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//===-- lib/CodeGen/GlobalISel/CallLowering.cpp - Call lowering -----------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file implements some simple delegations needed for call lowering.
#include "llvm/CodeGen/GlobalISel/CallLowering.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Target/TargetMachine.h"
#define DEBUG_TYPE "call-lowering"
using namespace llvm;
void CallLowering::anchor() {}
/// Helper function which updates \p Flags when \p AttrFn returns true.
static void
addFlagsUsingAttrFn(ISD::ArgFlagsTy &Flags,
const std::function<bool(Attribute::AttrKind)> &AttrFn) {
if (AttrFn(Attribute::SExt))
if (AttrFn(Attribute::ZExt))
if (AttrFn(Attribute::InReg))
if (AttrFn(Attribute::StructRet))
if (AttrFn(Attribute::Nest))
if (AttrFn(Attribute::ByVal))
if (AttrFn(Attribute::Preallocated))
if (AttrFn(Attribute::InAlloca))
if (AttrFn(Attribute::Returned))
if (AttrFn(Attribute::SwiftSelf))
if (AttrFn(Attribute::SwiftAsync))
if (AttrFn(Attribute::SwiftError))
ISD::ArgFlagsTy CallLowering::getAttributesForArgIdx(const CallBase &Call,
unsigned ArgIdx) const {
ISD::ArgFlagsTy Flags;
addFlagsUsingAttrFn(Flags, [&Call, &ArgIdx](Attribute::AttrKind Attr) {
return Call.paramHasAttr(ArgIdx, Attr);
return Flags;
CallLowering::getAttributesForReturn(const CallBase &Call) const {
ISD::ArgFlagsTy Flags;
addFlagsUsingAttrFn(Flags, [&Call](Attribute::AttrKind Attr) {
return Call.hasRetAttr(Attr);
return Flags;
void CallLowering::addArgFlagsFromAttributes(ISD::ArgFlagsTy &Flags,
const AttributeList &Attrs,
unsigned OpIdx) const {
addFlagsUsingAttrFn(Flags, [&Attrs, &OpIdx](Attribute::AttrKind Attr) {
return Attrs.hasAttributeAtIndex(OpIdx, Attr);
bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, const CallBase &CB,
ArrayRef<Register> ResRegs,
ArrayRef<ArrayRef<Register>> ArgRegs,
Register SwiftErrorVReg,
std::function<unsigned()> GetCalleeReg) const {
CallLoweringInfo Info;
const DataLayout &DL = MIRBuilder.getDataLayout();
MachineFunction &MF = MIRBuilder.getMF();
MachineRegisterInfo &MRI = MF.getRegInfo();
bool CanBeTailCalled = CB.isTailCall() &&
isInTailCallPosition(CB, MF.getTarget()) &&
.getValueAsString() != "true");
CallingConv::ID CallConv = CB.getCallingConv();
Type *RetTy = CB.getType();
bool IsVarArg = CB.getFunctionType()->isVarArg();
SmallVector<BaseArgInfo, 4> SplitArgs;
getReturnInfo(CallConv, RetTy, CB.getAttributes(), SplitArgs, DL);
Info.CanLowerReturn = canLowerReturn(MF, CallConv, SplitArgs, IsVarArg);
if (!Info.CanLowerReturn) {
// Callee requires sret demotion.
insertSRetOutgoingArgument(MIRBuilder, CB, Info);
// The sret demotion isn't compatible with tail-calls, since the sret
// argument points into the caller's stack frame.
CanBeTailCalled = false;
// First step is to marshall all the function's parameters into the correct
// physregs and memory locations. Gather the sequence of argument types that
// we'll pass to the assigner function.
unsigned i = 0;
unsigned NumFixedArgs = CB.getFunctionType()->getNumParams();
for (const auto &Arg : CB.args()) {
ArgInfo OrigArg{ArgRegs[i], *Arg.get(), i, getAttributesForArgIdx(CB, i),
i < NumFixedArgs};
setArgFlags(OrigArg, i + AttributeList::FirstArgIndex, DL, CB);
// If we have an explicit sret argument that is an Instruction, (i.e., it
// might point to function-local memory), we can't meaningfully tail-call.
if (OrigArg.Flags[0].isSRet() && isa<Instruction>(&Arg))
CanBeTailCalled = false;
// Try looking through a bitcast from one function type to another.
// Commonly happens with calls to objc_msgSend().
const Value *CalleeV = CB.getCalledOperand()->stripPointerCasts();
if (const Function *F = dyn_cast<Function>(CalleeV))
Info.Callee = MachineOperand::CreateGA(F, 0);
Info.Callee = MachineOperand::CreateReg(GetCalleeReg(), false);
Register ReturnHintAlignReg;
Align ReturnHintAlign;
Info.OrigRet = ArgInfo{ResRegs, RetTy, 0, getAttributesForReturn(CB)};
if (!Info.OrigRet.Ty->isVoidTy()) {
setArgFlags(Info.OrigRet, AttributeList::ReturnIndex, DL, CB);
if (MaybeAlign Alignment = CB.getRetAlign()) {
if (*Alignment > Align(1)) {
ReturnHintAlignReg = MRI.cloneVirtualRegister(ResRegs[0]);
Info.OrigRet.Regs[0] = ReturnHintAlignReg;
ReturnHintAlign = *Alignment;
auto Bundle = CB.getOperandBundle(LLVMContext::OB_kcfi);
if (Bundle && CB.isIndirectCall()) {
Info.CFIType = cast<ConstantInt>(Bundle->Inputs[0]);
assert(Info.CFIType->getType()->isIntegerTy(32) && "Invalid CFI type");
Info.CB = &CB;
Info.KnownCallees = CB.getMetadata(LLVMContext::MD_callees);
Info.CallConv = CallConv;
Info.SwiftErrorVReg = SwiftErrorVReg;
Info.IsMustTailCall = CB.isMustTailCall();
Info.IsTailCall = CanBeTailCalled;
Info.IsVarArg = IsVarArg;
if (!lowerCall(MIRBuilder, Info))
return false;
if (ReturnHintAlignReg && !Info.IsTailCall) {
MIRBuilder.buildAssertAlign(ResRegs[0], ReturnHintAlignReg,
return true;
template <typename FuncInfoTy>
void CallLowering::setArgFlags(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const FuncInfoTy &FuncInfo) const {
auto &Flags = Arg.Flags[0];
const AttributeList &Attrs = FuncInfo.getAttributes();
addArgFlagsFromAttributes(Flags, Attrs, OpIdx);
PointerType *PtrTy = dyn_cast<PointerType>(Arg.Ty->getScalarType());
if (PtrTy) {
Align MemAlign = DL.getABITypeAlign(Arg.Ty);
if (Flags.isByVal() || Flags.isInAlloca() || Flags.isPreallocated()) {
assert(OpIdx >= AttributeList::FirstArgIndex);
unsigned ParamIdx = OpIdx - AttributeList::FirstArgIndex;
Type *ElementTy = FuncInfo.getParamByValType(ParamIdx);
if (!ElementTy)
ElementTy = FuncInfo.getParamInAllocaType(ParamIdx);
if (!ElementTy)
ElementTy = FuncInfo.getParamPreallocatedType(ParamIdx);
assert(ElementTy && "Must have byval, inalloca or preallocated type");
// For ByVal, alignment should be passed from FE. BE will guess if
// this info is not there but there are cases it cannot get right.
