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[lld-macho] Allow deduplicate-literals to be overridden

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It's still uncertain but whether we want to have `deduplicate-literals` be the
default flag for LLD out of the box or not. If `deduplicate-literals` is the default
behavior, then we will need a way override it and not deduplicate. Luckily, we
have `no_deduplicate` to fill this gap. For now, I've set the default to be false
which aligns with the existing behavior. That can only always be changed after
discussions on D117250.

Reviewed By: #lld-macho, int3

Differential Revision: https://reviews.llvm.org/D117387
This commit is contained in:
Vincent Lee 2022-01-14 23:06:13 -08:00
parent a567961574
commit e5347f2556
4 changed files with 33 additions and 3 deletions
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5
lld/MachO/Driver.cpp
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@ -1281,8 +1281,9 @@ bool macho::link(ArrayRef<const char *> argsArr, bool canExitEarly,
config->emitDataInCodeInfo =
args.hasFlag(OPT_data_in_code_info, OPT_no_data_in_code_info, true);
config->icfLevel = getICFLevel(args);
config->dedupLiterals = args.hasArg(OPT_deduplicate_literals) ||
config->icfLevel != ICFLevel::none;
config->dedupLiterals =
args.hasFlag(OPT_deduplicate_literals, OPT_icf_eq, false) ||
config->icfLevel != ICFLevel::none;
config->warnDylibInstallName = args.hasFlag(
OPT_warn_dylib_install_name, OPT_no_warn_dylib_install_name, false);
config->callGraphProfileSort = args.hasFlag(

7
lld/MachO/ld64-vs-lld.rst
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@ -4,6 +4,13 @@ LD64 vs LLD-MACHO
This doc lists all significant deliberate differences in behavior between LD64 and LLD-MachO.
``-no_deduplicate`` Flag
**********************
- LD64:
* This turns off ICF (deduplication pass) in the linker.
- LLD
* This turns off ICF and string merging in the linker.
ObjC symbols treatment
**********************
There are differences in how LLD and LD64 handle ObjC symbols loaded from archives.

23
lld/test/MachO/literal-dedup.s
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@ -6,6 +6,29 @@
# RUN: llvm-objdump --macho --section="__TEXT,__literals" --section="__DATA,ptrs" --syms %t/test | FileCheck %s
# RUN: llvm-readobj --section-headers %t/test | FileCheck %s --check-prefix=HEADER
## Make sure literal deduplication can be overridden or that the later flag wins.
# RUN: %lld -dylib --deduplicate-literals -no_deduplicate %t/test.o %t/qux.o -o %t/no-dedup-test
# RUN: llvm-objdump --macho --section="__TEXT,__literals" --section="__DATA,ptrs" %t/no-dedup-test | FileCheck %s --check-prefix=NO-DEDUP
# RUN: %lld -dylib -no_deduplicate --deduplicate-literals %t/test.o %t/qux.o -o %t/test
# RUN: llvm-objdump --macho --section="__TEXT,__literals" --section="__DATA,ptrs" --syms %t/test | FileCheck %s
# RUN: llvm-readobj --section-headers %t/test | FileCheck %s --check-prefix=HEADER
# NO-DEDUP-NOT: Contents of (__TEXT,__literals) section
# NO-DEDUP: Contents of (__DATA,ptrs) section
# NO-DEDUP-NEXT: __TEXT:__literal16:0xdeadbeef 0xdeadbeef 0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal16:0xdeadbeef 0xdeadbeef 0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal16:0xfeedface 0xfeedface 0xfeedface 0xfeedface
# NO-DEDUP-NEXT: __TEXT:__literal16:0xdeadbeef 0xdeadbeef 0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal8:0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal8:0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal8:0xfeedface 0xfeedface
# NO-DEDUP-NEXT: __TEXT:__literal8:0xdeadbeef 0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal4:0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal4:0xdeadbeef
# NO-DEDUP-NEXT: __TEXT:__literal4:0xfeedface
# NO-DEDUP-NEXT: __TEXT:__literal4:0xdeadbeef
# CHECK: Contents of (__TEXT,__literals) section
# CHECK-NEXT: [[#%.16x,DEADBEEF16:]] ef be ad de ef be ad de ef be ad de ef be ad de
# CHECK-NEXT: [[#%.16x,FEEDFACE16:]] ce fa ed fe ce fa ed fe ce fa ed fe ce fa ed fe

1
lld/test/MachO/silent-ignore.s
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@ -6,7 +6,6 @@
## `--version` flag.)
# RUN: %lld --version \
# RUN: -dynamic \
# RUN: -no_deduplicate \
# RUN: -lto_library /lib/foo \
# RUN: -macosx_version_min 0 \
# RUN: -no_dtrace_dof \