Try to build alias checks even when non-affine accesses are allowed

  From now on we bail only if a non-trivial alias group contains a non-affine
  access, not when we discover aliasing and non-affine accesses are allowed.

llvm-svn: 261863

4 files changed, 65 insertions, 6 deletions

diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index c16d9fb20b2..d3ac0fc567b 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -232,12 +232,6 @@ ScopDetection::ScopDetection() : FunctionPass(ID) {
     PollyUseRuntimeAliasChecks = false;
     return;
   }
-
-  if (AllowNonAffine) {
-    DEBUG(errs() << "WARNING: We disable runtime alias checks as non affine "
-                    "accesses are enabled.\n");
-    PollyUseRuntimeAliasChecks = false;
-  }
 }
 
 template <class RR, typename... Args>
diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index dc18d618b3b..e549ba21327 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -2689,6 +2689,20 @@ bool Scop::buildAliasGroups(AliasAnalysis &AA) {
       continue;
     }
 
+    // Check if we have non-affine accesses left, if so bail out as we cannot
+    // generate a good access range yet.
+    for (auto *MA : AG)
+      if (!MA->isAffine()) {
+        invalidate(ALIASING, MA->getAccessInstruction()->getDebugLoc());
+        return false;
+      }
+    for (auto &ReadOnlyPair : ReadOnlyPairs)
+      for (auto *MA : ReadOnlyPair.second)
+        if (!MA->isAffine()) {
+          invalidate(ALIASING, MA->getAccessInstruction()->getDebugLoc());
+          return false;
+        }
+
     // Calculate minimal and maximal accesses for non read only accesses.
     MinMaxAliasGroups.emplace_back();
     MinMaxVectorPairTy &pair = MinMaxAliasGroups.back();
diff --git a/polly/test/Isl/Ast/alias_simple_2.ll b/polly/test/Isl/Ast/alias_simple_2.ll
index 155ad2607e4..42f6bb47515 100644
--- a/polly/test/Isl/Ast/alias_simple_2.ll
+++ b/polly/test/Isl/Ast/alias_simple_2.ll
@@ -3,6 +3,7 @@
 ; RUN: opt %loadPolly -polly-ast -analyze -disable-basicaa -tbaa < %s | FileCheck %s --check-prefix=TBAA
 ; RUN: opt %loadPolly -polly-ast -analyze -disable-basicaa -scev-aa < %s | FileCheck %s --check-prefix=SCEV
 ; RUN: opt %loadPolly -polly-ast -analyze -disable-basicaa -globals-aa < %s | FileCheck %s --check-prefix=GLOB
+; RUN: opt %loadPolly -polly-ast -analyze -disable-basicaa -globals-aa -polly-allow-nonaffine < %s | FileCheck %s --check-prefix=NONAFFINE
 ;
 ;    int A[1024], B[1024];
 ;
@@ -17,6 +18,7 @@
 ; TBAA: if (1 && (&MemRef_B[N] <= &MemRef_A[0] || &MemRef_A[N] <= &MemRef_B[0]))
 ; SCEV: if (1 && (&MemRef_B[N] <= &MemRef_A[0] || &MemRef_A[N] <= &MemRef_B[0]))
 ; GLOB: if (1 && (&MemRef_B[N] <= &MemRef_A[0] || &MemRef_A[N] <= &MemRef_B[0]))
+; NONAFFINE: if (1 && (&MemRef_B[N] <= &MemRef_A[0] || &MemRef_A[N] <= &MemRef_B[0]))
 ;
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
diff --git a/polly/test/ScopInfo/aliasing_with_non_affine_access.ll b/polly/test/ScopInfo/aliasing_with_non_affine_access.ll
new file mode 100644
index 00000000000..db719219e21
--- /dev/null
+++ b/polly/test/ScopInfo/aliasing_with_non_affine_access.ll
@@ -0,0 +1,49 @@
+; RUN: opt %loadPolly -analyze -polly-scops < %s | FileCheck %s
+; RUN: opt %loadPolly -analyze -polly-scops -pass-remarks-analysis="polly-scops" 2>&1 < %s | FileCheck %s --check-prefix=REMARK
+;
+; This test case has a non-affine access (the memset call) that aliases with
+; other accesses. Thus, we bail out.
+;
+; CHECK-NOT: Statements
+;
+; REMARK:        remark: <unknown>:0:0: SCoP begins here.
+; REMARK-NEXT:   remark: <unknown>:0:0: Possibly aliasing pointer, use restrict keyword.
+; REMARK-NEXT:   remark: <unknown>:0:0: Possibly aliasing pointer, use restrict keyword.
+; REMARK-NEXT:   remark: <unknown>:0:0: No-aliasing assumption:	{  : 1 = 0 }
+; REMARK-NEXT:   remark: <unknown>:0:0: SCoP ends here but was dismissed.
+;
+; ModuleID = 'bugpoint-reduced-simplified.bc'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.info = type { i32, %struct.ctr*, i32, %struct.ord*, %struct.ctr*, i32, i8*, i32, i32, double }
+%struct.ctr = type { i32, i8, i8, i32 }
+%struct.ord = type { i32, i8 }
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) #0
+
+; Function Attrs: nounwind uwtable
+define void @bestVirtualIndex(%struct.info** %ppIdxInfo) {
+entry:
+  %0 = load %struct.info*, %struct.info** %ppIdxInfo, align 8
+  br label %if.end125
+
+if.end125:                                        ; preds = %entry
+  %1 = load %struct.ctr*, %struct.ctr** undef, align 8
+  br label %for.end143
+
+for.end143:                                       ; preds = %if.end125
+  %2 = bitcast %struct.ctr* %1 to i8*
+  tail call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 32, i32 4, i1 false)
+  %needToFreeIdxStr = getelementptr inbounds %struct.info, %struct.info* %0, i64 0, i32 7
+  %3 = load i32, i32* %needToFreeIdxStr, align 8
+  br i1 false, label %if.end149, label %if.then148
+
+if.then148:                                       ; preds = %for.end143
+  br label %if.end149
+
+if.end149:                                        ; preds = %if.then148, %for.end143
+  unreachable
+}
+
+attributes #0 = { argmemonly nounwind }