diff options
Diffstat (limited to 'math/math-narrow.h')
| -rw-r--r-- | math/math-narrow.h | 45 |
1 files changed, 28 insertions, 17 deletions
diff --git a/math/math-narrow.h b/math/math-narrow.h index 93d1b4c52a..0194f8c97e 100644 --- a/math/math-narrow.h +++ b/math/math-narrow.h @@ -28,6 +28,7 @@ #include <math_private.h> #include <fenv_private.h> #include <math-narrow-alias.h> +#include <stdbool.h> /* Carry out a computation using round-to-odd. The computation is EXPR; the union type in which to store the result is UNION and the @@ -37,11 +38,15 @@ function rather than a C operator is used when argument and result types are the same) and the libc_fe* macros to ensure that the correct rounding mode is used, for platforms with multiple rounding - modes where those macros set only the relevant mode. This macro - does not work correctly if the sign of an exact zero result depends - on the rounding mode, so that case must be checked for - separately. */ -#define ROUND_TO_ODD(EXPR, UNION, SUFFIX, MANTISSA) \ + modes where those macros set only the relevant mode. + CLEAR_UNDERFLOW indicates whether underflow exceptions must be + cleared (in the case where a round-toward-zero underflow might not + indicate an underflow after narrowing, when that narrowing only + reduces precision not exponent range and the architecture uses + before-rounding tininess detection). This macro does not work + correctly if the sign of an exact zero result depends on the + rounding mode, so that case must be checked for separately. */ +#define ROUND_TO_ODD(EXPR, UNION, SUFFIX, MANTISSA, CLEAR_UNDERFLOW) \ ({ \ fenv_t env; \ UNION u; \ @@ -49,6 +54,8 @@ libc_feholdexcept_setround ## SUFFIX (&env, FE_TOWARDZERO); \ u.d = (EXPR); \ math_force_eval (u.d); \ + if (CLEAR_UNDERFLOW) \ + feclearexcept (FE_UNDERFLOW); \ u.ieee.MANTISSA \ |= libc_feupdateenv_test ## SUFFIX (&env, FE_INEXACT) != 0; \ \ @@ -91,7 +98,7 @@ ret = (TYPE) ((X) + (Y)); \ else \ ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) + (Y), \ - UNION, SUFFIX, MANTISSA); \ + UNION, SUFFIX, MANTISSA, false); \ \ CHECK_NARROW_ADD (ret, (X), (Y)); \ return ret; \ @@ -149,7 +156,7 @@ ret = (TYPE) ((X) - (Y)); \ else \ ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) - (Y), \ - UNION, SUFFIX, MANTISSA); \ + UNION, SUFFIX, MANTISSA, false); \ \ CHECK_NARROW_SUB (ret, (X), (Y)); \ return ret; \ @@ -194,15 +201,17 @@ while (0) /* Implement narrowing multiply using round-to-odd. The arguments are - X and Y, the return type is TYPE and UNION, MANTISSA and SUFFIX are - as for ROUND_TO_ODD. */ -#define NARROW_MUL_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA) \ + X and Y, the return type is TYPE and UNION, MANTISSA, SUFFIX and + CLEAR_UNDERFLOW are as for ROUND_TO_ODD. */ +#define NARROW_MUL_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA, \ + CLEAR_UNDERFLOW) \ do \ { \ TYPE ret; \ \ ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) * (Y), \ - UNION, SUFFIX, MANTISSA); \ + UNION, SUFFIX, MANTISSA, \ + CLEAR_UNDERFLOW); \ \ CHECK_NARROW_MUL (ret, (X), (Y)); \ return ret; \ @@ -246,16 +255,18 @@ } \ while (0) -/* Implement narrowing divide using round-to-odd. The arguments are - X and Y, the return type is TYPE and UNION, MANTISSA and SUFFIX are - as for ROUND_TO_ODD. */ -#define NARROW_DIV_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA) \ +/* Implement narrowing divide using round-to-odd. The arguments are X + and Y, the return type is TYPE and UNION, MANTISSA, SUFFIX and + CLEAR_UNDERFLOW are as for ROUND_TO_ODD. */ +#define NARROW_DIV_ROUND_TO_ODD(X, Y, TYPE, UNION, SUFFIX, MANTISSA, \ + CLEAR_UNDERFLOW) \ do \ { \ TYPE ret; \ \ ret = (TYPE) ROUND_TO_ODD (math_opt_barrier (X) / (Y), \ - UNION, SUFFIX, MANTISSA); \ + UNION, SUFFIX, MANTISSA, \ + CLEAR_UNDERFLOW); \ \ CHECK_NARROW_DIV (ret, (X), (Y)); \ return ret; \ @@ -308,7 +319,7 @@ TYPE ret; \ \ ret = (TYPE) ROUND_TO_ODD (sqrt ## SUFFIX (math_opt_barrier (X)), \ - UNION, SUFFIX, MANTISSA); \ + UNION, SUFFIX, MANTISSA, false); \ \ CHECK_NARROW_SQRT (ret, (X)); \ return ret; \ |