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switch jump threading to use getPredicateOnEdge in one place

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making the new LVI stuff smart enough to subsume some special
cases in the old code.  Disable them when LVI is around, the
testcase still passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86951 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-11-12 04:37:50 +00:00
parent b52675b643
commit 0e0ff29271
1 changed files with 13 additions and 10 deletions
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23
lib/Transforms/Scalar/JumpThreading.cpp
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@ -377,6 +377,7 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
// If comparing a live-in value against a constant, see if we know the
// live-in value on any predecessors.
if (LVI && isa<Constant>(Cmp->getOperand(1)) &&
Cmp->getType()->isInteger() && // Not vector compare.
(!isa<Instruction>(Cmp->getOperand(0)) ||
cast<Instruction>(Cmp->getOperand(0))->getParent() != BB)) {
Constant *RHSCst = cast<Constant>(Cmp->getOperand(1));
@ -384,14 +385,14 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
// If the value is known by LazyValueInfo to be a constant in a
// predecessor, use that information to try to thread this block.
Constant *PredCst = LVI->getConstantOnEdge(Cmp->getOperand(0), *PI, BB);
if (PredCst == 0)
LazyValueInfo::Tristate
Res = LVI->getPredicateOnEdge(Cmp->getPredicate(), Cmp->getOperand(0),
RHSCst, *PI, BB);
if (Res == LazyValueInfo::Unknown)
continue;
// Constant fold the compare.
Value *Res = SimplifyCmpInst(Cmp->getPredicate(), PredCst, RHSCst, TD);
if (isa<ConstantInt>(Res) || isa<UndefValue>(Res))
Result.push_back(std::make_pair(dyn_cast<ConstantInt>(Res), *PI));
Constant *ResC = ConstantInt::get(Cmp->getType(), Res);
Result.push_back(std::make_pair(cast<ConstantInt>(ResC), *PI));
}
return !Result.empty();
@ -498,7 +499,8 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
// br COND, BBX, BBY
// BBX:
// br COND, BBZ, BBW
if (!Condition->hasOneUse() && // Multiple uses.
if (!LVI &&
!Condition->hasOneUse() && // Multiple uses.
(CondInst == 0 || CondInst->getParent() != BB)) { // Non-local definition.
pred_iterator PI = pred_begin(BB), E = pred_end(BB);
if (isa<BranchInst>(BB->getTerminator())) {
@ -532,8 +534,9 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
return ProcessJumpOnPHI(PN);
if (CmpInst *CondCmp = dyn_cast<CmpInst>(CondInst)) {
if (!isa<PHINode>(CondCmp->getOperand(0)) ||
cast<PHINode>(CondCmp->getOperand(0))->getParent() != BB) {
if (!LVI &&
(!isa<PHINode>(CondCmp->getOperand(0)) ||
cast<PHINode>(CondCmp->getOperand(0))->getParent() != BB)) {
// If we have a comparison, loop over the predecessors to see if there is
// a condition with a lexically identical value.
pred_iterator PI = pred_begin(BB), E = pred_end(BB);