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[lld-macho] Make safe ICF conservative without __llvm_addrsig (#188400)

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MachO --icf=safe and --icf=safe_thunks used to keep folding code from
object files that did not contain __llvm_addrsig, which was inconsistent
with the conservative ELF/COFF behavior. Mark all symbols in such
objects as address-significant instead, and add regression coverage for
both safe ICF modes with and without addrsig.
This commit is contained in:
Zhaoxuan Jiang 2026-03-27 07:30:23 +08:00 committed by GitHub
parent b9b87dd796
commit 788ea11054
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GPG Key ID: B5690EEEBB952194
3 changed files with 117 additions and 1 deletions
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5
lld/MachO/ICF.cpp
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@ -514,8 +514,11 @@ void macho::markAddrSigSymbols() {
continue;
Section *addrSigSection = obj->addrSigSection;
if (!addrSigSection)
if (!addrSigSection) {
for (Symbol *sym : obj->symbols)
markSymAsAddrSig(sym);
continue;
}
assert(addrSigSection->subsections.size() == 1);
const InputSection *isec = addrSigSection->subsections[0].isec;

1
lld/test/MachO/icf-options.s
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@ -22,6 +22,7 @@
# RUN: llvm-objdump -d --syms %t/all | FileCheck %s --check-prefix=FOLD
# RUN: llvm-objdump -d --syms %t/all2 | FileCheck %s --check-prefix=FOLD
# RUN: llvm-objdump -d --syms %t/safe | FileCheck %s --check-prefix=NOOP
# RUN: llvm-objdump -d --syms %t/none | FileCheck %s --check-prefix=NOOP
# RUN: llvm-objdump -d --syms %t/none2 | FileCheck %s --check-prefix=NOOP
# RUN: llvm-objdump -d --syms %t/no_dedup | FileCheck %s --check-prefix=NOOP

112
lld/test/MachO/icf-safe-missing-addrsig.s Normal file
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@ -0,0 +1,112 @@
# REQUIRES: aarch64
# RUN: rm -rf %t && split-file %s %t
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/with-addrsig.s -o %t/with-addrsig.o
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/without-addrsig.s -o %t/without-addrsig.o
# RUN: %lld -arch arm64 -lSystem --icf=safe -dylib -map %t/with-addrsig-safe.map -o %t/with-addrsig.dylib %t/with-addrsig.o
# RUN: %lld -arch arm64 -lSystem --icf=safe -dylib -map %t/without-addrsig-safe.map -o %t/without-addrsig.dylib %t/without-addrsig.o
# RUN: %lld -arch arm64 -lSystem --icf=safe_thunks -dylib -map %t/with-addrsig-safe-thunks.map -o %t/with-addrsig-thunks.dylib %t/with-addrsig.o
# RUN: %lld -arch arm64 -lSystem --icf=safe_thunks -dylib -map %t/without-addrsig-safe-thunks.map -o %t/without-addrsig-thunks.dylib %t/without-addrsig.o
# RUN: FileCheck %s --check-prefix=ADDRSIG-SAFE < %t/with-addrsig-safe.map
# RUN: FileCheck %s --check-prefix=NO-ADDRSIG-SAFE < %t/without-addrsig-safe.map
# RUN: FileCheck %s --check-prefix=ADDRSIG-SAFE-THUNKS < %t/with-addrsig-safe-thunks.map
# RUN: FileCheck %s --check-prefix=NO-ADDRSIG-SAFE-THUNKS < %t/without-addrsig-safe-thunks.map
## Input has addrsig section: _g1 and _g2 are address-significant, so _g2 is
## thunk-folded in safe_thunks ICF and remains untouched in safe ICF.
## _f2 is always body-folded into _f1 regardless of ICF level.
# ADDRSIG-SAFE: 0x00000008 [ 2] _f1
# ADDRSIG-SAFE-NEXT: 0x00000000 [ 2] _f2
# ADDRSIG-SAFE: 0x00000008 [ 2] _g1
# ADDRSIG-SAFE-NEXT: 0x00000008 [ 2] _g2
# ADDRSIG-SAFE-THUNKS: 0x00000008 [ 2] _f1
# ADDRSIG-SAFE-THUNKS-NEXT: 0x00000000 [ 2] _f2
# ADDRSIG-SAFE-THUNKS: 0x00000008 [ 2] _g1
# ADDRSIG-SAFE-THUNKS: 0x00000004 [ 2] _g2
## Input does not have addrsig section: everything is address-significant, so
## no folding happened in safe ICF, and _f2, _g2 are thunk-folded into _f1, _g1
## respectively.
# NO-ADDRSIG-SAFE: 0x00000008 [ 2] _f1
# NO-ADDRSIG-SAFE-NEXT: 0x00000008 [ 2] _f2
# NO-ADDRSIG-SAFE-NEXT: 0x00000008 [ 2] _g1
# NO-ADDRSIG-SAFE-NEXT: 0x00000008 [ 2] _g2
# NO-ADDRSIG-SAFE-THUNKS: 0x00000008 [ 2] _f1
# NO-ADDRSIG-SAFE-THUNKS-NEXT: 0x00000008 [ 2] _g1
# NO-ADDRSIG-SAFE-THUNKS: 0x00000004 [ 2] _g2
# NO-ADDRSIG-SAFE-THUNKS-NEXT: 0x00000004 [ 2] _f2
#--- with-addrsig.s
.subsections_via_symbols
.text
.p2align 2
.globl _f1
_f1:
mov w0, #0
ret
.globl _f2
_f2:
mov w0, #0
ret
.globl _g1
_g1:
mov w0, #1
ret
.globl _g2
_g2:
mov w0, #1
ret
.globl _call_all
_call_all:
bl _f1
bl _f2
bl _g1
bl _g2
ret
.addrsig
.addrsig_sym _call_all
.addrsig_sym _g1
.addrsig_sym _g2
#--- without-addrsig.s
.subsections_via_symbols
.text
.p2align 2
.globl _f1
_f1:
mov w0, #0
ret
.globl _f2
_f2:
mov w0, #0
ret
.globl _g1
_g1:
mov w0, #1
ret
.globl _g2
_g2:
mov w0, #1
ret
.globl _call_all
_call_all:
bl _f1
bl _f2
bl _g1
bl _g2
ret