Don't attempt load PRE when there is no real redundancy (i.e., the load is in
a loop and is itself the only dependency).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97526 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index a4c0716..fcb802a 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1542,11 +1542,13 @@
// at least one of the values is LI. Since this means that we won't be able
// to eliminate LI even if we insert uses in the other predecessors, we will
// end up increasing code size. Reject this by scanning for LI.
- if (!EnableFullLoadPRE) {
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
- if (ValuesPerBlock[i].isSimpleValue() &&
- ValuesPerBlock[i].getSimpleValue() == LI)
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
+ if (ValuesPerBlock[i].isSimpleValue() &&
+ ValuesPerBlock[i].getSimpleValue() == LI) {
+ // Skip cases where LI is the only definition, even for EnableFullLoadPRE.
+ if (!EnableFullLoadPRE || e == 1)
return false;
+ }
}
// FIXME: It is extremely unclear what this loop is doing, other than