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
14 using namespace llvm;
15
LLVMInitializeSystemZTarget()16 extern "C" void LLVMInitializeSystemZTarget() {
17 // Register the target.
18 RegisterTargetMachine<SystemZTargetMachine> X(TheSystemZTarget);
19 }
20
SystemZTargetMachine(const Target & T,StringRef TT,StringRef CPU,StringRef FS,const TargetOptions & Options,Reloc::Model RM,CodeModel::Model CM,CodeGenOpt::Level OL)21 SystemZTargetMachine::SystemZTargetMachine(const Target &T, StringRef TT,
22 StringRef CPU, StringRef FS,
23 const TargetOptions &Options,
24 Reloc::Model RM,
25 CodeModel::Model CM,
26 CodeGenOpt::Level OL)
27 : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
28 Subtarget(TT, CPU, FS),
29 // Make sure that global data has at least 16 bits of alignment by default,
30 // so that we can refer to it using LARL. We don't have any special
31 // requirements for stack variables though.
32 DL("E-p:64:64:64-i1:8:16-i8:8:16-i16:16-i32:32-i64:64"
33 "-f32:32-f64:64-f128:64-a0:8:16-n32:64"),
34 InstrInfo(*this), TLInfo(*this), TSInfo(*this),
35 FrameLowering(*this, Subtarget) {
36 initAsmInfo();
37 }
38
39 namespace {
40 /// SystemZ Code Generator Pass Configuration Options.
41 class SystemZPassConfig : public TargetPassConfig {
42 public:
SystemZPassConfig(SystemZTargetMachine * TM,PassManagerBase & PM)43 SystemZPassConfig(SystemZTargetMachine *TM, PassManagerBase &PM)
44 : TargetPassConfig(TM, PM) {}
45
getSystemZTargetMachine() const46 SystemZTargetMachine &getSystemZTargetMachine() const {
47 return getTM<SystemZTargetMachine>();
48 }
49
50 virtual bool addInstSelector() LLVM_OVERRIDE;
51 virtual bool addPreSched2() LLVM_OVERRIDE;
52 virtual bool addPreEmitPass() LLVM_OVERRIDE;
53 };
54 } // end anonymous namespace
55
addInstSelector()56 bool SystemZPassConfig::addInstSelector() {
57 addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
58 return false;
59 }
60
addPreSched2()61 bool SystemZPassConfig::addPreSched2() {
62 if (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 addPass(createSystemZLongBranchPass(getSystemZTargetMachine()));
94 return true;
95 }
96
createPassConfig(PassManagerBase & PM)97 TargetPassConfig *SystemZTargetMachine::createPassConfig(PassManagerBase &PM) {
98 return new SystemZPassConfig(this, PM);
99 }
100