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llvm-project/llvm/test/ThinLTO/X86/devirt_pure_virtual_base.ll

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[WPD] Fix handling of pure virtual base class The fix in 3c4c205060c9398da705eb71b63ddd8a04999de9 caused an assert in the case of a pure virtual base class. In that case, the vTableFuncs list on the summary will be empty, so we were hitting the new assert that the linkage type was not available_externally. In the case of pure virtual, we do not want to assert, and additionally need to set VS so that we don't treat it conservatively and quit the analysis of the type id early. This exposed a pre-existing issue where we were not updating the vcall visibility on pure virtual functions when whole program visibility was specified. We were skipping updating the visibility on any global vars that didn't have any vTableFuncs, which meant all pure virtual were not updated, and the later analysis would block any devirtualization of calls that had a type id used on those pure virtual vtables (see the handling in the other code modified in this patch). Simply remove that check. It will mean that we may update the vcall visibility on global vars that aren't vtables, but that setting is ignored for any global vars that didn't have type metadata anyway. Added a new test case that asserted without removing the assert, and that requires the other fixes in this patch (updateVCallVisibilityInIndex and not skipping all vtables without virtual funcs) to get a successful devirtualization with index-only WPD. I added cases to test hybrid and regular LTO for completeness, although those already worked without the fixes here. With this final fix, a clang multistage bootstrap with WPD builds and runs all tests successfully. Differential Revision: https://reviews.llvm.org/D97126
2021-02-21 06:09:10 +08:00
;; Test that pure virtual base is handled correctly.
;; Index based WPD
;; Generate unsplit module with summary for ThinLTO index-based WPD.
; RUN: opt --thinlto-bc -o %t1a.o %s
; RUN: llvm-lto2 run %t1a.o -save-temps -pass-remarks=. \
; RUN: -whole-program-visibility \
; RUN: -o %t3a \
; RUN: -r=%t1a.o,_start,plx \
; RUN: -r=%t1a.o,_ZTV1A,p \
; RUN: -r=%t1a.o,_ZTV1B,p \
; RUN: -r=%t1a.o,_ZN1A1fEi,p \
; RUN: -r=%t1a.o,_ZN1A1nEi,p \
; RUN: -r=%t1a.o,_ZN1B1fEi,p \
; RUN: -r=%t1a.o,__cxa_pure_virtual, \
; RUN: 2>&1 | FileCheck %s --check-prefix=REMARK
; RUN: llvm-dis %t3a.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
;; Hybrid WPD
;; Generate split module with summary for hybrid Thin/Regular LTO WPD.
; RUN: opt --thinlto-bc --thinlto-split-lto-unit -o %t1b.o %s
; RUN: llvm-lto2 run %t1b.o -save-temps -pass-remarks=. \
; RUN: -whole-program-visibility \
; RUN: -o %t3b \
; RUN: -r=%t1b.o,_start,plx \
; RUN: -r=%t1b.o,_ZTV1A, \
; RUN: -r=%t1b.o,_ZTV1B, \
; RUN: -r=%t1b.o,__cxa_pure_virtual, \
; RUN: -r=%t1b.o,_ZN1A1fEi,p \
; RUN: -r=%t1b.o,_ZN1A1nEi,p \
; RUN: -r=%t1b.o,_ZN1B1fEi,p \
; RUN: -r=%t1b.o,_ZTV1A,p \
; RUN: -r=%t1b.o,_ZTV1B,p \
; RUN: -r=%t1b.o,_ZN1A1nEi, \
; RUN: -r=%t1b.o,_ZN1B1fEi, \
; RUN: -r=%t1b.o,__cxa_pure_virtual, \
; RUN: 2>&1 | FileCheck %s --check-prefix=REMARK
; RUN: llvm-dis %t3b.1.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
;; Regular LTO WPD
; RUN: opt -o %t1c.o %s
; RUN: llvm-lto2 run %t1c.o -save-temps -pass-remarks=. \
; RUN: -whole-program-visibility \
; RUN: -o %t3c \
; RUN: -r=%t1c.o,_start,plx \
; RUN: -r=%t1c.o,_ZTV1A,p \
; RUN: -r=%t1c.o,_ZTV1B,p \
; RUN: -r=%t1c.o,_ZN1A1fEi,p \
; RUN: -r=%t1c.o,_ZN1A1nEi,p \
; RUN: -r=%t1c.o,_ZN1B1fEi,p \
; RUN: -r=%t1c.o,__cxa_pure_virtual, \
; RUN: 2>&1 | FileCheck %s --check-prefix=REMARK
; RUN: llvm-dis %t3c.0.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
; REMARK-DAG: single-impl: devirtualized a call to _ZN1A1nEi
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-grtev4-linux-gnu"
%struct.A = type { i32 (...)** }
%struct.B = type { %struct.A }
@_ZTV1A = linkonce_odr unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (void ()* @__cxa_pure_virtual to i8*), i8* bitcast (void ()* @__cxa_pure_virtual to i8*)] }, !type !0, !vcall_visibility !2
@_ZTV1B = linkonce_odr unnamed_addr 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 !2
;; Prevent the vtables from being dead code eliminated.
@llvm.used = appending global [2 x i8*] [ i8* bitcast ( { [4 x i8*] }* @_ZTV1A to i8*), i8* bitcast ( { [4 x i8*] }* @_ZTV1B to i8*)]
; CHECK-IR-LABEL: define dso_local i32 @_start
define i32 @_start(%struct.A* %obj, i32 %a) {
entry:
%0 = bitcast %struct.A* %obj to i8***
%vtable = load i8**, i8*** %0
%1 = bitcast i8** %vtable to i8*
%p = call i1 @llvm.type.test(i8* %1, metadata !"_ZTS1A")
call void @llvm.assume(i1 %p)
%fptrptr = getelementptr i8*, i8** %vtable, i32 1
%2 = bitcast i8** %fptrptr to i32 (%struct.A*, i32)**
%fptr1 = load i32 (%struct.A*, i32)*, i32 (%struct.A*, i32)** %2, align 8
;; Check that the call was devirtualized.
; CHECK-IR: %call = tail call i32 @_ZN1A1nEi
; CHECK-NODEVIRT-IR: %call = tail call i32 %fptr1
%call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a)
ret i32 %call
}
; CHECK-IR-LABEL: ret i32
; CHECK-IR-NEXT: }
declare i1 @llvm.type.test(i8*, metadata)
declare void @llvm.assume(i1)
declare void @__cxa_pure_virtual() unnamed_addr
define linkonce_odr i32 @_ZN1A1fEi(%struct.A* %this, i32 %a) #0 {
ret i32 0
}
define linkonce_odr i32 @_ZN1A1nEi(%struct.A* %this, i32 %a) #0 {
ret i32 0
}
define linkonce_odr i32 @_ZN1B1fEi(%struct.B* %this, i32 %a) #0 {
ret i32 0
}
;; Make sure we don't inline or otherwise optimize out the direct calls.
attributes #0 = { noinline optnone }
!0 = !{i64 16, !"_ZTS1A"}
!1 = !{i64 16, !"_ZTS1B"}
!2 = !{i64 0}