commit 8286b83f97106fde561b28c7cb1fe7d5a479de6e
author Tobias Grosser <tobias@grosser.es> Mon Nov 02 11:29:32 2015 +0000
committer Tobias Grosser <tobias@grosser.es> Mon Nov 02 11:29:32 2015 +0000
tree 2b371542d3c1d0e2ed9e34175cd97fd62ed65bf8
parent 184864adc613334725ef9a1c6d2fe04e0947c531

ScopInfo: Bail out in case of mismatching array dimension sizes

In some cases different memory accesses access the very same array using a
different multi-dimensional array layout where the same dimensions have
different sizes. Instead of asserting when encountering this issue, we
gracefully bail out for this scop.

This fixes llvm.org/PR25252

llvm-svn: 251791

polly/lib/Analysis/ScopInfo.cpp

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index fdcf006..2c99d47 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -173,16 +173,16 @@
   return Space;
 }
 
-void ScopArrayInfo::updateSizes(ArrayRef<const SCEV *> NewSizes) {
-#ifndef NDEBUG
+bool ScopArrayInfo::updateSizes(ArrayRef<const SCEV *> NewSizes) {
   int SharedDims = std::min(NewSizes.size(), DimensionSizes.size());
   int ExtraDimsNew = NewSizes.size() - SharedDims;
   int ExtraDimsOld = DimensionSizes.size() - SharedDims;
-  for (int i = 0; i < SharedDims; i++) {
-    assert(NewSizes[i + ExtraDimsNew] == DimensionSizes[i + ExtraDimsOld] &&
-           "Array update with non-matching dimension sizes");
-  }
-#endif
+  for (int i = 0; i < SharedDims; i++)
+    if (NewSizes[i + ExtraDimsNew] != DimensionSizes[i + ExtraDimsOld])
+      return false;
+
+  if (DimensionSizes.size() >= NewSizes.size())
+    return true;
 
   DimensionSizes.clear();
   DimensionSizes.insert(DimensionSizes.begin(), NewSizes.begin(),
@@ -194,6 +194,7 @@
     isl_pw_aff *Size = S.getPwAff(Expr);
     DimensionSizesPw.push_back(Size);
   }
+  return true;
 }
 
 ScopArrayInfo::~ScopArrayInfo() {
@@ -2377,9 +2378,12 @@
   Loop *L = getLoopSurroundingRegion(R, LI);
   LoopSchedules[L];
   buildSchedule(&R, LoopSchedules);
-  updateAccessDimensionality();
   Schedule = LoopSchedules[L].first;
 
+  if (isl_set_is_empty(AssumedContext))
+    return;
+
+  updateAccessDimensionality();
   realignParams();
   addParameterBounds();
   addUserContext();
@@ -2640,8 +2644,10 @@
     SAI.reset(new ScopArrayInfo(BasePtr, AccessType, getIslCtx(), Sizes, IsPHI,
                                 this));
   } else {
-    if (Sizes.size() > SAI->getNumberOfDimensions())
-      SAI->updateSizes(Sizes);
+    // In case of mismatching array sizes, we bail out by setting the run-time
+    // context to false.
+    if (!SAI->updateSizes(Sizes))
+      addAssumption(isl_set_empty(getParamSpace()));
   }
   return SAI.get();
 }