cleanup some of the lifetime/invariant marker stuff, add a big fixme.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113144 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index e0e0cff..8390ee9 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -175,7 +175,7 @@
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
- // Debug intrinsics don't cause dependences.
+ // Debug intrinsics don't (and can't) cause dependences.
if (isa<DbgInfoIntrinsic>(II)) continue;
// If we pass an invariant-end marker, then we've just entered an
@@ -185,25 +185,30 @@
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point.
AliasAnalysis::AliasResult R = AA->alias(II->getArgOperand(2), MemPtr);
- if (R == AliasAnalysis::MustAlias) {
+ if (R == AliasAnalysis::MustAlias)
InvariantTag = II->getArgOperand(0);
- continue;
- }
-
+
+ continue;
+ }
+
// If we reach a lifetime begin or end marker, then the query ends here
// because the value is undefined.
- } else if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
// FIXME: This only considers queries directly on the invariant-tagged
// pointer, not on query pointers that are indexed off of them. It'd
// be nice to handle that at some point.
AliasAnalysis::AliasResult R = AA->alias(II->getArgOperand(1), MemPtr);
if (R == AliasAnalysis::MustAlias)
return MemDepResult::getDef(II);
+ continue;
}
}
// If we're querying on a load and we're in an invariant region, we're done
// at this point. Nothing a load depends on can live in an invariant region.
+ //
+ // FIXME: this will prevent us from returning load/load must-aliases, so GVN
+ // won't remove redundant loads.
if (isLoad && InvariantTag) continue;
// Values depend on loads if the pointers are must aliased. This means that