1//===-- SystemZTargetMachine.cpp - Define TargetMachine for SystemZ -------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "SystemZTargetMachine.h"
11#include "SystemZTargetTransformInfo.h"
12#include "llvm/CodeGen/Passes.h"
13#include "llvm/Support/TargetRegistry.h"
14#include "llvm/Transforms/Scalar.h"
15#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
16
17using namespace llvm;
18
19extern "C" void LLVMInitializeSystemZTarget() {
20  // Register the target.
21  RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
22}
23
24SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
25                                           StringRef CPU, StringRef FS,
26                                           const TargetOptions &Options,
27                                           Reloc::Model RM, CodeModel::Model CM,
28                                           CodeGenOpt::Level OL)
29    // Make sure that global data has at least 16 bits of alignment by
30    // default, so that we can refer to it using LARL.  We don't have any
31    // special requirements for stack variables though.
32    : LLVMTargetMachine(T, "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-a:8:16-n32:64",
33                        TT, CPU, FS, Options, RM, CM, OL),
34      TLOF(make_unique<TargetLoweringObjectFileELF>()),
35      Subtarget(TT, CPU, FS, *this) {
36  initAsmInfo();
37}
38
39SystemZTargetMachine::~SystemZTargetMachine() {}
40
41namespace {
42/// SystemZ Code Generator Pass Configuration Options.
43class SystemZPassConfig : public TargetPassConfig {
44public:
45  SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
46    : TargetPassConfig(TM, PM) {}
47
48  SystemZTargetMachine &getSystemZTargetMachine() const {
49    return getTM<SystemZTargetMachine>();
50  }
51
52  void addIRPasses() override;
53  bool addInstSelector() override;
54  void addPreSched2() override;
55  void addPreEmitPass() override;
56};
57} // end anonymous namespace
58
59void SystemZPassConfig::addIRPasses() {
60  TargetPassConfig::addIRPasses();
61}
62
63bool SystemZPassConfig::addInstSelector() {
64  addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
65
66 if (getOptLevel() != CodeGenOpt::None)
67    addPass(createSystemZLDCleanupPass(getSystemZTargetMachine()));
68
69  return false;
70}
71
72void SystemZPassConfig::addPreSched2() {
73  if (getOptLevel() != CodeGenOpt::None &&
74      getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
75    addPass(&IfConverterID);
76}
77
78void SystemZPassConfig::addPreEmitPass() {
79  // We eliminate comparisons here rather than earlier because some
80  // transformations can change the set of available CC values and we
81  // generally want those transformations to have priority.  This is
82  // especially true in the commonest case where the result of the comparison
83  // is used by a single in-range branch instruction, since we will then
84  // be able to fuse the compare and the branch instead.
85  //
86  // For example, two-address NILF can sometimes be converted into
87  // three-address RISBLG.  NILF produces a CC value that indicates whether
88  // the low word is zero, but RISBLG does not modify CC at all.  On the
89  // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
90  // The CC value produced by NILL isn't useful for our purposes, but the
91  // value produced by RISBG can be used for any comparison with zero
92  // (not just equality).  So there are some transformations that lose
93  // CC values (while still being worthwhile) and others that happen to make
94  // the CC result more useful than it was originally.
95  //
96  // Another reason is that we only want to use BRANCH ON COUNT in cases
97  // where we know that the count register is not going to be spilled.
98  //
99  // Doing it so late makes it more likely that a register will be reused
100  // between the comparison and the branch, but it isn't clear whether
101  // preventing that would be a win or not.
102  if (getOptLevel() != CodeGenOpt::None)
103    addPass(createSystemZElimComparePass(getSystemZTargetMachine()), false);
104  if (getOptLevel() != CodeGenOpt::None)
105    addPass(createSystemZShortenInstPass(getSystemZTargetMachine()), false);
106  addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
107}
108
109TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
110  return new SystemZPassConfig(this, PM);
111}
112
113TargetIRAnalysis SystemZTargetMachine::getTargetIRAnalysis() {
114  return TargetIRAnalysis([this](Function &F) {
115    return TargetTransformInfo(SystemZTTIImpl(this, F));
116  });
117}
118