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[ORC-RT][ORC] Handle dynamic unwind registration for libunwind 

This changes the ELFNix platform Orc runtime to use, when available,
the __unw_add_dynamic_eh_frame_section interface provided by libunwind
for registering .eh_frame sections loaded by JITLink. When libunwind
is not being used for unwinding, the ELFNix platform detects this and
defaults to the __register_frame interface provided by libgcc_s.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D114961
This commit is contained in:
Peter S. Housel 2021-12-01 23:11:49 -08:00
parent 509b631f84
commit 981523b2e4
9 changed files with 125 additions and 10 deletions
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14
compiler-rt/lib/orc/elfnix_platform.cpp
View File

@ -29,10 +29,10 @@ ORC_RT_JIT_DISPATCH_TAG(__orc_rt_elfnix_get_initializers_tag)
ORC_RT_JIT_DISPATCH_TAG(__orc_rt_elfnix_get_deinitializers_tag)
ORC_RT_JIT_DISPATCH_TAG(__orc_rt_elfnix_symbol_lookup_tag)
// eh-frame registration functions.
// We expect these to be available for all processes.
extern "C" void __register_frame(const void *);
extern "C" void __deregister_frame(const void *);
// eh-frame registration functions, made available via aliases
// installed by the Platform
extern "C" void __orc_rt_register_eh_frame_section(const void *);
extern "C" void __orc_rt_deregister_eh_frame_section(const void *);
namespace {
@ -172,7 +172,8 @@ void ELFNixPlatformRuntimeState::destroy() {
Error ELFNixPlatformRuntimeState::registerObjectSections(
ELFNixPerObjectSectionsToRegister POSR) {
if (POSR.EHFrameSection.Start)
__register_frame(POSR.EHFrameSection.Start.toPtr<const char *>());
__orc_rt_register_eh_frame_section(
POSR.EHFrameSection.Start.toPtr<const char *>());
if (POSR.ThreadDataSection.Start) {
if (auto Err = registerThreadDataSection(
@ -186,7 +187,8 @@ Error ELFNixPlatformRuntimeState::registerObjectSections(
Error ELFNixPlatformRuntimeState::deregisterObjectSections(
ELFNixPerObjectSectionsToRegister POSR) {
if (POSR.EHFrameSection.Start)
__deregister_frame(POSR.EHFrameSection.Start.toPtr<const char *>());
__orc_rt_deregister_eh_frame_section(
POSR.EHFrameSection.Start.toPtr<const char *>());
return Error::success();
}

14
compiler-rt/test/orc/TestCases/FreeBSD/ehframe-default.cpp Normal file
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@ -0,0 +1,14 @@
// RUN: %clangxx -fexceptions -fPIC -c -o %t %s
// RUN: %llvm_jitlink %t
extern "C" void llvm_jitlink_setTestResultOverride(long Value);
int main(int argc, char *argv[]) {
llvm_jitlink_setTestResultOverride(1);
try {
throw 0;
} catch (int X) {
llvm_jitlink_setTestResultOverride(X);
}
return 0;
}

15
compiler-rt/test/orc/TestCases/FreeBSD/ehframe-libunwind.cpp Normal file
View File

@ -0,0 +1,15 @@
// REQUIRES: libunwind-available
// RUN: %clangxx -fexceptions -fPIC -c -o %t %s
// RUN: env LD_PRELOAD=%shared_libunwind %llvm_jitlink %t
extern "C" void llvm_jitlink_setTestResultOverride(long Value);
int main(int argc, char *argv[]) {
llvm_jitlink_setTestResultOverride(1);
try {
throw 0;
} catch (int X) {
llvm_jitlink_setTestResultOverride(X);
}
return 0;
}

14
compiler-rt/test/orc/TestCases/Linux/ehframe-default.cpp Normal file
View File

@ -0,0 +1,14 @@
// RUN: %clangxx -fexceptions -fPIC -c -o %t %s
// RUN: %llvm_jitlink %t
extern "C" void llvm_jitlink_setTestResultOverride(long Value);
int main(int argc, char *argv[]) {
llvm_jitlink_setTestResultOverride(1);
try {
throw 0;
} catch (int X) {
llvm_jitlink_setTestResultOverride(X);
}
return 0;
}

15
compiler-rt/test/orc/TestCases/Linux/ehframe-libunwind.cpp Normal file
View File

@ -0,0 +1,15 @@
// REQUIRES: libunwind-available
// RUN: %clangxx -fexceptions -fPIC -c -o %t %s
// RUN: env LD_PRELOAD=%shared_libunwind %llvm_jitlink %t
extern "C" void llvm_jitlink_setTestResultOverride(long Value);
int main(int argc, char *argv[]) {
llvm_jitlink_setTestResultOverride(1);
try {
throw 0;
} catch (int X) {
llvm_jitlink_setTestResultOverride(X);
}
return 0;
}

