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//===-- SystemZTargetMachine.cpp - Define TargetMachine for SystemZ -------===//
// 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
#include "SystemZTargetMachine.h"
#include "MCTargetDesc/SystemZMCTargetDesc.h"
#include "SystemZ.h"
#include "SystemZMachineScheduler.h"
#include "SystemZTargetTransformInfo.h"
#include "TargetInfo/SystemZTargetInfo.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Transforms/Scalar.h"
#include <string>
using namespace llvm;
extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeSystemZTarget() {
// Register the target.
RegisterTargetMachine<SystemZTargetMachine> X(getTheSystemZTarget());
// Determine whether we use the vector ABI.
static bool UsesVectorABI(StringRef CPU, StringRef FS) {
// We use the vector ABI whenever the vector facility is avaiable.
// This is the case by default if CPU is z13 or later, and can be
// overridden via "[+-]vector" feature string elements.
bool VectorABI = true;
bool SoftFloat = false;
if (CPU.empty() || CPU == "generic" ||
CPU == "z10" || CPU == "z196" || CPU == "zEC12" ||
CPU == "arch8" || CPU == "arch9" || CPU == "arch10")
VectorABI = false;
SmallVector<StringRef, 3> Features;
FS.split(Features, ',', -1, false /* KeepEmpty */);
for (auto &Feature : Features) {
if (Feature == "vector" || Feature == "+vector")
VectorABI = true;
if (Feature == "-vector")
VectorABI = false;
if (Feature == "soft-float" || Feature == "+soft-float")
SoftFloat = true;
if (Feature == "-soft-float")
SoftFloat = false;
return VectorABI && !SoftFloat;
static std::string computeDataLayout(const Triple &TT, StringRef CPU,
StringRef FS) {
bool VectorABI = UsesVectorABI(CPU, FS);
std::string Ret;
// Big endian.
Ret += "E";
// Data mangling.
Ret += DataLayout::getManglingComponent(TT);
// Make sure that global data has at least 16 bits of alignment by
// default, so that we can refer to it using LARL. We don't have any
// special requirements for stack variables though.
Ret += "-i1:8:16-i8:8:16";
// 64-bit integers are naturally aligned.
Ret += "-i64:64";
// 128-bit floats are aligned only to 64 bits.
Ret += "-f128:64";
// When using the vector ABI, 128-bit vectors are also aligned to 64 bits.
if (VectorABI)
Ret += "-v128:64";
// We prefer 16 bits of aligned for all globals; see above.
Ret += "-a:8:16";
// Integer registers are 32 or 64 bits.
Ret += "-n32:64";
return Ret;
static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
// Static code is suitable for use in a dynamic executable; there is no
// separate DynamicNoPIC model.
if (!RM.hasValue() || *RM == Reloc::DynamicNoPIC)
return Reloc::Static;
return *RM;
// For SystemZ we define the models as follows:
// Small: BRASL can call any function and will use a stub if necessary.
// Locally-binding symbols will always be in range of LARL.
// Medium: BRASL can call any function and will use a stub if necessary.
// GOT slots and locally-defined text will always be in range
// of LARL, but other symbols might not be.
// Large: Equivalent to Medium for now.
// Kernel: Equivalent to Medium for now.
// This means that any PIC module smaller than 4GB meets the
// requirements of Small, so Small seems like the best default there.
// All symbols bind locally in a non-PIC module, so the choice is less
// obvious. There are two cases:
// - When creating an executable, PLTs and copy relocations allow
// us to treat external symbols as part of the executable.
// Any executable smaller than 4GB meets the requirements of Small,
// so that seems like the best default.
// - When creating JIT code, stubs will be in range of BRASL if the
// image is less than 4GB in size. GOT entries will likewise be
// in range of LARL. However, the JIT environment has no equivalent
// of copy relocs, so locally-binding data symbols might not be in
// the range of LARL. We need the Medium model in that case.
