On Dec 5, 2007, at 4:08 PM, Chris Lattner wrote: > On Dec 5, 2007, at 3:58 PM, Evan Cheng wrote: >> URL: http://llvm.org/viewvc/llvm-project?rev=44643&view=rev >> Log: >> If both result of the {s|z}xt and its source are live out, rewrite >> all uses of the source with result of extension. > > I assume this is experimental, right? What sort of case does it > fix? Testcase please :)
It's experimental. I'll reduce some a test case when it's enabled. :-) Evan > > > -Chris > >> Modified: >> llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp >> >> Modified: llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp >> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ >> Scalar/CodeGenPrepare.cpp?rev=44643&r1=44642&r2=44643&view=diff >> >> = >> ===================================================================== >> ======== >> --- llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp (original) >> +++ llvm/trunk/lib/Transforms/Scalar/CodeGenPrepare.cpp Wed Dec 5 >> 17:58:20 2007 >> @@ -28,11 +28,17 @@ >> #include "llvm/Transforms/Utils/Local.h" >> #include "llvm/ADT/DenseMap.h" >> #include "llvm/ADT/SmallSet.h" >> -#include "llvm/Support/Debug.h" >> +#include "llvm/Support/CommandLine.h" >> #include "llvm/Support/Compiler.h" >> +#include "llvm/Support/Debug.h" >> #include "llvm/Support/GetElementPtrTypeIterator.h" >> using namespace llvm; >> >> +namespace { >> + cl::opt<bool> OptExtUses("optimize-ext-uses", >> + cl::init(false), cl::Hidden); >> +} >> + >> namespace { >> class VISIBILITY_HIDDEN CodeGenPrepare : public FunctionPass { >> /// TLI - Keep a pointer of a TargetLowering to consult for >> determining >> @@ -52,6 +58,7 @@ >> bool OptimizeLoadStoreInst(Instruction *I, Value *Addr, >> const Type *AccessTy, >> DenseMap<Value*,Value*> &SunkAddrs); >> + bool OptimizeExtUses(Instruction *I); >> }; >> } >> >> @@ -913,6 +920,61 @@ >> return true; >> } >> >> +bool CodeGenPrepare::OptimizeExtUses(Instruction *I) { >> + BasicBlock *DefBB = I->getParent(); >> + >> + // If both result of the {s|z}xt and its source are live out, >> rewrite all >> + // other uses of the source with result of extension. >> + Value *Src = I->getOperand(0); >> + if (Src->hasOneUse()) >> + return false; >> + >> + bool DefIsLiveOut = false; >> + for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); >> + UI != E; ++UI) { >> + Instruction *User = cast<Instruction>(*UI); >> + >> + // Figure out which BB this ext is used in. >> + BasicBlock *UserBB = User->getParent(); >> + if (UserBB == DefBB) continue; >> + DefIsLiveOut = true; >> + break; >> + } >> + if (!DefIsLiveOut) >> + return false; >> + >> + // InsertedTruncs - Only insert one trunc in each block once. >> + DenseMap<BasicBlock*, Instruction*> InsertedTruncs; >> + >> + bool MadeChange = false; >> + for (Value::use_iterator UI = Src->use_begin(), E = Src- >> >use_end(); >> + UI != E; ++UI) { >> + Use &TheUse = UI.getUse(); >> + Instruction *User = cast<Instruction>(*UI); >> + >> + // Figure out which BB this ext is used in. >> + BasicBlock *UserBB = User->getParent(); >> + if (UserBB == DefBB) continue; >> + >> + // Both src and def are live in this block. Rewrite the use. >> + Instruction *&InsertedTrunc = InsertedTruncs[UserBB]; >> + >> + if (!InsertedTrunc) { >> + BasicBlock::iterator InsertPt = UserBB->begin(); >> + while (isa<PHINode>(InsertPt)) ++InsertPt; >> + >> + InsertedTrunc = new TruncInst(I, Src->getType(), "", >> InsertPt); >> + } >> + >> + // Replace a use of the {s|z}ext source with a use of the >> result. >> + TheUse = InsertedTrunc; >> + >> + MadeChange = true; >> + } >> + >> + return MadeChange; >> +} >> + >> // In this pass we look for GEP and cast instructions that are used >> // across basic blocks and rewrite them to improve basic-block-at- >> a-time >> // selection. >> @@ -948,8 +1010,14 @@ >> if (isa<Constant>(CI->getOperand(0))) >> continue; >> >> - if (TLI) >> - MadeChange |= OptimizeNoopCopyExpression(CI, *TLI); >> + bool Change = false; >> + if (TLI) { >> + Change = OptimizeNoopCopyExpression(CI, *TLI); >> + MadeChange |= Change; >> + } >> + >> + if (OptExtUses && !Change && (isa<ZExtInst>(I) || >> isa<SExtInst>(I))) >> + MadeChange |= OptimizeExtUses(I); >> } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) { >> MadeChange |= OptimizeCmpExpression(CI); >> } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) { >> >> >> _______________________________________________ >> llvm-commits mailing list >> llvm-commits@cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits > > _______________________________________________ > llvm-commits mailing list > llvm-commits@cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
