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Differential D86908

[lld-macho] Mark weak symbols in symbol table
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Authored by int3 on Aug 31 2020, 10:18 PM.

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smeenai
Group Reviewers
Restricted Project
Commits
rG0a7e56f74c2a: [lld-macho] Mark weak symbols in symbol table

Diff Detail

Event Timeline

int3 created this revision.Aug 31 2020, 10:18 PM
Herald added a project: Restricted Project. · View Herald TranscriptAug 31 2020, 10:18 PM
Herald added a subscriber: llvm-commits. · View Herald Transcript
int3 requested review of this revision.Aug 31 2020, 10:18 PM
Harbormaster completed remote builds in B70176: Diff 289074.Aug 31 2020, 10:46 PM
smeenai accepted this revision.Sep 8 2020, 1:47 PM
smeenai added a subscriber: smeenai.

LGTM

lld/MachO/SyntheticSections.cpp
476

Might wanna adjust this a little?

This revision is now accepted and ready to land.Sep 8 2020, 1:47 PM
int3 updated this revision to Diff 290604.Sep 8 2020, 4:25 PM
int3 marked an inline comment as done.

adjust comment

Harbormaster completed remote builds in B71014: Diff 290604.Sep 8 2020, 5:07 PM
int3 added a child revision: D86909: [lld-macho] Initial support for common symbols.Sep 17 2020, 3:54 PM
Closed by commit rG0a7e56f74c2a: [lld-macho] Mark weak symbols in symbol table (authored by int3). · Explain WhySep 20 2020, 8:44 PM
This revision was automatically updated to reflect the committed changes.
int3 added a commit: rG0a7e56f74c2a: [lld-macho] Mark weak symbols in symbol table.
gkm removed a child revision: D86909: [lld-macho] Initial support for common symbols.Sep 23 2020, 9:55 PM

Revision Contents

PathSize
lld/
MachO/
3 lines
test/
MachO/
4 lines

Diff 293053

lld/MachO/SyntheticSections.cpp

Show First 20 Lines • Show All 467 Lines • ▼ Show 20 Lines if (isa<Defined>(sym))
symbols.push_back({sym, stringTableSection.addString(sym->getName())}); symbols.push_back({sym, stringTableSection.addString(sym->getName())});
} }
void SymtabSection::writeTo(uint8_t *buf) const { void SymtabSection::writeTo(uint8_t *buf) const {
auto *nList = reinterpret_cast<structs::nlist_64 *>(buf); auto *nList = reinterpret_cast<structs::nlist_64 *>(buf);
for (const SymtabEntry &entry : symbols) { for (const SymtabEntry &entry : symbols) {
nList->n_strx = entry.strx; nList->n_strx = entry.strx;
// TODO support other symbol types // TODO support other symbol types
// TODO populate n_desc // TODO populate n_desc with more flags
smeenaiUnsubmitted
Done
ReplyInline Actions

Might wanna adjust this a little?

smeenai: Might wanna adjust this a little?
if (auto *defined = dyn_cast<Defined>(entry.sym)) { if (auto *defined = dyn_cast<Defined>(entry.sym)) {
nList->n_type = MachO::N_EXT | MachO::N_SECT; nList->n_type = MachO::N_EXT | MachO::N_SECT;
nList->n_sect = defined->isec->parent->index; nList->n_sect = defined->isec->parent->index;
nList->n_desc |= defined->isWeakDef() ? MachO::N_WEAK_DEF : 0;
// For the N_SECT symbol type, n_value is the address of the symbol // For the N_SECT symbol type, n_value is the address of the symbol
nList->n_value = defined->value + defined->isec->getVA(); nList->n_value = defined->value + defined->isec->getVA();
} }
++nList; ++nList;
} }
} }
StringTableSection::StringTableSection() StringTableSection::StringTableSection()
Show All 16 Lines

lld/test/MachO/symtab.s

Show All 14 Lines
# CHECK-NEXT: Value: # CHECK-NEXT: Value:
# CHECK-NEXT: } # CHECK-NEXT: }
# CHECK-NEXT: Symbol { # CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: bar # CHECK-NEXT: Name: bar
# CHECK-NEXT: Extern # CHECK-NEXT: Extern
# CHECK-NEXT: Type: Section (0xE) # CHECK-NEXT: Type: Section (0xE)
# CHECK-NEXT: Section: __text (0x1) # CHECK-NEXT: Section: __text (0x1)
# CHECK-NEXT: RefType: # CHECK-NEXT: RefType:
# CHECK-NEXT: Flags [ (0x0) # CHECK-NEXT: Flags [ (0x80)
# CHECK-NEXT: WeakDef (0x80)
# CHECK-NEXT: ] # CHECK-NEXT: ]
# CHECK-NEXT: Value: # CHECK-NEXT: Value:
# CHECK-NEXT: } # CHECK-NEXT: }
# CHECK-NEXT: Symbol { # CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: foo # CHECK-NEXT: Name: foo
# CHECK-NEXT: Extern # CHECK-NEXT: Extern
# CHECK-NEXT: Type: Section (0xE) # CHECK-NEXT: Type: Section (0xE)
# CHECK-NEXT: Section: __data # CHECK-NEXT: Section: __data
# CHECK-NEXT: RefType: # CHECK-NEXT: RefType:
# CHECK-NEXT: Flags [ (0x0) # CHECK-NEXT: Flags [ (0x0)
# CHECK-NEXT: ] # CHECK-NEXT: ]
# CHECK-NEXT: Value: # CHECK-NEXT: Value:
# CHECK-NEXT: } # CHECK-NEXT: }
# CHECK-NEXT: ] # CHECK-NEXT: ]
.data .data
.global foo .global foo
foo: foo:
.asciz "Hello world!\n" .asciz "Hello world!\n"
.text .text
.weak_definition bar
.global bar .global bar
.global _main .global _main
_main: _main:
mov $0, %rax mov $0, %rax
ret ret
bar: bar:
mov $2, %rax mov $2, %rax
ret ret