nasm_assert(): try to run at compile time if possible

Try to make nasm_assert() do a static assert if the argument can be
evaluated at compile time by any particular compiler. We also provide
nasm_try_static_assert() which will assert a compile-time expression
if and only if we can determine we have a constant at compile time
*and* we know that the compiler has a way to handle it.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin (Intel) 2018-12-14 14:21:16 -08:00
parent c3c6cea838
commit b7f24e7715
5 changed files with 71 additions and 21 deletions

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@ -207,9 +207,10 @@ PA_HAVE_FUNC(_byteswap_ulong, (0))
PA_HAVE_FUNC(_byteswap_uint64, (0))
dnl
dnl Check for __builtin_constant_p()
dnl Some rather useful gcc extensions...
dnl
PA_HAVE_FUNC(__builtin_constant_p, (0))
PA_HAVE_FUNC(__builtin_choose_expr, (0,1,2))
dnl
dnl Check for supported gcc attributes; some compilers (e.g. Sun CC)

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@ -358,6 +358,27 @@ size_t strnlen(const char *s, size_t maxlen);
# define is_constant(x) false
#endif
/*
* If we can guarantee that a particular expression is constant, use it,
* otherwise use a different version.
*/
#if defined(__GNUC__) && (__GNUC__ >= 3)
# define not_pedantic_start \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wpedantic\"")
# define not_pedantic_end \
_Pragma("GCC diagnostic pop")
#else
# define not_pedantic_start
# define not_pedantic_end
#endif
#ifdef HAVE___BUILTIN_CHOOSE_EXPR
# define if_constant(x,y) __builtin_choose_expr(is_constant(x),(x),(y))
#else
# define if_constant(x,y) (y)
#endif
/*
* The autoconf documentation states:
*

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@ -113,34 +113,62 @@ static inline size_t nasm_aprintf_size(void)
void nasm_read(void *, size_t, FILE *);
void nasm_write(const void *, size_t, FILE *);
/*
* NASM assert failure
*/
fatal_func nasm_assert_failed(const char *, int, const char *);
#define nasm_assert(x) \
do { \
if (unlikely(!(x))) \
nasm_assert_failed(__FILE__,__LINE__,#x); \
} while (0)
/*
* NASM failure at build time if the argument is false
*/
#ifdef static_assert
# define nasm_static_assert(x) static_assert(x, #x)
# define nasm_static_assert(x) static_assert((x), #x)
#elif defined(HAVE_FUNC_ATTRIBUTE_ERROR) && defined(__OPTIMIZE__)
# define nasm_static_assert(x) \
if (!(x)) { \
extern void __attribute__((error("assertion " #x " failed"))) \
_nasm_static_fail(void); \
_nasm_static_fail(); \
}
# define nasm_static_assert(x) \
do { \
if (!(x)) { \
extern void __attribute__((error("assertion " #x " failed"))) \
_nasm_static_fail(void); \
_nasm_static_fail(); \
} \
} while (0)
#else
/* See http://www.drdobbs.com/compile-time-assertions/184401873 */
# define nasm_static_assert(x) \
do { enum { _static_assert_failed = 1/(!!(x)) }; } while (0)
#endif
/*
* conditional static assert, if we know it is possible to determine
* the assert value at compile time. Since if_constant triggers
* pedantic warnings on gcc, turn them off explicitly around this code.
*/
#ifdef static_assert
# define nasm_try_static_assert(x) \
do { \
not_pedantic_start \
static_assert(if_constant(x, true), #x); \
not_pedantic_end \
} while (0)
#elif defined(HAVE_FUNC_ATTRIBUTE_ERROR) && defined(__OPTIMIZE__)
# define nasm_try_static_assert(x) \
do { \
if (!if_constant(x, true)) { \
extern void __attribute__((error("assertion " #x " failed"))) \
_nasm_static_fail(void); \
_nasm_static_fail(); \
} \
} while (0)
#else
# define nasm_try_static_assert(x) ((void)0)
#endif
/*
* NASM assert failure
*/
fatal_func nasm_assert_failed(const char *, int, const char *);
#define nasm_assert(x) \
do { \
nasm_try_static_assert(x); \
if (unlikely(!(x))) \
nasm_assert_failed(__FILE__,__LINE__,#x); \
} while (0)
/* Utility function to generate a string for an invalid enum */
const char *invalid_enum_str(int);

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@ -654,7 +654,7 @@ static uint16_t write_symbolinfo_properties(struct coff_Section *sect,
else if (win32)
section_write16(sect, 0x0006); /* machine */
else
nasm_assert(!"neither win32 nor win64 are set!");
nasm_panic("neither win32 nor win64 are set!");
section_write16(sect, 0); /* verFEMajor */
section_write16(sect, 0); /* verFEMinor */
section_write16(sect, 0); /* verFEBuild */
@ -711,7 +711,7 @@ static uint16_t write_symbolinfo_symbols(struct coff_Section *sect)
section_write8(sect, 0); /* FLAG */
break;
default:
nasm_assert(!"unknown symbol type");
nasm_panic("unknown symbol type");
}
section_wbytes(sect, sym->name, strlen(sym->name) + 1);

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@ -1507,7 +1507,7 @@ static void write_srecord(unsigned int len, unsigned int alen,
case 4:
break;
default:
nasm_assert(0);
panic();
break;
}