[SROA] Fix the loop exit placement to be prior to indexing the splits

array. This prevents it from walking out of bounds on the splits array.

Bug found with the existing tests by ASan and by the MSVC debug build.

llvm-svn: 225069

1 files changed, 8 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 683fab5cb65..3d00f38f7ef 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -3706,11 +3706,13 @@ bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
                    << ", " << NewSlices.back().endOffset() << "): " << *PLoad
                    << "\n");
 
+      // See if we've handled all the splits.
+      if (Idx >= Size)
+        break;
+
       // Setup the next partition.
       PartOffset = Offsets.Splits[Idx];
       ++Idx;
-      if (Idx > Size)
-        break;
       PartSize = (Idx < Size ? Offsets.Splits[Idx] : LoadSize) - PartOffset;
     }
 
@@ -3845,11 +3847,13 @@ bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
         DEBUG(dbgs() << "      of split load: " << *PLoad << "\n");
       }
 
+      // See if we've finished all the splits.
+      if (Idx >= Size)
+        break;
+
       // Setup the next partition.
       PartOffset = Offsets.Splits[Idx];
       ++Idx;
-      if (Idx > Size)
-        break;
       PartSize = (Idx < Size ? Offsets.Splits[Idx] : StoreSize) - PartOffset;
     }