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Fix some really nasty dominance bugs that were exposed by my patch to

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make the verifier more strict.  This fixes building zlib


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13002 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-04-16 18:08:07 +00:00
parent ea51deb18a
commit 657253119e
1 changed files with 12 additions and 29 deletions
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41
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -397,30 +397,6 @@ Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
// reassociate the expression from ((? op A) op B) to (? op (A op B))
if (ShouldApply) {
BasicBlock *BB = Root.getParent();
// All of the instructions have a single use and have no side-effects,
// because of this, we can pull them all into the current basic block.
if (LHSI->getParent() != BB) {
// Move all of the instructions from root to LHSI into the current
// block.
Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
Instruction *LastUse = &Root;
while (TmpLHSI->getParent() == BB) {
LastUse = TmpLHSI;
TmpLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
}
// Loop over all of the instructions in other blocks, moving them into
// the current one.
Value *TmpLHS = TmpLHSI;
do {
TmpLHSI = cast<Instruction>(TmpLHS);
// Remove from current block...
TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
// Insert before the last instruction...
BB->getInstList().insert(LastUse, TmpLHSI);
TmpLHS = TmpLHSI->getOperand(0);
} while (TmpLHSI != LHSI);
}
// Now all of the instructions are in the current basic block, go ahead
// and perform the reassociation.
@ -431,20 +407,27 @@ Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
// Make what used to be the LHS of the root be the user of the root...
Value *ExtraOperand = TmpLHSI->getOperand(1);
if (&Root != TmpLHSI)
Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
else {
if (&Root == TmpLHSI) {
Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
return 0;
}
Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
BB->getInstList().remove(&Root); // Remove root from the BB
BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
BasicBlock::iterator ARI = &Root; ++ARI;
BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
ARI = Root;
// Now propagate the ExtraOperand down the chain of instructions until we
// get to LHSI.
while (TmpLHSI != LHSI) {
Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
// Move the instruction to immediately before the chain we are
// constructing to avoid breaking dominance properties.
NextLHSI->getParent()->getInstList().remove(NextLHSI);
BB->getInstList().insert(ARI, NextLHSI);
ARI = NextLHSI;
Value *NextOp = NextLHSI->getOperand(1);
NextLHSI->setOperand(1, ExtraOperand);
TmpLHSI = NextLHSI;