From 4d879d2356667d4d93657e695518a04041de9da3 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 25 Mar 2021 14:20:58 -0400 Subject: [PATCH] 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: Id42a51759a1c7c669e63588c05f9d4485304c541 --- lib/bitfield.h | 39 +++------------------------------------ lttng-events.h | 2 +- 2 files changed, 4 insertions(+), 37 deletions(-) diff --git a/lib/bitfield.h b/lib/bitfield.h index 7d5eaeaa..c006ea18 100644 --- a/lib/bitfield.h +++ b/lib/bitfield.h @@ -26,30 +26,7 @@ #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. @@ -372,7 +349,6 @@ 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; \ @@ -384,11 +360,7 @@ 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 \ @@ -444,7 +416,6 @@ 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; \ @@ -456,11 +427,7 @@ 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 \ diff --git a/lttng-events.h b/lttng-events.h index 13b6abf5..52981937 100644 --- a/lttng-events.h +++ b/lttng-events.h @@ -22,7 +22,7 @@ #include #include -#define lttng_is_signed_type(type) (((type)(-1)) < 0) +#define lttng_is_signed_type(type) (((type) -1) < (type) 1) struct lttng_channel; struct lttng_session; -- 2.34.1