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* Implement expression type conversion for constant values
* Fix a problem setting a name on a constant value that died because no symbol table was passed in
* Add some comments describing the passes
* Implement a new peephole:
// Peephole optimize the following instructions:
// %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
// store <T2> %V, <T2>* %t
//
// Into:
// %t = cast <T2> %V to <T1>
// store <T1> %t2, <T1>* %P
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1080 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
edefaa1196
commit
dedee7bf15
@ -36,6 +36,7 @@
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#include "llvm/iMemory.h"
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#include "llvm/ConstPoolVals.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Optimizations/ConstantHandling.h"
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#include <map>
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#include <algorithm>
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@ -70,8 +71,8 @@ const TargetData TD("LevelRaise: Should be GCC though!");
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// another without gaining or losing precision, or altering the bits in any way.
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//
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static bool losslessCastableTypes(const Type *T1, const Type *T2) {
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assert(T1->isPrimitiveType() || isa<PointerType>(T1));
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assert(T2->isPrimitiveType() || isa<PointerType>(T2));
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if (!T1->isPrimitiveType() && !isa<PointerType>(T1)) return false;
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if (!T2->isPrimitiveType() && !isa<PointerType>(T2)) return false;
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if (T1->getPrimitiveID() == T2->getPrimitiveID())
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return true; // Handles identity cast, and cast of differing pointer types
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@ -195,7 +196,16 @@ static void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
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// ExpressionConvertableToType - Return true if it is possible
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static bool ExpressionConvertableToType(Value *V, const Type *Ty) {
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Instruction *I = dyn_cast<Instruction>(V);
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if (I == 0) return false; // Noninstructions can't convert
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if (I == 0) {
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// It's not an instruction, check to see if it's a constant... all constants
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// can be converted to an equivalent value (except pointers, they can't be
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// const prop'd in general).
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//
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if (isa<ConstPoolVal>(V) &&
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!isa<PointerType>(V->getType()) && !isa<PointerType>(Ty)) return true;
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return false; // Otherwise, we can't convert!
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}
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if (I->getType() == Ty) return false; // Expression already correct type!
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switch (I->getOpcode()) {
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@ -216,9 +226,20 @@ static bool ExpressionConvertableToType(Value *V, const Type *Ty) {
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}
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static Instruction *ConvertExpressionToType(Value *V, const Type *Ty) {
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Instruction *I = cast<Instruction>(V);
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assert(ExpressionConvertableToType(I, Ty) && "Inst is not convertable!");
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static Value *ConvertExpressionToType(Value *V, const Type *Ty) {
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assert(ExpressionConvertableToType(V, Ty) && "Value is not convertable!");
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Instruction *I = dyn_cast<Instruction>(V);
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if (I == 0)
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if (ConstPoolVal *CPV = cast<ConstPoolVal>(V)) {
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// Constants are converted by constant folding the cast that is required.
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// We assume here that all casts are implemented for constant prop.
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Value *Result = opt::ConstantFoldCastInstruction(CPV, Ty);
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if (!Result) cerr << "Couldn't fold " << CPV << " to " << Ty << endl;
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assert(Result && "ConstantFoldCastInstruction Failed!!!");
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return Result;
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}
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BasicBlock *BB = I->getParent();
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BasicBlock::InstListType &BIL = BB->getInstList();
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string Name = I->getName(); if (!Name.empty()) I->setName("");
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@ -438,6 +459,7 @@ static bool PeepholeMallocInst(BasicBlock *BB, BasicBlock::iterator &BI) {
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static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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Instruction *I = *BI;
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// TODO: replace this with a DCE call
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if (I->use_size() == 0 && I->getType() != Type::VoidTy) return false;
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if (CastInst *CI = dyn_cast<CastInst>(I)) {
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@ -451,7 +473,8 @@ static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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CI->replaceAllUsesWith(Src);
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if (!Src->hasName() && CI->hasName()) {
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string Name = CI->getName();
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CI->setName(""); Src->setName(Name);
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CI->setName(""); Src->setName(Name,
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BB->getParent()->getSymbolTable());
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}
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return true;
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}
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@ -473,10 +496,10 @@ static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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// Check to see if it's a cast of an instruction that does not depend on the
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// specific type of the operands to do it's job.
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if (SrcI && !isReinterpretingCast(CI) &&
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ExpressionConvertableToType(SrcI, DestTy)) {
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PRINT_PEEPHOLE2("EXPR-CONV:in ", CI, SrcI);
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CI->setOperand(0, ConvertExpressionToType(SrcI, DestTy));
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if (!isReinterpretingCast(CI) &&
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ExpressionConvertableToType(Src, DestTy)) {
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PRINT_PEEPHOLE2("EXPR-CONV:in ", CI, Src);
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CI->setOperand(0, ConvertExpressionToType(Src, DestTy));
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BI = BB->begin(); // Rescan basic block. BI might be invalidated.
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PRINT_PEEPHOLE2("EXPR-CONV:out", CI, CI->getOperand(0));
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return true;
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@ -489,6 +512,12 @@ static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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Value *Val = SI->getOperand(0);
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Value *Pointer = SI->getPtrOperand();
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// Peephole optimize the following instructions:
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// %t1 = getelementptr {<...>} * %StructPtr, <element indices>
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// store <elementty> %v, <elementty> * %t1
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//
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// Into: store <elementty> %v, {<...>} * %StructPtr, <element indices>
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//
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) {
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PRINT_PEEPHOLE2("gep-store:in", GEP, SI);
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ReplaceInstWithInst(BB->getInstList(), BI,
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@ -498,9 +527,45 @@ static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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return true;
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}
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// Peephole optimize the following instructions:
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// %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
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// store <T2> %V, <T2>* %t
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//
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// Into:
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// %t = cast <T2> %V to <T1>
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// store <T1> %t2, <T1>* %P
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//
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if (CastInst *CI = dyn_cast<CastInst>(Pointer))
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if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
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if (PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
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if (losslessCastableTypes(Val->getType(), // convertable types!
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CSPT->getValueType()) &&
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!SI->hasIndices()) { // No subscripts yet!
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PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);
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// Insert the new T cast instruction... stealing old T's name
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CastInst *NCI = new CastInst(Val, CSPT->getValueType(),
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CI->getName());
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CI->setName("");
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BI = BB->getInstList().insert(BI, NCI)+1;
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// Replace the old store with a new one!
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ReplaceInstWithInst(BB->getInstList(), BI,
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SI = new StoreInst(NCI, CastSrc));
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PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
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return true;
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}
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} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
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Value *Pointer = LI->getPtrOperand();
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// Peephole optimize the following instructions:
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// %t1 = getelementptr {<...>} * %StructPtr, <element indices>
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// %V = load <elementty> * %t1
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//
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// Into: load {<...>} * %StructPtr, <element indices>
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//
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) {
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PRINT_PEEPHOLE2("gep-load:in", GEP, LI);
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ReplaceInstWithInst(BB->getInstList(), BI,
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