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
15 using namespace llvm;
16
LLVMInitializeSystemZTarget()17 extern "C" void LLVMInitializeSystemZTarget() {
18 // Register the target.
19 RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
20 }
21
SystemZTargetMachine(const Target & T,StringRef TT,StringRef CPU,StringRef FS,const TargetOptions & Options,Reloc::Model RM,CodeModel::Model CM,CodeGenOpt::Level OL)22 SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
23 StringRef CPU, StringRef FS,
24 const TargetOptions &Options,
25 Reloc::Model RM, CodeModel::Model CM,
26 CodeGenOpt::Level OL)
27 : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
28 Subtarget(TT, CPU, FS, *this) {
29 initAsmInfo();
30 }
31
32 namespace {
33 /// SystemZ Code Generator Pass Configuration Options.
34 class SystemZPassConfig : public TargetPassConfig {
35 public:
SystemZPassConfig(SystemZTargetMachine * TM,PassManagerBase & PM)36 SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
37 : TargetPassConfig(TM, PM) {}
38
getSystemZTargetMachine() const39 SystemZTargetMachine &getSystemZTargetMachine() const {
40 return getTM<SystemZTargetMachine>();
41 }
42
43 void addIRPasses() override;
44 bool addInstSelector() override;
45 bool addPreSched2() override;
46 bool addPreEmitPass() override;
47 };
48 } // end anonymous namespace
49
addIRPasses()50 void SystemZPassConfig::addIRPasses() {
51 TargetPassConfig::addIRPasses();
52 addPass(createPartiallyInlineLibCallsPass());
53 }
54
addInstSelector()55 bool SystemZPassConfig::addInstSelector() {
56 addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
57 return false;
58 }
59
addPreSched2()60 bool SystemZPassConfig::addPreSched2() {
61 if (getOptLevel() != CodeGenOpt::None &&
62 getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
63 addPass(&IfConverterID);
64 return true;
65 }
66
addPreEmitPass()67 bool SystemZPassConfig::addPreEmitPass() {
68 // We eliminate comparisons here rather than earlier because some
69 // transformations can change the set of available CC values and we
70 // generally want those transformations to have priority. This is
71 // especially true in the commonest case where the result of the comparison
72 // is used by a single in-range branch instruction, since we will then
73 // be able to fuse the compare and the branch instead.
74 //
75 // For example, two-address NILF can sometimes be converted into
76 // three-address RISBLG. NILF produces a CC value that indicates whether
77 // the low word is zero, but RISBLG does not modify CC at all. On the
78 // other hand, 64-bit ANDs like NILL can sometimes be converted to RISBG.
79 // The CC value produced by NILL isn't useful for our purposes, but the
80 // value produced by RISBG can be used for any comparison with zero
81 // (not just equality). So there are some transformations that lose
82 // CC values (while still being worthwhile) and others that happen to make
83 // the CC result more useful than it was originally.
84 //
85 // Another reason is that we only want to use BRANCH ON COUNT in cases
86 // where we know that the count register is not going to be spilled.
87 //
88 // Doing it so late makes it more likely that a register will be reused
89 // between the comparison and the branch, but it isn't clear whether
90 // preventing that would be a win or not.
91 if (getOptLevel() != CodeGenOpt::None)
92 addPass(createSystemZElimComparePass(getSystemZTargetMachine()));
93 if (getOptLevel() != CodeGenOpt::None)
94 addPass(createSystemZShortenInstPass(getSystemZTargetMachine()));
95 addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
96 return true;
97 }
98
createPassConfig(PassManagerBase & PM)99 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
100 return new SystemZPassConfig(this, PM);
101 }
102