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 "SystemZTargetTransformInfo.h"
12 #include "llvm/CodeGen/Passes.h"
13 #include "llvm/CodeGen/TargetPassConfig.h"
14 #include "llvm/Support/TargetRegistry.h"
15 #include "llvm/Transforms/Scalar.h"
16 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
20 extern cl::opt<bool> MISchedPostRA;
21 extern "C" void LLVMInitializeSystemZTarget() {
22 // Register the target.
23 RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
26 // Determine whether we use the vector ABI.
27 static bool UsesVectorABI(StringRef CPU, StringRef FS) {
28 // We use the vector ABI whenever the vector facility is avaiable.
29 // This is the case by default if CPU is z13 or later, and can be
30 // overridden via "[+-]vector" feature string elements.
31 bool VectorABI = true;
32 if (CPU.empty() || CPU == "generic" ||
33 CPU == "z10" || CPU == "z196" || CPU == "zEC12")
36 SmallVector<StringRef, 3> Features;
37 FS.split(Features, ',', -1, false /* KeepEmpty */);
38 for (auto &Feature : Features) {
39 if (Feature == "vector" || Feature == "+vector")
41 if (Feature == "-vector")
48 static std::string computeDataLayout(const Triple &TT, StringRef CPU,
50 bool VectorABI = UsesVectorABI(CPU, FS);
57 Ret += DataLayout::getManglingComponent(TT);
59 // Make sure that global data has at least 16 bits of alignment by
60 // default, so that we can refer to it using LARL. We don't have any
61 // special requirements for stack variables though.
62 Ret += "-i1:8:16-i8:8:16";
64 // 64-bit integers are naturally aligned.
67 // 128-bit floats are aligned only to 64 bits.
70 // When using the vector ABI, 128-bit vectors are also aligned to 64 bits.
74 // We prefer 16 bits of aligned for all globals; see above.
77 // Integer registers are 32 or 64 bits.
83 static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
84 // Static code is suitable for use in a dynamic executable; there is no
85 // separate DynamicNoPIC model.
86 if (!RM.hasValue() || *RM == Reloc::DynamicNoPIC)
91 SystemZTargetMachine::SystemZTargetMachine(const Target &T, const Triple &TT,
92 StringRef CPU, StringRef FS,
93 const TargetOptions &Options,
94 Optional<Reloc::Model> RM,
97 : LLVMTargetMachine(T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
98 getEffectiveRelocModel(RM), CM, OL),
99 TLOF(make_unique<TargetLoweringObjectFileELF>()),
100 Subtarget(TT, CPU, FS, *this) {
104 SystemZTargetMachine::~SystemZTargetMachine() {}
107 /// SystemZ Code Generator Pass Configuration Options.
108 class SystemZPassConfig : public TargetPassConfig {
110 SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
111 : TargetPassConfig(TM, PM) {}
113 SystemZTargetMachine &getSystemZTargetMachine() const {
114 return getTM<SystemZTargetMachine>();
117 void addIRPasses() override;
118 bool addInstSelector() override;
119 void addPreSched2() override;
120 void addPreEmitPass() override;
122 } // end anonymous namespace
124 void SystemZPassConfig::addIRPasses() {
125 if (getOptLevel() != CodeGenOpt::None)
126 addPass(createSystemZTDCPass());
128 TargetPassConfig::addIRPasses();
131 bool SystemZPassConfig::addInstSelector() {
132 addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
134 if (getOptLevel() != CodeGenOpt::None)
135 addPass(createSystemZLDCleanupPass(getSystemZTargetMachine()));
140 void SystemZPassConfig::addPreSched2() {
141 if (getOptLevel() != CodeGenOpt::None)
142 addPass(&IfConverterID);
145 void SystemZPassConfig::addPreEmitPass() {
147 // Do instruction shortening before compare elimination because some
148 // vector instructions will be shortened into opcodes that compare
149 // elimination recognizes.
150 if (getOptLevel() != CodeGenOpt::None)
151 addPass(createSystemZShortenInstPass(getSystemZTargetMachine()), false);
153 // We eliminate comparisons here rather than earlier because some
154 // transformations can change the set of available CC values and we
155 // generally want those transformations to have priority. This is
156 // especially true in the commonest case where the result of the comparison
157 // is used by a single in-range branch instruction, since we will then
158 // be able to fuse the compare and the branch instead.
160 // For example, two-address NILF can sometimes be converted into
161 // three-address RISBLG. NILF produces a CC value that indicates whether
162 // the low word is zero, but RISBLG does not modify CC at all. On the
163 // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
164 // The CC value produced by NILL isn't useful for our purposes, but the
165 // value produced by RISBG can be used for any comparison with zero
166 // (not just equality). So there are some transformations that lose
167 // CC values (while still being worthwhile) and others that happen to make
168 // the CC result more useful than it was originally.
170 // Another reason is that we only want to use BRANCH ON COUNT in cases
171 // where we know that the count register is not going to be spilled.
173 // Doing it so late makes it more likely that a register will be reused
174 // between the comparison and the branch, but it isn't clear whether
175 // preventing that would be a win or not.
176 if (getOptLevel() != CodeGenOpt::None)
177 addPass(createSystemZElimComparePass(getSystemZTargetMachine()), false);
178 addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
180 // Do final scheduling after all other optimizations, to get an
181 // optimal input for the decoder (branch relaxation must happen
182 // after block placement).
183 if (getOptLevel() != CodeGenOpt::None) {
185 addPass(&PostMachineSchedulerID);
187 addPass(&PostRASchedulerID);
191 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
192 return new SystemZPassConfig(this, PM);
195 TargetIRAnalysis SystemZTargetMachine::getTargetIRAnalysis() {
196 return TargetIRAnalysis([this](const Function &F) {
197 return TargetTransformInfo(SystemZTTIImpl(this, F));