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[ELF] Add --export-dynamic-symbol-list
This is available in GNU ld 2.35 and can be seen as a shortcut for multiple --export-dynamic-symbol, or a --dynamic-list variant without the symbolic intention. In the long term, this option probably should be preferred over --dynamic-list. Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D107317
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‎lld/ELF/Driver.cpp

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1379,7 +1379,8 @@ static void readConfigs(opt::InputArgList &args) {
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// symbols not specified by --dynamic-list are non-preemptible.
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config->symbolic =
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config->bsymbolic == BsymbolicKind::All || args.hasArg(OPT_dynamic_list);
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for (auto *arg : args.filtered(OPT_dynamic_list))
1382+
for (auto *arg :
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args.filtered(OPT_dynamic_list, OPT_export_dynamic_symbol_list))
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if (Optional<MemoryBufferRef> buffer = readFile(arg->getValue()))
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readDynamicList(*buffer);
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‎lld/ELF/Options.td

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -156,10 +156,8 @@ def discard_none: F<"discard-none">,
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defm dynamic_linker: Eq<"dynamic-linker", "Which dynamic linker to use">;
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158158
defm dynamic_list : Eq<"dynamic-list",
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"Read a list of dynamic symbols. (executable) Put matched non-local defined"
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"symbols to the dynamic symbol table. (shared object) References to matched"
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"non-local STV_DEFAULT symbols shouldn't be bound to definitions within the "
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"shared object. Implies -Bsymbolic but does not set DF_SYMBOLIC">,
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"Similar to --export-dynamic-symbol-list. When creating a shared object, "
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"this additionally implies -Bsymbolic but does not set DF_SYMBOLIC">,
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MetaVarName<"<file>">;
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165163
def eb: F<"EB">, HelpText<"Select the big-endian format in OUTPUT_FORMAT">;
@@ -209,6 +207,10 @@ defm export_dynamic_symbol : EEq<"export-dynamic-symbol",
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"Does not imply -Bsymbolic.">,
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MetaVarName<"glob">;
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210+
defm export_dynamic_symbol_list : EEq<"export-dynamic-symbol-list",
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"Read a list of dynamic symbol patterns. Apply --export-dynamic-symbol on each pattern">,
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MetaVarName<"file">;
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212214
defm fatal_warnings: B<"fatal-warnings",
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"Treat warnings as errors",
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"Do not treat warnings as errors (default)">;

‎lld/docs/ReleaseNotes.rst

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -24,8 +24,8 @@ Non-comprehensive list of changes in this release
2424
ELF Improvements
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----------------
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27-
* ``-Bsymbolic-non-weak-functions`` has been added as a ``STB_GLOBAL`` subset of ``-Bsymbolic-functions``.
28-
(`D102570 <https://reviews.llvm.org/D102570>`_)
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* ``--export-dynamic-symbol-list`` has been added.
28+
(`D107317 <https://reviews.llvm.org/D107317>`_)
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Breaking changes
3131
----------------

‎lld/docs/ld.lld.1

Lines changed: 9 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -167,10 +167,9 @@ Specify the dynamic linker to be used for a dynamically linked executable.
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This is recorded in an ELF segment of type
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.Dv PT_INTERP .
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.It Fl -dynamic-list Ns = Ns Ar file
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Read a list of dynamic symbols from
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.Ar file .
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(executable) Put matched non-local defined symbols to the dynamic symbol table.
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(shared object) References to matched non-local STV_DEFAULT symbols shouldn't be bound to definitions within the shared object. Implies
170+
Similar to
171+
.Cm --export-dynamic-symbol-list .
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When creating a shared object, implies
174173
.Cm -Bsymbolic
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but does not set DF_SYMBOLIC
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.It Fl -EB
@@ -225,6 +224,12 @@ Put symbols in the dynamic symbol table.
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.Cm -Bsymbolic-functions
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or
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.Cm --dynamic-list
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.It Fl -export-dynamic-symbol-list Ns = Ns Ar file
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Read a list of dynamic symbol patterns from
229+
.Ar file .
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Apply
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.Cm --export-dynamic-symbol
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on each pattern.
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.It Fl -fatal-warnings
229234
Treat warnings as errors.
230235
.It Fl -filter Ns = Ns Ar value , Fl F Ar value

‎lld/test/ELF/export-dynamic-symbol.s

Lines changed: 31 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,11 @@
33
# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
44

