[lld] 1309c18 - [lld][MachO] Add first bits to support special symbols
Alexander Shaposhnikov via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 4 23:34:35 PDT 2021
Author: Alexander Shaposhnikov
Date: 2021-06-04T23:32:26-07:00
New Revision: 1309c181a85233c80051544f43008963c3d5fe71
URL: https://github.com/llvm/llvm-project/commit/1309c181a85233c80051544f43008963c3d5fe71
DIFF: https://github.com/llvm/llvm-project/commit/1309c181a85233c80051544f43008963c3d5fe71.diff
LOG: [lld][MachO] Add first bits to support special symbols
This diff adds first bits to support special symbols $ld$previous* in LLD.
$ld$* symbols modify properties/behavior of the library
(e.g. its install name, compatibility version or hide/add symbols)
for specific target versions.
Test plan: make check-lld-macho
Differential revision: https://reviews.llvm.org/D103505
Added:
lld/test/MachO/special-symbol-ld-previous.s
Modified:
lld/MachO/Config.h
lld/MachO/InputFiles.cpp
lld/MachO/InputFiles.h
lld/MachO/Writer.cpp
Removed:
################################################################################
diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
index 93e88cfe7eb6..8c5a18484776 100644
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -38,6 +38,12 @@ struct PlatformInfo {
llvm::VersionTuple sdk;
};
+inline uint32_t encodeVersion(const llvm::VersionTuple &version) {
+ return ((version.getMajor() << 020) |
+ (version.getMinor().getValueOr(0) << 010) |
+ version.getSubminor().getValueOr(0));
+}
+
enum class NamespaceKind {
twolevel,
flat,
diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index 5aedf003458f..4c2c9fde76d4 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -848,10 +848,13 @@ DylibFile::DylibFile(MemoryBufferRef mb, DylibFile *umbrella,
auto *c = reinterpret_cast<const dyld_info_command *>(cmd);
parseTrie(buf + c->export_off, c->export_size,
[&](const Twine &name, uint64_t flags) {
+ StringRef savedName = saver.save(name);
+ if (handleLdSymbol(savedName))
+ return;
bool isWeakDef = flags & EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION;
bool isTlv = flags & EXPORT_SYMBOL_FLAGS_KIND_THREAD_LOCAL;
- symbols.push_back(symtab->addDylib(
- saver.save(name), exportingFile, isWeakDef, isTlv));
+ symbols.push_back(symtab->addDylib(savedName, exportingFile,
+ isWeakDef, isTlv));
});
} else {
error("LC_DYLD_INFO_ONLY not found in " + toString(this));
@@ -934,6 +937,9 @@ DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella,
if (!symbol->getArchitectures().has(config->arch()))
continue;
+ if (handleLdSymbol(symbol->getName()))
+ continue;
+
switch (symbol->getKind()) {
case SymbolKind::GlobalSymbol:
addSymbol(symbol->getName());
@@ -965,6 +971,73 @@ void DylibFile::parseReexports(const InterfaceFile &interface) {
}
}
+// $ld$ symbols modify the properties/behavior of the library (e.g. its install
+// name, compatibility version or hide/add symbols) for specific target
+// versions.
+bool DylibFile::handleLdSymbol(StringRef originalName) {
+ // $ld$ previous $ <installname> $ <compatversion> $ <platformstr> $
+ // <startversion> $ <endversion> $ <symbol-name> $
+ if (!originalName.startswith("$ld$"))
+ return false;
+
+ StringRef action;
+ StringRef name;
+ std::tie(action, name) = originalName.drop_front(4 /* $ld$ */).split('$');
+ if (action.empty() || action != "previous")
+ return true;
+
+ StringRef installName;
+ StringRef compatVersion;
+ StringRef platformStr;
+ StringRef startVersion;
+ StringRef endVersion;
+ StringRef symbolName;
+ StringRef rest;
+
+ std::tie(installName, name) = name.split('$');
+ std::tie(compatVersion, name) = name.split('$');
+ std::tie(platformStr, name) = name.split('$');
+ std::tie(startVersion, name) = name.split('$');
+ std::tie(endVersion, symbolName) = name.split('$');
+ std::tie(symbolName, rest) = symbolName.split('$');
+ // TODO: ld64 contains some logic for non-empty symbolName as well.
+ if (!symbolName.empty())
+ return true;
+ unsigned platform;
+ if (platformStr.getAsInteger(10, platform) ||
+ platform != static_cast<unsigned>(config->platform()))
+ return true;
+
+ VersionTuple start;
+ if (start.tryParse(startVersion)) {
+ warn("failed to parse start version, symbol '" + originalName +
+ "' ignored");
+ return true;
+ }
+ VersionTuple end;
+ if (end.tryParse(endVersion)) {
+ warn("failed to parse end version, symbol '" + originalName + "' ignored");
+ return true;
+ }
+ if (config->platformInfo.minimum < start ||
+ config->platformInfo.minimum >= end)
+ return true;
+
+ dylibName = saver.save(installName);
+
+ if (!compatVersion.empty()) {
+ VersionTuple cVersion;
+ if (cVersion.tryParse(compatVersion)) {
+ warn("failed to parse compatibility version, symbol '" + originalName +
+ "' ignored");
+ return true;
+ }
+ compatibilityVersion = encodeVersion(cVersion);
+ }
+
+ return true;
+}
+
ArchiveFile::ArchiveFile(std::unique_ptr<object::Archive> &&f)
: InputFile(ArchiveKind, f->getMemoryBufferRef()), file(std::move(f)) {
for (const object::Archive::Symbol &sym : file->symbols())
diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h
index 5665ee20a641..21a54347fdac 100644
--- a/lld/MachO/InputFiles.h
+++ b/lld/MachO/InputFiles.h
@@ -173,6 +173,9 @@ class DylibFile : public InputFile {
// implemented in the bundle. When used like this, it is very similar
// to a Dylib, so we re-used the same class to represent it.
