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Index: head/contrib/libcxxrt/exception.cc
===================================================================
--- head/contrib/libcxxrt/exception.cc
+++ head/contrib/libcxxrt/exception.cc
@@ -572,6 +572,19 @@
}
}
+#ifdef __LP64__
+/**
+ * There's an ABI bug in __cxa_exception: unwindHeader requires 16-byte
+ * alignment but it was broken by the addition of the referenceCount.
+ * The unwindHeader is at offset 0x58 in __cxa_exception. In order to keep
+ * compatibility with consumers of the broken __cxa_exception, explicitly add
+ * padding on allocation (and account for it on free).
+ */
+static const int exception_alignment_padding = 8;
+#else
+static const int exception_alignment_padding = 0;
+#endif
+
/**
* Allocates an exception structure. Returns a pointer to the space that can
* be used to store an object of thrown_size bytes. This function will use an
@@ -580,16 +593,19 @@
*/
extern "C" void *__cxa_allocate_exception(size_t thrown_size)
{
- size_t size = thrown_size + sizeof(__cxa_exception);
+ size_t size = exception_alignment_padding + sizeof(__cxa_exception) +
+ thrown_size;
char *buffer = alloc_or_die(size);
- return buffer+sizeof(__cxa_exception);
+ return buffer + exception_alignment_padding + sizeof(__cxa_exception);
}
extern "C" void *__cxa_allocate_dependent_exception(void)
{
- size_t size = sizeof(__cxa_dependent_exception);
+ size_t size = exception_alignment_padding +
+ sizeof(__cxa_dependent_exception);
char *buffer = alloc_or_die(size);
- return buffer+sizeof(__cxa_dependent_exception);
+ return buffer + exception_alignment_padding +
+ sizeof(__cxa_dependent_exception);
}
/**
@@ -617,7 +633,8 @@
}
}
- free_exception(reinterpret_cast<char*>(ex));
+ free_exception(reinterpret_cast<char*>(ex) -
+ exception_alignment_padding);
}
static void releaseException(__cxa_exception *exception)
@@ -644,7 +661,8 @@
{
releaseException(realExceptionFromException(reinterpret_cast<__cxa_exception*>(ex)));
}
- free_exception(reinterpret_cast<char*>(ex));
+ free_exception(reinterpret_cast<char*>(ex) -
+ exception_alignment_padding);
}
/**

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