[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225069 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp
index 683fab5cb651f5967f888f4c9f20c698691e088a..3d00f38f7efd24030cc5f55b7b22ccbadf897c58 100644 (file)
--- a/lib/Transforms/Scalar/SROA.cpp
+++ b/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;
     }