if (auto ParamAlign = FuncInfo.getParamStackAlign(ParamIdx))
MemAlign = *ParamAlign;
else if ((ParamAlign = FuncInfo.getParamAlign(ParamIdx)))
MemAlign = *ParamAlign;
MemAlign = Align(getTLI()->getByValTypeAlignment(ElementTy, DL));
} else if (OpIdx >= AttributeList::FirstArgIndex) {
if (auto ParamAlign =
FuncInfo.getParamStackAlign(OpIdx - AttributeList::FirstArgIndex))
MemAlign = *ParamAlign;
// Don't try to use the returned attribute if the argument is marked as
// swiftself, since it won't be passed in x0.
if (Flags.isSwiftSelf())
template void
CallLowering::setArgFlags<Function>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const Function &FuncInfo) const;
template void
CallLowering::setArgFlags<CallBase>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
const DataLayout &DL,
const CallBase &FuncInfo) const;
void CallLowering::splitToValueTypes(const ArgInfo &OrigArg,
SmallVectorImpl<ArgInfo> &SplitArgs,
const DataLayout &DL,
CallingConv::ID CallConv,
SmallVectorImpl<uint64_t> *Offsets) const {
LLVMContext &Ctx = OrigArg.Ty->getContext();
SmallVector<EVT, 4> SplitVTs;
ComputeValueVTs(*TLI, DL, OrigArg.Ty, SplitVTs, Offsets, 0);
if (SplitVTs.size() == 0)
if (SplitVTs.size() == 1) {
// No splitting to do, but we want to replace the original type (e.g. [1 x
// double] -> double).
SplitArgs.emplace_back(OrigArg.Regs[0], SplitVTs[0].getTypeForEVT(Ctx),
OrigArg.OrigArgIndex, OrigArg.Flags[0],
OrigArg.IsFixed, OrigArg.OrigValue);
// Create one ArgInfo for each virtual register in the original ArgInfo.
assert(OrigArg.Regs.size() == SplitVTs.size() && "Regs / types mismatch");
bool NeedsRegBlock = TLI->functionArgumentNeedsConsecutiveRegisters(
OrigArg.Ty, CallConv, false, DL);
for (unsigned i = 0, e = SplitVTs.size(); i < e; ++i) {
Type *SplitTy = SplitVTs[i].getTypeForEVT(Ctx);
SplitArgs.emplace_back(OrigArg.Regs[i], SplitTy, OrigArg.OrigArgIndex,
OrigArg.Flags[0], OrigArg.IsFixed);
if (NeedsRegBlock)
/// Pack values \p SrcRegs to cover the vector type result \p DstRegs.
static MachineInstrBuilder
mergeVectorRegsToResultRegs(MachineIRBuilder &B, ArrayRef<Register> DstRegs,
ArrayRef<Register> SrcRegs) {
MachineRegisterInfo &MRI = *B.getMRI();
LLT LLTy = MRI.getType(DstRegs[0]);
LLT PartLLT = MRI.getType(SrcRegs[0]);
// Deal with v3s16 split into v2s16
LLT LCMTy = getCoverTy(LLTy, PartLLT);
if (LCMTy == LLTy) {
// Common case where no padding is needed.
assert(DstRegs.size() == 1);
return B.buildConcatVectors(DstRegs[0], SrcRegs);
// We need to create an unmerge to the result registers, which may require
// widening the original value.
Register UnmergeSrcReg;
if (LCMTy != PartLLT) {
assert(DstRegs.size() == 1);
return B.buildDeleteTrailingVectorElements(
DstRegs[0], B.buildMergeLikeInstr(LCMTy, SrcRegs));
} else {
// We don't need to widen anything if we're extracting a scalar which was
// promoted to a vector e.g. s8 -> v4s8 -> s8
assert(SrcRegs.size() == 1);
UnmergeSrcReg = SrcRegs[0];
int NumDst = LCMTy.getSizeInBits() / LLTy.getSizeInBits();
SmallVector<Register, 8> PadDstRegs(NumDst);
std::copy(DstRegs.begin(), DstRegs.end(), PadDstRegs.begin());
// Create the excess dead defs for the unmerge.
for (int I = DstRegs.size(); I != NumDst; ++I)
PadDstRegs[I] = MRI.createGenericVirtualRegister(LLTy);
if (PadDstRegs.size() == 1)
return B.buildDeleteTrailingVectorElements(DstRegs[0], UnmergeSrcReg);
return B.buildUnmerge(PadDstRegs, UnmergeSrcReg);
/// Create a sequence of instructions to combine pieces split into register
/// typed values to the original IR value. \p OrigRegs contains the destination
/// value registers of type \p LLTy, and \p Regs contains the legalized pieces
/// with type \p PartLLT. This is used for incoming values (physregs to vregs).
