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[lld-macho]Limit "cannot-export-hidden-symbol" warnings to only 3 to avoid crowding logs.

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Details:
We often use wildcard symbols in the exported_symbols list, and sometimes they match autohide symbols, which triggers these "cannot export hidden symbols" warnings that can be a bit noisy.
It'd be more user-friendly if LLD could truncate these.

Differential Revision: https://reviews.llvm.org/D159095
This commit is contained in:
Vy Nguyen 2023-09-06 15:20:59 -04:00
parent 4792ae5cd5
commit 84a2155921
2 changed files with 66 additions and 3 deletions
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15
lld/MachO/Driver.cpp
View File

@ -1355,8 +1355,10 @@ static void createAliases() {
}
static void handleExplicitExports() {
static constexpr int kMaxWarnings = 3;
if (config->hasExplicitExports) {
parallelForEach(symtab->getSymbols(), [](Symbol *sym) {
std::atomic<uint64_t> warningsCount{0};
parallelForEach(symtab->getSymbols(), [&warningsCount](Symbol *sym) {
if (auto *defined = dyn_cast<Defined>(sym)) {
if (config->exportedSymbols.match(sym->getName())) {
if (defined->privateExtern) {
@ -1367,8 +1369,12 @@ static void handleExplicitExports() {
// The former can be exported but the latter cannot.
defined->privateExtern = false;
} else {
warn("cannot export hidden symbol " + toString(*defined) +
"\n>>> defined in " + toString(defined->getFile()));
// Only print the first 3 warnings verbosely, and
// shorten the rest to avoid crowding logs.
if (warningsCount.fetch_add(1, std::memory_order_relaxed) <
kMaxWarnings)
warn("cannot export hidden symbol " + toString(*defined) +
"\n>>> defined in " + toString(defined->getFile()));
}
}
} else {
@ -1378,6 +1384,9 @@ static void handleExplicitExports() {
dysym->shouldReexport = config->exportedSymbols.match(sym->getName());
}
});
if (warningsCount > kMaxWarnings)
warn("<... " + Twine(warningsCount - kMaxWarnings) +
" more similar warnings...>");
} else if (!config->unexportedSymbols.empty()) {
parallelForEach(symtab->getSymbols(), [](Symbol *sym) {
if (auto *defined = dyn_cast<Defined>(sym))

54
lld/test/MachO/export-options.s
View File

@ -4,6 +4,7 @@
# RUN: echo "" | llvm-mc -filetype=obj -triple=x86_64-apple-macos -o %t/empty.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos %t/default.s -o %t/default.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos %t/lazydef.s -o %t/lazydef.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos %t/too-many-warnings.s -o %t/too-many-warnings.o
# RUN: llvm-ar --format=darwin rcs %t/lazydef.a %t/lazydef.o
## Check that mixing exported and unexported symbol options yields an error
@ -209,6 +210,17 @@
# RUN: llvm-objdump --macho --exports-trie %t/unexport-dylib | FileCheck %s \
# RUN: --check-prefix=EMPTY-TRIE
## Check that warnings are truncated to the first 3 only.
# RUN: %no-fatal-warnings-lld -dylib %t/too-many-warnings.o -o %t/too-many.out \
# RUN: -exported_symbol "_private_extern*" 2>&1 | \
# RUN: FileCheck --check-prefix=TRUNCATE %s
# TRUNCATE: warning: cannot export hidden symbol _private_extern{{.+}}
# TRUNCATE: warning: cannot export hidden symbol _private_extern{{.+}}
# TRUNCATE: warning: cannot export hidden symbol _private_extern{{.+}}
# TRUNCATE: warning: <... 7 more similar warnings...>
# TRUNCATE-EMPTY:
#--- default.s
.globl _keep_globl, _hide_globl, _tlv
@ -283,3 +295,45 @@ _foo:
.private_extern _foo
_foo:
retq
#--- too-many-warnings.s
.private_extern _private_extern1
.private_extern _private_extern2
.private_extern _private_extern3
.private_extern _private_extern4
.private_extern _private_extern5
.private_extern _private_extern6
.private_extern _private_extern7
.private_extern _private_extern8
.private_extern _private_extern9
.private_extern _private_extern10
_private_extern1:
retq
_private_extern2:
retq
_private_extern3:
retq
_private_extern4:
retq
_private_extern5:
retq
_private_extern6:
retq
_private_extern7:
retq
_private_extern8:
retq
_private_extern9:
retq
_private_extern10:
retq