55
## For an executable, --export-dynamic-symbol exports a symbol if it is non-local and defined.
6-
# RUN: ld.lld -pie --export-dynamic-symbol foo %t.o -o %t
6+
# RUN: ld.lld -pie --export-dynamic-symbol foo --export-dynamic-symbol qux %t.o -o %t
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# RUN: llvm-nm -D -p %t | FileCheck %s
8+
# RUN: echo '{ foo; };' > %t1.list
9+
# RUN: echo '{ foo; qux; };' > %t2.list
10+
# RUN: ld.lld -pie --export-dynamic-symbol-list=%t2.list %t.o -o %t
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# RUN: llvm-nm -D -p %t | FileCheck %s
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913
## --export-dynamic exports all non-local defined symbols.
@@ -14,6 +18,7 @@
1418
# CHECK-NOT: .
1519
# START: T _start
1620
# CHECK: T foo
21+
# CHECK: T qux
1722
# CHECK-NOT: .
1823

1924
## --export-dynamic-symbol does not imply -u: %t1.a(%t1.o) is not fetched.
@@ -23,36 +28,53 @@
2328
# RUN: ld.lld --export-dynamic-symbol bar %t1.a %t.o -o %t.nofetch
2429
# RUN: llvm-nm %t.nofetch | FileCheck /dev/null --implicit-check-not=bar
2530

31+
## For -shared, if no option expresses a symbolic intention, --export-dynamic-symbol is a no-op.
32+
# RUN: ld.lld -shared --export-dynamic-symbol foo %t.o -o %t.noop
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# RUN: llvm-objdump -d %t.noop | FileCheck --check-prefix=PLT2 %s
34+
# RUN: ld.lld -shared --export-dynamic-symbol-list %t2.list %t.o -o %t.noop
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# RUN: llvm-objdump -d %t.noop | FileCheck --check-prefix=PLT2 %s
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2637
## --export-dynamic-symbol can make a symbol preemptible even if it would be otherwise
2738
## non-preemptible (due to -Bsymbolic, -Bsymbolic-functions or --dynamic-list).
2839
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol nomatch %t.o -o %t.nopreempt
2940
# RUN: llvm-objdump -d %t.nopreempt | FileCheck --check-prefix=NOPLT %s
3041
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol foo %t.o -o %t.preempt
31-
# RUN: llvm-objdump -d %t.preempt | FileCheck --check-prefix=PLT %s
42+
# RUN: llvm-objdump -d %t.preempt | FileCheck --check-prefix=PLT1 %s
43+
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol-list %t1.list %t.o -o %t.preempt
44+
# RUN: llvm-objdump -d %t.preempt | FileCheck --check-prefix=PLT1 %s
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3346
## 'nomatch' does not match any symbol. Don't warn.
3447
# RUN: ld.lld --fatal-warnings -shared -Bsymbolic-functions --export-dynamic-symbol nomatch %t.o -o %t.nopreempt2
3548
# RUN: llvm-objdump -d %t.nopreempt2 | FileCheck --check-prefix=NOPLT %s
3649
# RUN: ld.lld -shared -Bsymbolic-functions --export-dynamic-symbol foo %t.o -o %t.preempt2
37-
# RUN: llvm-objdump -d %t.preempt2 | FileCheck --check-prefix=PLT %s
50+
# RUN: llvm-objdump -d %t.preempt2 | FileCheck --check-prefix=PLT1 %s
3851

3952
# RUN: echo '{};' > %t.list
4053
# RUN: ld.lld -shared --dynamic-list %t.list --export-dynamic-symbol foo %t.o -o %t.preempt3
41-
# RUN: llvm-objdump -d %t.preempt3 | FileCheck --check-prefix=PLT %s
54+
# RUN: llvm-objdump -d %t.preempt3 | FileCheck --check-prefix=PLT1 %s
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4356
## The option value is a glob.
4457
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol 'f*' %t.o -o - | \
45-
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT %s
58+
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT1 %s
4659
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol '[f]o[o]' %t.o -o - | \
47-
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT %s
60+
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT1 %s
4861
# RUN: ld.lld -shared -Bsymbolic --export-dynamic-symbol 'f?o' %t.o -o - | \
49-
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT %s
62+
# RUN: llvm-objdump -d - | FileCheck --check-prefix=PLT1 %s
63+
64+
# PLT1: <foo@plt>
65+
# PLT1: <qux>
66+
67+
# PLT2: <foo@plt>
68+
# PLT2: <qux@plt>
5069

51-
# PLT: <foo@plt>
5270
# NOPLT-NOT: <foo@plt>
71+
# NOPLT-NOT: <qux@plt>
5372

54-
.global _start, foo
73+
.global _start, foo, qux
5574
.type foo, @function
75+
.type qux, @function
5676
_start:
5777
call foo
78+
call qux
5879
foo:
80+
qux:

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