From: Mathieu Desnoyers Date: Thu, 25 Mar 2021 18:32:40 +0000 (-0400) Subject: compiler warning cleanup: is_signed_type: compare -1 to 1 X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=534d93a8b2ba86f56dfdf6aa7a10911da5f6432c compiler warning cleanup: is_signed_type: compare -1 to 1 Comparing -1 to 0 triggers compiler warnings (gcc -Wtype-limits and -Wbool-compare) and Coverity warning "Macro compares unsigned to 0". Comparing -1 to 1 instead takes care of silencing those warnings while keeping the same behavior. Signed-off-by: Mathieu Desnoyers Change-Id: I7d3a2d5a813838cef0e7b42d8c80ccf46f27ac62 Reviewed-on: https://review.lttng.org/c/babeltrace/+/5188 CI-Build: Jérémie Galarneau Tested-by: jenkins Reviewed-by: Jérémie Galarneau --- diff --git a/src/compat/bitfield.h b/src/compat/bitfield.h index 7c1b9307..e0a3885c 100644 --- a/src/compat/bitfield.h +++ b/src/compat/bitfield.h @@ -25,30 +25,7 @@ #error "bitfield.h requires the compiler representation of signed integers to be two's complement." #endif -/* - * _bt_is_signed_type() willingly generates comparison of unsigned - * expression < 0, which is always false. Silence compiler warnings. - * GCC versions lower than 4.6.0 do not accept diagnostic pragma inside - * functions. - */ -#if defined(__GNUC__) && (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) >= 40600 -# define _BT_DIAG_PUSH _Pragma("GCC diagnostic push") -# define _BT_DIAG_POP _Pragma("GCC diagnostic pop") - -# define _BT_DIAG_STRINGIFY_1(x) #x -# define _BT_DIAG_STRINGIFY(x) _BT_DIAG_STRINGIFY_1(x) - -# define _BT_DIAG_IGNORE(option) \ - _Pragma(_BT_DIAG_STRINGIFY(GCC diagnostic ignored option)) -# define _BT_DIAG_IGNORE_TYPE_LIMITS _BT_DIAG_IGNORE("-Wtype-limits") -#else -# define _BT_DIAG_PUSH -# define _BT_DIAG_POP -# define _BT_DIAG_IGNORE -# define _BT_DIAG_IGNORE_TYPE_LIMITS -#endif - -#define _bt_is_signed_type(type) ((type) -1 < (type) 0) +#define _bt_is_signed_type(type) ((type) -1 < (type) 1) /* * Produce a build-time error if the condition `cond` is non-zero. @@ -371,7 +348,6 @@ do { \ unsigned long _ts = sizeof(type) * CHAR_BIT; /* type size */ \ unsigned long _start_unit, _end_unit, _this_unit; \ unsigned long _end, _cshift; /* _cshift is "complement shift" */ \ - bool _is_signed_type; \ \ if (!_length) { \ *_vptr = 0; \ @@ -383,11 +359,7 @@ do { \ _end_unit = (_end + (_ts - 1)) / _ts; \ \ _this_unit = _end_unit - 1; \ - _BT_DIAG_PUSH \ - _BT_DIAG_IGNORE_TYPE_LIMITS \ - _is_signed_type = _bt_is_signed_type(__typeof__(_v)); \ - _BT_DIAG_POP \ - if (_is_signed_type \ + if (_bt_is_signed_type(__typeof__(_v)) \ && (_ptr[_this_unit] & _bt_lshift((type) 1, (_end % _ts ? _end % _ts : _ts) - 1))) \ _v = ~(__typeof__(_v)) 0; \ else \ @@ -443,7 +415,6 @@ do { \ unsigned long _ts = sizeof(type) * CHAR_BIT; /* type size */ \ unsigned long _start_unit, _end_unit, _this_unit; \ unsigned long _end, _cshift; /* _cshift is "complement shift" */ \ - bool _is_signed_type; \ \ if (!_length) { \ *_vptr = 0; \ @@ -455,11 +426,7 @@ do { \ _end_unit = (_end + (_ts - 1)) / _ts; \ \ _this_unit = _start_unit; \ - _BT_DIAG_PUSH \ - _BT_DIAG_IGNORE_TYPE_LIMITS \ - _is_signed_type = _bt_is_signed_type(__typeof__(_v)); \ - _BT_DIAG_POP \ - if (_is_signed_type \ + if (_bt_is_signed_type(__typeof__(_v)) \ && (_ptr[_this_unit] & _bt_lshift((type) 1, _ts - (_start % _ts) - 1))) \ _v = ~(__typeof__(_v)) 0; \ else \