static void buildCopyFromRegs(MachineIRBuilder &B, ArrayRef<Register> OrigRegs,
ArrayRef<Register> Regs, LLT LLTy, LLT PartLLT,
const ISD::ArgFlagsTy Flags) {
MachineRegisterInfo &MRI = *B.getMRI();
if (PartLLT == LLTy) {
// We should have avoided introducing a new virtual register, and just
// directly assigned here.
assert(OrigRegs[0] == Regs[0]);
if (PartLLT.getSizeInBits() == LLTy.getSizeInBits() && OrigRegs.size() == 1 &&
Regs.size() == 1) {
B.buildBitcast(OrigRegs[0], Regs[0]);
// A vector PartLLT needs extending to LLTy's element size.
// E.g. <2 x s64> = G_SEXT <2 x s32>.
if (PartLLT.isVector() == LLTy.isVector() &&
PartLLT.getScalarSizeInBits() > LLTy.getScalarSizeInBits() &&
(!PartLLT.isVector() ||
PartLLT.getNumElements() == LLTy.getNumElements()) &&
OrigRegs.size() == 1 && Regs.size() == 1) {
Register SrcReg = Regs[0];
LLT LocTy = MRI.getType(SrcReg);
if (Flags.isSExt()) {
SrcReg = B.buildAssertSExt(LocTy, SrcReg, LLTy.getScalarSizeInBits())
} else if (Flags.isZExt()) {
SrcReg = B.buildAssertZExt(LocTy, SrcReg, LLTy.getScalarSizeInBits())
// Sometimes pointers are passed zero extended.
LLT OrigTy = MRI.getType(OrigRegs[0]);
if (OrigTy.isPointer()) {
LLT IntPtrTy = LLT::scalar(OrigTy.getSizeInBits());
B.buildIntToPtr(OrigRegs[0], B.buildTrunc(IntPtrTy, SrcReg));
B.buildTrunc(OrigRegs[0], SrcReg);
if (!LLTy.isVector() && !PartLLT.isVector()) {
assert(OrigRegs.size() == 1);
LLT OrigTy = MRI.getType(OrigRegs[0]);
unsigned SrcSize = PartLLT.getSizeInBits().getFixedValue() * Regs.size();
if (SrcSize == OrigTy.getSizeInBits())
B.buildMergeValues(OrigRegs[0], Regs);
else {
auto Widened = B.buildMergeLikeInstr(LLT::scalar(SrcSize), Regs);
B.buildTrunc(OrigRegs[0], Widened);
if (PartLLT.isVector()) {
assert(OrigRegs.size() == 1);
SmallVector<Register> CastRegs(Regs.begin(), Regs.end());
// If PartLLT is a mismatched vector in both number of elements and element
// size, e.g. PartLLT == v2s64 and LLTy is v3s32, then first coerce it to
// have the same elt type, i.e. v4s32.
if (PartLLT.getSizeInBits() > LLTy.getSizeInBits() &&
PartLLT.getScalarSizeInBits() == LLTy.getScalarSizeInBits() * 2 &&
Regs.size() == 1) {
LLT NewTy = PartLLT.changeElementType(LLTy.getElementType())
.changeElementCount(PartLLT.getElementCount() * 2);
CastRegs[0] = B.buildBitcast(NewTy, Regs[0]).getReg(0);
PartLLT = NewTy;
if (LLTy.getScalarType() == PartLLT.getElementType()) {
mergeVectorRegsToResultRegs(B, OrigRegs, CastRegs);
} else {
unsigned I = 0;
LLT GCDTy = getGCDType(LLTy, PartLLT);
// We are both splitting a vector, and bitcasting its element types. Cast
// the source pieces into the appropriate number of pieces with the result
// element type.
for (Register SrcReg : CastRegs)
CastRegs[I++] = B.buildBitcast(GCDTy, SrcReg).getReg(0);
mergeVectorRegsToResultRegs(B, OrigRegs, CastRegs);
assert(LLTy.isVector() && !PartLLT.isVector());
LLT DstEltTy = LLTy.getElementType();
// Pointer information was discarded. We'll need to coerce some register types
// to avoid violating type constraints.
LLT RealDstEltTy = MRI.getType(OrigRegs[0]).getElementType();
assert(DstEltTy.getSizeInBits() == RealDstEltTy.getSizeInBits());
if (DstEltTy == PartLLT) {
// Vector was trivially scalarized.
if (RealDstEltTy.isPointer()) {
for (Register Reg : Regs)
MRI.setType(Reg, RealDstEltTy);
B.buildBuildVector(OrigRegs[0], Regs);
} else if (DstEltTy.getSizeInBits() > PartLLT.getSizeInBits()) {
// Deal with vector with 64-bit elements decomposed to 32-bit
// registers. Need to create intermediate 64-bit elements.
SmallVector<Register, 8> EltMerges;
int PartsPerElt = DstEltTy.getSizeInBits() / PartLLT.getSizeInBits();
assert(DstEltTy.getSizeInBits() % PartLLT.getSizeInBits() == 0);
for (int I = 0, NumElts = LLTy.getNumElements(); I != NumElts; ++I) {
auto Merge =
B.buildMergeLikeInstr(RealDstEltTy, Regs.take_front(PartsPerElt));
// Fix the type in case this is really a vector of pointers.
MRI.setType(Merge.getReg(0), RealDstEltTy);
Regs = Regs.drop_front(PartsPerElt);
B.buildBuildVector(OrigRegs[0], EltMerges);
} else {
// Vector was split, and elements promoted to a wider type.
// FIXME: Should handle floating point promotions.
