0f46e31cfb
As part of the migration to ptradd (https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699), we need to change the representation of the `inrange` attribute, which is used for vtable splitting. Currently, inrange is specified as follows: ``` getelementptr inbounds ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, inrange i32 1, i64 2) ``` The `inrange` is placed on a GEP index, and all accesses must be "in range" of that index. The new representation is as follows: ``` getelementptr inbounds inrange(-16, 16) ({ [4 x ptr], [4 x ptr] }, ptr @vt, i64 0, i32 1, i64 2) ``` This specifies which offsets are "in range" of the GEP result. The new representation will continue working when canonicalizing to ptradd representation: ``` getelementptr inbounds inrange(-16, 16) (i8, ptr @vt, i64 48) ``` The inrange offsets are relative to the return value of the GEP. An alternative design could make them relative to the source pointer instead. The result-relative format was chosen on the off-chance that we want to extend support to non-constant GEPs in the future, in which case this variant is more expressive. This implementation "upgrades" the old inrange representation in bitcode by simply dropping it. This is a very niche feature, and I don't think trying to upgrade it is worthwhile. Let me know if you disagree.
110 lines
4.6 KiB
LLVM
110 lines
4.6 KiB
LLVM
; REQUIRES: x86
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;; Test that that a vtable defined locally in one module but external in another
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;; does not prevent devirtualization.
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;; Hybrid WPD
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; RUN: split-file %s %t
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; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t/Cat.o %t/Cat.ll
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; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t/User.o %t/User.ll
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; RUN: echo '{ global: _Z17useDoThingWithCatv; local: *; };' > %t/version.exp
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; RUN: ld.lld %t/Cat.o %t/User.o -shared -o %t/libA.so -save-temps --lto-whole-program-visibility \
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; RUN: -mllvm -pass-remarks=. --version-script %t/version.exp 2>&1 | \
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; RUN: FileCheck %s --check-prefix=REMARK
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; REMARK-DAG: <unknown>:0:0: single-impl: devirtualized a call to _ZNK3Cat9makeNoiseEv
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; REMARK-DAG: <unknown>:0:0: single-impl: devirtualized a call to _ZNK3Cat9makeNoiseEv
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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;--- Cat.ll
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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%struct.Cat = type { %struct.Animal }
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%struct.Animal = type { ptr }
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$_ZTS6Animal = comdat any
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$_ZTI6Animal = comdat any
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@.str = private unnamed_addr constant [5 x i8] c"Meow\00", align 1
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@_ZTV3Cat = dso_local unnamed_addr constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr @_ZTI3Cat, ptr @_ZNK3Cat9makeNoiseEv] }, align 8, !type !0, !type !1, !type !2, !type !3
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@_ZTVN10__cxxabiv120__si_class_type_infoE = external dso_local global ptr
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@_ZTS3Cat = dso_local constant [5 x i8] c"3Cat\00", align 1
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@_ZTVN10__cxxabiv117__class_type_infoE = external dso_local global ptr
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@_ZTS6Animal = linkonce_odr dso_local constant [8 x i8] c"6Animal\00", comdat, align 1
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@_ZTI6Animal = linkonce_odr dso_local constant { ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), ptr @_ZTS6Animal }, comdat, align 8
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@_ZTI3Cat = dso_local constant { ptr, ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr @_ZTS3Cat, ptr @_ZTI6Animal }, align 8
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define dso_local void @_ZNK3Cat9makeNoiseEv(ptr nocapture nonnull readnone dereferenceable(8) %this) unnamed_addr align 2 {
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entry:
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%call = tail call i32 @puts(ptr nonnull dereferenceable(1) @.str)
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ret void
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}
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declare dso_local noundef i32 @puts(ptr nocapture noundef readonly) local_unnamed_addr
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define dso_local void @_Z14doThingWithCatP6Animal(ptr %a) local_unnamed_addr {
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entry:
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%tobool.not = icmp eq ptr %a, null
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br i1 %tobool.not, label %if.end, label %if.then
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if.then: ; preds = %entry
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%vtable = load ptr, ptr %a, align 8, !tbaa !4
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%0 = tail call i1 @llvm.type.test(ptr %vtable, metadata !"_ZTS3Cat")
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tail call void @llvm.assume(i1 %0)
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%1 = load ptr, ptr %vtable, align 8
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tail call void %1(ptr nonnull dereferenceable(8) %a)
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br label %if.end
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if.end: ; preds = %if.then, %entry
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ret void
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}
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declare i1 @llvm.type.test(ptr, metadata)
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declare void @llvm.assume(i1 noundef)
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!0 = !{i64 16, !"_ZTS3Cat"}
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!1 = !{i64 16, !"_ZTSM3CatKFvvE.virtual"}
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!2 = !{i64 16, !"_ZTS6Animal"}
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!3 = !{i64 16, !"_ZTSM6AnimalKFvvE.virtual"}
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!4 = !{!5, !5, i64 0}
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!5 = !{!"vtable pointer", !6, i64 0}
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!6 = !{!"Simple C++ TBAA"}
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;--- User.ll
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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%struct.Animal = type { ptr }
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%struct.Cat = type { %struct.Animal }
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@_ZTV3Cat = available_externally dso_local unnamed_addr constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr @_ZTI3Cat, ptr @_ZNK3Cat9makeNoiseEv] }, align 8, !type !0, !type !1, !type !2, !type !3
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@_ZTI3Cat = external dso_local constant ptr
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@llvm.compiler.used = appending global [1 x ptr] [ptr @_ZTV3Cat], section "llvm.metadata"
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declare dso_local void @_ZNK3Cat9makeNoiseEv(ptr nonnull dereferenceable(8)) unnamed_addr
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define dso_local void @_Z17useDoThingWithCatv() local_unnamed_addr {
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entry:
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%call = tail call noalias nonnull dereferenceable(8) ptr @_Znwm(i64 8)
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store ptr getelementptr inbounds inrange(-16, 8) ({ [3 x ptr] }, ptr @_ZTV3Cat, i64 0, i32 0, i64 2), ptr %call, align 8, !tbaa !4
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tail call void @_Z14doThingWithCatP6Animal(ptr nonnull %call)
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ret void
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}
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declare dso_local nonnull ptr @_Znwm(i64) local_unnamed_addr
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declare dso_local void @_Z14doThingWithCatP6Animal(ptr) local_unnamed_addr
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!0 = !{i64 16, !"_ZTS3Cat"}
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!1 = !{i64 16, !"_ZTSM3CatKFvvE.virtual"}
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!2 = !{i64 16, !"_ZTS6Animal"}
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!3 = !{i64 16, !"_ZTSM6AnimalKFvvE.virtual"}
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!4 = !{!5, !5, i64 0}
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!5 = !{!"vtable pointer", !6, i64 0}
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!6 = !{!"Simple C++ TBAA"}
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