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switch jump threading to use getPredicateOnEdge in one place 

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.

llvm-svn: 86951
This commit is contained in:
Chris Lattner 2009-11-12 04:37:50 +00:00
parent 565ee2f1bd
commit c893c4ed10
1 changed files with 13 additions and 10 deletions
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21
llvm/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);