN);
for (auto &R : CSI)
if (!MBB.isLiveIn(R.getReg()))
MBB.addLiveIn(R.getReg());
if (BN != SaveN)
for (auto &SB : MBB.successors())
Worklist.insert(SB->getNumber());
}
}
bool HexagonFrameLowering::updateExitPaths(MachineBasicBlock &MBB,
MachineBasicBlock &RestoreB, BitVector &DoneT, BitVector &DoneF,
BitVector &Path) const {
assert(MBB.getNumber() >= 0);
unsigned BN = MBB.getNumber();
if (Path[BN] || DoneF[BN])
return false;
if (DoneT[BN])
return true;
auto &CSI = MBB.getParent()->getFrameInfo().getCalleeSavedInfo();
Path[BN] = true;
bool ReachedExit = false;
for (auto &SB : MBB.successors())
ReachedExit |= updateExitPaths(*SB, RestoreB, DoneT, DoneF, Path);
if (!MBB.empty() && MBB.back().isReturn()) {
// Add implicit uses of all callee-saved registers to the reached
// return instructions. This is to prevent the anti-dependency breaker
// from renaming these registers.
MachineInstr &RetI = MBB.back();
if (!isRestoreCall(RetI.getOpcode()))
for (auto &R : CSI)
RetI.addOperand(MachineOperand::CreateReg(R.getReg(), false, true));
ReachedExit = true;
}
// We don't want to add unnecessary live-ins to the restore block: since
// the callee-saved registers are being defined in it, the entry of the
// restore block cannot be on the path from the definitions to any exit.
if (ReachedExit && &MBB != &RestoreB) {
for (auto &R : CSI)
if (!MBB.isLiveIn(R.getReg()))
MBB.addLiveIn(R.getReg());
DoneT[BN] = true;
}
if (!ReachedExit)
DoneF[BN] = true;
Path[BN] = false;
return ReachedExit;
}
static std::optional<MachineBasicBlock::iterator>
findCFILocation(MachineBasicBlock &B) {
// The CFI instructions need to be inserted right after allocframe.
// An exception to this is a situation where allocframe is bundled
// with a call: then the CFI instructions need to be inserted before
// the packet with the allocframe+call (in case the call throws an
// exception).
auto End = B.instr_end();
for (MachineInstr &I : B) {
MachineBasicBlock::iterator It = I.getIterator();
if (!I.isBundle()) {
if (I.getOpcode() == Hexagon::S2_allocframe)
return std::next(It);
continue;
}
// I is a bundle.
bool HasCall = false, HasAllocFrame = false;
auto T = It.getInstrIterator();
while (++T != End && T->isBundled()) {
if (T->getOpcode() == Hexagon::S2_allocframe)
HasAllocFrame = true;
else if (T->isCall())
HasCall = true;
}
if (HasAllocFrame)
return HasCall ? It : std::next(It);
}
return std::nullopt;
}
void HexagonFrameLowering::insertCFIInstructions(MachineFunction &MF) const {
for (auto &B : MF)
if (auto At = findCFILocation(B))
insertCFIInstructionsAt(B, *At);
}
void HexagonFrameLowering::insertCFIInstructionsAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator At) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
// If CFI instructions have debug information attached, something goes
// wrong with the final assembly generation: the prolog_end is placed
// in a wrong location.
DebugLoc DL;
const MCInstrDesc &CFID = HII.get(TargetOpcode::CFI_INSTRUCTION);
MCSymbol *FrameLabel = MF.getContext().createTempSymbol();
bool HasFP = hasFP(MF);
if (HasFP) {
unsigned DwFPReg = HRI.getDwarfRegNum(HRI.getFrameRegister(), true);
unsigned DwRAReg = HRI.getDwarfRegNum(HRI.getRARegister(), true);
// Define CFA via an offset from the value of FP.
//
// -8 -4 0 (SP)
// --+----+----+---------------------
// | FP | LR | increasing addresses -->
// --+----+----+---------------------
// | +-- Old SP (before allocframe)
// +-- New FP (after allocframe)
//
// MCCFIInstruction::cfiDefCfa adds the offset from the register.
// MCCFIInstruction::createOffset takes the offset without sign change.
auto DefCfa = MCCFIInstruction::cfiDefCfa(FrameLabel, DwFPReg, 8);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(DefCfa));
// R31 (return addr) = CFA - 4
auto OffR31 = MCCFIInstruction::createOffset(FrameLabel, DwRAReg, -4);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffR31));
// R30 (frame ptr) = CFA - 8
auto OffR30 = MCCFIInstruction::createOffset(FrameLabel, DwFPReg, -8);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffR30));
}
static const MCPhysReg RegsToMove[] = {
Hexagon::R1, Hexagon::R0, Hexagon::R3, Hexagon::R2,
Hexagon::R17, Hexagon::R16, Hexagon::R19, Hexagon::R18,
Hexagon::R21, Hexagon::R20, Hexagon::R23, Hexagon::R22,
Hexagon::R25, Hexagon::R24, Hexagon::R27, Hexagon::R26,
Hexagon::D0, Hexagon::D1, Hexagon::D8, Hexagon::D9,
Hexagon::D10, Hexagon::D11, Hexagon::D12, Hexagon::D13
};
const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
for (MCPhysReg Reg : RegsToMove) {
auto IfR = [Reg] (const CalleeSavedInfo &C) -> bool {
return C.getReg() == Reg;
};
auto F = find_if(CSI, IfR);
if (F == CSI.end())
continue;
int64_t Offset;
if (HasFP) {
// If the function has a frame pointer (i.e. has an allocframe),
// then the CFA has been defined in terms of FP. Any offsets in
// the following CFI instructions have to be defined relative
// to FP, which points to the bottom of the stack frame.
// The function getFrameIndexReference can still choose to use SP
// for the offset calculation, so we cannot simply call it here.
// Instead, get the offset (relative to the FP) directly.
Offset = MFI.getObjectOffset(F->getFrameIdx());
} else {
Register FrameReg;
Offset =
getFrameIndexReference(MF, F->getFrameIdx(), FrameReg).getFixed();
}
// Subtract 8 to make room for R30 and R31, which are added above.
Offset -= 8;
if (Reg < Hexagon::D0 || Reg > Hexagon::D15) {
unsigned DwarfReg = HRI.getDwarfRegNum(Reg, true);
auto OffReg = MCCFIInstruction::createOffset(FrameLabel, DwarfReg,
Offset);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffReg));
} else {
// Split the double regs into subregs, and generate appropriate
// cfi_offsets.
// The only reason, we are split double regs is, llvm-mc does not
// understand paired registers for cfi_offset.
// Eg .cfi_offset r1:0, -64
Register HiReg = HRI.getSubReg(Reg, Hexagon::isub_hi);
Register LoReg = HRI.getSubReg(Reg, Hexagon::isub_lo);
unsigned HiDwarfReg = HRI.getDwarfRegNum(HiReg, true);
unsigned LoDwarfReg = HRI.getDwarfRegNum(LoReg, true);
auto OffHi = MCCFIInstruction::createOffset(FrameLabel, HiDwarfReg,
Offset+4);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffHi));
auto OffLo = MCCFIInstruction::createOffset(FrameLabel, LoDwarfReg,
Offset);
BuildMI(MBB, At, DL, CFID)
.addCFIIndex(MF.addFrameInst(OffLo));
}
}
}
bool HexagonFrameLowering::hasFPImpl(const MachineFunction &MF) const {
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
bool HasExtraAlign = HRI.hasStackRealignment(MF);
bool HasAlloca = MFI.hasVarSizedObjects();
// Insert ALLOCFRAME if we need to or at -O0 for the debugger. Think
// that this shouldn't be required, but doing so now because gcc does and
// gdb can't break at the start of the function without it. Will remove if
// this turns out to be a gdb bug.
