1 //===-- SystemZTargetMachine.cpp - Define TargetMachine for SystemZ -------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "SystemZTargetMachine.h"
11 #include "llvm/CodeGen/Passes.h"
12 #include "llvm/Support/TargetRegistry.h"
13 #include "llvm/Transforms/Scalar.h"
14 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
18 extern "C" void LLVMInitializeSystemZTarget() {
19 // Register the target.
20 RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
23 SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
24 StringRef CPU, StringRef FS,
25 const TargetOptions &Options,
26 Reloc::Model RM, CodeModel::Model CM,
28 : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
29 TLOF(make_unique<TargetLoweringObjectFileELF>()),
30 Subtarget(TT, CPU, FS, *this) {
34 SystemZTargetMachine::~SystemZTargetMachine() {}
37 /// SystemZ Code Generator Pass Configuration Options.
38 class SystemZPassConfig : public TargetPassConfig {
40 SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
41 : TargetPassConfig(TM, PM) {}
43 SystemZTargetMachine &getSystemZTargetMachine() const {
44 return getTM<SystemZTargetMachine>();
47 void addIRPasses() override;
48 bool addInstSelector() override;
49 bool addPreSched2() override;
50 bool addPreEmitPass() override;
52 } // end anonymous namespace
54 void SystemZPassConfig::addIRPasses() {
55 TargetPassConfig::addIRPasses();
58 bool SystemZPassConfig::addInstSelector() {
59 addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
63 bool SystemZPassConfig::addPreSched2() {
64 if (getOptLevel() != CodeGenOpt::None &&
65 getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
66 addPass(&IfConverterID);
70 bool SystemZPassConfig::addPreEmitPass() {
71 // We eliminate comparisons here rather than earlier because some
72 // transformations can change the set of available CC values and we
73 // generally want those transformations to have priority. This is
74 // especially true in the commonest case where the result of the comparison
75 // is used by a single in-range branch instruction, since we will then
76 // be able to fuse the compare and the branch instead.
78 // For example, two-address NILF can sometimes be converted into
79 // three-address RISBLG. NILF produces a CC value that indicates whether
80 // the low word is zero, but RISBLG does not modify CC at all. On the
81 // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
82 // The CC value produced by NILL isn't useful for our purposes, but the
83 // value produced by RISBG can be used for any comparison with zero
84 // (not just equality). So there are some transformations that lose
85 // CC values (while still being worthwhile) and others that happen to make
86 // the CC result more useful than it was originally.
88 // Another reason is that we only want to use BRANCH ON COUNT in cases
89 // where we know that the count register is not going to be spilled.
91 // Doing it so late makes it more likely that a register will be reused
92 // between the comparison and the branch, but it isn't clear whether
93 // preventing that would be a win or not.
94 if (getOptLevel() != CodeGenOpt::None)
95 addPass(createSystemZElimComparePass(getSystemZTargetMachine()));
96 if (getOptLevel() != CodeGenOpt::None)
97 addPass(createSystemZShortenInstPass(getSystemZTargetMachine()));
98 addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
102 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
103 return new SystemZPassConfig(this, PM);