[llvm-commits] CVS: llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
Chris Lattner
sabre at nondot.org
Sat Mar 3 14:49:05 PST 2007
Changes in directory llvm/lib/Transforms/Scalar:
IndVarSimplify.cpp updated: 1.111 -> 1.112
---
Log message:
Make RewriteLoopExitValues far less nested by using continue in the loop
---
Diffs of the changes: (+94 -91)
IndVarSimplify.cpp | 185 ++++++++++++++++++++++++++---------------------------
1 files changed, 94 insertions(+), 91 deletions(-)
Index: llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
diff -u llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.111 llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.112
--- llvm/lib/Transforms/Scalar/IndVarSimplify.cpp:1.111 Thu Mar 1 18:28:52 2007
+++ llvm/lib/Transforms/Scalar/IndVarSimplify.cpp Sat Mar 3 16:48:48 2007
@@ -322,102 +322,105 @@
std::set<Instruction*> InstructionsToDelete;
- for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i)
- if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop...
- BasicBlock *BB = L->getBlocks()[i];
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
- if (I->getType()->isInteger()) { // Is an integer instruction
- SCEVHandle SH = SE->getSCEV(I);
- if (SH->hasComputableLoopEvolution(L) || // Varies predictably
- HasConstantItCount) {
- // Find out if this predictably varying value is actually used
- // outside of the loop. "extra" as opposed to "intra".
- std::vector<Instruction*> ExtraLoopUsers;
- 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;
- }
- ExtraLoopUsers.push_back(User);
- }
- }
-
- if (!ExtraLoopUsers.empty()) {
- // Okay, this instruction has a user outside of the current loop
- // and varies predictably in this loop. Evaluate the value it
- // contains when the loop exits, and insert code for it.
- SCEVHandle ExitValue = SE->getSCEVAtScope(I, L->getParentLoop());
- if (!isa<SCEVCouldNotCompute>(ExitValue)) {
- Changed = true;
- ++NumReplaced;
- // Remember the next instruction. The rewriter can move code
- // around in some cases.
- BasicBlock::iterator NextI = I; ++NextI;
-
- Value *NewVal = Rewriter.expandCodeFor(ExitValue, InsertPt,
- I->getType());
-
- DOUT << "INDVARS: RLEV: AfterLoopVal = " << *NewVal
- << " LoopVal = " << *I << "\n";
-
- // 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) {
- PHINode* PN = dyn_cast<PHINode>(ExtraLoopUsers[i]);
- if (PN && PN->getNumOperands() == 2 &&
- !L->contains(PN->getParent())) {
- // We're dealing with an LCSSA Phi. Handle it specially.
- Instruction* LCSSAInsertPt = BlockToInsertInto->begin();
-
- Instruction* NewInstr = dyn_cast<Instruction>(NewVal);
- if (NewInstr && !isa<PHINode>(NewInstr) &&
- !L->contains(NewInstr->getParent()))
- 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())
- InstructionsToDelete.insert(I);
- I = NextI;
- continue; // Skip the ++I
+ // Loop over all of the integer-valued instructions in this loop, but that are
+ // not in a subloop.
+ for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) {
+ if (LI->getLoopFor(L->getBlocks()[i]) != L)
+ continue; // The Block is in a subloop, skip it.
+ BasicBlock *BB = L->getBlocks()[i];
+ for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ) {
+ Instruction *I = II++;
+
+ if (!I->getType()->isInteger())
+ continue; // SCEV only supports integer expressions for now.
+
+ SCEVHandle SH = SE->getSCEV(I);
+ if (!HasConstantItCount &&
+ !SH->hasComputableLoopEvolution(L)) { // Varies predictably
+ continue; // Cannot exit evolution for the loop value.
+ }
+
+ // Find out if this predictably varying value is actually used
+ // outside of the loop. "Extra" is as opposed to "intra".
+ std::vector<Instruction*> ExtraLoopUsers;
+ 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;
+ }
+ ExtraLoopUsers.push_back(User);
+ }
+ }
+
+ // If nothing outside the loop uses this value, don't rewrite it.
+ if (ExtraLoopUsers.empty())
+ continue;
+
+ // Okay, this instruction has a user outside of the current loop
+ // and varies predictably *inside* the loop. Evaluate the value it
+ // contains when the loop exits if possible.
+ SCEVHandle ExitValue = SE->getSCEVAtScope(I, L->getParentLoop());
+ if (isa<SCEVCouldNotCompute>(ExitValue))
+ continue;
+
+ Changed = true;
+ ++NumReplaced;
+
+ Value *NewVal = Rewriter.expandCodeFor(ExitValue, InsertPt,
+ I->getType());
+
+ DOUT << "INDVARS: RLEV: AfterLoopVal = " << *NewVal
+ << " LoopVal = " << *I << "\n";
+
+ // 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) {
+ PHINode* PN = dyn_cast<PHINode>(ExtraLoopUsers[i]);
+ if (PN && PN->getNumOperands() == 2 &&
+ !L->contains(PN->getParent())) {
+ // We're dealing with an LCSSA Phi. Handle it specially.
+ Instruction* LCSSAInsertPt = BlockToInsertInto->begin();
+
+ Instruction* NewInstr = dyn_cast<Instruction>(NewVal);
+ if (NewInstr && !isa<PHINode>(NewInstr) &&
+ !L->contains(NewInstr->getParent()))
+ 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);
}
-
- // Next instruction. Continue instruction skips this.
- ++I;
}
- }
+ // If this instruction is dead now, schedule it to be removed.
+ if (I->use_empty())
+ InstructionsToDelete.insert(I);
+ }
+ }
+
DeleteTriviallyDeadInstructions(InstructionsToDelete);
}
More information about the llvm-commits
mailing list