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Fixes and cleanups pointed out by Chris. In general, be careful to handle 0 results from ComputeValueKnownInPredecessors 

(indicating undef), and re-use existing constant folding APIs.

llvm-svn: 112539
This commit is contained in:
Owen Anderson 2010-08-30 22:07:52 +00:00
parent 87bb14c566
commit 75f6037c7c
1 changed files with 20 additions and 16 deletions
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36
llvm/lib/Transforms/Scalar/JumpThreading.cpp
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@ -16,6 +16,7 @@
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/Loads.h"
@ -86,6 +87,7 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
if (EnableLVI)
AU.addRequired<LazyValueInfo>();
AU.addPreserved<LazyValueInfo>();
}
void FindLoopHeaders(Function &F);
@ -325,9 +327,10 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
} else if (LVI) {
Constant *CI = LVI->getConstantOnEdge(InVal,
PN->getIncomingBlock(i), BB);
ConstantInt *CInt = dyn_cast_or_null<ConstantInt>(CI);
if (CInt)
Result.push_back(std::make_pair(CInt, PN->getIncomingBlock(i)));
// LVI returns null is no value could be determined.
if (!CI) continue;
ConstantInt *CInt = dyn_cast<ConstantInt>(CI);
Result.push_back(std::make_pair(CInt, PN->getIncomingBlock(i)));
}
}
return !Result.empty();
@ -373,10 +376,6 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
}
}
return !Result.empty();
// Try to process a few other binary operator patterns.
} else if (isa<BinaryOperator>(I)) {
}
// Handle the NOT form of XOR.
@ -400,12 +399,14 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
// AND or OR of a value with itself is that value.
ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1));
if (CI && (BO->getOpcode() == Instruction::And ||
BO->getOpcode() == Instruction::Or)) {
BO->getOpcode() == Instruction::Or)) {
SmallVector<std::pair<ConstantInt*, BasicBlock*>, 8> LHSVals;
ComputeValueKnownInPredecessors(BO->getOperand(0), BB, LHSVals);
for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
if (LHSVals[i].first == CI)
Result.push_back(std::make_pair(CI, LHSVals[i].second));
for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
if (LHSVals[i].first == 0)
Result.push_back(std::make_pair((ConstantInt*)0, LHSVals[i].second));
else if (LHSVals[i].first == CI)
Result.push_back(std::make_pair(CI, LHSVals[i].second));
return !Result.empty();
}
@ -450,7 +451,7 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
if (LVI && isa<Constant>(Cmp->getOperand(1)) &&
Cmp->getType()->isIntegerTy()) {
if (!isa<Instruction>(Cmp->getOperand(0)) ||
cast<Instruction>(Cmp->getOperand(0))->getParent() != BB) {
cast<Instruction>(Cmp->getOperand(0))->getParent() != BB) {
Constant *RHSCst = cast<Constant>(Cmp->getOperand(1));
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB);PI != E; ++PI){
@ -472,17 +473,20 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
// Try to find a constant value for the LHS of an equality comparison,
// and evaluate it statically if we can.
if (Cmp->getPredicate() == CmpInst::ICMP_EQ ||
Cmp->getPredicate() == CmpInst::ICMP_NE) {
if (Constant *CmpConst = dyn_cast<Constant>(Cmp->getOperand(1))) {
SmallVector<std::pair<ConstantInt*, BasicBlock*>, 8> LHSVals;
ComputeValueKnownInPredecessors(I->getOperand(0), BB, LHSVals);
ConstantInt *True = ConstantInt::getTrue(I->getContext());
ConstantInt *False = ConstantInt::getFalse(I->getContext());
if (Cmp->getPredicate() == CmpInst::ICMP_NE) std::swap(True, False);
for (unsigned i = 0, e = LHSVals.size(); i != e; ++i) {
if (LHSVals[i].first == Cmp->getOperand(1))
if (LHSVals[i].first == 0)
Result.push_back(std::make_pair((ConstantInt*)0,
LHSVals[i].second));
else if (ConstantFoldCompareInstOperands(Cmp->getPredicate(),
LHSVals[i].first,
CmpConst))
Result.push_back(std::make_pair(True, LHSVals[i].second));
else
Result.push_back(std::make_pair(False, LHSVals[i].second));