diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp --- a/lld/ELF/LTO.cpp +++ b/lld/ELF/LTO.cpp @@ -249,8 +249,9 @@ usedStartStop.count(objSym.getSectionName()); // Identify symbols exported dynamically, and that therefore could be // referenced by a shared library not visible to the linker. - r.ExportDynamic = sym->isExportDynamic(sym->kind(), sym->visibility) || - sym->exportDynamic || sym->inDynamicList; + r.ExportDynamic = sym->computeBinding() != STB_LOCAL && + (sym->isExportDynamic(sym->kind(), sym->visibility) || + sym->exportDynamic || sym->inDynamicList); const auto *dr = dyn_cast(sym); r.FinalDefinitionInLinkageUnit = (isExec || sym->visibility != STV_DEFAULT) && dr && diff --git a/lld/test/ELF/lto/devirt_vcall_vis_localize.ll b/lld/test/ELF/lto/devirt_vcall_vis_localize.ll new file mode 100644 --- /dev/null +++ b/lld/test/ELF/lto/devirt_vcall_vis_localize.ll @@ -0,0 +1,71 @@ +; REQUIRES: x86 +;; If the vtable symbols are localized by a version script, devirtualization +;; can still happen. + +; RUN: opt --thinlto-bc -o %t1.o %s +; RUN: opt --thinlto-bc -o %t2.o %S/Inputs/devirt_vcall_vis_shared_def.ll +; RUN: echo '{ global: _start; local: *; };' > %t.ver + +; RUN: ld.lld %t1.o %t2.o -o %t.out --save-temps --lto-whole-program-visibility -shared \ +; RUN: -mllvm -pass-remarks=. 2>&1 | count 0 + +; RUN: ld.lld %t1.o %t2.o -o %t.out --save-temps --lto-whole-program-visibility -shared \ +; RUN: --version-script=%t.ver -mllvm -pass-remarks=. 2>&1 | FileCheck %s --check-prefix=REMARK +; RUN: llvm-dis < %t1.o.4.opt.bc | FileCheck %s --check-prefix=CHECK-IR + +; REMARK: 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 = available_externally unnamed_addr constant { [4 x i8*] } { [4 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1fEi to i8*), i8* bitcast (i32 (%struct.A*, i32)* @_ZN1A1nEi 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: @_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 + %call = tail call i32 %fptr1(%struct.A* nonnull %obj, i32 %a) + + ret i32 %call +} +; CHECK-IR-LABEL: ret i32 +; CHECK-IR-LABEL: } + +declare i1 @llvm.type.test(i8*, metadata) +declare void @llvm.assume(i1) + +define available_externally i32 @_ZN1A1fEi(%struct.A* %this, i32 %a) #0 { + ret i32 0 +} + +define available_externally 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}