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authorOwen Anderson <resistor@mac.com>2010-08-30 22:07:52 +0000
committerOwen Anderson <resistor@mac.com>2010-08-30 22:07:52 +0000
commit1e35610f20ba04daf3aa3048219914421b9931af (patch)
treedef5835b9af95ae32eb08785fa9260a19e7e0ccf
parent55c134a26188291f60c44d027a837f05d797194f (diff)
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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. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112539 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r--lib/Transforms/Scalar/JumpThreading.cpp36
1 files changed, 20 insertions, 16 deletions
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index c0b0cbebde..2955ca1ab5 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -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));