From: Florian Weimer Date: Wed, 6 Nov 2024 15:09:05 +0000 (+0100) Subject: math: Fix incorrect results of exp10m1f with some GCC versions X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=ba60be873554ecd141b55ea82647714933c0dbd4;p=glibc.git math: Fix incorrect results of exp10m1f with some GCC versions On GCC 11 (x86-64), the previous code produced test failures like this one: Failure: Test: exp10m1_towardzero (-0x1.1p+4) Result: is: -1.00000000e+00 -0x1.000000p+0 should be: -9.99999940e-01 -0x1.fffffep-1 difference: 5.96046447e-08 0x1.000000p-24 ulp : 1.0000 max.ulp : 0.0000 Apply a similar fix to exp2m1f. Co-authored-by: Paul Zimmermann Reviewed-by: Adhemerval Zanella --- diff --git a/sysdeps/ieee754/flt-32/s_exp10m1f.c b/sysdeps/ieee754/flt-32/s_exp10m1f.c index 04a068ee32..ea3173a174 100644 --- a/sysdeps/ieee754/flt-32/s_exp10m1f.c +++ b/sysdeps/ieee754/flt-32/s_exp10m1f.c @@ -40,7 +40,7 @@ __exp10m1f (float x) { /* x < -7.52575 */ if (ax > (0xffu << 23)) return x + x; /* nan */ - return (ux == 0xff800000) ? -0x1p+0 : -0x1p+0 + 0x1p-26f; + return (ux == 0xff800000) ? -0x1p+0f : -0x1p+0f + 0x1p-26f; } else if (__glibc_unlikely (ax > 0x421a209au)) { /* x > 38.5318 */ diff --git a/sysdeps/ieee754/flt-32/s_exp2m1f.c b/sysdeps/ieee754/flt-32/s_exp2m1f.c index b3f86409cc..325ffb11b0 100644 --- a/sysdeps/ieee754/flt-32/s_exp2m1f.c +++ b/sysdeps/ieee754/flt-32/s_exp2m1f.c @@ -41,7 +41,7 @@ __exp2m1f (float x) { /* x <= -25 */ if (ax > (0xffu << 23)) return x + x; /* nan */ - return (ux == 0xff800000) ? -0x1p+0 : -0x1p+0 + 0x1p-26f; + return (ux == 0xff800000) ? -0x1p+0f : -0x1p+0f + 0x1p-26f; } else if (__glibc_unlikely (ax >= 0x43000000u)) { /* x >= 128 */