LLT BVType = LLT::fixed_vector(LLTy.getNumElements(), PartLLT);
auto BV = B.buildBuildVector(BVType, Regs);
B.buildTrunc(OrigRegs[0], BV);
/// Create a sequence of instructions to expand the value in \p SrcReg (of type
/// \p SrcTy) to the types in \p DstRegs (of type \p PartTy). \p ExtendOp should
/// contain the type of scalar value extension if necessary.
/// This is used for outgoing values (vregs to physregs)
static void buildCopyToRegs(MachineIRBuilder &B, ArrayRef<Register> DstRegs,
Register SrcReg, LLT SrcTy, LLT PartTy,
unsigned ExtendOp = TargetOpcode::G_ANYEXT) {
// We could just insert a regular copy, but this is unreachable at the moment.
assert(SrcTy != PartTy && "identical part types shouldn't reach here");
const unsigned PartSize = PartTy.getSizeInBits();
if (PartTy.isVector() == SrcTy.isVector() &&
PartTy.getScalarSizeInBits() > SrcTy.getScalarSizeInBits()) {
assert(DstRegs.size() == 1);
B.buildInstr(ExtendOp, {DstRegs[0]}, {SrcReg});
if (SrcTy.isVector() && !PartTy.isVector() &&
PartSize > SrcTy.getElementType().getSizeInBits()) {
// Vector was scalarized, and the elements extended.
auto UnmergeToEltTy = B.buildUnmerge(SrcTy.getElementType(), SrcReg);
for (int i = 0, e = DstRegs.size(); i != e; ++i)
B.buildAnyExt(DstRegs[i], UnmergeToEltTy.getReg(i));
if (SrcTy.isVector() && PartTy.isVector() &&
PartTy.getScalarSizeInBits() == SrcTy.getScalarSizeInBits() &&
SrcTy.getNumElements() < PartTy.getNumElements()) {
// A coercion like: v2f32 -> v4f32.
Register DstReg = DstRegs.front();
B.buildPadVectorWithUndefElements(DstReg, SrcReg);
LLT GCDTy = getGCDType(SrcTy, PartTy);
if (GCDTy == PartTy) {
// If this already evenly divisible, we can create a simple unmerge.
B.buildUnmerge(DstRegs, SrcReg);
MachineRegisterInfo &MRI = *B.getMRI();
LLT DstTy = MRI.getType(DstRegs[0]);
LLT LCMTy = getCoverTy(SrcTy, PartTy);
if (PartTy.isVector() && LCMTy == PartTy) {
assert(DstRegs.size() == 1);
B.buildPadVectorWithUndefElements(DstRegs[0], SrcReg);
const unsigned DstSize = DstTy.getSizeInBits();
const unsigned SrcSize = SrcTy.getSizeInBits();
unsigned CoveringSize = LCMTy.getSizeInBits();
Register UnmergeSrc = SrcReg;
if (!LCMTy.isVector() && CoveringSize != SrcSize) {
// For scalars, it's common to be able to use a simple extension.
if (SrcTy.isScalar() && DstTy.isScalar()) {
CoveringSize = alignTo(SrcSize, DstSize);
LLT CoverTy = LLT::scalar(CoveringSize);
UnmergeSrc = B.buildInstr(ExtendOp, {CoverTy}, {SrcReg}).getReg(0);
} else {
// Widen to the common type.
// FIXME: This should respect the extend type
Register Undef = B.buildUndef(SrcTy).getReg(0);
SmallVector<Register, 8> MergeParts(1, SrcReg);
for (unsigned Size = SrcSize; Size != CoveringSize; Size += SrcSize)
UnmergeSrc = B.buildMergeLikeInstr(LCMTy, MergeParts).getReg(0);
if (LCMTy.isVector() && CoveringSize != SrcSize)
UnmergeSrc = B.buildPadVectorWithUndefElements(LCMTy, SrcReg).getReg(0);
B.buildUnmerge(DstRegs, UnmergeSrc);
bool CallLowering::determineAndHandleAssignments(
ValueHandler &Handler, ValueAssigner &Assigner,
SmallVectorImpl<ArgInfo> &Args, MachineIRBuilder &MIRBuilder,
CallingConv::ID CallConv, bool IsVarArg,
ArrayRef<Register> ThisReturnRegs) const {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, F.getContext());
if (!determineAssignments(Assigner, Args, CCInfo))
return false;
return handleAssignments(Handler, Args, CCInfo, ArgLocs, MIRBuilder,
static unsigned extendOpFromFlags(llvm::ISD::ArgFlagsTy Flags) {
if (Flags.isSExt())
return TargetOpcode::G_SEXT;
if (Flags.isZExt())
return TargetOpcode::G_ZEXT;
return TargetOpcode::G_ANYEXT;
bool CallLowering::determineAssignments(ValueAssigner &Assigner,
SmallVectorImpl<ArgInfo> &Args,
CCState &CCInfo) const {
LLVMContext &Ctx = CCInfo.getContext();
const CallingConv::ID CallConv = CCInfo.getCallingConv();
unsigned NumArgs = Args.size();
for (unsigned i = 0; i != NumArgs; ++i) {
EVT CurVT = EVT::getEVT(Args[i].Ty);
MVT NewVT = TLI->getRegisterTypeForCallingConv(Ctx, CallConv, CurVT);
// If we need to split the type over multiple regs, check it's a scenario
// we currently support.
unsigned NumParts =
TLI->getNumRegistersForCallingConv(Ctx, CallConv, CurVT);
if (NumParts == 1) {
// Try to use the register type if we couldn't assign the VT.
if (Assigner.assignArg(i, CurVT, NewVT, NewVT, CCValAssign::Full, Args[i],
Args[i].Flags[0], CCInfo))
return false;
// For incoming arguments (physregs to vregs), we could have values in
// physregs (or memlocs) which we want to extract and copy to vregs.
// During this, we might have to deal with the LLT being split across
// multiple regs, so we have to record this information for later.
// If we have outgoing args, then we have the opposite case. We have a
// vreg with an LLT which we want to assign to a physical location, and
// we might have to record that the value has to be split later.