//
if (MF.getTarget().getOptLevel() == CodeGenOptLevel::None)
return true;
// By default we want to use SP (since it's always there). FP requires
// some setup (i.e. ALLOCFRAME).
// Both, alloca and stack alignment modify the stack pointer by an
// undetermined value, so we need to save it at the entry to the function
// (i.e. use allocframe).
if (HasAlloca || HasExtraAlign)
return true;
if (MFI.getStackSize() > 0) {
// If FP-elimination is disabled, we have to use FP at this point.
const TargetMachine &TM = MF.getTarget();
if (TM.Options.DisableFramePointerElim(MF) || !EliminateFramePointer)
return true;
if (EnableStackOVFSanitizer)
return true;
}
const auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
if ((MFI.hasCalls() && !enableAllocFrameElim(MF)) || HMFI.hasClobberLR())
return true;
return false;
}
enum SpillKind {
SK_ToMem,
SK_FromMem,
SK_FromMemTailcall
};
static const char *getSpillFunctionFor(Register MaxReg, SpillKind SpillType,
bool Stkchk = false) {
const char * V4SpillToMemoryFunctions[] = {
"__save_r16_through_r17",
"__save_r16_through_r19",
"__save_r16_through_r21",
"__save_r16_through_r23",
"__save_r16_through_r25",
"__save_r16_through_r27" };
const char * V4SpillToMemoryStkchkFunctions[] = {
"__save_r16_through_r17_stkchk",
"__save_r16_through_r19_stkchk",
"__save_r16_through_r21_stkchk",
"__save_r16_through_r23_stkchk",
"__save_r16_through_r25_stkchk",
"__save_r16_through_r27_stkchk" };
const char * V4SpillFromMemoryFunctions[] = {
"__restore_r16_through_r17_and_deallocframe",
"__restore_r16_through_r19_and_deallocframe",
"__restore_r16_through_r21_and_deallocframe",
"__restore_r16_through_r23_and_deallocframe",
"__restore_r16_through_r25_and_deallocframe",
"__restore_r16_through_r27_and_deallocframe" };
const char * V4SpillFromMemoryTailcallFunctions[] = {
"__restore_r16_through_r17_and_deallocframe_before_tailcall",
"__restore_r16_through_r19_and_deallocframe_before_tailcall",
"__restore_r16_through_r21_and_deallocframe_before_tailcall",
"__restore_r16_through_r23_and_deallocframe_before_tailcall",
"__restore_r16_through_r25_and_deallocframe_before_tailcall",
"__restore_r16_through_r27_and_deallocframe_before_tailcall"
};
const char **SpillFunc = nullptr;
switch(SpillType) {
case SK_ToMem:
SpillFunc = Stkchk ? V4SpillToMemoryStkchkFunctions
: V4SpillToMemoryFunctions;
break;
case SK_FromMem:
SpillFunc = V4SpillFromMemoryFunctions;
break;
case SK_FromMemTailcall:
SpillFunc = V4SpillFromMemoryTailcallFunctions;
break;
}
assert(SpillFunc && "Unknown spill kind");
// Spill all callee-saved registers up to the highest register used.
switch (MaxReg) {
case Hexagon::R17:
return SpillFunc[0];
case Hexagon::R19:
return SpillFunc[1];
case Hexagon::R21:
return SpillFunc[2];
case Hexagon::R23:
return SpillFunc[3];
case Hexagon::R25:
return SpillFunc[4];
case Hexagon::R27:
return SpillFunc[5];
default:
llvm_unreachable("Unhandled maximum callee save register");
}
return nullptr;
}
StackOffset
HexagonFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const {
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
int Offset = MFI.getObjectOffset(FI);
bool HasAlloca = MFI.hasVarSizedObjects();
bool HasExtraAlign = HRI.hasStackRealignment(MF);
bool NoOpt = MF.getTarget().getOptLevel() == CodeGenOptLevel::None;
auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
unsigned FrameSize = MFI.getStackSize();
Register SP = HRI.getStackRegister();
Register FP = HRI.getFrameRegister();
Register AP = HMFI.getStackAlignBaseReg();
// It may happen that AP will be absent even HasAlloca && HasExtraAlign
// is true. HasExtraAlign may be set because of vector spills, without
// aligned locals or aligned outgoing function arguments. Since vector
// spills will ultimately be "unaligned", it is safe to use FP as the
// base register.
// In fact, in such a scenario the stack is actually not required to be
// aligned, although it may end up being aligned anyway, since this
// particular case is not easily detectable. The alignment will be
// unnecessary, but not incorrect.
// Unfortunately there is no quick way to verify that the above is
// indeed the case (and that it's not a result of an error), so just
// assume that missing AP will be replaced by FP.
// (A better fix would be to rematerialize AP from FP and always align
// vector spills.)
bool UseFP = false, UseAP = false; // Default: use SP (except at -O0).
// Use FP at -O0, except when there are objects with extra alignment.
// That additional alignment requirement may cause a pad to be inserted,
// which will make it impossible to use FP to access objects located
// past the pad.
if (NoOpt && !HasExtraAlign)
UseFP = true;
if (MFI.isFixedObjectIndex(FI) || MFI.isObjectPreAllocated(FI)) {
// Fixed and preallocated objects will be located before any padding
// so FP must be used to access them.
UseFP |= (HasAlloca || HasExtraAlign);
} else {
if (HasAlloca) {
if (HasExtraAlign)
UseAP = true;
else
UseFP = true;
}
}
// If FP was picked, then there had better be FP.
bool HasFP = hasFP(MF);
assert((HasFP || !UseFP) && "This function must have frame pointer");
// Having FP implies allocframe. Allocframe will store extra 8 bytes:
// FP/LR. If the base register is used to access an object across these
// 8 bytes, then the offset will need to be adjusted by 8.
//
// After allocframe:
// HexagonISelLowering adds 8 to ---+
// the offsets of all stack-based |
// arguments (*) |
// |
// getObjectOffset < 0 0 8 getObjectOffset >= 8
// ------------------------+-----+------------------------> increasing
// <local objects> |FP/LR| <input arguments> addresses
// -----------------+------+-----+------------------------>
// | |
// SP/AP point --+ +-- FP points here (**)
// somewhere on
// this side of FP/LR
//
// (*) See LowerFormalArguments. The FP/LR is assumed to be present.
// (**) *FP == old-FP. FP+0..7 are the bytes of FP/LR.
// The lowering assumes that FP/LR is present, and so the offsets of
// the formal arguments start at 8. If FP/LR is not there we need to
// reduce the offset by 8.
if (Offset > 0 && !HasFP)
Offset -= 8;
if (UseFP)
FrameReg = FP;
else if (UseAP)
FrameReg = AP;
else
FrameReg = SP;
// Calculate the actual offset in the instruction. If there is no FP
// (in other words, no allocframe), then SP will not be adjusted (i.e.
// there will be no SP -= FrameSize), so the frame size should not be
// added to the calculated offset.
int RealOffset = Offset;
if (!UseFP && !UseAP)
RealOffset = FrameSize+Offset;
return StackOffset::getFixed(RealOffset);
}
bool HexagonFrameLowering::insertCSRSpillsInBlock(MachineBasicBlock &MBB,
const CSIVect &CSI, const HexagonRegisterInfo &HRI,
bool &PrologueStubs) const {
if (CSI.empty())
return true;
MachineBasicBlock::iterator MI = MBB.begin();
PrologueStubs = false;
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
if (useSpillFunction(MF, CSI)) {
PrologueStubs = true;
Register MaxReg = getMaxCalleeSavedReg(CSI, HRI);
bool StkOvrFlowEnabled = EnableStackOVFSanitizer;
const char *SpillFun = getSpillFunctionFor(MaxReg, SK_ToMem,
StkOvrFlowEnabled);
auto &HTM = static_cast<const HexagonTargetMachine&>(MF.getTarget());
bool IsPIC = HTM.isPositionIndependent();
bool LongCalls = HST.useLongCalls() || EnableSaveRestoreLong;
// Call spill function.
DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc() : DebugLoc();
unsigned SpillOpc;
if (StkOvrFlowEnabled) {
if (LongCalls)
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4STK_EXT_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4STK_EXT;
else
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4STK_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4STK;
} else {
if (LongCalls)
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4_EXT_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4_EXT;
else
SpillOpc = IsPIC ? Hexagon::SAVE_REGISTERS_CALL_V4_PIC
: Hexagon::SAVE_REGISTERS_CALL_V4;
}
MachineInstr *SaveRegsCall =
BuildMI(MBB, MI, DL, HII.get(SpillOpc))
.addExternalSymbol(SpillFun);
// Add callee-saved registers as use.
addCalleeSaveRegistersAsImpOperand(SaveRegsCall, CSI, false, true);
// Add live in registers.
for (const CalleeSavedInfo &I : CSI)
MBB.addLiveIn(I.getReg());
return true;
}
for (const CalleeSavedInfo &I : CSI) {
MCRegister Reg = I.getReg();
// Add live in registers. We treat eh_return callee saved register r0 - r3
// specially. They are not really callee saved registers as they are not
// supposed to be killed.
bool IsKill = !HRI.isEHReturnCalleeSaveReg(Reg);
int FI = I.getFrameIdx();
const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
HII.storeRegToStackSlot(MBB, MI, Reg, IsKill, FI, RC, &HRI, Register());
if (IsKill)
MBB.addLiveIn(Reg);
}
return true;
}
bool HexagonFrameLowering::insertCSRRestoresInBlock(MachineBasicBlock &MBB,
const CSIVect &CSI, const HexagonRegisterInfo &HRI) const {
if (CSI.empty())
return false;
MachineBasicBlock::iterator MI = MBB.getFirstTerminator();
MachineFunction &MF = *MBB.getParent();
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
if (useRestoreFunction(MF, CSI)) {
bool HasTC = hasTailCall(MBB) || !hasReturn(MBB);
Register MaxR = getMaxCalleeSavedReg(CSI, HRI);
SpillKind Kind = HasTC ? SK_FromMemTailcall : SK_FromMem;
const char *RestoreFn = getSpillFunctionFor(MaxR, Kind);
auto &HTM = static_cast<const HexagonTargetMachine&>(MF.getTarget());
bool IsPIC = HTM.isPositionIndependent();
bool LongCalls = HST.useLongCalls() || EnableSaveRestoreLong;
// Call spill function.
DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc()
: MBB.findDebugLoc(MBB.end());
MachineInstr *DeallocCall = nullptr;
if (HasTC) {
unsigned RetOpc;
if (LongCalls)
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT_PIC
: Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_EXT;
else
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4_PIC
: Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4;
DeallocCall = BuildMI(MBB, MI, DL, HII.get(RetOpc))
.addExternalSymbol(RestoreFn);
} else {
// The block has a return.
MachineBasicBlock::iterator It = MBB.getFirstTerminator();
assert(It->isReturn() && std::next(It) == MBB.end());
unsigned RetOpc;
if (LongCalls)
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT_PIC
: Hexagon::RESTORE_DEALLOC_RET_JMP_V4_EXT;
else
RetOpc = IsPIC ? Hexagon::RESTORE_DEALLOC_RET_JMP_V4_PIC
: Hexagon::RESTORE_DEALLOC_RET_JMP_V4;
DeallocCall = BuildMI(MBB, It, DL, HII.get(RetOpc))
.addExternalSymbol(RestoreFn);
// Transfer the function live-out registers.
DeallocCall->copyImplicitOps(MF, *It);
}
addCalleeSaveRegistersAsImpOperand(DeallocCall, CSI, true, false);
return true;
}
for (const CalleeSavedInfo &I : CSI) {
MCRegister Reg = I.getReg();
const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
int FI = I.getFrameIdx();
HII.loadRegFromStackSlot(MBB, MI, Reg, FI, RC, &HRI, Register());
}
return true;
}
MachineBasicBlock::iterator HexagonFrameLowering::eliminateCallFramePseudoInstr(
MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
MachineInstr &MI = *I;
unsigned Opc = MI.getOpcode();
(void)Opc; // Silence compiler warning.
assert((Opc == Hexagon::ADJCALLSTACKDOWN || Opc == Hexagon::ADJCALLSTACKUP) &&
"Cannot handle this call frame pseudo instruction");
return MBB.erase(I);
}
void HexagonFrameLowering::processFunctionBeforeFrameFinalized(
MachineFunction &MF, RegScavenger *RS) const {
// If this function has uses aligned stack and also has variable sized stack
// objects, then we need to map all spill slots to fixed positions, so that
// they can be accessed through FP. Otherwise they would have to be accessed
// via AP, which may not be available at the particular place in the program.
MachineFrameInfo &MFI = MF.getFrameInfo();
bool HasAlloca = MFI.hasVarSizedObjects();
bool NeedsAlign = (MFI.getMaxAlign() > getStackAlign());
if (!HasAlloca || !NeedsAlign)
return;
// Set the physical aligned-stack base address register.
MCRegister AP;
if (const MachineInstr *AI = getAlignaInstr(MF))
AP = AI->getOperand(0).getReg();
auto &HMFI = *MF.getInfo<HexagonMachineFunctionInfo>();
assert(!AP.isValid() || AP.isPhysical());
HMFI.setStackAlignBaseReg(AP);
}
/// Returns true if there are no caller-saved registers available in class RC.
static bool needToReserveScavengingSpillSlots(MachineFunction &MF,
const HexagonRegisterInfo &HRI, const TargetRegisterClass *RC) {
MachineRegisterInfo &MRI = MF.getRegInfo();
auto IsUsed = [&HRI,&MRI] (Register Reg) -> bool {
for (MCRegAliasIterator AI(Reg, &HRI, true); AI.isValid(); ++AI)
if (MRI.isPhysRegUsed(*AI))
return true;
return false;
};
// Check for an unused caller-saved register. Callee-saved registers
// have become pristine by now.
for (const MCPhysReg *P = HRI.getCallerSavedRegs(&MF, RC); *P; ++P)
if (!IsUsed(*P))
return false;
// All caller-saved registers are used.
return true;
}
#ifndef NDEBUG
static void dump_registers(BitVector &Regs, const TargetRegisterInfo &TRI) {
dbgs() << '{';
for (int x = Regs.find_first(); x >= 0; x = Regs.find_next(x)) {
Register R = x;
dbgs() << ' ' << printReg(R, &TRI);
}
dbgs() << " }";
}
#endif
bool HexagonFrameLowering::assignCalleeSavedSpillSlots(MachineFunction &MF,
const TargetRegisterInfo *TRI, std::vector<CalleeSavedInfo> &CSI) const {
LLVM_DEBUG(dbgs() << __func__ << " on " << MF.getName() << '\n');
MachineFrameInfo &MFI = MF.getFrameInfo();
BitVector SRegs(Hexagon::NUM_TARGET_REGS);
// Generate a set of unique, callee-saved registers (SRegs), where each
// register in the set is maximal in terms of sub-/super-register relation,
// i.e. for each R in SRegs, no proper super-register of R is also in SRegs.
// (1) For each callee-saved register, add that register and all of its
// sub-registers to SRegs.
