https://github.com/xingxue-ibm updated
https://github.com/llvm/llvm-project/pull/112436
>From edabcb3b43800c3e12a55325a786600064ccde10 Mon Sep 17 00:00:00 2001
From: Xing Xue <xing...@outlook.com>
Date: Tue, 15 Oct 2024 16:21:29 -0400
Subject: [PATCH 1/3] Remove weak definition "__xlcxx_personality_v0".
---
libunwind/src/UnwindCursor.hpp | 52 ++++++++++++++--------------------
1 file changed, 22 insertions(+), 30 deletions(-)
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index ce6dced535e781..8869be5236b1e6 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -2033,7 +2033,6 @@ typedef _Unwind_Reason_Code __xlcxx_personality_v0_t(int,
_Unwind_Action,
uint64_t,
_Unwind_Exception *,
struct _Unwind_Context *);
-__attribute__((__weak__)) __xlcxx_personality_v0_t __xlcxx_personality_v0;
}
static __xlcxx_personality_v0_t *xlcPersonalityV0;
@@ -2126,42 +2125,35 @@ bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc,
R ®isters) {
// function __xlcxx_personality_v0(), which is the personality for the
state
// table and is exported from libc++abi, is directly assigned as the
// handler here. When a legacy XLC++ frame is encountered, the symbol
- // is resolved dynamically using dlopen() to avoid hard dependency from
- // libunwind on libc++abi.
+ // is resolved dynamically using dlopen() to avoid a hard dependency of
+ // libunwind on libc++abi in cases such as non-C++ applications.
// Resolve the function pointer to the state table personality if it has
- // not already.
+ // not already done.
if (xlcPersonalityV0 == NULL) {
xlcPersonalityV0InitLock.lock();
if (xlcPersonalityV0 == NULL) {
- // If libc++abi is statically linked in, symbol __xlcxx_personality_v0
- // has been resolved at the link time.
- xlcPersonalityV0 = &__xlcxx_personality_v0;
+ // Resolve __xlcxx_personality_v0 using dlopen().
+ const char libcxxabi[] = "libc++abi.a(libc++abi.so.1)";
+ void *libHandle;
+ // The AIX dlopen() sets errno to 0 when it is successful, which
+ // clobbers the value of errno from the user code. This is an AIX
+ // bug because according to POSIX it should not set errno to 0. To
+ // workaround before AIX fixes the bug, errno is saved and restored.
+ int saveErrno = errno;
+ libHandle = dlopen(libcxxabi, RTLD_MEMBER | RTLD_NOW);
+ if (libHandle == NULL) {
+ _LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n",
+ errno);
+ assert(0 && "dlopen() failed");
+ }
+ xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
+ dlsym(libHandle, "__xlcxx_personality_v0"));
if (xlcPersonalityV0 == NULL) {
- // libc++abi is dynamically linked. Resolve __xlcxx_personality_v0
- // using dlopen().
- const char libcxxabi[] = "libc++abi.a(libc++abi.so.1)";
- void *libHandle;
- // The AIX dlopen() sets errno to 0 when it is successful, which
- // clobbers the value of errno from the user code. This is an AIX
- // bug because according to POSIX it should not set errno to 0. To
- // workaround before AIX fixes the bug, errno is saved and restored.
- int saveErrno = errno;
- libHandle = dlopen(libcxxabi, RTLD_MEMBER | RTLD_NOW);
- if (libHandle == NULL) {
- _LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n",
- errno);
- assert(0 && "dlopen() failed");
- }
- xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
- dlsym(libHandle, "__xlcxx_personality_v0"));
- if (xlcPersonalityV0 == NULL) {
- _LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n",
errno);
- assert(0 && "dlsym() failed");
- }
- dlclose(libHandle);
- errno = saveErrno;
+ _LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
+ assert(0 && "dlsym() failed");
}
+ errno = saveErrno;
}
xlcPersonalityV0InitLock.unlock();
}
>From b85f82b879da7dd30532b315eb1ea7278e45b132 Mon Sep 17 00:00:00 2001
From: Xing Xue <xing...@outlook.com>
Date: Tue, 15 Oct 2024 16:57:44 -0400
Subject: [PATCH 2/3] Fix formatting.
---
libunwind/src/UnwindCursor.hpp | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index 8869be5236b1e6..60079bd9cd18a2 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -2143,8 +2143,7 @@ bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R
®isters) {
int saveErrno = errno;
libHandle = dlopen(libcxxabi, RTLD_MEMBER | RTLD_NOW);
if (libHandle == NULL) {
- _LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n",
- errno);
+ _LIBUNWIND_TRACE_UNWINDING("dlopen() failed with errno=%d\n", errno);
assert(0 && "dlopen() failed");
}
xlcPersonalityV0 = reinterpret_cast<__xlcxx_personality_v0_t *>(
>From 44000d5a80a61efbddd5dc6147dd4321586b6d6a Mon Sep 17 00:00:00 2001
From: Xing Xue <xing...@outlook.com>
Date: Wed, 16 Oct 2024 13:26:28 -0400
Subject: [PATCH 3/3] Addressed comments: - fix comments - add a LIT test case
- will put driver-by fix to remove dlclose() in a separate PR
---
libunwind/src/UnwindCursor.hpp | 5 +++--
libunwind/test/aix_runtime_link.pass.cpp | 20 ++++++++++++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)
create mode 100644 libunwind/test/aix_runtime_link.pass.cpp
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp
index 60079bd9cd18a2..2a3aba28fb6ca5 100644
--- a/libunwind/src/UnwindCursor.hpp
+++ b/libunwind/src/UnwindCursor.hpp
@@ -2129,12 +2129,12 @@ bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc,
R ®isters) {
// libunwind on libc++abi in cases such as non-C++ applications.
// Resolve the function pointer to the state table personality if it has
- // not already done.
+ // not already been done.
if (xlcPersonalityV0 == NULL) {
xlcPersonalityV0InitLock.lock();
if (xlcPersonalityV0 == NULL) {
// Resolve __xlcxx_personality_v0 using dlopen().
- const char libcxxabi[] = "libc++abi.a(libc++abi.so.1)";
+ const char *libcxxabi = "libc++abi.a(libc++abi.so.1)";
void *libHandle;
// The AIX dlopen() sets errno to 0 when it is successful, which
// clobbers the value of errno from the user code. This is an AIX
@@ -2152,6 +2152,7 @@ bool UnwindCursor<A, R>::getInfoFromTBTable(pint_t pc, R
®isters) {
_LIBUNWIND_TRACE_UNWINDING("dlsym() failed with errno=%d\n", errno);
assert(0 && "dlsym() failed");
}
+ dlclose(libHandle);
errno = saveErrno;
}
xlcPersonalityV0InitLock.unlock();
diff --git a/libunwind/test/aix_runtime_link.pass.cpp
b/libunwind/test/aix_runtime_link.pass.cpp
new file mode 100644
index 00000000000000..deb192c07981eb
--- /dev/null
+++ b/libunwind/test/aix_runtime_link.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM
Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Test that libunwind loads successfully independently of libc++abi with
+// runtime linking on AIX.
+
+// REQUIRES: target={{.+}}-aix{{.*}}
+// ADDITIONAL_COMPILE_FLAGS: -Wl,-brtl
+
+#include <unwind.h>
+extern "C" int printf(const char *, ...);
+int main(void) {
+ void *fp = (void *)&_Unwind_Backtrace;
+ printf("%p\n", fp);
+}
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