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Fix PR255: [tailduplication] Single basic block loops are very rare

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Note that this is a band-aid put over a band-aid.  This just undisables
tail duplication in on very specific case that it seems to work in.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11989 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-02-29 06:41:20 +00:00
parent e9f6f2c049
commit 4279f3c984
1 changed files with 2 additions and 1 deletions
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3
lib/Transforms/Scalar/TailDuplication.cpp
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@@ -125,6 +125,7 @@ bool TailDup::shouldEliminateUnconditionalBranch(TerminatorInst *TI) {
bool TailDup::canEliminateUnconditionalBranch(TerminatorInst *TI) { bool TailDup::canEliminateUnconditionalBranch(TerminatorInst *TI) {
// Basically, we refuse to make the transformation if any of the values // Basically, we refuse to make the transformation if any of the values
// computed in the 'tail' are used in any other basic blocks. // computed in the 'tail' are used in any other basic blocks.
BasicBlock *BB = TI->getParent();
BasicBlock *Tail = TI->getSuccessor(0); BasicBlock *Tail = TI->getSuccessor(0);
assert(isa<BranchInst>(TI) && cast<BranchInst>(TI)->isUnconditional()); assert(isa<BranchInst>(TI) && cast<BranchInst>(TI)->isUnconditional());
@@ -132,7 +133,7 @@ bool TailDup::canEliminateUnconditionalBranch(TerminatorInst *TI) {
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
++UI) { ++UI) {
Instruction *User = cast<Instruction>(*UI); Instruction *User = cast<Instruction>(*UI);
if (User->getParent() != Tail || isa<PHINode>(User)) if (User->getParent() != Tail && User->getParent() != BB)
return false; return false;
} }
return true; return true;