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//===-- SystemZTargetMachine.cpp - Define TargetMachine for SystemZ -------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "SystemZTargetMachine.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
using namespace llvm;
extern "C" void LLVMInitializeSystemZTarget() {
// Register the target.
RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
}
SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Reloc::Model RM, CodeModel::Model CM,
CodeGenOpt::Level OL)
: LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
TLOF(make_unique<TargetLoweringObjectFileELF>()),
Subtarget(TT, CPU, FS, *this) {
initAsmInfo();
}
SystemZTargetMachine::~SystemZTargetMachine() {}
namespace {
/// SystemZ Code Generator Pass Configuration Options.
class SystemZPassConfig : public TargetPassConfig {
public:
SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
: TargetPassConfig(TM, PM) {}
SystemZTargetMachine &getSystemZTargetMachine() const {
return getTM<SystemZTargetMachine>();
}
void addIRPasses() override;
bool addInstSelector() override;
bool addPreSched2() override;
bool addPreEmitPass() override;
};
} // end anonymous namespace
void SystemZPassConfig::addIRPasses() {
TargetPassConfig::addIRPasses();
}
bool SystemZPassConfig::addInstSelector() {
addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
return false;
}
bool SystemZPassConfig::addPreSched2() {
if (getOptLevel() != CodeGenOpt::None &&
getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
addPass(&IfConverterID);
return true;
}
bool SystemZPassConfig::addPreEmitPass() {
// 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()));
if (getOptLevel() != CodeGenOpt::None)
addPass(createSystemZShortenInstPass(getSystemZTargetMachine()));
addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
return true;
}
TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
return new SystemZPassConfig(this, PM);
}
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