Fix a case where SROA did not correctly detect dead PHI or selects due
to chains or cycles between PHIs and/or selects. Also add a couple of
really nice test cases reduced from Kostya's reports in PR13905 and
PR13906. Both are fixed by this patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164596 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index dbda627..b3e63ae 100644
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/lib/Transforms/Scalar/SROA.cpp
@@ -522,8 +522,10 @@
void insertUse(Instruction &I, int64_t Offset, uint64_t Size,
bool IsSplittable = false) {
- // Completely skip uses which don't overlap the allocation.
- if ((Offset >= 0 && (uint64_t)Offset >= AllocSize) ||
+ // Completely skip uses which have a zero size or don't overlap the
+ // allocation.
+ if (Size == 0 ||
+ (Offset >= 0 && (uint64_t)Offset >= AllocSize) ||
(Offset < 0 && (uint64_t)-Offset >= Size)) {
DEBUG(dbgs() << "WARNING: Ignoring " << Size << " byte use @" << Offset
<< " which starts past the end of the " << AllocSize
@@ -697,6 +699,9 @@
SmallVector<std::pair<Instruction *, Instruction *>, 4> Uses;
Visited.insert(Root);
Uses.push_back(std::make_pair(cast<Instruction>(*U), Root));
+ // If there are no loads or stores, the access is dead. We mark that as
+ // a size zero access.
+ Size = 0;
do {
Instruction *I, *UsedI;
llvm::tie(UsedI, I) = Uses.pop_back_val();
@@ -824,9 +829,9 @@
}
void insertUse(Instruction &User, int64_t Offset, uint64_t Size) {
- // If the use extends outside of the allocation, record it as a dead use
- // for elimination later.
- if ((uint64_t)Offset >= AllocSize ||
+ // If the use has a zero size or extends outside of the allocation, record
+ // it as a dead use for elimination later.
+ if (Size == 0 || (uint64_t)Offset >= AllocSize ||
(Offset < 0 && (uint64_t)-Offset >= Size))
return markAsDead(User);