[DAG] Teach BaseIndexOffset to correctly handle with indexed operations

BaseIndexOffset address analysis incorrectly ignores offsets folded
into indexed memory operations causing potential errors in alias
analysis of pre-indexed operations.

Reviewers: efriedma, RKSimon, hfinkel, jyknight

Subscribers: hiraditya, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D41701

llvm-svn: 322003

1 files changed, 2 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 7e99863b1ee..e91a7906005 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7947,11 +7947,8 @@ bool SelectionDAG::areNonVolatileConsecutiveLoads(LoadSDNode *LD,
   if (VT.getSizeInBits() / 8 != Bytes)
     return false;
 
-  SDValue Loc = LD->getOperand(1);
-  SDValue BaseLoc = Base->getOperand(1);
-
-  auto BaseLocDecomp = BaseIndexOffset::match(BaseLoc, *this);
-  auto LocDecomp = BaseIndexOffset::match(Loc, *this);
+  auto BaseLocDecomp = BaseIndexOffset::match(Base, *this);
+  auto LocDecomp = BaseIndexOffset::match(LD, *this);
 
   int64_t Offset = 0;
   if (BaseLocDecomp.equalBaseIndex(LocDecomp, *this, Offset))