init pass and addpass
Init the pass¶
./include/llvm/PassSupport.h
通过下面的宏定义来生成 所需要的initializePPCEarlyReturnPass函数。
C++
207 INITIALIZE_PASS(PPCEarlyReturn, DEBUG_TYPE,
208 "PowerPC Early-Return Creation", false, false)
Bash
35 #define INITIALIZE_PASS(passName, arg, name, cfg, analysis) \
36 static void *initialize##passName##PassOnce(PassRegistry &Registry) { \
37 PassInfo *PI = new PassInfo( \
38 name, arg, &passName::ID, \
39 PassInfo::NormalCtor_t(callDefaultCtor<passName>), cfg, analysis); \
40 dbgs() << "name = " << name << " PassSupport1\n"; \
41 Registry.registerPass(*PI, true); \
42 return PI; \
43 } \
44 static llvm::once_flag Initialize##passName##PassFlag; \
45 void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
46 dbgs() << "name = " << name << " PassSupport2\n"; \
47 llvm::call_once(Initialize##passName##PassFlag, \
48 initialize##passName##PassOnce, std::ref(Registry)); \
49 }
初始化会注册pass的信息，比如用于调度等stop-afeer=passname
initialize用于注册pass，后面可以使用create类似的方法，通过 addPass进行添加执行。
CodeGen Pass¶
在./include/llvm/InitializePasses.h中声明init函数。通过INITIALIZE_PASS宏进行实现
C++
155 void initializeEarlyCSEMemSSALegacyPassPass(PassRegistry&);
156 void initializeEarlyIfConverterPass(PassRegistry&);
157 void initializeEarlyIfPredicatorPass(PassRegistry &);
158 void initializeEarlyMachineLICMPass(PassRegistry&);
159 void initializeEarlyTailDuplicatePass(PassRegistry&);
160 void initializeEdgeBundlesPass(PassRegistry&);
161 void initializeEliminateAvailableExternallyLegacyPassPass(PassRegistry&);
162 void initializeEntryExitInstrumenterPass(PassRegistry&);
在./lib/CodeGen/CodeGen.cpp中调用init函数对pass进行初始化
C++
21 void llvm::initializeCodeGen(PassRegistry &Registry) {
这些init系列函数是通过调用INITIALIZE_PASS来生成的b
22 initializeAtomicExpandPass(Registry);
23 initializeBranchFolderPassPass(Registry);
24 initializeBranchRelaxationPass(Registry);
25 initializeCFGuardLongjmpPass(Registry);
26 initializeCFIInstrInserterPass(Registry);
27 initializeCodeGenPreparePass(Registry);
28 initializeDeadMachineInstructionElimPass(Registry);
29 initializeDetectDeadLanesPass(Registry);
30 initializeDwarfEHPreparePass(Registry);
31 initializeEarlyIfConverterPass(Registry);
32 initializeEarlyIfPredicatorPass(Registry);
33 initializeEarlyMachineLICMPass(Registry);
34 initializeEarlyTailDuplicatePass(Registry);
...
}
PPC pass¶
lib/Target/PowerPC/PPCEarlyReturn.cpp
C++
207 INITIALIZE_PASS(PPCEarlyReturn, DEBUG_TYPE,
208 "PowerPC Early-Return Creation", false, false)
209
210 char PPCEarlyReturn::ID = 0;
211 FunctionPass*
212 llvm::createPPCEarlyReturnPass() { return new PPCEarlyReturn(); }
C++
49 PPCEarlyReturn() : MachineFunctionPass(ID) {
50 dbgs() << "initializePPCEarlyReturnPass\n";
51 initializePPCEarlyReturnPass(*PassRegistry::getPassRegistry());
52 }
./lib/Target/PowerPC/PPCTargetMachine.cpp
注意PPCEarlyReturnPass未使用PassID,不存在PPCEarlyReturnPass,注册pass时使用addPass(createPPCEarlyReturnPass(), false);。
没有类似下面的赋值,只是初始化为0，未对ID进行任何引用。
Add the pass¶
PPCTargetMachine.cpp
C++
97 extern "C" void LLVMInitializePowerPCTarget() {
98 // Register the targets
99 RegisterTargetMachine<PPCTargetMachine> A(getThePPC32Target());
100 RegisterTargetMachine<PPCTargetMachine> B(getThePPC64Target());
101 RegisterTargetMachine<PPCTargetMachine> C(getThePPC64LETarget());
102
103 PassRegistry &PR = *PassRegistry::getPassRegistry();
104 #ifndef NDEBUG
105 initializePPCCTRLoopsVerifyPass(PR);
106 #endif
107 initializePPCLoopInstrFormPrepPass(PR);
108 initializePPCTOCRegDepsPass(PR);
109 initializePPCEarlyReturnPass(PR);
110 initializePPCVSXCopyPass(PR);
111 initializePPCVSXFMAMutatePass(PR);
112 initializePPCVSXSwapRemovalPass(PR);
113 initializePPCReduceCRLogicalsPass(PR);
114 initializePPCBSelPass(PR);
115 initializePPCBranchCoalescingPass(PR);
116 initializePPCQPXLoadSplatPass(PR);
117 initializePPCBoolRetToIntPass(PR);
118 initializePPCExpandISELPass(PR);
119 initializePPCPreEmitPeepholePass(PR);
120 initializePPCTLSDynamicCallPass(PR);
121 initializePPCMIPeepholePass(PR);
122 initializePPCLowerMASSVEntriesPass(PR);
123 }
522 void PPCPassConfig::addPreEmitPass() {
523 addPass(createPPCPreEmitPeepholePass());
524 addPass(createPPCExpandISELPass());
525
526 if (getOptLevel() != CodeGenOpt::None)
****************************************
527 addPass(createPPCEarlyReturnPass(), false);
****************************************
528 // Must run branch selection immediately preceding the asm printer.
529 addPass(createPPCBranchSelectionPass(), false);
530 }
531
PassID用于添加Pass时
C++
./include/llvm/CodeGen/Passes.h: extern char &EarlyIfConverterID;
./lib/Target/PowerPC/PPCTargetMachine.cpp: addPass(&EarlyIfConverterID);
./lib/Target/X86/X86TargetMachine.cpp: addPass(&EarlyIfConverterID);
./lib/Target/AMDGPU/AMDGPUTargetMachine.cpp: addPass(&EarlyIfConverterID);
./lib/Target/SystemZ/SystemZTargetMachine.cpp: addPass(&EarlyIfConverterID);
./lib/Target/AArch64/AArch64TargetMachine.cpp: addPass(&EarlyIfConverterID);
./lib/CodeGen/EarlyIfConversion.cpp:char &llvm::EarlyIfConverterID = EarlyIfConverter::ID;
./lib/CodeGen/TargetPassConfig.cpp: if (StandardID == &EarlyIfConverterID)
对于未add进pass，是不会运行到的。但我们依然可以使用run-pass强行让只运行某个pass。如early-if-predicator pass.