Testcase for "More conservatively report status from LoopIdiomRecognize"

[jroelofs]

Summary

See: https://reviews.llvm.org/D84071#2169440

[fhahn]

Thanks for sharing. I did not manage to get it to crash with the patches removed though :(

[jroelofs]

In D84450#2173234, @fhahn wrote:

Thanks for sharing. I did not manage to get it to crash with the patches removed though :(

This must be super sensitive to something in the in-memory representation, since it doesn't even repro if I dump the IR and pass it back to the pass in question.

[nikic]

Can you check whether it reproduces if you export the IR with --preserve-bc-uselistorder / --preserve-ll-uselistorder?

[fhahn]

Thanks for sharing, but I don;t think this is needed any longer.

llvm/test/Transforms/LoopIdiom/loop-strided-store-cleanup.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -S -loop-idiom -debug-pass=Details 2>&1 | FileCheck %s
+
+;; Check that processLoopStridedStore cleans up after itself, but still reports
+;; that it modified the IR (even though the textual IR remains the same).
+
+; CHECK: Executing Pass 'Recognize loop idioms' on Loop 'bb1'...
+; CHECK: Made Modification 'Recognize loop idioms' on Loop 'bb1'...
+; CHECK: Freeing Pass 'Recognize loop idioms' on Loop 'bb1'...
+
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+%struct.foo = type { %struct.pluto }
+%struct.pluto = type { %struct.wombat }
+%struct.wombat = type { %struct.barney }
+%struct.barney = type { %struct.widget }
+%struct.widget = type { %struct.hoge }
+%struct.hoge = type { i64, i64, i8* }
+
+; Function Attrs: argmemonly nounwind willreturn writeonly
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg) #0
+
+; Function Attrs: argmemonly nounwind willreturn
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* noalias nocapture writeonly, i8* noalias nocapture readonly, i64, i1 immarg) #1
+
+define void @pluto() local_unnamed_addr #2 align 2 {
+; CHECK-LABEL: @pluto(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[ROCK:%.*]] = phi %struct.foo* [ [[ROCK2:%.*]], [[BB1]] ], [ null, [[BB:%.*]] ]
+; CHECK-NEXT:    [[ROCK2]] = getelementptr inbounds [[STRUCT_FOO:%.*]], %struct.foo* [[ROCK]], i64 -1
+; CHECK-NEXT:    [[ROCK3:%.*]] = bitcast %struct.foo* [[ROCK2]] to i8*
+; CHECK-NEXT:    tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull align 8 dereferenceable(24) undef, i8* nonnull align 8 dereferenceable(24) [[ROCK3]], i64 24, i1 false) #3
+; CHECK-NEXT:    tail call void @llvm.memset.p0i8.i64(i8* nonnull align 8 dereferenceable(24) [[ROCK3]], i8 0, i64 24, i1 false) #3
+; CHECK-NEXT:    [[ROCK4:%.*]] = icmp eq %struct.foo* [[ROCK2]], undef
+; CHECK-NEXT:    br i1 [[ROCK4]], label [[BB5:%.*]], label [[BB1]]
+; CHECK:       bb5:
+; CHECK-NEXT:    unreachable
+;
+bb:
+  br label %bb1
+
+bb1:                                              ; preds = %bb1, %bb
+  %rock = phi %struct.foo* [ %rock2, %bb1 ], [ null, %bb ]
+  %rock2 = getelementptr inbounds %struct.foo, %struct.foo* %rock, i64 -1
+  %rock3 = bitcast %struct.foo* %rock2 to i8*
+  tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull align 8 dereferenceable(24) undef, i8* nonnull align 8 dereferenceable(24) %rock3, i64 24, i1 false) #3
+  tail call void @llvm.memset.p0i8.i64(i8* nonnull align 8 dereferenceable(24) %rock3, i8 0, i64 24, i1 false) #3
+  %rock4 = icmp eq %struct.foo* %rock2, undef
+  br i1 %rock4, label %bb5, label %bb1
+
+bb5:                                              ; preds = %bb1
+  unreachable
+}
+
+attributes #0 = { argmemonly nounwind willreturn writeonly }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { "use-soft-float"="false" }
+attributes #3 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 12.0.0 ([e-mail]:llvm/llvm-project.git 994fb86bc2a83b24340b803bde243341dee651fa)"}