LLVM_DEBUG(dbgs() << "Initial CS registers: {");
for (const CalleeSavedInfo &I : CSI) {
Register R = I.getReg();
LLVM_DEBUG(dbgs() << ' ' << printReg(R, TRI));
for (MCPhysReg SR : TRI->subregs_inclusive(R))
SRegs[SR] = true;
}
LLVM_DEBUG(dbgs() << " }\n");
LLVM_DEBUG(dbgs() << "SRegs.1: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (2) For each reserved register, remove that register and all of its
// sub- and super-registers from SRegs.
BitVector Reserved = TRI->getReservedRegs(MF);
// Unreserve the stack align register: it is reserved for this function
// only, it still needs to be saved/restored.
Register AP =
MF.getInfo<HexagonMachineFunctionInfo>()->getStackAlignBaseReg();
if (AP.isValid()) {
Reserved[AP] = false;
// Unreserve super-regs if no other subregisters are reserved.
for (MCPhysReg SP : TRI->superregs(AP)) {
bool HasResSub = false;
for (MCPhysReg SB : TRI->subregs(SP)) {
if (!Reserved[SB])
continue;
HasResSub = true;
break;
}
if (!HasResSub)
Reserved[SP] = false;
}
}
for (int x = Reserved.find_first(); x >= 0; x = Reserved.find_next(x)) {
Register R = x;
for (MCPhysReg SR : TRI->superregs_inclusive(R))
SRegs[SR] = false;
}
LLVM_DEBUG(dbgs() << "Res: "; dump_registers(Reserved, *TRI);
dbgs() << "\n");
LLVM_DEBUG(dbgs() << "SRegs.2: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (3) Collect all registers that have at least one sub-register in SRegs,
// and also have no sub-registers that are reserved. These will be the can-
// didates for saving as a whole instead of their individual sub-registers.
// (Saving R17:16 instead of R16 is fine, but only if R17 was not reserved.)
BitVector TmpSup(Hexagon::NUM_TARGET_REGS);
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
Register R = x;
for (MCPhysReg SR : TRI->superregs(R))
TmpSup[SR] = true;
}
for (int x = TmpSup.find_first(); x >= 0; x = TmpSup.find_next(x)) {
Register R = x;
for (MCPhysReg SR : TRI->subregs_inclusive(R)) {
if (!Reserved[SR])
continue;
TmpSup[R] = false;
break;
}
}
LLVM_DEBUG(dbgs() << "TmpSup: "; dump_registers(TmpSup, *TRI);
dbgs() << "\n");
// (4) Include all super-registers found in (3) into SRegs.
SRegs |= TmpSup;
LLVM_DEBUG(dbgs() << "SRegs.4: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// (5) For each register R in SRegs, if any super-register of R is in SRegs,
// remove R from SRegs.
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
Register R = x;
for (MCPhysReg SR : TRI->superregs(R)) {
if (!SRegs[SR])
continue;
SRegs[R] = false;
break;
}
}
LLVM_DEBUG(dbgs() << "SRegs.5: "; dump_registers(SRegs, *TRI);
dbgs() << "\n");
// Now, for each register that has a fixed stack slot, create the stack
// object for it.
CSI.clear();
using SpillSlot = TargetFrameLowering::SpillSlot;
unsigned NumFixed;
int64_t MinOffset = 0; // CS offsets are negative.
const SpillSlot *FixedSlots = getCalleeSavedSpillSlots(NumFixed);
for (const SpillSlot *S = FixedSlots; S != FixedSlots+NumFixed; ++S) {
if (!SRegs[S->Reg])
continue;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(S->Reg);
int FI = MFI.CreateFixedSpillStackObject(TRI->getSpillSize(*RC), S->Offset);
MinOffset = std::min(MinOffset, S->Offset);
CSI.push_back(CalleeSavedInfo(S->Reg, FI));
SRegs[S->Reg] = false;
}
// There can be some registers that don't have fixed slots. For example,
// we need to store R0-R3 in functions with exception handling. For each
// such register, create a non-fixed stack object.
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
Register R = x;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(R);
unsigned Size = TRI->getSpillSize(*RC);
int64_t Off = MinOffset - Size;
Align Alignment = std::min(TRI->getSpillAlign(*RC), getStackAlign());
Off &= -Alignment.value();
int FI = MFI.CreateFixedSpillStackObject(Size, Off);
MinOffset = std::min(MinOffset, Off);
CSI.push_back(CalleeSavedInfo(R, FI));
SRegs[R] = false;
}
LLVM_DEBUG({
dbgs() << "CS information: {";
for (const CalleeSavedInfo &I : CSI) {
int FI = I.getFrameIdx();
int Off = MFI.getObjectOffset(FI);
dbgs() << ' ' << printReg(I.getReg(), TRI) << ":fi#" << FI << ":sp";
if (Off >= 0)
dbgs() << '+';
dbgs() << Off;
}
dbgs() << " }\n";
});
#ifndef NDEBUG
// Verify that all registers were handled.
bool MissedReg = false;
for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
Register R = x;
dbgs() << printReg(R, TRI) << ' ';
MissedReg = true;
}
if (MissedReg)
llvm_unreachable("...there are unhandled callee-saved registers!");
#endif
return true;
}
bool HexagonFrameLowering::expandCopy(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineInstr *MI = &*It;
DebugLoc DL = MI->getDebugLoc();
Register DstR = MI->getOperand(0).getReg();
Register SrcR = MI->getOperand(1).getReg();
if (!Hexagon::ModRegsRegClass.contains(DstR) ||
!Hexagon::ModRegsRegClass.contains(SrcR))
return false;
Register TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, It, DL, HII.get(TargetOpcode::COPY), TmpR).add(MI->getOperand(1));
BuildMI(B, It, DL, HII.get(TargetOpcode::COPY), DstR)
.addReg(TmpR, RegState::Kill);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreInt(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned Opc = MI->getOpcode();
Register SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
// TmpR = C2_tfrpr SrcR if SrcR is a predicate register
// TmpR = A2_tfrcrr SrcR if SrcR is a modifier register
Register TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
unsigned TfrOpc = (Opc == Hexagon::STriw_pred) ? Hexagon::C2_tfrpr
: Hexagon::A2_tfrcrr;
BuildMI(B, It, DL, HII.get(TfrOpc), TmpR)
.addReg(SrcR, getKillRegState(IsKill));
// S2_storeri_io FI, 0, TmpR
BuildMI(B, It, DL, HII.get(Hexagon::S2_storeri_io))
.addFrameIndex(FI)
.addImm(0)
.addReg(TmpR, RegState::Kill)
.cloneMemRefs(*MI);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadInt(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
unsigned Opc = MI->getOpcode();
Register DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
// TmpR = L2_loadri_io FI, 0
Register TmpR = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
BuildMI(B, It, DL, HII.get(Hexagon::L2_loadri_io), TmpR)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
// DstR = C2_tfrrp TmpR if DstR is a predicate register
// DstR = A2_tfrrcr TmpR if DstR is a modifier register
unsigned TfrOpc = (Opc == Hexagon::LDriw_pred) ? Hexagon::C2_tfrrp
: Hexagon::A2_tfrrcr;
BuildMI(B, It, DL, HII.get(TfrOpc), DstR)
.addReg(TmpR, RegState::Kill);
NewRegs.push_back(TmpR);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVecPred(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
Register SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
auto *RC = &Hexagon::HvxVRRegClass;
// Insert transfer to general vector register.
