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Make RewriteLoopExitValues far less nested by using continue in the loop

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34891 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-03-03 22:48:48 +00:00
parent a9569f10de
commit c9838f25d5
1 changed files with 97 additions and 94 deletions
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51
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -322,16 +322,26 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
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...
// 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 I = BB->begin(), E = BB->end(); I != E;) {
if (I->getType()->isInteger()) { // Is an integer instruction
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 (SH->hasComputableLoopEvolution(L) || // Varies predictably
HasConstantItCount) {
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" as opposed to "intra".
// 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) {
@ -352,17 +362,19 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
}
}
if (!ExtraLoopUsers.empty()) {
// 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 in this loop. Evaluate the value it
// contains when the loop exits, and insert code for it.
// 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)) {
if (isa<SCEVCouldNotCompute>(ExitValue))
continue;
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());
@ -382,7 +394,7 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
Instruction* NewInstr = dyn_cast<Instruction>(NewVal);
if (NewInstr && !isa<PHINode>(NewInstr) &&
!L->contains(NewInstr->getParent()))
for (unsigned j = 0; j < NewInstr->getNumOperands(); ++j){
for (unsigned j = 0; j != NewInstr->getNumOperands(); ++j) {
Instruction* PredI =
dyn_cast<Instruction>(NewInstr->getOperand(j));
if (PredI && L->contains(PredI->getParent())) {
@ -406,15 +418,6 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
// If this instruction is dead now, schedule it to be removed.
if (I->use_empty())
InstructionsToDelete.insert(I);
I = NextI;
continue; // Skip the ++I
}
}
}
}
// Next instruction. Continue instruction skips this.
++I;
}
}