[LAA] LLE 2/6: Fix a NoDep case that should be a Forward dependence

Summary:
When the dependence distance in zero then we have a loop-independent
dependence from the earlier to the later access.

No current client of LAA uses forward dependences so other than
potentially hitting the MaxDependences threshold earlier, this change
shouldn't affect anything right now.

This and the previous patch were tested together for compile-time
regression.  None found in LNT/SPEC.

Reviewers: hfinkel

Subscribers: rengolin, llvm-commits

Differential Revision: http://reviews.llvm.org/D13255

llvm-svn: 251973

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index b4b646f8144..80d6575a9c2 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1090,7 +1090,7 @@ MemoryDepChecker::isDependent(const MemAccessInfo &A, unsigned AIdx,
   // Could be improved to assert type sizes are the same (i32 == float, etc).
   if (Val == 0) {
     if (ATy == BTy)
-      return Dependence::NoDep;
+      return Dependence::Forward;
     DEBUG(dbgs() << "LAA: Zero dependence difference but different types\n");
     return Dependence::Unknown;
   }