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If the loop executes a constant number of times, try a bit harder to replace

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exit values.

llvm-svn: 13018
This commit is contained in:
Chris Lattner 2004-04-17 18:44:09 +00:00
parent 9a73de2ba2
commit 740ae78ae6
1 changed files with 5 additions and 2 deletions
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7
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -276,6 +276,8 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
BasicBlock::iterator InsertPt = BlockToInsertInto->begin();
while (isa<PHINode>(InsertPt)) ++InsertPt;
bool HasConstantItCount = isa<SCEVConstant>(SE->getIterationCount(L));
std::set<Instruction*> InstructionsToDelete;
for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i)
@ -284,7 +286,8 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (I->getType()->isInteger()) { // Is an integer instruction
SCEVHandle SH = SE->getSCEV(I);
if (SH->hasComputableLoopEvolution(L)) { // Varies predictably
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<User*> ExtraLoopUsers;
@ -296,7 +299,7 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L) {
// 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());
SCEVHandle ExitValue = SE->getSCEVAtScope(I, L->getParentLoop());
if (!isa<SCEVCouldNotCompute>(ExitValue)) {
Changed = true;
++NumReplaced;