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
17 using namespace llvm;
18
LLVMInitializeSystemZTarget()19 extern "C" void LLVMInitializeSystemZTarget() {
20 // Register the target.
21 RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
22 }
23
SystemZTargetMachine(const Target & T,StringRef TT,StringRef CPU,StringRef FS,const TargetOptions & Options,Reloc::Model RM,CodeModel::Model CM,CodeGenOpt::Level OL)24 SystemZTargetMachine::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
~SystemZTargetMachine()39 SystemZTargetMachine::~SystemZTargetMachine() {}
40
41 namespace {
42 /// SystemZ Code Generator Pass Configuration Options.
43 class SystemZPassConfig : public TargetPassConfig {
44 public:
SystemZPassConfig(SystemZTargetMachine * TM,PassManagerBase & PM)45 SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
46 : TargetPassConfig(TM, PM) {}
47
getSystemZTargetMachine() const48 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
addIRPasses()59 void SystemZPassConfig::addIRPasses() {
60 TargetPassConfig::addIRPasses();
61 }
62
addInstSelector()63 bool SystemZPassConfig::addInstSelector() {
64 addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
65
66 if (getOptLevel() != CodeGenOpt::None)
67 addPass(createSystemZLDCleanupPass(getSystemZTargetMachine()));
68
69 return false;
70 }
71
addPreSched2()72 void SystemZPassConfig::addPreSched2() {
73 if (getOptLevel() != CodeGenOpt::None &&
74 getSystemZTargetMachine().getSubtargetImpl()->hasLoadStoreOnCond())
75 addPass(&IfConverterID);
76 }
77
addPreEmitPass()78 void 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
createPassConfig(PassManagerBase & PM)109 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
110 return new SystemZPassConfig(this, PM);
111 }
112
getTargetIRAnalysis()113 TargetIRAnalysis SystemZTargetMachine::getTargetIRAnalysis() {
114 return TargetIRAnalysis([this](Function &F) {
115 return TargetTransformInfo(SystemZTTIImpl(this, F));
116 });
117 }
118