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when checking if we should move a split edge block outside of a loop,

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check the presplit pred, not the post-split pred.  This was causing us
to make the wrong decision in some cases, leaving the critical edge block
in the loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23601 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-03 00:31:52 +00:00
parent 9390368970
commit 37edbf0b21
1 changed files with 6 additions and 7 deletions
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13
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -462,20 +462,19 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
// code on all predecessor/successor paths. We do this unless this is the
// canonical backedge for this loop, as this can make some inserted code
// be in an illegal position.
if (e != 1 &&
PN->getIncomingBlock(i)->getTerminator()->getNumSuccessors() > 1 &&
(PN->getParent() != L->getHeader() ||
!L->contains(PN->getIncomingBlock(i)))) {
BasicBlock *PHIPred = PN->getIncomingBlock(i);
if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
(PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
// First step, split the critical edge.
SplitCriticalEdge(PN->getIncomingBlock(i), PN->getParent(), P);
SplitCriticalEdge(PHIPred, PN->getParent(), P);
// Next step: move the basic block. In particular, if the PHI node
// is outside of the loop, and PredTI is in the loop, we want to
// move the block to be immediately before the PHI block, not
// immediately after PredTI.
if (L->contains(PN->getIncomingBlock(i)) &&
!L->contains(PN->getParent())) {
if (L->contains(PHIPred) && !L->contains(PN->getParent())) {
BasicBlock *NewBB = PN->getIncomingBlock(i);
NewBB->moveBefore(PN->getParent());
}