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Fix lto0.test_exceptions_allowed_uncaught failure #19165

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Merged
sbc100 merged 1 commit into from
Apr 12, 2023
Merged

Fix lto0.test_exceptions_allowed_uncaught failure #19165

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1 change: 1 addition & 0 deletions .circleci/config.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -492,6 +492,7 @@ jobs:
title: "core3+extras"
test_targets: "
lto2.test_dylink_syslibs_all
lto0.test_exceptions_allowed_uncaught
core3
core2g.test_externref
corez.test_dylink_iostream
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3 changes: 2 additions & 1 deletion system/lib/libcxxabi/src/cxa_exception.h
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Expand Up @@ -24,7 +24,8 @@ namespace __cxxabiv1 {
struct _LIBCXXABI_HIDDEN __cxa_exception {
size_t referenceCount;
std::type_info *exceptionType;
void (*exceptionDestructor)(void *);
// In wasm, destructors return 'this' as in ARM
void* (*exceptionDestructor)(void *);
Comment on lines +27 to +28
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@aheejin aheejin Apr 13, 2023

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I remember adding this years ago... I guess it was somehow lost during library updates. https://github.com/aheejin/emscripten/blob/d57db5bea1719319a680699c50b91fa3d88fa0ec/system/lib/libcxxabi/src/cxa_exception.hpp#L41-L46

By the way, wouldn't it be better to add ifdef as in the old code, in case when we try to upstream our changes?

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@sbc100 sbc100 Apr 13, 2023

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This entire block is already within #ifdef __USING_EMSCRIPTEN_EXCEPTIONS__.

BTW, is there some way we can undef the destructors return 'this' as in ARM decision, since it makes all these patches needed? Is there some reason we need this behaviour?

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@dschuff dschuff Apr 13, 2023

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Maybe? AFAIK @sunfishcode added that way back at the beginning, as a performance optimization. I don't know how much impact it actually has.

uint8_t caught;
uint8_t rethrown;
void *adjustedPtr;
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13 changes: 7 additions & 6 deletions system/lib/libcxxabi/src/cxa_exception_emscripten.cpp
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Expand Up @@ -20,7 +20,8 @@

// Define to enable extra debugging on stderr.
#if EXCEPTIONS_DEBUG
#define DEBUG printf
#include "emscripten/console.h"
#define DEBUG _emscripten_errf
#else
#define DEBUG(...)
#endif
Expand Down Expand Up @@ -48,7 +49,7 @@ inline
__cxa_exception*
cxa_exception_from_thrown_object(void* thrown_object)
{
DEBUG("cxa_exception_from_thrown_object %p -> %p\n",
DEBUG("cxa_exception_from_thrown_object %p -> %p",
thrown_object, static_cast<__cxa_exception*>(thrown_object) - 1);
return static_cast<__cxa_exception*>(thrown_object) - 1;
}
Expand All @@ -60,7 +61,7 @@ inline
void*
thrown_object_from_cxa_exception(__cxa_exception* exception_header)
{
DEBUG("thrown_object_from_cxa_exception %p -> %p\n",
DEBUG("thrown_object_from_cxa_exception %p -> %p",
exception_header, static_cast<void*>(exception_header + 1));
return static_cast<void*>(exception_header + 1);
}
Expand Down Expand Up @@ -118,7 +119,7 @@ __cxa_increment_exception_refcount(void *thrown_object) _NOEXCEPT {
if (thrown_object != NULL )
{
__cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
DEBUG("INC: %p refcnt=%zu\n", thrown_object, exception_header->referenceCount);
DEBUG("INC: %p refcnt=%zu", thrown_object, exception_header->referenceCount);
std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(1));
}
}
Expand All @@ -136,12 +137,12 @@ void __cxa_decrement_exception_refcount(void *thrown_object) _NOEXCEPT {
if (thrown_object != NULL )
{
__cxa_exception* exception_header = cxa_exception_from_thrown_object(thrown_object);
DEBUG("DEC: %p refcnt=%zu rethrown=%d\n", thrown_object,
DEBUG("DEC: %p refcnt=%zu rethrown=%d", thrown_object,
exception_header->referenceCount, exception_header->rethrown);
assert(exception_header->referenceCount > 0);
if (std::__libcpp_atomic_add(&exception_header->referenceCount, size_t(-1)) == 0 && !exception_header->rethrown)
{
DEBUG("DEL: %p\n", thrown_object);
DEBUG("DEL: %p (dtor=%p)", thrown_object, exception_header->exceptionDestructor);
if (NULL != exception_header->exceptionDestructor)
exception_header->exceptionDestructor(thrown_object);
__cxa_free_exception(thrown_object);
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