static CodeModel::Model
getEffectiveSystemZCodeModel(Optional<CodeModel::Model> CM, Reloc::Model RM,
bool JIT) {
if (CM) {
if (*CM == CodeModel::Tiny)
report_fatal_error("Target does not support the tiny CodeModel", false);
if (*CM == CodeModel::Kernel)
report_fatal_error("Target does not support the kernel CodeModel", false);
return *CM;
if (JIT)
return RM == Reloc::PIC_ ? CodeModel::Small : CodeModel::Medium;
return CodeModel::Small;
SystemZTargetMachine::SystemZTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<Reloc::Model> RM,
Optional<CodeModel::Model> CM,
CodeGenOpt::Level OL, bool JIT)
: LLVMTargetMachine(
T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
getEffectiveSystemZCodeModel(CM, getEffectiveRelocModel(RM), JIT),
TLOF(std::make_unique<TargetLoweringObjectFileELF>()) {
SystemZTargetMachine::~SystemZTargetMachine() = default;
const SystemZSubtarget *
SystemZTargetMachine::getSubtargetImpl(const Function &F) const {
Attribute CPUAttr = F.getFnAttribute("target-cpu");
Attribute FSAttr = F.getFnAttribute("target-features");
std::string CPU =
CPUAttr.isValid() ? CPUAttr.getValueAsString().str() : TargetCPU;
std::string FS =
FSAttr.isValid() ? FSAttr.getValueAsString().str() : TargetFS;
// FIXME: This is related to the code below to reset the target options,
// we need to know whether or not the soft float flag is set on the
// function, so we can enable it as a subtarget feature.
bool softFloat = F.getFnAttribute("use-soft-float").getValueAsBool();
if (softFloat)
FS += FS.empty() ? "+soft-float" : ",+soft-float";
auto &I = SubtargetMap[CPU + FS];
if (!I) {
// This needs to be done before we create a new subtarget since any
// creation will depend on the TM and the code generation flags on the
// function that reside in TargetOptions.
I = std::make_unique<SystemZSubtarget>(TargetTriple, CPU, FS, *this);
return I.get();
namespace {
/// SystemZ Code Generator Pass Configuration Options.
class SystemZPassConfig : public TargetPassConfig {
SystemZPassConfig(SystemZTargetMachine &TM, PassManagerBase &PM)
: TargetPassConfig(TM, PM) {}
SystemZTargetMachine &getSystemZTargetMachine() const {
return getTM<SystemZTargetMachine>();
ScheduleDAGInstrs *
createPostMachineScheduler(MachineSchedContext *C) const override {
return new ScheduleDAGMI(C,
void addIRPasses() override;
bool addInstSelector() override;
bool addILPOpts() override;
void addPreRegAlloc() override;
void addPostRewrite() override;
void addPostRegAlloc() override;
void addPreSched2() override;
void addPreEmitPass() override;
} // end anonymous namespace
void SystemZPassConfig::addIRPasses() {
if (getOptLevel() != CodeGenOpt::None) {
bool SystemZPassConfig::addInstSelector() {
addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
if (getOptLevel() != CodeGenOpt::None)
return false;
bool SystemZPassConfig::addILPOpts() {
return true;
void SystemZPassConfig::addPreRegAlloc() {
void SystemZPassConfig::addPostRewrite() {
void SystemZPassConfig::addPostRegAlloc() {
// PostRewrite needs to be run at -O0 also (in which case addPostRewrite()
// is not called).
if (getOptLevel() == CodeGenOpt::None)
void SystemZPassConfig::addPreSched2() {
if (getOptLevel() != CodeGenOpt::None)
void SystemZPassConfig::addPreEmitPass() {
// Do instruction shortening before compare elimination because some
// vector instructions will be shortened into opcodes that compare
// elimination recognizes.
if (getOptLevel() != CodeGenOpt::None)
addPass(createSystemZShortenInstPass(getSystemZTargetMachine()), false);
// We eliminate comparisons here rather than earlier because some
// transformations can change the set of available CC values and we
// generally want those transformations to have priority. This is
// especially true in the commonest case where the result of the comparison
// is used by a single in-range branch instruction, since we will then
// be able to fuse the compare and the branch instead.
// For example, two-address NILF can sometimes be converted into
// three-address RISBLG. NILF produces a CC value that indicates whether
// the low word is zero, but RISBLG does not modify CC at all. On the
// other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
// The CC value produced by NILL isn't useful for our purposes, but the
// value produced by RISBG can be used for any comparison with zero
// (not just equality). So there are some transformations that lose
// CC values (while still being worthwhile) and others that happen to make
// the CC result more useful than it was originally.
// Another reason is that we only want to use BRANCH ON COUNT in cases
// where we know that the count register is not going to be spilled.
// Doing it so late makes it more likely that a register will be reused
// between the comparison and the branch, but it isn't clear whether
// preventing that would be a win or not.
if (getOptLevel() != CodeGenOpt::None)
addPass(createSystemZElimComparePass(getSystemZTargetMachine()), false);
// Do final scheduling after all other optimizations, to get an
// optimal input for the decoder (branch relaxation must happen
// after block placement).
if (getOptLevel() != CodeGenOpt::None)
TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
return new SystemZPassConfig(*this, PM);
SystemZTargetMachine::getTargetTransformInfo(const Function &F) {
return TargetTransformInfo(SystemZTTIImpl(this, F));