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Adding SDL_Assume macro to give hint to the optimiser #6309

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Adding SDL_Assume macro to give hint to the optimiser #6309

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668a52b
Adding SDL_Assume macro to give hint to the optimiser
devnexen Oct 1, 2022
cdbcd73
fix build
devnexen Mar 10, 2024
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12 changes: 12 additions & 0 deletions include/SDL3/SDL_assert.h
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,18 @@ assert can have unique static variables associated with it.
#define SDL_TriggerBreakpoint()
#endif

#if defined(_MSC_VER) && (_MSC_VER > 1400)
#define SDL_Assume(cond) __assume(cond)
#elif SDL_HAS_BUILTIN(__builtin_assume)
#define SDL_Assume(cond) __builtin_assume(cond)
#elif defined(__clang__) || (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 4)))
#define SDL_Assume(cond) do { \
(__builtin_expect(!(cond), 0) ? __builtin_unreachable() : (void)0); \
} while (0)
#else
#define SDL_Assume(cond)
#endif

#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 supports __func__ as a standard. */
# define SDL_FUNCTION __func__
#elif ((defined(__GNUC__) && (__GNUC__ >= 2)) || defined(_MSC_VER) || defined (__WATCOMC__))
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16 changes: 15 additions & 1 deletion test/testplatform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -438,7 +438,20 @@ static int TestAssertions(SDL_bool verbose)
return 0;
}

int main(int argc, char *argv[])
int
TestAssume(SDL_bool verbose)
{
int max, count, i;

max = 16;
count = SDLTest_RandomIntegerInRange(0, max);
SDL_Assume(count <= max);
for (i = 0; i < count; i ++);
return (0);
}

int
main(int argc, char *argv[])
{
int i;
SDL_bool verbose = SDL_TRUE;
Expand Down Expand Up @@ -483,6 +496,7 @@ int main(int argc, char *argv[])
status += Test64Bit(verbose);
status += TestCPUInfo(verbose);
status += TestAssertions(verbose);
status += TestAssume(verbose);

SDLTest_CommonDestroyState(state);

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