From: Pedro Alves Date: Tue, 17 Nov 2015 15:17:46 +0000 (+0000) Subject: [C++] Always use setjmp/longjmp for exceptions X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=eec461d0a8e7ae14c7fe8f0196ab8d0e30285d83;p=binutils-gdb.git [C++] Always use setjmp/longjmp for exceptions We currently throw exceptions from signal handlers (e.g., for Quit/ctrl-c). But throwing C++ exceptions from signal handlers is undefined. (That doesn't restore signal masks, like siglongjmp does, and, because asynchronous signals can arrive at any instruction, we'd have to build _everything_ with -fasync-unwind-tables to make it reliable.) It happens to work on x86_64 GNU/Linux at least, but it's likely broken on other ports. Until we stop throwing from signal handlers, use setjmp/longjmp based exceptions in C++ mode as well. gdb/ChangeLog: 2015-11-17 Pedro Alves * common/common-exceptions.h (GDB_XCPT_SJMP, GDB_XCPT_TRY) (GDB_XCPT_RAW_TRY, GDB_XCPT): Define. Replace __cplusplus checks with GDB_XCPT checks throughout. * common/common-exceptions.c: Replace __cplusplus checks with GDB_XCPT checks throughout. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 044140ec590..57451bcdab6 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2015-11-17 Pedro Alves + + * common/common-exceptions.h (GDB_XCPT_SJMP, GDB_XCPT_TRY) + (GDB_XCPT_RAW_TRY, GDB_XCPT): Define. + Replace __cplusplus checks with GDB_XCPT checks throughout. + * common/common-exceptions.c: Replace __cplusplus checks with + GDB_XCPT checks throughout. + 2015-11-17 Pedro Alves * common/common-defs.h (ATTRIBUTE_PRINTF): Redefine in terms of diff --git a/gdb/common/common-exceptions.c b/gdb/common/common-exceptions.c index ce476a257b1..231bab56000 100644 --- a/gdb/common/common-exceptions.c +++ b/gdb/common/common-exceptions.c @@ -22,7 +22,7 @@ const struct gdb_exception exception_none = { (enum return_reason) 0, GDB_NO_ERROR, NULL }; -#ifndef __cplusplus +#if GDB_XCPT == GDB_XCPT_SJMP /* Possible catcher states. */ enum catcher_state { @@ -213,7 +213,7 @@ exceptions_state_mc_action_iter_1 (void) return exceptions_state_mc (CATCH_ITER_1); } -#else /* !__cplusplus */ +#else /* !GDB_XCPT_SJMP */ /* How many nested TRY blocks we have. See exception_messages and throw_it. */ @@ -261,7 +261,7 @@ gdb_exception_sliced_copy (struct gdb_exception *to, const struct gdb_exception *to = *from; } -#endif /* !__cplusplus */ +#endif /* !GDB_XCPT_SJMP */ /* Return EXCEPTION to the nearest containing catch_errors(). */ @@ -272,7 +272,7 @@ throw_exception (struct gdb_exception exception) do_cleanups (all_cleanups ()); -#ifndef __cplusplus +#if GDB_XCPT == GDB_XCPT_SJMP /* Jump to the containing catch_errors() call, communicating REASON to that call via setjmp's return value. Note that REASON can't be zero, by definition in defs.h. */ @@ -320,7 +320,7 @@ throw_it (enum return_reason reason, enum errors error, const char *fmt, { struct gdb_exception e; char *new_message; -#ifndef __cplusplus +#if GDB_XCPT == GDB_XCPT_SJMP int depth = catcher_list_size (); #else int depth = try_scope_depth; diff --git a/gdb/common/common-exceptions.h b/gdb/common/common-exceptions.h index 51795b17157..def08b1f9dc 100644 --- a/gdb/common/common-exceptions.h +++ b/gdb/common/common-exceptions.h @@ -116,12 +116,32 @@ struct gdb_exception const char *message; }; +/* The different exception mechanisms that TRY/CATCH can map to. */ + +/* Make GDB exceptions use setjmp/longjmp behind the scenes. This is + the only mode supported when GDB is built as a C program. */ +#define GDB_XCPT_SJMP 1 + +/* Make GDB exceptions use try/catch behind the scenes. Can't be made + the default until we stop throwing exceptions from signal + handlers. */ +#define GDB_XCPT_TRY 2 + +/* Specify this mode to build with TRY/CATCH mapped directly to raw + try/catch. GDB won't work correctly, but building that way catches + code tryin to break/continue out of the try block, along with + spurious code between the TRY and the CATCH block. */ +#define GDB_XCPT_RAW_TRY 3 + +/* Always use setjmp/longmp, even in C++ mode. */ +#define GDB_XCPT GDB_XCPT_SJMP + /* Functions to drive the exceptions state machine. Though declared here by necessity, these functions should be considered internal to the exceptions subsystem and not used other than via the TRY/CATCH macros defined below. */ -#ifndef __cplusplus +#if GDB_XCPT == GDB_XCPT_SJMP extern SIGJMP_BUF *exceptions_state_mc_init (void); extern int exceptions_state_mc_action_iter (void); extern int exceptions_state_mc_action_iter_1 (void); @@ -157,7 +177,7 @@ extern void exception_rethrow (void); */ -#ifndef __cplusplus +#if GDB_XCPT == GDB_XCPT_SJMP #define TRY \ { \ @@ -176,7 +196,9 @@ extern void exception_rethrow (void); #define END_CATCH \ } -#else +#endif /* GDB_XCPT_SJMP */ + +#if GDB_XCPT == GDB_XCPT_TRY || GDB_XCPT == GDB_XCPT_RAW_TRY /* Prevent error/quit during TRY from calling cleanups established prior to here. This pops out the scope in either case of normal @@ -195,13 +217,7 @@ struct exception_try_scope void *saved_state; }; -/* Define this to build with TRY/CATCH mapped directly to raw - try/catch. GDB won't work correctly, but building that way catches - code tryin to break/continue out of the try block, along with - spurious code between the TRY and the CATCH block. */ -//#define USE_RAW_CXX_TRY - -#ifndef USE_RAW_CXX_TRY +#if GDB_XCPT == GDB_XCPT_TRY /* We still need to wrap TRY/CATCH in C++ so that cleanups and C++ exceptions can coexist. The TRY blocked is wrapped in a @@ -224,6 +240,7 @@ struct exception_try_scope { \ exception_rethrow (); \ } + #else #define TRY try @@ -249,7 +266,7 @@ struct gdb_exception_RETURN_MASK_QUIT : public gdb_exception_RETURN_MASK_ALL { }; -#endif +#endif /* GDB_XCPT_TRY || GDB_XCPT_RAW_TRY */ /* *INDENT-ON* */