5
compiler-rt/test/orc/lit.cfg.py
View File

@ -18,6 +18,11 @@ if config.host_os == 'Darwin':
else:
orc_rt_path = '%s/libclang_rt.orc%s.a' % (config.compiler_rt_libdir, config.target_suffix)
if config.libunwind_shared:
config.available_features.add('libunwind-available')
shared_libunwind_path = os.path.join(config.libunwind_install_dir, 'libunwind.so')
config.substitutions.append( ("%shared_libunwind", shared_libunwind_path) )
config.substitutions.append(
('%clang ', build_invocation([config.target_cflags])))
config.substitutions.append(

2
compiler-rt/test/orc/lit.site.cfg.py.in
View File

@ -6,6 +6,8 @@ config.orc_lit_source_dir = "@ORC_LIT_SOURCE_DIR@"
config.target_cflags = "@ORC_TEST_TARGET_CFLAGS@"
config.target_arch = "@ORC_TEST_TARGET_ARCH@"
config.built_with_llvm = ("@COMPILER_RT_STANDALONE_BUILD@" != "TRUE")
config.libunwind_shared = "@LIBUNWIND_ENABLE_SHARED@"
config.libunwind_install_dir = "@LLVM_BINARY_DIR@/@LIBUNWIND_INSTALL_LIBRARY_DIR@"
# Load common config for all compiler-rt lit tests
lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")

3
llvm/include/llvm/ExecutionEngine/Orc/ELFNixPlatform.h
View File

@ -109,7 +109,8 @@ public:
/// Returns an AliasMap containing the default aliases for the ELFNixPlatform.
/// This can be modified by clients when constructing the platform to add
/// or remove aliases.
static SymbolAliasMap standardPlatformAliases(ExecutionSession &ES);
static Expected<SymbolAliasMap> standardPlatformAliases(ExecutionSession &ES,
JITDylib &PlatformJD);
/// Returns the array of required CXX aliases.
static ArrayRef<std::pair<const char *, const char *>> requiredCXXAliases();

53
llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
View File

@ -117,8 +117,12 @@ ELFNixPlatform::Create(ExecutionSession &ES,
inconvertibleErrorCode());
// Create default aliases if the caller didn't supply any.
if (!RuntimeAliases)
RuntimeAliases = standardPlatformAliases(ES);
if (!RuntimeAliases) {
auto StandardRuntimeAliases = standardPlatformAliases(ES, PlatformJD);
if (!StandardRuntimeAliases)
return StandardRuntimeAliases.takeError();
RuntimeAliases = std::move(*StandardRuntimeAliases);
}
// Define the aliases.
if (auto Err = PlatformJD.define(symbolAliases(std::move(*RuntimeAliases))))
@ -189,10 +193,53 @@ static void addAliases(ExecutionSession &ES, SymbolAliasMap &Aliases,
}
}
SymbolAliasMap ELFNixPlatform::standardPlatformAliases(ExecutionSession &ES) {
Expected<SymbolAliasMap>
ELFNixPlatform::standardPlatformAliases(ExecutionSession &ES,
JITDylib &PlatformJD) {
SymbolAliasMap Aliases;
addAliases(ES, Aliases, requiredCXXAliases());
addAliases(ES, Aliases, standardRuntimeUtilityAliases());
// Determine whether or not the libunwind extended-API function for
// dynamically registering an entire .eh_frame section is available.
// If it is not, we assume that libgcc_s is being used, and alias to
// its __register_frame with the same functionality.
auto RTRegisterFrame = ES.intern("__orc_rt_register_eh_frame_section");
auto LibUnwindRegisterFrame = ES.intern("__unw_add_dynamic_eh_frame_section");
auto RTDeregisterFrame = ES.intern("__orc_rt_deregister_eh_frame_section");
auto LibUnwindDeregisterFrame =
ES.intern("__unw_remove_dynamic_eh_frame_section");
auto SM = ES.lookup(makeJITDylibSearchOrder(&PlatformJD),
SymbolLookupSet()
.add(LibUnwindRegisterFrame,
SymbolLookupFlags::WeaklyReferencedSymbol)
.add(LibUnwindDeregisterFrame,
SymbolLookupFlags::WeaklyReferencedSymbol));
if (!SM) { // Weak-ref means no "missing symbol" errors, so this must be
// something more serious that we should report.
return SM.takeError();
} else if (SM->size() == 2) {
LLVM_DEBUG({
dbgs() << "Using libunwind " << LibUnwindRegisterFrame
<< " for unwind info registration\n";
});
Aliases[std::move(RTRegisterFrame)] = {LibUnwindRegisterFrame,
JITSymbolFlags::Exported};
Aliases[std::move(RTDeregisterFrame)] = {LibUnwindDeregisterFrame,
JITSymbolFlags::Exported};
} else {
// Since LLVM libunwind is not present, we assume that unwinding
// is provided by libgcc
LLVM_DEBUG({
dbgs() << "Using libgcc __register_frame"
<< " for unwind info registration\n";
});
Aliases[std::move(RTRegisterFrame)] = {ES.intern("__register_frame"),
JITSymbolFlags::Exported};
Aliases[std::move(RTDeregisterFrame)] = {ES.intern("__deregister_frame"),
JITSymbolFlags::Exported};
}
return Aliases;
}