// We're handling an incoming arg which is split over multiple regs.
// E.g. passing an s128 on AArch64.
ISD::ArgFlagsTy OrigFlags = Args[i].Flags[0];
for (unsigned Part = 0; Part < NumParts; ++Part) {
ISD::ArgFlagsTy Flags = OrigFlags;
if (Part == 0) {
} else {
if (Part == NumParts - 1)
if (Assigner.assignArg(i, CurVT, NewVT, NewVT, CCValAssign::Full, Args[i],
Args[i].Flags[Part], CCInfo)) {
// Still couldn't assign this smaller part type for some reason.
return false;
return true;
bool CallLowering::handleAssignments(ValueHandler &Handler,
SmallVectorImpl<ArgInfo> &Args,
CCState &CCInfo,
SmallVectorImpl<CCValAssign> &ArgLocs,
MachineIRBuilder &MIRBuilder,
ArrayRef<Register> ThisReturnRegs) const {
MachineFunction &MF = MIRBuilder.getMF();
MachineRegisterInfo &MRI = MF.getRegInfo();
const Function &F = MF.getFunction();
const DataLayout &DL = F.getParent()->getDataLayout();
const unsigned NumArgs = Args.size();
// Stores thunks for outgoing register assignments. This is used so we delay
// generating register copies until mem loc assignments are done. We do this
// so that if the target is using the delayed stack protector feature, we can
// find the split point of the block accurately. E.g. if we have:
// G_STORE %val, %memloc
// $x0 = COPY %foo
// $x1 = COPY %bar
// CALL func
// ... then the split point for the block will correctly be at, and including,
// the copy to $x0. If instead the G_STORE instruction immediately precedes
// the CALL, then we'd prematurely choose the CALL as the split point, thus
// generating a split block with a CALL that uses undefined physregs.
SmallVector<std::function<void()>> DelayedOutgoingRegAssignments;
for (unsigned i = 0, j = 0; i != NumArgs; ++i, ++j) {
assert(j < ArgLocs.size() && "Skipped too many arg locs");
CCValAssign &VA = ArgLocs[j];
assert(VA.getValNo() == i && "Location doesn't correspond to current arg");
if (VA.needsCustom()) {
std::function<void()> Thunk;
unsigned NumArgRegs = Handler.assignCustomValue(
Args[i], ArrayRef(ArgLocs).slice(j), &Thunk);
if (Thunk)
if (!NumArgRegs)
return false;
j += NumArgRegs;
const MVT ValVT = VA.getValVT();
const MVT LocVT = VA.getLocVT();
const LLT LocTy(LocVT);
const LLT ValTy(ValVT);
const LLT NewLLT = Handler.isIncomingArgumentHandler() ? LocTy : ValTy;
const EVT OrigVT = EVT::getEVT(Args[i].Ty);
const LLT OrigTy = getLLTForType(*Args[i].Ty, DL);
// Expected to be multiple regs for a single incoming arg.
// There should be Regs.size() ArgLocs per argument.
// This should be the same as getNumRegistersForCallingConv
const unsigned NumParts = Args[i].Flags.size();
// Now split the registers into the assigned types.
Args[i].OrigRegs.assign(Args[i].Regs.begin(), Args[i].Regs.end());
if (NumParts != 1 || NewLLT != OrigTy) {
// If we can't directly assign the register, we need one or more
// intermediate values.
// For each split register, create and assign a vreg that will store
// the incoming component of the larger value. These will later be
// merged to form the final vreg.
for (unsigned Part = 0; Part < NumParts; ++Part)
Args[i].Regs[Part] = MRI.createGenericVirtualRegister(NewLLT);
assert((j + (NumParts - 1)) < ArgLocs.size() &&
"Too many regs for number of args");
// Coerce into outgoing value types before register assignment.
if (!Handler.isIncomingArgumentHandler() && OrigTy != ValTy) {
assert(Args[i].OrigRegs.size() == 1);
buildCopyToRegs(MIRBuilder, Args[i].Regs, Args[i].OrigRegs[0], OrigTy,
ValTy, extendOpFromFlags(Args[i].Flags[0]));
bool BigEndianPartOrdering = TLI->hasBigEndianPartOrdering(OrigVT, DL);
for (unsigned Part = 0; Part < NumParts; ++Part) {
Register ArgReg = Args[i].Regs[Part];
// There should be Regs.size() ArgLocs per argument.
unsigned Idx = BigEndianPartOrdering ? NumParts - 1 - Part : Part;
CCValAssign &VA = ArgLocs[j + Idx];
const ISD::ArgFlagsTy Flags = Args[i].Flags[Part];
if (VA.isMemLoc() && !Flags.isByVal()) {
// Individual pieces may have been spilled to the stack and others
// passed in registers.
// TODO: The memory size may be larger than the value we need to
// store. We may need to adjust the offset for big endian targets.
LLT MemTy = Handler.getStackValueStoreType(DL, VA, Flags);
MachinePointerInfo MPO;
Register StackAddr = Handler.getStackAddress(
MemTy.getSizeInBytes(), VA.getLocMemOffset(), MPO, Flags);
Handler.assignValueToAddress(Args[i], Part, StackAddr, MemTy, MPO, VA);
if (VA.isMemLoc() && Flags.isByVal()) {
assert(Args[i].Regs.size() == 1 &&
"didn't expect split byval pointer");
if (Handler.isIncomingArgumentHandler()) {
// We just need to copy the frame index value to the pointer.
