1860331932
When MemCpyOpt performs call slot optimization it will concatenate the `alias.scope` metadata between the function call and the memcpy. However, scoped AA relies on the domains in metadata to be maintained in a caller-callee relationship. Naive concatenation breaks this assumption leading to bad AA results. The fix is to take the intersection of domains then union the scopes within those domains. The original bug came from a case of rust bad codegen which uses this bad aliasing to perform additional memcpy optimizations. As show in the added test case `%src` got forwarded past its lifetime leading to a dereference of garbage data. Testing ninja check-llvm Reviewed By: jeroen.dobbelaere Differential Revision: https://reviews.llvm.org/D91576
70 lines
2.7 KiB
LLVM
70 lines
2.7 KiB
LLVM
; RUN: opt -instcombine -S < %s | FileCheck %s
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@g1 = common global i32* null, align 8
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%struct.S1 = type { i32, float }
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%struct.S2 = type { float, i32 }
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; Check that instcombine preserves metadata when it merges two loads.
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;
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; CHECK: return:
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; CHECK: load i32*, i32** %{{[a-z0-9.]+}}, align 8, !nonnull ![[EMPTYNODE:[0-9]+]]
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; CHECK: load i32, i32* %{{[a-z0-9.]+}}, align 4, !tbaa ![[TBAA:[0-9]+]], !range ![[RANGE:[0-9]+]], !invariant.load ![[EMPTYNODE:[0-9]+]], !alias.scope ![[ALIAS_SCOPE:[0-9]+]], !noalias ![[NOALIAS:[0-9]+]]
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; Function Attrs: nounwind ssp uwtable
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define i32 @phi_load_metadata(%struct.S1* %s1, %struct.S2* %s2, i32 %c, i32** %x0, i32 **%x1) #0 {
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entry:
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%tobool = icmp eq i32 %c, 0
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br i1 %tobool, label %if.end, label %if.then
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if.then: ; preds = %entry
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%i = getelementptr inbounds %struct.S2, %struct.S2* %s2, i64 0, i32 1
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%val = load i32, i32* %i, align 4, !tbaa !0, !alias.scope !13, !noalias !14, !invariant.load !17, !range !18
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%p0 = load i32*, i32** %x0, align 8, !nonnull !17
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br label %return
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if.end: ; preds = %entry
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%i2 = getelementptr inbounds %struct.S1, %struct.S1* %s1, i64 0, i32 0
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%val2 = load i32, i32* %i2, align 4, !tbaa !2, !alias.scope !15, !noalias !16, !invariant.load !17, !range !19
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%p1 = load i32*, i32** %x1, align 8, !nonnull !17
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br label %return
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return: ; preds = %if.end, %if.then
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%retval = phi i32 [ %val, %if.then ], [ %val2, %if.end ]
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%pval = phi i32* [ %p0, %if.then ], [ %p1, %if.end ]
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store i32* %pval, i32** @g1, align 8
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ret i32 %retval
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}
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; CHECK: ![[EMPTYNODE]] = !{}
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; CHECK: ![[TBAA]] = !{![[TAG1:[0-9]+]], ![[TAG1]], i64 0}
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; CHECK: ![[TAG1]] = !{!"int", !{{[0-9]+}}, i64 0}
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; CHECK: ![[RANGE]] = !{i32 10, i32 25}
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; CHECK: ![[ALIAS_SCOPE]] = !{![[SCOPE0:[0-9]+]], ![[SCOPE1:[0-9]+]], ![[SCOPE2:[0-9]+]]}
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; CHECK: ![[SCOPE0]] = distinct !{![[SCOPE0]], !{{[0-9]+}}, !"scope0"}
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; CHECK: ![[SCOPE1]] = distinct !{![[SCOPE1]], !{{[0-9]+}}, !"scope1"}
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; CHECK: ![[SCOPE2]] = distinct !{![[SCOPE2]], !{{[0-9]+}}, !"scope2"}
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; CHECK: ![[NOALIAS]] = !{![[SCOPE3:[0-9]+]]}
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; CHECK: ![[SCOPE3]] = distinct !{![[SCOPE3]], !{{[0-9]+}}, !"scope3"}
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!0 = !{!1, !4, i64 4}
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!1 = !{!"", !7, i64 0, !4, i64 4}
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!2 = !{!3, !4, i64 0}
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!3 = !{!"", !4, i64 0, !7, i64 4}
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!4 = !{!"int", !5, i64 0}
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!5 = !{!"omnipotent char", !6, i64 0}
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!6 = !{!"Simple C/C++ TBAA"}
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!7 = !{!"float", !5, i64 0}
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!8 = !{!8, !"some domain"}
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!9 = !{!9, !8, !"scope0"}
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!10 = !{!10, !8, !"scope1"}
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!11 = !{!11, !8, !"scope2"}
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!12 = !{!12, !8, !"scope3"}
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!13 = !{!9, !10}
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!14 = !{!11, !12}
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!15 = !{!9, !11}
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!16 = !{!10, !12}
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!17 = !{}
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!18 = !{i32 10, i32 20}
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!19 = !{i32 15, i32 25}
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