Commit 72fcce70 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Petr Mladek
Browse files

vsprintf: uninline simple_strntoull(), reorder arguments 



* uninline simple_strntoull(),
  gcc overinlines and this function is not performance critical

* reorder arguments, so that appending INT_MAX as 4th argument
  generates very efficient tail call

Space savings:

	add/remove: 1/0 grow/shrink: 0/3 up/down: 27/-179 (-152)
	Function                            old     new   delta
	simple_strntoll                       -      27     +27
	simple_strtoull                      15      10      -5
	simple_strtoll                       41       7     -34
	vsscanf                            1930    1790    -140

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/all/82a2af6e-9b6c-4a09-89d7-ca90cc1cdad1@p183/
parent 3f6074cf

lib/vsprintf.c

+12 −13
Original line number Diff line number Diff line
@@ -60,7 +60,8 @@ 
bool no_hash_pointers __ro_after_init;

EXPORT_SYMBOL_GPL(no_hash_pointers);



static noinline unsigned long long simple_strntoull(const char *startp, size_t max_chars, char **endp, unsigned int base)

noinline

static unsigned long long simple_strntoull(const char *startp, char **endp, unsigned int base, size_t max_chars)

{

	const char *cp;

	unsigned long long result = 0ULL;
@@ -95,7 +96,7 @@ static noinline unsigned long long simple_strntoull(const char *startp, size_t m 
noinline

unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)

{

	return simple_strntoull(cp, INT_MAX, endp, base);

	return simple_strntoull(cp, endp, base, INT_MAX);

}

EXPORT_SYMBOL(simple_strtoull);
@@ -130,8 +131,8 @@ long simple_strtol(const char *cp, char **endp, unsigned int base) 
}

EXPORT_SYMBOL(simple_strtol);



static long long simple_strntoll(const char *cp, size_t max_chars, char **endp,

				 unsigned int base)

noinline

static long long simple_strntoll(const char *cp, char **endp, unsigned int base, size_t max_chars)

{

	/*

	 * simple_strntoull() safely handles receiving max_chars==0 in the
@@ -140,9 +141,9 @@ static long long simple_strntoll(const char *cp, size_t max_chars, char **endp, 
	 * and the content of *cp is irrelevant.

	 */

	if (*cp == '-' && max_chars > 0)

		return -simple_strntoull(cp + 1, max_chars - 1, endp, base);

		return -simple_strntoull(cp + 1, endp, base, max_chars - 1);



	return simple_strntoull(cp, max_chars, endp, base);

	return simple_strntoull(cp, endp, base, max_chars);

}



/**
@@ -155,7 +156,7 @@ static long long simple_strntoll(const char *cp, size_t max_chars, char **endp, 
 */

long long simple_strtoll(const char *cp, char **endp, unsigned int base)

{

	return simple_strntoll(cp, INT_MAX, endp, base);

	return simple_strntoll(cp, endp, base, INT_MAX);

}

EXPORT_SYMBOL(simple_strtoll);
@@ -3648,13 +3649,11 @@ int vsscanf(const char *buf, const char *fmt, va_list args) 
			break;



		if (is_sign)

			val.s = simple_strntoll(str,

						field_width >= 0 ? field_width : INT_MAX,

						&next, base);

			val.s = simple_strntoll(str, &next, base,

						field_width >= 0 ? field_width : INT_MAX);

		else

			val.u = simple_strntoull(str,

						 field_width >= 0 ? field_width : INT_MAX,

						 &next, base);

			val.u = simple_strntoull(str, &next, base,

						 field_width >= 0 ? field_width : INT_MAX);



		switch (qualifier) {

		case 'H':	/* that's 'hh' in format */