Disable the main feature of 130180, the elimination of loads that are

redundant with partially-aliasing loads.

When computing what portion of a clobbering load value is needed,
it doesn't consider phi-translation which may have occurred
between the clobbing load and the redundant load.

llvm-svn: 132631

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index a412425770f..5f640c01d25 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -374,10 +374,16 @@ getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
         if (R == AliasAnalysis::MustAlias)
           return MemDepResult::getDef(Inst);
 
+#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads
+      // in terms of clobbering loads, but since it does this by looking
+      // at the clobbering load directly, it doesn't know about any
+      // phi translation that may have happened along the way.
+
         // If we have a partial alias, then return this as a clobber for the
         // client to handle.
         if (R == AliasAnalysis::PartialAlias)
           return MemDepResult::getClobber(Inst);
+#endif
         
         // Random may-alias loads don't depend on each other without a
         // dependence.