// TmpR0 = A2_tfrsi 0x01010101
// TmpR1 = V6_vandqrt Qx, TmpR0
// store FI, 0, TmpR1
Register TmpR0 = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
Register TmpR1 = MRI.createVirtualRegister(RC);
BuildMI(B, It, DL, HII.get(Hexagon::A2_tfrsi), TmpR0)
.addImm(0x01010101);
BuildMI(B, It, DL, HII.get(Hexagon::V6_vandqrt), TmpR1)
.addReg(SrcR, getKillRegState(IsKill))
.addReg(TmpR0, RegState::Kill);
auto *HRI = B.getParent()->getSubtarget<HexagonSubtarget>().getRegisterInfo();
HII.storeRegToStackSlot(B, It, TmpR1, true, FI, RC, HRI, Register());
expandStoreVec(B, std::prev(It), MRI, HII, NewRegs);
NewRegs.push_back(TmpR0);
NewRegs.push_back(TmpR1);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVecPred(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
Register DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
auto *RC = &Hexagon::HvxVRRegClass;
// TmpR0 = A2_tfrsi 0x01010101
// TmpR1 = load FI, 0
// DstR = V6_vandvrt TmpR1, TmpR0
Register TmpR0 = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
Register TmpR1 = MRI.createVirtualRegister(RC);
BuildMI(B, It, DL, HII.get(Hexagon::A2_tfrsi), TmpR0)
.addImm(0x01010101);
MachineFunction &MF = *B.getParent();
auto *HRI = MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
HII.loadRegFromStackSlot(B, It, TmpR1, FI, RC, HRI, Register());
expandLoadVec(B, std::prev(It), MRI, HII, NewRegs);
BuildMI(B, It, DL, HII.get(Hexagon::V6_vandvrt), DstR)
.addReg(TmpR1, RegState::Kill)
.addReg(TmpR0, RegState::Kill);
NewRegs.push_back(TmpR0);
NewRegs.push_back(TmpR1);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVec2(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
// It is possible that the double vector being stored is only partially
// defined. From the point of view of the liveness tracking, it is ok to
// store it as a whole, but if we break it up we may end up storing a
// register that is entirely undefined.
LivePhysRegs LPR(HRI);
LPR.addLiveIns(B);
SmallVector<std::pair<MCPhysReg, const MachineOperand*>,2> Clobbers;
for (auto R = B.begin(); R != It; ++R) {
Clobbers.clear();
LPR.stepForward(*R, Clobbers);
}
DebugLoc DL = MI->getDebugLoc();
Register SrcR = MI->getOperand(2).getReg();
Register SrcLo = HRI.getSubReg(SrcR, Hexagon::vsub_lo);
Register SrcHi = HRI.getSubReg(SrcR, Hexagon::vsub_hi);
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
unsigned Size = HRI.getSpillSize(Hexagon::HvxVRRegClass);
Align NeedAlign = HRI.getSpillAlign(Hexagon::HvxVRRegClass);
Align HasAlign = MFI.getObjectAlign(FI);
unsigned StoreOpc;
// Store low part.
if (LPR.contains(SrcLo)) {
StoreOpc = NeedAlign <= HasAlign ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(0)
.addReg(SrcLo, getKillRegState(IsKill))
.cloneMemRefs(*MI);
}
// Store high part.
if (LPR.contains(SrcHi)) {
StoreOpc = NeedAlign <= HasAlign ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(Size)
.addReg(SrcHi, getKillRegState(IsKill))
.cloneMemRefs(*MI);
}
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVec2(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
DebugLoc DL = MI->getDebugLoc();
Register DstR = MI->getOperand(0).getReg();
Register DstHi = HRI.getSubReg(DstR, Hexagon::vsub_hi);
Register DstLo = HRI.getSubReg(DstR, Hexagon::vsub_lo);
int FI = MI->getOperand(1).getIndex();
unsigned Size = HRI.getSpillSize(Hexagon::HvxVRRegClass);
Align NeedAlign = HRI.getSpillAlign(Hexagon::HvxVRRegClass);
Align HasAlign = MFI.getObjectAlign(FI);
unsigned LoadOpc;
// Load low part.
LoadOpc = NeedAlign <= HasAlign ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstLo)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
// Load high part.
LoadOpc = NeedAlign <= HasAlign ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstHi)
.addFrameIndex(FI)
.addImm(Size)
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandStoreVec(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(0).isFI())
return false;
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
DebugLoc DL = MI->getDebugLoc();
Register SrcR = MI->getOperand(2).getReg();
bool IsKill = MI->getOperand(2).isKill();
int FI = MI->getOperand(0).getIndex();
Align NeedAlign = HRI.getSpillAlign(Hexagon::HvxVRRegClass);
Align HasAlign = MFI.getObjectAlign(FI);
unsigned StoreOpc = NeedAlign <= HasAlign ? Hexagon::V6_vS32b_ai
: Hexagon::V6_vS32Ub_ai;
BuildMI(B, It, DL, HII.get(StoreOpc))
.addFrameIndex(FI)
.addImm(0)
.addReg(SrcR, getKillRegState(IsKill))
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandLoadVec(MachineBasicBlock &B,
MachineBasicBlock::iterator It, MachineRegisterInfo &MRI,
const HexagonInstrInfo &HII, SmallVectorImpl<Register> &NewRegs) const {
MachineFunction &MF = *B.getParent();
auto &MFI = MF.getFrameInfo();
MachineInstr *MI = &*It;
if (!MI->getOperand(1).isFI())
return false;
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
DebugLoc DL = MI->getDebugLoc();
Register DstR = MI->getOperand(0).getReg();
int FI = MI->getOperand(1).getIndex();
Align NeedAlign = HRI.getSpillAlign(Hexagon::HvxVRRegClass);
Align HasAlign = MFI.getObjectAlign(FI);
unsigned LoadOpc = NeedAlign <= HasAlign ? Hexagon::V6_vL32b_ai
: Hexagon::V6_vL32Ub_ai;
BuildMI(B, It, DL, HII.get(LoadOpc), DstR)
.addFrameIndex(FI)
.addImm(0)
.cloneMemRefs(*MI);
B.erase(It);
return true;
}
bool HexagonFrameLowering::expandSpillMacros(MachineFunction &MF,
SmallVectorImpl<Register> &NewRegs) const {
auto &HII = *MF.getSubtarget<HexagonSubtarget>().getInstrInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
bool Changed = false;
for (auto &B : MF) {
// Traverse the basic block.
MachineBasicBlock::iterator NextI;
for (auto I = B.begin(), E = B.end(); I != E; I = NextI) {
MachineInstr *MI = &*I;
NextI = std::next(I);
unsigned Opc = MI->getOpcode();
switch (Opc) {
case TargetOpcode::COPY:
Changed |= expandCopy(B, I, MRI, HII, NewRegs);
break;
case Hexagon::STriw_pred:
case Hexagon::STriw_ctr:
Changed |= expandStoreInt(B, I, MRI, HII, NewRegs);
break;
case Hexagon::LDriw_pred:
case Hexagon::LDriw_ctr:
Changed |= expandLoadInt(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vstorerq_ai:
Changed |= expandStoreVecPred(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vloadrq_ai:
Changed |= expandLoadVecPred(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vloadrw_ai:
Changed |= expandLoadVec2(B, I, MRI, HII, NewRegs);
break;
case Hexagon::PS_vstorerw_ai:
Changed |= expandStoreVec2(B, I, MRI, HII, NewRegs);
break;
}
}
}
return Changed;
}
void HexagonFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
SavedRegs.resize(HRI.getNumRegs());
// If we have a function containing __builtin_eh_return we want to spill and
// restore all callee saved registers. Pretend that they are used.
if (MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn())
for (const MCPhysReg *R = HRI.getCalleeSavedRegs(&MF); *R; ++R)
SavedRegs.set(*R);
// Replace predicate register pseudo spill code.
