Fix non-synthesizable loop exit values.

Polly recognizes affine loops that ScalarEvolution does not, in
particular those with loop conditions that depend on hoisted invariant
loads. Check for SCEVAddRec dependencies on such loops and do not
consider their exit values as synthesizable because SCEVExpander would
generate them as expressions that depend on the original induction
variables. These are not available in generated code.

llvm-svn: 262404

1 files changed, 15 insertions, 8 deletions

diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index 4776a7f2ab8..47bf54786fb 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -716,7 +716,8 @@ ScopDetection::getDelinearizationTerms(DetectionContext &Context,
 
 bool ScopDetection::hasValidArraySizes(DetectionContext &Context,
                                        SmallVectorImpl<const SCEV *> &Sizes,
-                                       const SCEVUnknown *BasePointer) const {
+                                       const SCEVUnknown *BasePointer,
+                                       Loop *Scope) const {
   Value *BaseValue = BasePointer->getValue();
   Region &CurRegion = Context.CurRegion;
   for (const SCEV *DelinearizedSize : Sizes) {
@@ -733,7 +734,7 @@ bool ScopDetection::hasValidArraySizes(DetectionContext &Context,
         continue;
       }
     }
-    if (hasScalarDepsInsideRegion(DelinearizedSize, &CurRegion))
+    if (hasScalarDepsInsideRegion(DelinearizedSize, &CurRegion, Scope, false))
       return invalid<ReportNonAffineAccess>(
           Context, /*Assert=*/true, DelinearizedSize,
           Context.Accesses[BasePointer].front().first, BaseValue);
@@ -813,8 +814,9 @@ bool ScopDetection::computeAccessFunctions(
   return true;
 }
 
-bool ScopDetection::hasBaseAffineAccesses(
-    DetectionContext &Context, const SCEVUnknown *BasePointer) const {
+bool ScopDetection::hasBaseAffineAccesses(DetectionContext &Context,
+                                          const SCEVUnknown *BasePointer,
+                                          Loop *Scope) const {
   auto Shape = std::shared_ptr<ArrayShape>(new ArrayShape(BasePointer));
 
   auto Terms = getDelinearizationTerms(Context, BasePointer);
@@ -822,7 +824,8 @@ bool ScopDetection::hasBaseAffineAccesses(
   SE->findArrayDimensions(Terms, Shape->DelinearizedSizes,
                           Context.ElementSize[BasePointer]);
 
-  if (!hasValidArraySizes(Context, Shape->DelinearizedSizes, BasePointer))
+  if (!hasValidArraySizes(Context, Shape->DelinearizedSizes, BasePointer,
+                          Scope))
     return false;
 
   return computeAccessFunctions(Context, BasePointer, Shape);
@@ -834,13 +837,16 @@ bool ScopDetection::hasAffineMemoryAccesses(DetectionContext &Context) const {
   if (Context.HasUnknownAccess && !Context.NonAffineAccesses.empty())
     return AllowNonAffine;
 
-  for (const SCEVUnknown *BasePointer : Context.NonAffineAccesses)
-    if (!hasBaseAffineAccesses(Context, BasePointer)) {
+  for (auto &Pair : Context.NonAffineAccesses) {
+    auto *BasePointer = Pair.first;
+    auto *Scope = Pair.second;
+    if (!hasBaseAffineAccesses(Context, BasePointer, Scope)) {
       if (KeepGoing)
         continue;
       else
         return false;
     }
+  }
   return true;
 }
 
@@ -901,7 +907,8 @@ bool ScopDetection::isValidAccess(Instruction *Inst, const SCEV *AF,
     Context.Accesses[BP].push_back({Inst, AF});
 
     if (!IsAffine)
-      Context.NonAffineAccesses.insert(BP);
+      Context.NonAffineAccesses.insert(
+          std::make_pair(BP, LI->getLoopFor(Inst->getParent())));
   } else if (!AllowNonAffine && !IsAffine) {
     return invalid<ReportNonAffineAccess>(Context, /*Assert=*/true, AF, Inst,
                                           BV);