[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
Chris Lattner
lattner at cs.uiuc.edu
Fri Apr 16 13:08:02 PDT 2004
Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.190 -> 1.191
---
Log message:
Fix some really nasty dominance bugs that were exposed by my patch to
make the verifier more strict. This fixes building zlib
---
Diffs of the changes: (+12 -29)
Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.190 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.191
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.190 Tue Apr 13 22:28:36 2004
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Fri Apr 16 13:08:07 2004
@@ -397,30 +397,6 @@
// 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 @@
// 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;
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