[llvm-commits] [llvm] r86267 - /llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
Chris Lattner
sabre at nondot.org
Fri Nov 6 10:22:55 PST 2009
Author: lattner
Date: Fri Nov 6 12:22:54 2009
New Revision: 86267
URL: http://llvm.org/viewvc/llvm-project?rev=86267&view=rev
Log:
eliminate some more code subsumed by r86264
Modified:
llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=86267&r1=86266&r2=86267&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Fri Nov 6 12:22:54 2009
@@ -1005,47 +1005,10 @@
bool JumpThreading::ProcessJumpOnPHI(PHINode *PN) {
BasicBlock *BB = PN->getParent();
- // See if the phi node has any constant integer or undef values. If so, we
- // can determine where the corresponding predecessor will branch.
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- Value *PredVal = PN->getIncomingValue(i);
-
- // Check to see if this input is a constant integer. If so, the direction
- // of the branch is predictable.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(PredVal)) {
- // Merge any common predecessors that will act the same.
- BasicBlock *PredBB = FactorCommonPHIPreds(PN, CI);
-
- BasicBlock *SuccBB;
- if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
- SuccBB = BI->getSuccessor(CI->isZero());
- else {
- SwitchInst *SI = cast<SwitchInst>(BB->getTerminator());
- SuccBB = SI->getSuccessor(SI->findCaseValue(CI));
- }
-
- // Ok, try to thread it!
- return ThreadEdge(BB, PredBB, SuccBB);
- }
-
- // If the input is an undef, then it doesn't matter which way it will go.
- // Pick an arbitrary dest and thread the edge.
- if (UndefValue *UV = dyn_cast<UndefValue>(PredVal)) {
- // Merge any common predecessors that will act the same.
- BasicBlock *PredBB = FactorCommonPHIPreds(PN, UV);
- BasicBlock *SuccBB =
- BB->getTerminator()->getSuccessor(GetBestDestForJumpOnUndef(BB));
-
- // Ok, try to thread it!
- return ThreadEdge(BB, PredBB, SuccBB);
- }
- }
-
- // If the incoming values are all variables, we don't know the destination of
- // any predecessors. However, if any of the predecessor blocks end in an
- // unconditional branch, we can *duplicate* the jump into that block in order
- // to further encourage jump threading and to eliminate cases where we have
- // branch on a phi of an icmp (branch on icmp is much better).
+ // If any of the predecessor blocks end in an unconditional branch, we can
+ // *duplicate* the jump into that block in order to further encourage jump
+ // threading and to eliminate cases where we have branch on a phi of an icmp
+ // (branch on icmp is much better).
// We don't want to do this tranformation for switches, because we don't
// really want to duplicate a switch.
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