MachinePointerInfo MPO;
Register StackAddr = Handler.getStackAddress(
Flags.getByValSize(), VA.getLocMemOffset(), MPO, Flags);
MIRBuilder.buildCopy(Args[i].Regs[0], StackAddr);
} else {
// For outgoing byval arguments, insert the implicit copy byval
// implies, such that writes in the callee do not modify the caller's
// value.
uint64_t MemSize = Flags.getByValSize();
int64_t Offset = VA.getLocMemOffset();
MachinePointerInfo DstMPO;
Register StackAddr =
Handler.getStackAddress(MemSize, Offset, DstMPO, Flags);
MachinePointerInfo SrcMPO(Args[i].OrigValue);
if (!Args[i].OrigValue) {
// We still need to accurately track the stack address space if we
// don't know the underlying value.
const LLT PtrTy = MRI.getType(StackAddr);
SrcMPO = MachinePointerInfo(PtrTy.getAddressSpace());
Align DstAlign = std::max(Flags.getNonZeroByValAlign(),
inferAlignFromPtrInfo(MF, DstMPO));
Align SrcAlign = std::max(Flags.getNonZeroByValAlign(),
inferAlignFromPtrInfo(MF, SrcMPO));
Handler.copyArgumentMemory(Args[i], StackAddr, Args[i].Regs[0],
DstMPO, DstAlign, SrcMPO, SrcAlign,
MemSize, VA);
assert(!VA.needsCustom() && "custom loc should have been handled already");
if (i == 0 && !ThisReturnRegs.empty() &&
Handler.isIncomingArgumentHandler() &&
isTypeIsValidForThisReturn(ValVT)) {
Handler.assignValueToReg(ArgReg, ThisReturnRegs[Part], VA);
if (Handler.isIncomingArgumentHandler())
Handler.assignValueToReg(ArgReg, VA.getLocReg(), VA);
else {
DelayedOutgoingRegAssignments.emplace_back([=, &Handler]() {
Handler.assignValueToReg(ArgReg, VA.getLocReg(), VA);
// Now that all pieces have been assigned, re-pack the register typed values
// into the original value typed registers.
if (Handler.isIncomingArgumentHandler() && OrigVT != LocVT) {
// Merge the split registers into the expected larger result vregs of
// the original call.
buildCopyFromRegs(MIRBuilder, Args[i].OrigRegs, Args[i].Regs, OrigTy,
LocTy, Args[i].Flags[0]);
j += NumParts - 1;
for (auto &Fn : DelayedOutgoingRegAssignments)
return true;
void CallLowering::insertSRetLoads(MachineIRBuilder &MIRBuilder, Type *RetTy,
ArrayRef<Register> VRegs, Register DemoteReg,
int FI) const {
MachineFunction &MF = MIRBuilder.getMF();
MachineRegisterInfo &MRI = MF.getRegInfo();
const DataLayout &DL = MF.getDataLayout();
SmallVector<EVT, 4> SplitVTs;
SmallVector<uint64_t, 4> Offsets;
ComputeValueVTs(*TLI, DL, RetTy, SplitVTs, &Offsets, 0);
assert(VRegs.size() == SplitVTs.size());
unsigned NumValues = SplitVTs.size();
Align BaseAlign = DL.getPrefTypeAlign(RetTy);
Type *RetPtrTy = RetTy->getPointerTo(DL.getAllocaAddrSpace());
LLT OffsetLLTy = getLLTForType(*DL.getIndexType(RetPtrTy), DL);
MachinePointerInfo PtrInfo = MachinePointerInfo::getFixedStack(MF, FI);
for (unsigned I = 0; I < NumValues; ++I) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, DemoteReg, OffsetLLTy, Offsets[I]);
auto *MMO = MF.getMachineMemOperand(PtrInfo, MachineMemOperand::MOLoad,
commonAlignment(BaseAlign, Offsets[I]));
MIRBuilder.buildLoad(VRegs[I], Addr, *MMO);
void CallLowering::insertSRetStores(MachineIRBuilder &MIRBuilder, Type *RetTy,
ArrayRef<Register> VRegs,
Register DemoteReg) const {
MachineFunction &MF = MIRBuilder.getMF();
MachineRegisterInfo &MRI = MF.getRegInfo();
const DataLayout &DL = MF.getDataLayout();
SmallVector<EVT, 4> SplitVTs;
SmallVector<uint64_t, 4> Offsets;
ComputeValueVTs(*TLI, DL, RetTy, SplitVTs, &Offsets, 0);
assert(VRegs.size() == SplitVTs.size());
unsigned NumValues = SplitVTs.size();
Align BaseAlign = DL.getPrefTypeAlign(RetTy);
unsigned AS = DL.getAllocaAddrSpace();
LLT OffsetLLTy = getLLTForType(*DL.getIndexType(RetTy->getPointerTo(AS)), DL);
MachinePointerInfo PtrInfo(AS);
for (unsigned I = 0; I < NumValues; ++I) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, DemoteReg, OffsetLLTy, Offsets[I]);
auto *MMO = MF.getMachineMemOperand(PtrInfo, MachineMemOperand::MOStore,
commonAlignment(BaseAlign, Offsets[I]));
MIRBuilder.buildStore(VRegs[I], Addr, *MMO);
void CallLowering::insertSRetIncomingArgument(
const Function &F, SmallVectorImpl<ArgInfo> &SplitArgs, Register &DemoteReg,
MachineRegisterInfo &MRI, const DataLayout &DL) const {
unsigned AS = DL.getAllocaAddrSpace();
DemoteReg = MRI.createGenericVirtualRegister(
LLT::pointer(AS, DL.getPointerSizeInBits(AS)));
Type *PtrTy = PointerType::get(F.getReturnType(), AS);
SmallVector<EVT, 1> ValueVTs;
ComputeValueVTs(*TLI, DL, PtrTy, ValueVTs);
// NOTE: Assume that a pointer won't get split into more than one VT.