SmallVector<Register,8> NewRegs;
expandSpillMacros(MF, NewRegs);
if (OptimizeSpillSlots && !isOptNone(MF))
optimizeSpillSlots(MF, NewRegs);
// We need to reserve a spill slot if scavenging could potentially require
// spilling a scavenged register.
if (!NewRegs.empty() || mayOverflowFrameOffset(MF)) {
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
SetVector<const TargetRegisterClass*> SpillRCs;
// Reserve an int register in any case, because it could be used to hold
// the stack offset in case it does not fit into a spill instruction.
SpillRCs.insert(&Hexagon::IntRegsRegClass);
for (Register VR : NewRegs)
SpillRCs.insert(MRI.getRegClass(VR));
for (const auto *RC : SpillRCs) {
if (!needToReserveScavengingSpillSlots(MF, HRI, RC))
continue;
unsigned Num = 1;
switch (RC->getID()) {
case Hexagon::IntRegsRegClassID:
Num = NumberScavengerSlots;
break;
case Hexagon::HvxQRRegClassID:
Num = 2; // Vector predicate spills also need a vector register.
break;
}
unsigned S = HRI.getSpillSize(*RC);
Align A = HRI.getSpillAlign(*RC);
for (unsigned i = 0; i < Num; i++) {
int NewFI = MFI.CreateSpillStackObject(S, A);
RS->addScavengingFrameIndex(NewFI);
}
}
}
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
}
Register HexagonFrameLowering::findPhysReg(MachineFunction &MF,
HexagonBlockRanges::IndexRange &FIR,
HexagonBlockRanges::InstrIndexMap &IndexMap,
HexagonBlockRanges::RegToRangeMap &DeadMap,
const TargetRegisterClass *RC) const {
auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
auto &MRI = MF.getRegInfo();
auto isDead = [&FIR,&DeadMap] (Register Reg) -> bool {
auto F = DeadMap.find({Reg,0});
if (F == DeadMap.end())
return false;
for (auto &DR : F->second)
if (DR.contains(FIR))
return true;
return false;
};
for (Register Reg : RC->getRawAllocationOrder(MF)) {
bool Dead = true;
for (auto R : HexagonBlockRanges::expandToSubRegs({Reg,0}, MRI, HRI)) {
if (isDead(R.Reg))
continue;
Dead = false;
break;
}
if (Dead)
return Reg;
}
return 0;
}
void HexagonFrameLowering::optimizeSpillSlots(MachineFunction &MF,
SmallVectorImpl<Register> &VRegs) const {
auto &HST = MF.getSubtarget<HexagonSubtarget>();
auto &HII = *HST.getInstrInfo();
auto &HRI = *HST.getRegisterInfo();
auto &MRI = MF.getRegInfo();
HexagonBlockRanges HBR(MF);
using BlockIndexMap =
std::map<MachineBasicBlock *, HexagonBlockRanges::InstrIndexMap>;
using BlockRangeMap =
std::map<MachineBasicBlock *, HexagonBlockRanges::RangeList>;
using IndexType = HexagonBlockRanges::IndexType;
struct SlotInfo {
BlockRangeMap Map;
unsigned Size = 0;
const TargetRegisterClass *RC = nullptr;
SlotInfo() = default;
};
BlockIndexMap BlockIndexes;
SmallSet<int,4> BadFIs;
std::map<int,SlotInfo> FIRangeMap;
// Accumulate register classes: get a common class for a pre-existing
// class HaveRC and a new class NewRC. Return nullptr if a common class
// cannot be found, otherwise return the resulting class. If HaveRC is
// nullptr, assume that it is still unset.
auto getCommonRC =
[](const TargetRegisterClass *HaveRC,
const TargetRegisterClass *NewRC) -> const TargetRegisterClass * {
if (HaveRC == nullptr || HaveRC == NewRC)
return NewRC;
// Different classes, both non-null. Pick the more general one.
if (HaveRC->hasSubClassEq(NewRC))
return HaveRC;
if (NewRC->hasSubClassEq(HaveRC))
return NewRC;
return nullptr;
};
// Scan all blocks in the function. Check all occurrences of frame indexes,
// and collect relevant information.
for (auto &B : MF) {
std::map<int,IndexType> LastStore, LastLoad;
auto P = BlockIndexes.emplace(&B, HexagonBlockRanges::InstrIndexMap(B));
auto &IndexMap = P.first->second;
LLVM_DEBUG(dbgs() << "Index map for " << printMBBReference(B) << "\n"
<< IndexMap << '\n');
for (auto &In : B) {
int LFI, SFI;
bool Load = HII.isLoadFromStackSlot(In, LFI) && !HII.isPredicated(In);
bool Store = HII.isStoreToStackSlot(In, SFI) && !HII.isPredicated(In);
if (Load && Store) {
// If it's both a load and a store, then we won't handle it.
BadFIs.insert(LFI);
BadFIs.insert(SFI);
continue;
}
// Check for register classes of the register used as the source for
// the store, and the register used as the destination for the load.
// Also, only accept base+imm_offset addressing modes. Other addressing
// modes can have side-effects (post-increments, etc.). For stack
// slots they are very unlikely, so there is not much loss due to
// this restriction.
if (Load || Store) {
int TFI = Load ? LFI : SFI;
unsigned AM = HII.getAddrMode(In);
SlotInfo &SI = FIRangeMap[TFI];
bool Bad = (AM != HexagonII::BaseImmOffset);
if (!Bad) {
// If the addressing mode is ok, check the register class.
unsigned OpNum = Load ? 0 : 2;
auto *RC = HII.getRegClass(In.getDesc(), OpNum, &HRI);
RC = getCommonRC(SI.RC, RC);
if (RC == nullptr)
Bad = true;
else
SI.RC = RC;
}
if (!Bad) {
// Check sizes.
unsigned S = HII.getMemAccessSize(In);
if (SI.Size != 0 && SI.Size != S)
Bad = true;
else
SI.Size = S;
}
if (!Bad) {
for (auto *Mo : In.memoperands()) {
if (!Mo->isVolatile() && !Mo->isAtomic())
continue;
Bad = true;
break;
}
}
if (Bad)
BadFIs.insert(TFI);
}
// Locate uses of frame indices.
for (unsigned i = 0, n = In.getNumOperands(); i < n; ++i) {
const MachineOperand &Op = In.getOperand(i);
if (!Op.isFI())
continue;
int FI = Op.getIndex();
// Make sure that the following operand is an immediate and that
// it is 0. This is the offset in the stack object.
if (i+1 >= n || !In.getOperand(i+1).isImm() ||
In.getOperand(i+1).getImm() != 0)
BadFIs.insert(FI);
if (BadFIs.count(FI))
continue;
IndexType Index = IndexMap.getIndex(&In);
auto &LS = LastStore[FI];
auto &LL = LastLoad[FI];
if (Load) {
if (LS == IndexType::None)
LS = IndexType::Entry;
LL = Index;
} else if (Store) {
HexagonBlockRanges::RangeList &RL = FIRangeMap[FI].Map[&B];
if (LS != IndexType::None)
RL.add(LS, LL, false, false);
else if (LL != IndexType::None)
RL.add(IndexType::Entry, LL, false, false);
LL = IndexType::None;
LS = Index;
} else {
BadFIs.insert(FI);
}
}
}
for (auto &I : LastLoad) {
IndexType LL = I.second;
if (LL == IndexType::None)
continue;
auto &RL = FIRangeMap[I.first].Map[&B];
IndexType &LS = LastStore[I.first];
if (LS != IndexType::None)
RL.add(LS, LL, false, false);
else
RL.add(IndexType::Entry, LL, false, false);
LS = IndexType::None;
}
for (auto &I : LastStore) {
IndexType LS = I.second;
if (LS == IndexType::None)
continue;
auto &RL = FIRangeMap[I.first].Map[&B];
RL.add(LS, IndexType::None, false, false);
}
}
LLVM_DEBUG({
for (auto &P : FIRangeMap) {
dbgs() << "fi#" << P.first;
if (BadFIs.count(P.first))
dbgs() << " (bad)";
dbgs() << " RC: ";
if (P.second.RC != nullptr)
dbgs() << HRI.getRegClassName(P.second.RC) << '\n';
else
dbgs() << "<null>\n";
for (auto &R : P.second.Map)
dbgs() << " " << printMBBReference(*R.first) << " { " << R.second
<< "}\n";
}
});
// When a slot is loaded from in a block without being stored to in the
// same block, it is live-on-entry to this block. To avoid CFG analysis,
// consider this slot to be live-on-exit from all blocks.
