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/include/polly/ScopInfo.h

@@ -103,7 +103,8 @@ public:
   ///
   ///  @param A vector of array sizes where the rightmost array sizes need to
   ///         match the innermost array sizes already defined in SAI.
-  void updateSizes(ArrayRef<const SCEV *> Sizes);
+  ///  @returns Returns true if the update was successful, otherwise false.
+  bool updateSizes(ArrayRef<const SCEV *> Sizes);
 
   /// @brief Destructor to free the isl id of the base pointer.
   ~ScopArrayInfo();

polly/lib/Analysis/ScopInfo.cpp

@@ -173,16 +173,16 @@ __isl_give isl_space *ScopArrayInfo::getSpace() const {
   return Space;
 }
 
-void ScopArrayInfo::updateSizes(ArrayRef<const SCEV *> NewSizes) {
+bool ScopArrayInfo::updateSizes(ArrayRef<const SCEV *> NewSizes) {
-#ifndef NDEBUG
   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++) {
+  for (int i = 0; i < SharedDims; i++)
-    assert(NewSizes[i + ExtraDimsNew] == DimensionSizes[i + ExtraDimsOld] &&
+    if (NewSizes[i + ExtraDimsNew] != DimensionSizes[i + ExtraDimsOld])
-           "Array update with non-matching dimension sizes");
+      return false;
-  }
+
-#endif
+  if (DimensionSizes.size() >= NewSizes.size())
+    return true;
 
   DimensionSizes.clear();
   DimensionSizes.insert(DimensionSizes.begin(), NewSizes.begin(),
@@ -194,6 +194,7 @@ void ScopArrayInfo::updateSizes(ArrayRef<const SCEV *> NewSizes) {
     isl_pw_aff *Size = S.getPwAff(Expr);
     DimensionSizesPw.push_back(Size);
   }
+  return true;
 }
 
 ScopArrayInfo::~ScopArrayInfo() {
@@ -2377,9 +2378,12 @@ void Scop::init(AliasAnalysis &AA) {
   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 @@ Scop::getOrCreateScopArrayInfo(Value *BasePtr, Type *AccessType,
     SAI.reset(new ScopArrayInfo(BasePtr, AccessType, getIslCtx(), Sizes, IsPHI,
                                 this));
   } else {
-    if (Sizes.size() > SAI->getNumberOfDimensions())
+    // In case of mismatching array sizes, we bail out by setting the run-time
-      SAI->updateSizes(Sizes);
+    // context to false.
+    if (!SAI->updateSizes(Sizes))
+      addAssumption(isl_set_empty(getParamSpace()));
   }
   return SAI.get();
 }

polly/test/ScopInfo/mismatching-array-dimensions.ll

@@ -0,0 +1,55 @@
+; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
+
+; CHECK-NOT: AssumedContext
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+; Function Attrs: nounwind ssp uwtable
+define void @hoge([38 x [64 x float]]* %arg, [32 x [2 x float]]* %arg5, i32 %arg6) #0 {
+bb:
+  br i1 undef, label %bb7, label %bb25
+
+bb7:                                              ; preds = %bb21, %bb
+  %tmp8 = phi i64 [ %tmp22, %bb21 ], [ 0, %bb ]
+  %tmp9 = icmp sgt i32 %arg6, 0
+  br i1 %tmp9, label %bb10, label %bb21
+
+bb10:                                             ; preds = %bb10, %bb7
+  %tmp11 = getelementptr inbounds [32 x [2 x float]], [32 x [2 x float]]* %arg5, i64 %tmp8, i64 0
+  %tmp = bitcast [2 x float]* %tmp11 to i32*
+  %tmp12 = load i32, i32* %tmp, align 4, !tbaa !4
+  %tmp13 = getelementptr inbounds [32 x [2 x float]], [32 x [2 x float]]* %arg5, i64 %tmp8, i64 0, i64 1
+  %tmp14 = bitcast float* %tmp13 to i32*
+  %tmp15 = load i32, i32* %tmp14, align 4, !tbaa !4
+  %tmp16 = getelementptr inbounds [38 x [64 x float]], [38 x [64 x float]]* %arg, i64 1, i64 0, i64 %tmp8
+  %tmp17 = bitcast float* %tmp16 to i32*
+  store i32 %tmp15, i32* %tmp17, align 4, !tbaa !4
+  %tmp18 = add nuw nsw i64 0, 1
+  %tmp19 = trunc i64 %tmp18 to i32
+  %tmp20 = icmp ne i32 %tmp19, %arg6
+  br i1 %tmp20, label %bb10, label %bb21
+
+bb21:                                             ; preds = %bb10, %bb7
+  %tmp22 = add nsw i64 %tmp8, 1
+  %tmp23 = trunc i64 %tmp22 to i32
+  %tmp24 = icmp ne i32 %tmp23, 64
+  br i1 %tmp24, label %bb7, label %bb25
+
+bb25:                                             ; preds = %bb21, %bb
+  ret void
+}
+
+attributes #0 = { nounwind ssp uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="core2" "target-features"="+cx16,+fxsr,+mmx,+sse,+sse2,+sse3,+ssse3" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0, !1, !2}
+!llvm.ident = !{!3}
+
+!0 = !{i32 2, !"Dwarf Version", i32 2}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = !{i32 1, !"PIC Level", i32 2}
+!3 = !{!"clang version 3.8.0 (trunk 251760) (llvm/trunk 251765)"}
+!4 = !{!5, !5, i64 0}
+!5 = !{!"float", !6, i64 0}
+!6 = !{!"omnipotent char", !7, i64 0}
+!7 = !{!"Simple C/C++ TBAA"}