fee0bde4c6
Extend -wholeprogramdevirt-check to support both the existing trapping mode on an incorrect devirtualization, as well as a new mode to fallback to an indirect call on a mismatch. The new mode is The new mode is useful in cases where we want to enable devirtualization but cannot fully guarantee whole program visibility (e.g in the case where LTO has been disabled for a small set of objects that could potentially override virtual methods without having a symbol reference to anything in the base class including the vtable). Remove !prof and !callees metadata (which are used by indirect call promotion) from both the new direct call and the fallback indirect call (so that we don't perform another round of promotion on the latter). Also remove it from the direct call in the non-fallback cases, which was an oversight, although it didn't seem to cause any issues. Add tests for the metadata removal covering the various cases. Differential Revision: https://reviews.llvm.org/D121419
113 lines
4.1 KiB
LLVM
113 lines
4.1 KiB
LLVM
; REQUIRES: x86-registered-target
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; Test that devirtualization option -wholeprogramdevirt-check adds code to check
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; that the devirtualization decision was correct and trap or fallback if not.
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; The vtables have vcall_visibility metadata with hidden visibility, to enable
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; devirtualization.
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; Generate unsplit module with summary for ThinLTO index-based WPD.
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; RUN: opt -thinlto-bc -o %t2.o %s
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; Check first in trapping mode.
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; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
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; RUN: -wholeprogramdevirt-check=trap \
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; RUN: -o %t3 \
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; RUN: -r=%t2.o,test,px \
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; RUN: -r=%t2.o,_ZN1A1nEi,p \
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; RUN: -r=%t2.o,_ZN1B1fEi,p \
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; RUN: -r=%t2.o,_ZTV1B,px 2>&1 | FileCheck %s --check-prefix=REMARK
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; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK --check-prefix=TRAP
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; Check next in fallback mode.
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; RUN: llvm-lto2 run %t2.o -save-temps -use-new-pm -pass-remarks=. \
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; RUN: -wholeprogramdevirt-check=fallback \
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; RUN: -o %t3 \
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; RUN: -r=%t2.o,test,px \
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; RUN: -r=%t2.o,_ZN1A1nEi,p \
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; RUN: -r=%t2.o,_ZN1B1fEi,p \
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; RUN: -r=%t2.o,_ZTV1B,px 2>&1 | FileCheck %s --check-prefix=REMARK
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; RUN: llvm-dis %t3.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK --check-prefix=FALLBACK
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; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
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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-grtev4-linux-gnu"
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%struct.A = type { i32 (...)** }
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%struct.B = type { %struct.A }
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@_ZTV1B = constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.B*, i32)* @_ZN1B1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi to i8*)] }, !type !0, !type !1, !vcall_visibility !5
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; CHECK-LABEL: define i32 @test
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define i32 @test(%struct.A* %obj, i32 %a) {
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entry:
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%0 = bitcast %struct.A* %obj to i8***
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%vtable = load i8**, i8*** %0
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%1 = bitcast i8** %vtable to i8*
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%p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
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call void @llvm.assume(i1 %p)
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%fptrptr = getelementptr i8*, i8** %vtable, i32 1
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%2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
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%fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
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; Check that the call was devirtualized, but preceeded by a check guarding
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; a trap if the function pointer doesn't match.
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; TRAP: %.not = icmp eq i32 (%struct.A*, i32)* %fptr1, @_ZN1A1nEi
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; TRAP-NOT: prof
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; TRAP-NOT: callees
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; TRAP: br i1 %.not, label %3, label %2
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; TRAP: 2:
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; TRAP: tail call void @llvm.debugtrap()
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; TRAP: br label %3
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; TRAP: 3:
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; TRAP: tail call i32 @_ZN1A1nEi
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; Check that the call was devirtualized, but preceeded by a check guarding
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; a fallback if the function pointer doesn't match.
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; FALLBACK: %2 = icmp eq i32 (%struct.A*, i32)* %fptr1, @_ZN1A1nEi
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; FALLBACK: br i1 %2, label %if.true.direct_targ, label %if.false.orig_indirect
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; FALLBACK: if.true.direct_targ:
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; FALLBACK: tail call i32 @_ZN1A1nEi
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; FALLBACK-NOT: prof
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; FALLBACK-NOT: callees
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; FALLBACK: br label %if.end.icp
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; FALLBACK: if.false.orig_indirect:
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; FALLBACK: tail call i32 %fptr1
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; Ensure !prof and !callees metadata for indirect call promotion removed.
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; In particular, if left on the fallback indirect call ICP may perform an
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; additional round of promotion.
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; FALLBACK-NOT: prof
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; FALLBACK-NOT: callees
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; FALLBACK: br label %if.end.icp
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%call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a), !prof !6, !callees !7
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ret i32 %call
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}
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; CHECK-LABEL: ret i32
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; CHECK-LABEL: }
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declare i1 @llvm.type.test(i8*, metadata)
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declare void @llvm.assume(i1)
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define i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
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ret i32 0;
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}
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define i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
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ret i32 0;
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}
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; Make sure we don't inline or otherwise optimize out the direct calls.
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attributes #0 = { noinline optnone }
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!0 = !{i64 16, !"_ZTS1A"}
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!1 = !{i64 16, !"_ZTS1B"}
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!3 = !{i64 16, !4}
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!4 = distinct !{}
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!5 = !{i64 1}
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!6 = !{!"VP", i32 0, i64 1, i64 1621563287929432257, i64 1}
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!7 = !{i32 (%struct.A*, i32)* @_ZN1A1nEi}
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