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[LTO] Don't internalize declarations 

Summary:
Some links were failing with "Global is external, but doesn't have
external or weak linkage!" in ThinLTO builds with debug
information. This happened when we elide the body of a global that is
referenced by debug info. This results in a declaration, which we
would then internalize - but declarations cannot be internal. This
change avoids the problem by not internalizing these declarations.

Fixes PR38046.

Reviewers: pcc, tejohnson

Subscribers: mehdi_amini, aprantl, hiraditya, JDevlieghere, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D49777

llvm-svn: 338100
This commit is contained in:
Bob Haarman 2018-07-27 05:40:29 +00:00
parent a8301fce51
commit eae4742d81
2 changed files with 36 additions and 1 deletions
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3
llvm/lib/LTO/LTO.cpp
View File

@ -872,7 +872,8 @@ Error LTO::runRegularLTO(AddStreamFn AddStream) {
GlobalValue *GV =
RegularLTO.CombinedModule->getNamedValue(R.second.IRName);
// Ignore symbols defined in other partitions.
if (!GV || GV->hasLocalLinkage())
// Also skip declarations, which are not allowed to have internal linkage.
if (!GV || GV->hasLocalLinkage() || GV->isDeclaration())
continue;
GV->setUnnamedAddr(R.second.UnnamedAddr ? GlobalValue::UnnamedAddr::Global
: GlobalValue::UnnamedAddr::None);

34
llvm/test/LTO/X86/pr38046.ll Normal file
View File

@ -0,0 +1,34 @@
; RUN: opt -module-summary -o %t.o %s
; RUN: llvm-lto2 run -save-temps -o %t.lto.o %t.o \
; RUN: -r=%t.o,foo,plx \
; RUN: -r=%t.o,get,pl
; RUN: llvm-dis %t.lto.o.0.2.internalize.bc >/dev/null 2>%t.dis.stderr || true
; RUN: FileCheck -allow-empty %s < %t.dis.stderr
; CHECK-NOT: Global is external, but doesn't have external or weak linkage
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define i32 @foo() {
call void @llvm.dbg.value(metadata i32 ()* @get, metadata !7, metadata !DIExpression()), !dbg !DILocation(scope: !6)
ret i32 0
}
define i32 @get() {
ret i32 0
}
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4, !5}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1)
!1 = !DIFile(filename: "t.cc", directory: "/tmp/t")
!2 = !{i32 2, !"Dwarf Version", i32 4}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = !{i32 1, !"ThinLTO", i32 0}
!6 = distinct !DISubprogram(unit: !0)
!7 = !DILocalVariable(name: "get", scope: !6)