6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-31 09:25:42 +00:00
Code Issues Projects Releases Wiki Activity

Nick pointed out on IRC that GVN's propagateEquality wasn't propagating

Browse Source 
equalities into phi node operands for which the equality is known to
hold in the incoming basic block.  That's because replaceAllDominatedUsesWith
wasn't handling phi nodes correctly in general (that this didn't give wrong
results was just luck: the specific way GVN uses replaceAllDominatedUsesWith
precluded wrong changes to phi nodes).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152006 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands
2012-03-04 13:25:19 +00:00
parent ed7692a136
commit 190e5a3314
2 changed files with 28 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
lib/Transforms/Scalar/GVN.cpp
View File

@@ -1953,7 +1953,17 @@ unsigned GVN::replaceAllDominatedUsesWith(Value *From, Value *To,
for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
UI != UE; ) {
Use &U = (UI++).getUse();
if (DT->dominates(Root, cast<Instruction>(U.getUser())->getParent())) {
// If From occurs as a phi node operand then the use implicitly lives in the
// corresponding incoming block. Otherwise it is the block containing the
// user that must be dominated by Root.
BasicBlock *UsingBlock;
if (PHINode *PN = dyn_cast<PHINode>(U.getUser()))
UsingBlock = PN->getIncomingBlock(U);
else
UsingBlock = cast<Instruction>(U.getUser())->getParent();
if (DT->dominates(Root, UsingBlock)) {
U.set(To);
++Count;
}