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[ELF] Respect ltoCanOmit for symbols in non-prevailing COMDAT #119332

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Merged
merged 3 commits into from
Dec 11, 2024
Merged

[ELF] Respect ltoCanOmit for symbols in non-prevailing COMDAT #119332

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b1038ce
[𝘀𝗽𝗿] initial version
MaskRay Dec 10, 2024
d0c4824
rebase
MaskRay Dec 10, 2024
5be42ea
test comment
MaskRay Dec 11, 2024
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8 changes: 3 additions & 5 deletions lld/ELF/InputFiles.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1709,7 +1709,6 @@ static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
}

static void createBitcodeSymbol(Ctx &ctx, Symbol *&sym,
const std::vector<bool> &keptComdats,
const lto::InputFile::Symbol &objSym,
BitcodeFile &f) {
uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
Expand All @@ -1726,8 +1725,7 @@ static void createBitcodeSymbol(Ctx &ctx, Symbol *&sym,
sym = ctx.symtab->insert(objSym.getName());
}

int c = objSym.getComdatIndex();
if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
if (objSym.isUndefined()) {
Undefined newSym(&f, StringRef(), binding, visibility, type);
sym->resolve(ctx, newSym);
sym->referenced = true;
Expand Down Expand Up @@ -1766,10 +1764,10 @@ void BitcodeFile::parse() {
// ObjFile<ELFT>::initializeSymbols.
for (auto [i, irSym] : llvm::enumerate(obj->symbols()))
if (!irSym.isUndefined())
createBitcodeSymbol(ctx, symbols[i], keptComdats, irSym, *this);
createBitcodeSymbol(ctx, symbols[i], irSym, *this);
for (auto [i, irSym] : llvm::enumerate(obj->symbols()))
if (irSym.isUndefined())
createBitcodeSymbol(ctx, symbols[i], keptComdats, irSym, *this);
createBitcodeSymbol(ctx, symbols[i], irSym, *this);

for (auto l : obj->getDependentLibraries())
addDependentLibrary(ctx, l, this);
Expand Down
25 changes: 25 additions & 0 deletions lld/test/ELF/lto/Inputs/internalize-exportdyn.ll
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Original file line number Diff line number Diff line change
@@ -1,6 +1,31 @@
target triple = "x86_64-unknown-linux-gnu"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"

$ext_and_ext = comdat any
$lo_and_ext = comdat any
$lo_and_wo = comdat any
$wo_and_lo = comdat any

declare void @foo(i64)

define weak_odr void @bah() {
ret void
}

define void @ext_and_ext() local_unnamed_addr comdat {
call void @foo(i64 2)
ret void
}

define linkonce_odr void @lo_and_ext() local_unnamed_addr comdat {
call void @foo(i64 2)
ret void
}

define weak_odr void @lo_and_wo() local_unnamed_addr comdat {
ret void
}

define linkonce_odr void @wo_and_lo() local_unnamed_addr comdat {
ret void
}
54 changes: 48 additions & 6 deletions lld/test/ELF/lto/internalize-exportdyn.ll
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@@ -1,21 +1,31 @@
; REQUIRES: x86
; RUN: llvm-as %s -o %t.o
; RUN: llvm-as %p/Inputs/internalize-exportdyn.ll -o %t2.o
; RUN: ld.lld %t.o %t2.o -o %t2 --export-dynamic -save-temps
; RUN: llvm-dis < %t2.0.2.internalize.bc | FileCheck %s
; RUN: ld.lld %t.o %t2.o -o %t3 -shared -save-temps
; RUN: llvm-dis < %t3.0.2.internalize.bc | FileCheck %s --check-prefix=DSO
; RUN: rm -rf %t && split-file %s %t && cd %t
; RUN: llvm-as a.ll -o a.bc
; RUN: llvm-as %p/Inputs/internalize-exportdyn.ll -o b.bc
; RUN: llvm-mc -filetype=obj -triple=x86_64 lib.s -o lib.o
; RUN: ld.lld a.bc b.bc lib.o -o out --export-dynamic -save-temps
; RUN: llvm-dis < out.0.2.internalize.bc | FileCheck %s
; RUN: ld.lld a.bc b.bc lib.o -o out2 -shared -save-temps
; RUN: llvm-dis < out2.0.2.internalize.bc | FileCheck %s --check-prefix=DSO

;--- a.ll
target triple = "x86_64-unknown-linux-gnu"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"

$ext_and_ext = comdat any
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@smithp35 smithp35 Dec 10, 2024

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It took me a while to work out what these meant, as I didn't realise that the definitions in Inputs were different. Could be worth a quick comment explaining the naming convention.

$lo_and_ext = comdat any
$lo_and_wo = comdat any
$wo_and_lo = comdat any

@c = linkonce_odr constant i32 1
@g = linkonce_odr global i32 1
@u_c = linkonce_odr unnamed_addr constant i32 1
@u_g = linkonce_odr unnamed_addr global i32 1
@lu_c = linkonce_odr local_unnamed_addr constant i32 1
@lu_g = linkonce_odr local_unnamed_addr global i32 1

declare void @lib(i64)

define void @_start() {
ret void
}
Expand Down Expand Up @@ -46,6 +56,24 @@ define linkonce_odr void @baz() {

@use_baz = global ptr @baz

define void @ext_and_ext() local_unnamed_addr comdat {
call void @foo(i64 1)
ret void
}

define linkonce_odr void @lo_and_ext() local_unnamed_addr comdat {
call void @foo(i64 1)
ret void
}

define linkonce_odr void @lo_and_wo() local_unnamed_addr comdat {
ret void
}

define weak_odr void @wo_and_lo() local_unnamed_addr comdat {
ret void
}

; Check what gets internalized.
; CHECK: @c = weak_odr dso_local constant i32 1
; CHECK: @g = weak_odr dso_local global i32 1
Expand All @@ -60,6 +88,12 @@ define linkonce_odr void @baz() {
; CHECK: define internal void @zed2()
; CHECK: define weak_odr dso_local void @bah()
; CHECK: define weak_odr dso_local void @baz()
; CHECK: define dso_local void @ext_and_ext() comdat
; CHECK-NEXT: call void @foo(i64 1)
; CHECK: define internal void @lo_and_ext() comdat
; CHECK-NEXT: call void @foo(i64 1)
; CHECK: define weak_odr dso_local void @lo_and_wo() comdat
; CHECK: define weak_odr dso_local void @wo_and_lo() comdat

; DSO: @c = weak_odr constant i32 1
; DSO: @g = weak_odr global i32 1
Expand All @@ -74,3 +108,11 @@ define linkonce_odr void @baz() {
; DSO: define internal void @zed2()
; DSO: define weak_odr void @bah()
; DSO: define weak_odr void @baz()
; DSO: define void @ext_and_ext() comdat
; DSO: define internal void @lo_and_ext() comdat
; DSO: define weak_odr void @lo_and_wo() comdat
; DSO: define weak_odr void @wo_and_lo() comdat

;--- lib.s
.globl lib
lib:
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