[PATCH] D68082: [LV] Emitting SCEV checks with OptForSize
Sjoerd Meijer via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 9 06:23:35 PDT 2019
This revision was automatically updated to reflect the committed changes.
Closed by commit rGd1170dbe5831: [LV] Emitting SCEV checks with OptForSize (authored by SjoerdMeijer).
Changed prior to commit:
https://reviews.llvm.org/D68082?vs=224012&id=224040#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D68082/new/
https://reviews.llvm.org/D68082
Files:
llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
llvm/test/Transforms/LoopVectorize/optsize.ll
Index: llvm/test/Transforms/LoopVectorize/optsize.ll
===================================================================
--- llvm/test/Transforms/LoopVectorize/optsize.ll
+++ llvm/test/Transforms/LoopVectorize/optsize.ll
@@ -84,6 +84,43 @@
ret i32 0
}
+; PR43371: don't run into an assert due to emitting SCEV runtime checks
+; with OptForSize.
+;
+ at cm_array = external global [2592 x i16], align 1
+
+define void @pr43371() optsize {
+;
+; CHECK-LABEL: @pr43371
+; CHECK-NOT: vector.scevcheck
+;
+; We do not want to generate SCEV predicates when optimising for size, because
+; that will lead to extra code generation such as the SCEV overflow runtime
+; checks. Not generating SCEV predicates can still result in vectorisation as
+; the non-consecutive loads/stores can be scalarized:
+;
+; CHECK: vector.body:
+; CHECK: store i16 0, i16* %{{.*}}, align 1
+; CHECK: store i16 0, i16* %{{.*}}, align 1
+; CHECK: br i1 {{.*}}, label %vector.body
+;
+entry:
+ br label %for.body29
+
+for.cond.cleanup28:
+ unreachable
+
+for.body29:
+ %i24.0170 = phi i16 [ 0, %entry], [ %inc37, %for.body29]
+ %add33 = add i16 undef, %i24.0170
+ %idxprom34 = zext i16 %add33 to i32
+ %arrayidx35 = getelementptr [2592 x i16], [2592 x i16] * @cm_array, i32 0, i32 %idxprom34
+ store i16 0, i16 * %arrayidx35, align 1
+ %inc37 = add i16 %i24.0170, 1
+ %cmp26 = icmp ult i16 %inc37, 756
+ br i1 %cmp26, label %for.body29, label %for.cond.cleanup28
+}
+
!llvm.module.flags = !{!0}
!0 = !{i32 1, !"ProfileSummary", !1}
!1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
Index: llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -409,7 +409,8 @@
const ValueToValueMap &Strides =
getSymbolicStrides() ? *getSymbolicStrides() : ValueToValueMap();
- int Stride = getPtrStride(PSE, Ptr, TheLoop, Strides, true, false);
+ bool CanAddPredicate = !TheLoop->getHeader()->getParent()->hasOptSize();
+ int Stride = getPtrStride(PSE, Ptr, TheLoop, Strides, CanAddPredicate, false);
if (Stride == 1 || Stride == -1)
return Stride;
return 0;
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