bool isBundleLoader;
+
+private:
+ bool handleLdSymbol(StringRef name);
};
// .a file
diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
index 477ccb761789..f01aeb22e18c 100644
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -359,12 +359,6 @@ class LCRPath : public LoadCommand {
StringRef path;
};
-static uint32_t encodeVersion(const VersionTuple &version) {
- return ((version.getMajor() << 020) |
- (version.getMinor().getValueOr(0) << 010) |
- version.getSubminor().getValueOr(0));
-}
-
class LCMinVersion : public LoadCommand {
public:
explicit LCMinVersion(const PlatformInfo &platformInfo)
diff --git a/lld/test/MachO/special-symbol-ld-previous.s b/lld/test/MachO/special-symbol-ld-previous.s
new file mode 100644
index 000000000000..62d6272d45fc
--- /dev/null
+++ b/lld/test/MachO/special-symbol-ld-previous.s
@@ -0,0 +1,67 @@
+# REQUIRES: x86
+
+# RUN: rm -rf %t; split-file --no-leading-lines %s %t
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo.s -o %t/foo.o
+
+## Case 1: special symbol $ld$previous affects the install name / compatibility version
+## since the specified version 11.0.0 is within the affected range [3.0, 14.0).
+
+# RUN: %lld -o %t/libfoo1.dylib %t/libLDPreviousInstallName.tbd %t/foo.o -dylib -platform_version macos 11.0.0 11.0.0
+# RUN: llvm-objdump --macho --dylibs-used %t/libfoo1.dylib | FileCheck --check-prefix=CASE1 %s
+# CASE1: /New (compatibility version 1.2.3, current version 5.0.0)
+
+## Case 2: special symbol $ld$previous does not affect the install name / compatibility version
+## since the specified version 2.0.0 is lower than the affected range [3.0, 14.0).
+
+# RUN: %lld -o %t/libfoo2.dylib %t/libLDPreviousInstallName.tbd %t.o -dylib -platform_version macos 2.0.0 2.0.0
+# RUN: llvm-objdump --macho --dylibs-used %t/libfoo2.dylib | FileCheck --check-prefix=CASE2 %s
+# CASE2: /Old (compatibility version 1.1.1, current version 5.0.0)
+
+## Case 3: special symbol $ld$previous does not affect the install name / compatibility version
+## since the specified version 14.0.0 is higher than the affected range [3.0, 14.0).
+
+# RUN: %lld -o %t/libfoo3.dylib %t/libLDPreviousInstallName.tbd %t.o -dylib -platform_version macos 2.0.0 2.0.0
+# RUN: llvm-objdump --macho --dylibs-used %t/libfoo3.dylib | FileCheck --check-prefix=CASE3 %s
+# CASE3: /Old (compatibility version 1.1.1, current version 5.0.0)
+
+## Check that we emit a warning for an invalid start, end and compatibility versions.
+
+# RUN: %no_fatal_warnings_lld -o %t/libfoo1.dylib %t/libLDPreviousInvalid.tbd %t/foo.o -dylib \
+# RUN: -platform_version macos 11.0.0 11.0.0 2>&1 | FileCheck --check-prefix=INVALID-VERSION %s
+
+# INVALID-VERSION-DAG: failed to parse start version, symbol '$ld$previous$/New$1.2.3$1$3.a$14.0$$' ignored
+# INVALID-VERSION-DAG: failed to parse end version, symbol '$ld$previous$/New$1.2.3$1$3.0$14.b$$' ignored
+# INVALID-VERSION-DAG: failed to parse compatibility version, symbol '$ld$previous$/New$1.2.c$1$3.0$14.0$$' ignored
+
+#--- foo.s
+.long _xxx at GOTPCREL
+
+#--- libLDPreviousInstallName.tbd
+--- !tapi-tbd-v3
+archs: [ x86_64 ]
+uuids: [ 'x86_64: 19311019-01AB-342E-812B-73A74271A715' ]
+platform: macosx
+install-name: '/Old'
+current-version: 5
+compatibility-version: 1.1.1
+exports:
+ - archs: [ x86_64 ]
+ symbols: [ '$ld$previous$/New$1.2.3$1$3.0$14.0$$', _xxx ]
+...
+
+#--- libLDPreviousInvalid.tbd
+--- !tapi-tbd-v3
+archs: [ x86_64 ]
+uuids: [ 'x86_64: 19311019-01AB-342E-112B-73A74271A715' ]
+platform: macosx
+install-name: '/Old'
+current-version: 5
+compatibility-version: 1.1.1
+exports:
+ - archs: [ x86_64 ]
+ symbols: [ '$ld$previous$/New$1.2.3$1$3.a$14.0$$',
+ '$ld$previous$/New$1.2.3$1$3.0$14.b$$',
+ '$ld$previous$/New$1.2.c$1$3.0$14.0$$',
+ _xxx ]
+...
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