Changes in directory llvm/lib/Transforms/Scalar:
IndVarSimplify.cpp updated: 1.83 -> 1.84
---
Log message:
De-pessimize the handling of LCSSA Phi nodes in IndVarSimplify. Hopefully this
will make Shootout-C/nestedloop faster.
---
Diffs of the changes: (+29 -15)
IndVarSimplify.cpp | 44 +++++++++++++++++++++++++++++---------------
1 files changed, 29 insertions(+), 15 deletions(-)
Index: llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
diff -u llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.83
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.84
--- llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.83 Fri Jun 16 20:02:31 2006
+++ llvm/lib/Transforms/Scalar/IndVarSimplify.cpp Mon Jun 26 21:17:08 2006
@@ -325,20 +325,8 @@
for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
- if (!L->contains(User->getParent())) {
- // If this is a PHI node in the exit block and we're inserting,
- // into the exit block, it must have a single entry. In this
- // case, we can't insert the code after the PHI and have the
PHI
- // still use it. Instead, don't insert the the PHI.
- if (PHINode *PN = dyn_cast<PHINode>(User)) {
- // FIXME: This is a case where LCSSA pessimizes code, this
- // should be fixed better.
- if (PN->getNumOperands() == 2 &&
- PN->getParent() == BlockToInsertInto)
- continue;
- }
+ if (!L->contains(User->getParent()))
ExtraLoopUsers.push_back(User);
- }
}
if (!ExtraLoopUsers.empty()) {
@@ -358,8 +346,34 @@
// Rewrite any users of the computed value outside of the loop
// with the newly computed value.
- for (unsigned i = 0, e = ExtraLoopUsers.size(); i != e; ++i)
- ExtraLoopUsers[i]->replaceUsesOfWith(I, NewVal);
+ for (unsigned i = 0, e = ExtraLoopUsers.size(); i != e; ++i) {
+ PHINode* PN = dyn_cast<PHINode>(ExtraLoopUsers[i]);
+ if (PN && PN->getParent() == BlockToInsertInto) {
+ // We're dealing with an LCSSA Phi. Handle it specially.
+ Instruction* LCSSAInsertPt = BlockToInsertInto->begin();
+
+ Instruction* NewInstr = dyn_cast<Instruction>(NewVal);
+ if (Instruction* NewInstr = dyn_cast<Instruction>(NewVal))
+ for (unsigned j = 0; j < NewInstr->getNumOperands();
++j){
+ Instruction* PredI =
+
dyn_cast<Instruction>(NewInstr->getOperand(j));
+ if (PredI && L->contains(PredI->getParent())) {
+ PHINode* NewLCSSA = new PHINode(PredI->getType(),
+ PredI->getName() +
".lcssa",
+ LCSSAInsertPt);
+ NewLCSSA->addIncoming(PredI,
+
BlockToInsertInto->getSinglePredecessor());
+
+ NewInstr->replaceUsesOfWith(PredI, NewLCSSA);
+ }
+ }
+
+ PN->replaceAllUsesWith(NewVal);
+ PN->eraseFromParent();
+ } else {
+ ExtraLoopUsers[i]->replaceUsesOfWith(I, NewVal);
+ }
+ }
// If this instruction is dead now, schedule it to be removed.
if (I->use_empty())
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