assert(ValueVTs.size() == 1);
ArgInfo DemoteArg(DemoteReg, ValueVTs[0].getTypeForEVT(PtrTy->getContext()),
setArgFlags(DemoteArg, AttributeList::ReturnIndex, DL, F);
SplitArgs.insert(SplitArgs.begin(), DemoteArg);
void CallLowering::insertSRetOutgoingArgument(MachineIRBuilder &MIRBuilder,
const CallBase &CB,
CallLoweringInfo &Info) const {
const DataLayout &DL = MIRBuilder.getDataLayout();
Type *RetTy = CB.getType();
unsigned AS = DL.getAllocaAddrSpace();
LLT FramePtrTy = LLT::pointer(AS, DL.getPointerSizeInBits(AS));
int FI = MIRBuilder.getMF().getFrameInfo().CreateStackObject(
DL.getTypeAllocSize(RetTy), DL.getPrefTypeAlign(RetTy), false);
Register DemoteReg = MIRBuilder.buildFrameIndex(FramePtrTy, FI).getReg(0);
ArgInfo DemoteArg(DemoteReg, PointerType::get(RetTy, AS),
setArgFlags(DemoteArg, AttributeList::ReturnIndex, DL, CB);
Info.OrigArgs.insert(Info.OrigArgs.begin(), DemoteArg);
Info.DemoteStackIndex = FI;
Info.DemoteRegister = DemoteReg;
bool CallLowering::checkReturn(CCState &CCInfo,
SmallVectorImpl<BaseArgInfo> &Outs,
CCAssignFn *Fn) const {
for (unsigned I = 0, E = Outs.size(); I < E; ++I) {
MVT VT = MVT::getVT(Outs[I].Ty);
if (Fn(I, VT, VT, CCValAssign::Full, Outs[I].Flags[0], CCInfo))
return false;
return true;
void CallLowering::getReturnInfo(CallingConv::ID CallConv, Type *RetTy,
AttributeList Attrs,
SmallVectorImpl<BaseArgInfo> &Outs,
const DataLayout &DL) const {
LLVMContext &Context = RetTy->getContext();
ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy();
SmallVector<EVT, 4> SplitVTs;
ComputeValueVTs(*TLI, DL, RetTy, SplitVTs);
addArgFlagsFromAttributes(Flags, Attrs, AttributeList::ReturnIndex);
for (EVT VT : SplitVTs) {
unsigned NumParts =
TLI->getNumRegistersForCallingConv(Context, CallConv, VT);
MVT RegVT = TLI->getRegisterTypeForCallingConv(Context, CallConv, VT);
Type *PartTy = EVT(RegVT).getTypeForEVT(Context);
for (unsigned I = 0; I < NumParts; ++I) {
Outs.emplace_back(PartTy, Flags);
bool CallLowering::checkReturnTypeForCallConv(MachineFunction &MF) const {
const auto &F = MF.getFunction();
Type *ReturnType = F.getReturnType();
CallingConv::ID CallConv = F.getCallingConv();
SmallVector<BaseArgInfo, 4> SplitArgs;
getReturnInfo(CallConv, ReturnType, F.getAttributes(), SplitArgs,
return canLowerReturn(MF, CallConv, SplitArgs, F.isVarArg());
bool CallLowering::parametersInCSRMatch(
const MachineRegisterInfo &MRI, const uint32_t *CallerPreservedMask,
const SmallVectorImpl<CCValAssign> &OutLocs,
const SmallVectorImpl<ArgInfo> &OutArgs) const {
for (unsigned i = 0; i < OutLocs.size(); ++i) {
const auto &ArgLoc = OutLocs[i];
// If it's not a register, it's fine.
if (!ArgLoc.isRegLoc())
MCRegister PhysReg = ArgLoc.getLocReg();
// Only look at callee-saved registers.
if (MachineOperand::clobbersPhysReg(CallerPreservedMask, PhysReg))
<< "... Call has an argument passed in a callee-saved register.\n");
// Check if it was copied from.
const ArgInfo &OutInfo = OutArgs[i];
if (OutInfo.Regs.size() > 1) {
dbgs() << "... Cannot handle arguments in multiple registers.\n");
return false;
// Check if we copy the register, walking through copies from virtual
// registers. Note that getDefIgnoringCopies does not ignore copies from
// physical registers.
MachineInstr *RegDef = getDefIgnoringCopies(OutInfo.Regs[0], MRI);
if (!RegDef || RegDef->getOpcode() != TargetOpcode::COPY) {
<< "... Parameter was not copied into a VReg, cannot tail call.\n");
return false;
// Got a copy. Verify that it's the same as the register we want.
Register CopyRHS = RegDef->getOperand(1).getReg();
if (CopyRHS != PhysReg) {
LLVM_DEBUG(dbgs() << "... Callee-saved register was not copied into "
"VReg, cannot tail call.\n");
return false;
return true;
bool CallLowering::resultsCompatible(CallLoweringInfo &Info,
MachineFunction &MF,
SmallVectorImpl<ArgInfo> &InArgs,
ValueAssigner &CalleeAssigner,
ValueAssigner &CallerAssigner) const {
const Function &F = MF.getFunction();
CallingConv::ID CalleeCC = Info.CallConv;
CallingConv::ID CallerCC = F.getCallingConv();
if (CallerCC == CalleeCC)
return true;
SmallVector<CCValAssign, 16> ArgLocs1;
CCState CCInfo1(CalleeCC, Info.IsVarArg, MF, ArgLocs1, F.getContext());
if (!determineAssignments(CalleeAssigner, InArgs, CCInfo1))
return false;
SmallVector<CCValAssign, 16> ArgLocs2;
CCState CCInfo2(CallerCC, F.isVarArg(), MF, ArgLocs2, F.getContext());
if (!determineAssignments(CallerAssigner, InArgs, CCInfo2))
return false;
// We need the argument locations to match up exactly. If there's more in
// one than the other, then we are done.
if (ArgLocs1.size() != ArgLocs2.size())
return false;
// Make sure that each location is passed in exactly the same way.
for (unsigned i = 0, e = ArgLocs1.size(); i < e; ++i) {
const CCValAssign &Loc1 = ArgLocs1[i];
const CCValAssign &Loc2 = ArgLocs2[i];
// We need both of them to be the same. So if one is a register and one
// isn't, we're done.
if (Loc1.isRegLoc() != Loc2.isRegLoc())
return false;
if (Loc1.isRegLoc()) {
// If they don't have the same register location, we're done.
if (Loc1.getLocReg() != Loc2.getLocReg())
return false;
// They matched, so we can move to the next ArgLoc.
