SystemZTargetMachine.cpp revision 263508 
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 "llvm/CodeGen/Passes.h"
12#include "llvm/Support/TargetRegistry.h"
13#include "llvm/Transforms/Scalar.h"
14
15using namespace llvm;
16
17extern "C" void LLVMInitializeSystemZTarget() {
18  // Register the target.
19  RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
20}
21
22SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
23                                           StringRef CPU, StringRef FS,
24                                           const TargetOptions &Options,
25                                           Reloc::Model RM,
26                                           CodeModel::Model CM,
27                                           CodeGenOpt::Level OL)
28  : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
29    Subtarget(TT, CPU, FS),
30    // Make sure that global data has at least 16 bits of alignment by default,
31    // so that we can refer to it using LARL.  We don't have any special
32    // requirements for stack variables though.
33    DL("E-p:64:64:64-i1:8:16-i8:8:16-i16:16-i32:32-i64:64"
34       "-f32:32-f64:64-f128:64-a0:8:16-n32:64"),
35    InstrInfo(*this), TLInfo(*this), TSInfo(*this),
36    FrameLowering(*this, Subtarget) {
37  initAsmInfo();
38}
39
40namespace {
41/// SystemZ Code Generator Pass Configuration Options.
42class SystemZPassConfig : public TargetPassConfig {
43public:
44  SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
45    : TargetPassConfig(TM, PM) {}
46
47  SystemZTargetMachine &getSystemZTargetMachine() const {
48    return getTM<SystemZTargetMachine>();
49  }
50
51  virtual void addIRPasses() LLVM_OVERRIDE;
52  virtual bool addInstSelector() LLVM_OVERRIDE;
53  virtual bool addPreSched2() LLVM_OVERRIDE;
54  virtual bool addPreEmitPass() LLVM_OVERRIDE;
55};
56} // end anonymous namespace
57
58void SystemZPassConfig::addIRPasses() {
59  TargetPassConfig::addIRPasses();
60  addPass(createPartiallyInlineLibCallsPass());
61}
62
63bool SystemZPassConfig::addInstSelector() {
64  addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
65  return false;
66}
67
68bool SystemZPassConfig::addPreSched2() {
69  if (getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
70    addPass(&IfConverterID);
71  return true;
72}
73
74bool SystemZPassConfig::addPreEmitPass() {
75  // We eliminate comparisons here rather than earlier because some
76  // transformations can change the set of available CC values and we
77  // generally want those transformations to have priority.  This is
78  // especially true in the commonest case where the result of the comparison
79  // is used by a single in-range branch instruction, since we will then
80  // be able to fuse the compare and the branch instead.
81  //
82  // For example, two-address NILF can sometimes be converted into
83  // three-address RISBLG.  NILF produces a CC value that indicates whether
84  // the low word is zero, but RISBLG does not modify CC at all.  On the
85  // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
86  // The CC value produced by NILL isn't useful for our purposes, but the
87  // value produced by RISBG can be used for any comparison with zero
88  // (not just equality).  So there are some transformations that lose
89  // CC values (while still being worthwhile) and others that happen to make
90  // the CC result more useful than it was originally.
91  //
92  // Another reason is that we only want to use BRANCH ON COUNT in cases
93  // where we know that the count register is not going to be spilled.
94  //
95  // Doing it so late makes it more likely that a register will be reused
96  // between the comparison and the branch, but it isn't clear whether
97  // preventing that would be a win or not.
98  if (getOptLevel() != CodeGenOpt::None)
99    addPass(createSystemZElimComparePass(getSystemZTargetMachine()));
100  if (getOptLevel() != CodeGenOpt::None)
101    addPass(createSystemZShortenInstPass(getSystemZTargetMachine()));
102  addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
103  return true;
104}
105
106TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
107  return new SystemZPassConfig(this, PM);
108}
109