SmallSet<int,4> LoxFIs;
std::map<MachineBasicBlock*,std::vector<int>> BlockFIMap;
for (auto &P : FIRangeMap) {
// P = pair(FI, map: BB->RangeList)
if (BadFIs.count(P.first))
continue;
for (auto &B : MF) {
auto F = P.second.Map.find(&B);
// F = pair(BB, RangeList)
if (F == P.second.Map.end() || F->second.empty())
continue;
HexagonBlockRanges::IndexRange &IR = F->second.front();
if (IR.start() == IndexType::Entry)
LoxFIs.insert(P.first);
BlockFIMap[&B].push_back(P.first);
}
}
LLVM_DEBUG({
dbgs() << "Block-to-FI map (* -- live-on-exit):\n";
for (auto &P : BlockFIMap) {
auto &FIs = P.second;
if (FIs.empty())
continue;
dbgs() << " " << printMBBReference(*P.first) << ": {";
for (auto I : FIs) {
dbgs() << " fi#" << I;
if (LoxFIs.count(I))
dbgs() << '*';
}
dbgs() << " }\n";
}
});
#ifndef NDEBUG
bool HasOptLimit = SpillOptMax.getPosition();
#endif
// eliminate loads, when all loads eliminated, eliminate all stores.
for (auto &B : MF) {
auto F = BlockIndexes.find(&B);
assert(F != BlockIndexes.end());
HexagonBlockRanges::InstrIndexMap &IM = F->second;
HexagonBlockRanges::RegToRangeMap LM = HBR.computeLiveMap(IM);
HexagonBlockRanges::RegToRangeMap DM = HBR.computeDeadMap(IM, LM);
LLVM_DEBUG(dbgs() << printMBBReference(B) << " dead map\n"
<< HexagonBlockRanges::PrintRangeMap(DM, HRI));
for (auto FI : BlockFIMap[&B]) {
if (BadFIs.count(FI))
continue;
LLVM_DEBUG(dbgs() << "Working on fi#" << FI << '\n');
HexagonBlockRanges::RangeList &RL = FIRangeMap[FI].Map[&B];
for (auto &Range : RL) {
LLVM_DEBUG(dbgs() << "--Examining range:" << RL << '\n');
if (!IndexType::isInstr(Range.start()) ||
!IndexType::isInstr(Range.end()))
continue;
MachineInstr &SI = *IM.getInstr(Range.start());
MachineInstr &EI = *IM.getInstr(Range.end());
assert(SI.mayStore() && "Unexpected start instruction");
assert(EI.mayLoad() && "Unexpected end instruction");
MachineOperand &SrcOp = SI.getOperand(2);
HexagonBlockRanges::RegisterRef SrcRR = { SrcOp.getReg(),
SrcOp.getSubReg() };
auto *RC = HII.getRegClass(SI.getDesc(), 2, &HRI);
// The this-> is needed to unconfuse MSVC.
Register FoundR = this->findPhysReg(MF, Range, IM, DM, RC);
LLVM_DEBUG(dbgs() << "Replacement reg:" << printReg(FoundR, &HRI)
<< '\n');
if (FoundR == 0)
continue;
#ifndef NDEBUG
if (HasOptLimit) {
if (SpillOptCount >= SpillOptMax)
return;
SpillOptCount++;
}
#endif
// Generate the copy-in: "FoundR = COPY SrcR" at the store location.
MachineBasicBlock::iterator StartIt = SI.getIterator(), NextIt;
MachineInstr *CopyIn = nullptr;
if (SrcRR.Reg != FoundR || SrcRR.Sub != 0) {
const DebugLoc &DL = SI.getDebugLoc();
CopyIn = BuildMI(B, StartIt, DL, HII.get(TargetOpcode::COPY), FoundR)
.add(SrcOp);
}
++StartIt;
// Check if this is a last store and the FI is live-on-exit.
if (LoxFIs.count(FI) && (&Range == &RL.back())) {
// Update store's source register.
if (unsigned SR = SrcOp.getSubReg())
SrcOp.setReg(HRI.getSubReg(FoundR, SR));
else
SrcOp.setReg(FoundR);
SrcOp.setSubReg(0);
// We are keeping this register live.
SrcOp.setIsKill(false);
} else {
B.erase(&SI);
IM.replaceInstr(&SI, CopyIn);
}
auto EndIt = std::next(EI.getIterator());
for (auto It = StartIt; It != EndIt; It = NextIt) {
MachineInstr &MI = *It;
NextIt = std::next(It);
int TFI;
if (!HII.isLoadFromStackSlot(MI, TFI) || TFI != FI)
continue;
Register DstR = MI.getOperand(0).getReg();
assert(MI.getOperand(0).getSubReg() == 0);
MachineInstr *CopyOut = nullptr;
if (DstR != FoundR) {
DebugLoc DL = MI.getDebugLoc();
unsigned MemSize = HII.getMemAccessSize(MI);
assert(HII.getAddrMode(MI) == HexagonII::BaseImmOffset);
unsigned CopyOpc = TargetOpcode::COPY;
if (HII.isSignExtendingLoad(MI))
CopyOpc = (MemSize == 1) ? Hexagon::A2_sxtb : Hexagon::A2_sxth;
else if (HII.isZeroExtendingLoad(MI))
CopyOpc = (MemSize == 1) ? Hexagon::A2_zxtb : Hexagon::A2_zxth;
CopyOut = BuildMI(B, It, DL, HII.get(CopyOpc), DstR)
.addReg(FoundR, getKillRegState(&MI == &EI));
}
IM.replaceInstr(&MI, CopyOut);
B.erase(It);
}
// Update the dead map.
HexagonBlockRanges::RegisterRef FoundRR = { FoundR, 0 };
for (auto RR : HexagonBlockRanges::expandToSubRegs(FoundRR, MRI, HRI))
DM[RR].subtract(Range);
} // for Range in range list
}
}
}
void HexagonFrameLowering::expandAlloca(MachineInstr *AI,
const HexagonInstrInfo &HII, Register SP, unsigned CF) const {
MachineBasicBlock &MB = *AI->getParent();
DebugLoc DL = AI->getDebugLoc();
unsigned A = AI->getOperand(2).getImm();
// Have
// Rd = alloca Rs, #A
//
// If Rs and Rd are different registers, use this sequence:
// Rd = sub(r29, Rs)
// r29 = sub(r29, Rs)
// Rd = and(Rd, #-A) ; if necessary
// r29 = and(r29, #-A) ; if necessary
// Rd = add(Rd, #CF) ; CF size aligned to at most A
// otherwise, do
// Rd = sub(r29, Rs)
// Rd = and(Rd, #-A) ; if necessary
// r29 = Rd
// Rd = add(Rd, #CF) ; CF size aligned to at most A
MachineOperand &RdOp = AI->getOperand(0);
MachineOperand &RsOp = AI->getOperand(1);
Register Rd = RdOp.getReg(), Rs = RsOp.getReg();
// Rd = sub(r29, Rs)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), Rd)
.addReg(SP)
.addReg(Rs);
if (Rs != Rd) {
// r29 = sub(r29, Rs)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), SP)
.addReg(SP)
.addReg(Rs);
}
if (A > 8) {
// Rd = and(Rd, #-A)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), Rd)
.addReg(Rd)
.addImm(-int64_t(A));
if (Rs != Rd)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), SP)
.addReg(SP)
.addImm(-int64_t(A));
}
if (Rs == Rd) {
// r29 = Rd
BuildMI(MB, AI, DL, HII.get(TargetOpcode::COPY), SP)
.addReg(Rd);
}
if (CF > 0) {
// Rd = add(Rd, #CF)
BuildMI(MB, AI, DL, HII.get(Hexagon::A2_addi), Rd)
.addReg(Rd)
.addImm(CF);
}
}
bool HexagonFrameLowering::needsAligna(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (!MFI.hasVarSizedObjects())
return false;
// Do not check for max stack object alignment here, because the stack
// may not be complete yet. Assume that we will need PS_aligna if there
// are variable-sized objects.
