[polly] r251225 - ScopDetection: Always refuse multi-dimensional memory accesses with 'undef' in

[Tobias Grosser via llvm-commits]

Author: grosser
Date: Sun Oct 25 03:40:38 2015
New Revision: 251225

URL: http://llvm.org/viewvc/llvm-project?rev=251225&view=rev
Log:
ScopDetection: Always refuse multi-dimensional memory accesses with 'undef' in
               the size expression.

We previously only checked if the size expression is 'undef', but allowed size
expressions of the form 'undef * undef' by accident. After this change we now
require size expressions to be affine which implies no 'undef' appears anywhere
in the expression.

Added:
    polly/trunk/test/ScopDetect/multidim-with-undef-size.ll
Modified:
    polly/trunk/lib/Analysis/ScopDetection.cpp

Modified: polly/trunk/lib/Analysis/ScopDetection.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopDetection.cpp?rev=251225&r1=251224&r2=251225&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopDetection.cpp (original)
+++ polly/trunk/lib/Analysis/ScopDetection.cpp Sun Oct 25 03:40:38 2015
@@ -535,28 +535,25 @@ bool ScopDetection::hasAffineMemoryAcces
     SE->findArrayDimensions(Terms, Shape->DelinearizedSizes,
                             Context.ElementSize[BasePointer]);
 
-    if (!AllowNonAffine)
-      for (const SCEV *DelinearizedSize : Shape->DelinearizedSizes) {
-        if (auto *Unknown = dyn_cast<SCEVUnknown>(DelinearizedSize)) {
-          auto *V = dyn_cast<Value>(Unknown->getValue());
-          if (isa<UndefValue>(V)) {
-            invalid<ReportDifferentArrayElementSize>(
-                Context, /*Assert=*/true,
-                Context.Accesses[BasePointer].front().first, BaseValue);
-            return false;
-          }
-          if (auto *Load = dyn_cast<LoadInst>(V)) {
-            if (Context.CurRegion.contains(Load) &&
-                isHoistableLoad(Load, CurRegion, *LI, *SE))
-              Context.RequiredILS.insert(Load);
-            continue;
-          }
+    for (const SCEV *DelinearizedSize : Shape->DelinearizedSizes) {
+      if (!isAffine(DelinearizedSize, Context, nullptr)) {
+        Shape->DelinearizedSizes.clear();
+        break;
+      }
+      if (auto *Unknown = dyn_cast<SCEVUnknown>(DelinearizedSize)) {
+        auto *V = dyn_cast<Value>(Unknown->getValue());
+        if (auto *Load = dyn_cast<LoadInst>(V)) {
+          if (Context.CurRegion.contains(Load) &&
+              isHoistableLoad(Load, CurRegion, *LI, *SE))
+            Context.RequiredILS.insert(Load);
+          continue;
         }
-        if (hasScalarDepsInsideRegion(DelinearizedSize, &CurRegion))
-          invalid<ReportNonAffineAccess>(
-              Context, /*Assert=*/true, DelinearizedSize,
-              Context.Accesses[BasePointer].front().first, BaseValue);
       }
+      if (hasScalarDepsInsideRegion(DelinearizedSize, &CurRegion))
+        invalid<ReportNonAffineAccess>(
+            Context, /*Assert=*/true, DelinearizedSize,
+            Context.Accesses[BasePointer].front().first, BaseValue);
+    }
 
     // No array shape derived.
     if (Shape->DelinearizedSizes.empty()) {

Added: polly/trunk/test/ScopDetect/multidim-with-undef-size.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScopDetect/multidim-with-undef-size.ll?rev=251225&view=auto
==============================================================================
--- polly/trunk/test/ScopDetect/multidim-with-undef-size.ll (added)
+++ polly/trunk/test/ScopDetect/multidim-with-undef-size.ll Sun Oct 25 03:40:38 2015
@@ -0,0 +1,36 @@
+; RUN: opt %loadPolly -polly-detect -analyze < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; CHECK: Valid Region for Scop: bb14 => bb17
+
+; Make sure we do not detect the larger region bb14->bb19 that contains
+; a multi-dimensional memory access with a size of 'undef * undef'.
+
+define void @hoge(i8* %arg) {
+bb:
+  br label %bb6
+
+bb6:                                              ; preds = %bb
+  %tmp = mul i64 undef, undef
+  %tmp7 = add i64 %tmp, undef
+  %tmp8 = add i64 %tmp7, 0
+  %tmp9 = add i64 %tmp8, 8
+  %tmp10 = sub i64 %tmp9, undef
+  %tmp11 = getelementptr i8, i8* %arg, i64 %tmp10
+  %tmp12 = getelementptr inbounds i8, i8* %tmp11, i64 4
+  %tmp13 = getelementptr inbounds i8, i8* %tmp12, i64 20
+  br label %bb14
+
+bb14:                                             ; preds = %bb14, %bb6
+  %tmp15 = phi i32 [ %tmp16, %bb14 ], [ 2, %bb6 ]
+  %tmp16 = add nuw nsw i32 %tmp15, 1
+  br i1 false, label %bb14, label %bb17
+
+bb17:                                             ; preds = %bb14
+  %tmp18 = bitcast i8* %tmp13 to i32*
+  store i32 undef, i32* %tmp18, align 4
+  br label %bb19
+
+bb19:                                             ; preds = %bb17
+  unreachable
+}