[MemorySSA] Consider callsite args for hashing and equality.

We use a `DenseMap<MemoryLocOrCall, MemlocStackInfo>` to keep track of
prior work when optimizing uses in MemorySSA. Because we weren't
accounting for callsite arguments in either the hash code or equality
tests for `MemoryLocOrCall`s, we optimized uses too aggressively in
some rare cases.

Fix by Daniel Berlin.

Should fix PR36883.

llvm-svn: 328748

1 files changed, 20 insertions, 9 deletions

diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp
index ce8504b87a7..e67d95782ae 100644
--- a/llvm/lib/Analysis/MemorySSA.cpp
+++ b/llvm/lib/Analysis/MemorySSA.cpp
@@ -153,9 +153,14 @@ public:
     if (IsCall != Other.IsCall)
       return false;
 
-    if (IsCall)
-      return CS.getCalledValue() == Other.CS.getCalledValue();
-    return Loc == Other.Loc;
+    if (!IsCall)
+      return Loc == Other.Loc;
+
+    if (CS.getCalledValue() != Other.CS.getCalledValue())
+      return false;
+
+    assert(CS.arg_size() == Other.CS.arg_size());
+    return std::equal(CS.arg_begin(), CS.arg_end(), Other.CS.arg_begin());
   }
 
 private:
@@ -179,12 +184,18 @@ template <> struct DenseMapInfo<MemoryLocOrCall> {
   }
 
   static unsigned getHashValue(const MemoryLocOrCall &MLOC) {
-    if (MLOC.IsCall)
-      return hash_combine(MLOC.IsCall,
-                          DenseMapInfo<const Value *>::getHashValue(
-                              MLOC.getCS().getCalledValue()));
-    return hash_combine(
-        MLOC.IsCall, DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));
+    if (!MLOC.IsCall)
+      return hash_combine(
+          MLOC.IsCall,
+          DenseMapInfo<MemoryLocation>::getHashValue(MLOC.getLoc()));
+
+    hash_code hash =
+        hash_combine(MLOC.IsCall, DenseMapInfo<const Value *>::getHashValue(
+                                      MLOC.getCS().getCalledValue()));
+
+    for (const Value *Arg : MLOC.getCS().args())
+      hash = hash_combine(hash, DenseMapInfo<const Value *>::getHashValue(Arg));
+    return hash;
   }
 
   static bool isEqual(const MemoryLocOrCall &LHS, const MemoryLocOrCall &RHS) {