return true;
}
const MachineInstr *HexagonFrameLowering::getAlignaInstr(
const MachineFunction &MF) const {
for (auto &B : MF)
for (auto &I : B)
if (I.getOpcode() == Hexagon::PS_aligna)
return &I;
return nullptr;
}
/// Adds all callee-saved registers as implicit uses or defs to the
/// instruction.
void HexagonFrameLowering::addCalleeSaveRegistersAsImpOperand(MachineInstr *MI,
const CSIVect &CSI, bool IsDef, bool IsKill) const {
// Add the callee-saved registers as implicit uses.
for (auto &R : CSI)
MI->addOperand(MachineOperand::CreateReg(R.getReg(), IsDef, true, IsKill));
}
/// Determine whether the callee-saved register saves and restores should
/// be generated via inline code. If this function returns "true", inline
/// code will be generated. If this function returns "false", additional
/// checks are performed, which may still lead to the inline code.
bool HexagonFrameLowering::shouldInlineCSR(const MachineFunction &MF,
const CSIVect &CSI) const {
if (MF.getSubtarget<HexagonSubtarget>().isEnvironmentMusl())
return true;
if (MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn())
return true;
if (!hasFP(MF))
return true;
if (!isOptSize(MF) && !isMinSize(MF))
if (MF.getTarget().getOptLevel() > CodeGenOptLevel::Default)
return true;
// Check if CSI only has double registers, and if the registers form
// a contiguous block starting from D8.
BitVector Regs(Hexagon::NUM_TARGET_REGS);
for (const CalleeSavedInfo &I : CSI) {
MCRegister R = I.getReg();
if (!Hexagon::DoubleRegsRegClass.contains(R))
return true;
Regs[R] = true;
}
int F = Regs.find_first();
if (F != Hexagon::D8)
return true;
while (F >= 0) {
int N = Regs.find_next(F);
if (N >= 0 && N != F+1)
return true;
F = N;
}
return false;
}
bool HexagonFrameLowering::useSpillFunction(const MachineFunction &MF,
const CSIVect &CSI) const {
if (shouldInlineCSR(MF, CSI))
return false;
unsigned NumCSI = CSI.size();
if (NumCSI <= 1)
return false;
unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs
: SpillFuncThreshold;
return Threshold < NumCSI;
}
bool HexagonFrameLowering::useRestoreFunction(const MachineFunction &MF,
const CSIVect &CSI) const {
if (shouldInlineCSR(MF, CSI))
return false;
// The restore functions do a bit more than just restoring registers.
// The non-returning versions will go back directly to the caller's
// caller, others will clean up the stack frame in preparation for
// a tail call. Using them can still save code size even if only one
// register is getting restores. Make the decision based on -Oz:
// using -Os will use inline restore for a single register.
if (isMinSize(MF))
return true;
unsigned NumCSI = CSI.size();
if (NumCSI <= 1)
return false;
unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs-1
: SpillFuncThreshold;
return Threshold < NumCSI;
}
bool HexagonFrameLowering::mayOverflowFrameOffset(MachineFunction &MF) const {
unsigned StackSize = MF.getFrameInfo().estimateStackSize(MF);
auto &HST = MF.getSubtarget<HexagonSubtarget>();
// A fairly simplistic guess as to whether a potential load/store to a
// stack location could require an extra register.
if (HST.useHVXOps() && StackSize > 256)
return true;
// Check if the function has store-immediate instructions that access
// the stack. Since the offset field is not extendable, if the stack
// size exceeds the offset limit (6 bits, shifted), the stores will
// require a new base register.
bool HasImmStack = false;
unsigned MinLS = ~0u; // Log_2 of the memory access size.
for (const MachineBasicBlock &B : MF) {
for (const MachineInstr &MI : B) {
unsigned LS = 0;
switch (MI.getOpcode()) {
case Hexagon::S4_storeirit_io:
case Hexagon::S4_storeirif_io:
case Hexagon::S4_storeiri_io:
++LS;
[[fallthrough]];
case Hexagon::S4_storeirht_io:
case Hexagon::S4_storeirhf_io:
case Hexagon::S4_storeirh_io:
++LS;
[[fallthrough]];
case Hexagon::S4_storeirbt_io:
case Hexagon::S4_storeirbf_io:
case Hexagon::S4_storeirb_io:
if (MI.getOperand(0).isFI())
HasImmStack = true;
MinLS = std::min(MinLS, LS);
break;
}
}
}
if (HasImmStack)
return !isUInt<6>(StackSize >> MinLS);
return false;
}
namespace {
// Struct used by orderFrameObjects to help sort the stack objects.
struct HexagonFrameSortingObject {
bool IsValid = false;
unsigned Index = 0; // Index of Object into MFI list.
unsigned Size = 0;
Align ObjectAlignment = Align(1); // Alignment of Object in bytes.
};
struct HexagonFrameSortingComparator {
inline bool operator()(const HexagonFrameSortingObject &A,
const HexagonFrameSortingObject &B) const {
return std::make_tuple(!A.IsValid, A.ObjectAlignment, A.Size) <
std::make_tuple(!B.IsValid, B.ObjectAlignment, B.Size);
}
};
} // namespace
// Sort objects on the stack by alignment value and then by size to minimize
// padding.
void HexagonFrameLowering::orderFrameObjects(
const MachineFunction &MF, SmallVectorImpl<int> &ObjectsToAllocate) const {
if (ObjectsToAllocate.empty())
return;
const MachineFrameInfo &MFI = MF.getFrameInfo();
int NObjects = ObjectsToAllocate.size();
// Create an array of all MFI objects.
SmallVector<HexagonFrameSortingObject> SortingObjects(
MFI.getObjectIndexEnd());
for (int i = 0, j = 0, e = MFI.getObjectIndexEnd(); i < e && j != NObjects;
++i) {
if (i != ObjectsToAllocate[j])
continue;
j++;
// A variable size object has size equal to 0. Since Hexagon sets
// getUseLocalStackAllocationBlock() to true, a local block is allocated
// earlier. This case is not handled here for now.
int Size = MFI.getObjectSize(i);
if (Size == 0)
return;
SortingObjects[i].IsValid = true;
SortingObjects[i].Index = i;
SortingObjects[i].Size = Size;
SortingObjects[i].ObjectAlignment = MFI.getObjectAlign(i);
}
// Sort objects by alignment and then by size.
llvm::stable_sort(SortingObjects, HexagonFrameSortingComparator());
// Modify the original list to represent the final order.
int i = NObjects;
for (auto &Obj : SortingObjects) {
if (i == 0)
break;
ObjectsToAllocate[--i] = Obj.Index;
}
}