// Loc1 wasn't a RegLoc, so they both must be MemLocs. Check if they match.
if (Loc1.getLocMemOffset() != Loc2.getLocMemOffset())
return false;
return true;
LLT CallLowering::ValueHandler::getStackValueStoreType(
const DataLayout &DL, const CCValAssign &VA, ISD::ArgFlagsTy Flags) const {
const MVT ValVT = VA.getValVT();
if (ValVT != MVT::iPTR) {
LLT ValTy(ValVT);
// We lost the pointeriness going through CCValAssign, so try to restore it
// based on the flags.
if (Flags.isPointer()) {
LLT PtrTy = LLT::pointer(Flags.getPointerAddrSpace(),
if (ValVT.isVector())
return LLT::vector(ValTy.getElementCount(), PtrTy);
return PtrTy;
return ValTy;
unsigned AddrSpace = Flags.getPointerAddrSpace();
return LLT::pointer(AddrSpace, DL.getPointerSize(AddrSpace));
void CallLowering::ValueHandler::copyArgumentMemory(
const ArgInfo &Arg, Register DstPtr, Register SrcPtr,
const MachinePointerInfo &DstPtrInfo, Align DstAlign,
const MachinePointerInfo &SrcPtrInfo, Align SrcAlign, uint64_t MemSize,
CCValAssign &VA) const {
MachineFunction &MF = MIRBuilder.getMF();
MachineMemOperand *SrcMMO = MF.getMachineMemOperand(
MachineMemOperand::MOLoad | MachineMemOperand::MODereferenceable, MemSize,
MachineMemOperand *DstMMO = MF.getMachineMemOperand(
MachineMemOperand::MOStore | MachineMemOperand::MODereferenceable,
MemSize, DstAlign);
const LLT PtrTy = MRI.getType(DstPtr);
const LLT SizeTy = LLT::scalar(PtrTy.getSizeInBits());
auto SizeConst = MIRBuilder.buildConstant(SizeTy, MemSize);
MIRBuilder.buildMemCpy(DstPtr, SrcPtr, SizeConst, *DstMMO, *SrcMMO);
Register CallLowering::ValueHandler::extendRegister(Register ValReg,
CCValAssign &VA,
unsigned MaxSizeBits) {
LLT LocTy{VA.getLocVT()};
LLT ValTy{VA.getValVT()};
if (LocTy.getSizeInBits() == ValTy.getSizeInBits())
return ValReg;
if (LocTy.isScalar() && MaxSizeBits && MaxSizeBits < LocTy.getSizeInBits()) {
if (MaxSizeBits <= ValTy.getSizeInBits())
return ValReg;
LocTy = LLT::scalar(MaxSizeBits);
const LLT ValRegTy = MRI.getType(ValReg);
if (ValRegTy.isPointer()) {
// The x32 ABI wants to zero extend 32-bit pointers to 64-bit registers, so
// we have to cast to do the extension.
LLT IntPtrTy = LLT::scalar(ValRegTy.getSizeInBits());
ValReg = MIRBuilder.buildPtrToInt(IntPtrTy, ValReg).getReg(0);
switch (VA.getLocInfo()) {
default: break;
case CCValAssign::Full:
case CCValAssign::BCvt:
// FIXME: bitconverting between vector types may or may not be a
// nop in big-endian situations.
return ValReg;
case CCValAssign::AExt: {
auto MIB = MIRBuilder.buildAnyExt(LocTy, ValReg);
return MIB.getReg(0);
case CCValAssign::SExt: {
Register NewReg = MRI.createGenericVirtualRegister(LocTy);
MIRBuilder.buildSExt(NewReg, ValReg);
return NewReg;
case CCValAssign::ZExt: {
Register NewReg = MRI.createGenericVirtualRegister(LocTy);
MIRBuilder.buildZExt(NewReg, ValReg);
return NewReg;
llvm_unreachable("unable to extend register");
void CallLowering::ValueAssigner::anchor() {}
Register CallLowering::IncomingValueHandler::buildExtensionHint(CCValAssign &VA,
Register SrcReg,
LLT NarrowTy) {
switch (VA.getLocInfo()) {
case CCValAssign::LocInfo::ZExt: {
return MIRBuilder
.buildAssertZExt(MRI.cloneVirtualRegister(SrcReg), SrcReg,
case CCValAssign::LocInfo::SExt: {
return MIRBuilder
.buildAssertSExt(MRI.cloneVirtualRegister(SrcReg), SrcReg,
return SrcReg;
/// Check if we can use a basic COPY instruction between the two types.
/// We're currently building on top of the infrastructure using MVT, which loses
/// pointer information in the CCValAssign. We accept copies from physical
/// registers that have been reported as integers if it's to an equivalent sized
/// pointer LLT.
static bool isCopyCompatibleType(LLT SrcTy, LLT DstTy) {
if (SrcTy == DstTy)
return true;
if (SrcTy.getSizeInBits() != DstTy.getSizeInBits())
return false;
SrcTy = SrcTy.getScalarType();
DstTy = DstTy.getScalarType();
return (SrcTy.isPointer() && DstTy.isScalar()) ||
(DstTy.isPointer() && SrcTy.isScalar());
void CallLowering::IncomingValueHandler::assignValueToReg(Register ValVReg,
Register PhysReg,
CCValAssign VA) {
const MVT LocVT = VA.getLocVT();
const LLT LocTy(LocVT);
const LLT RegTy = MRI.getType(ValVReg);
if (isCopyCompatibleType(RegTy, LocTy)) {
MIRBuilder.buildCopy(ValVReg, PhysReg);
auto Copy = MIRBuilder.buildCopy(LocTy, PhysReg);
auto Hint = buildExtensionHint(VA, Copy.getReg(0), RegTy);
MIRBuilder.buildTrunc(ValVReg, Hint);