diff options
Diffstat (limited to 'main/musl/0003-fix-fmaf-wrong-result.patch')
| -rw-r--r-- | main/musl/0003-fix-fmaf-wrong-result.patch | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/main/musl/0003-fix-fmaf-wrong-result.patch b/main/musl/0003-fix-fmaf-wrong-result.patch new file mode 100644 index 0000000000..1fdaf2571a --- /dev/null +++ b/main/musl/0003-fix-fmaf-wrong-result.patch @@ -0,0 +1,35 @@ +From 282b1cd26649d69de038111f5876853df6ddc345 Mon Sep 17 00:00:00 2001 +From: Szabolcs Nagy <nsz@port70.net> +Date: Sun, 1 Apr 2018 20:02:01 +0000 +Subject: [PATCH] fix fmaf wrong result + +if double precision r=x*y+z is not a half way case between two single +precision floats or it is an exact result then fmaf returns (float)r. + +however the exactness check was wrong when |x*y| < |z| and could cause +incorrectly rounded result in nearest rounding mode when r is a half +way case. + +fmaf(-0x1.26524ep-54, -0x1.cb7868p+11, 0x1.d10f5ep-29) +was incorrectly rounded up to 0x1.d117ap-29 instead of 0x1.d1179ep-29. +(exact result is 0x1.d1179efffffffecp-29, r is 0x1.d1179fp-29) +--- + src/math/fmaf.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/src/math/fmaf.c b/src/math/fmaf.c +index aa57feb6..80f5cd8a 100644 +--- a/src/math/fmaf.c ++++ b/src/math/fmaf.c +@@ -50,7 +50,7 @@ float fmaf(float x, float y, float z) + /* Common case: The double precision result is fine. */ + if ((u.i & 0x1fffffff) != 0x10000000 || /* not a halfway case */ + e == 0x7ff || /* NaN */ +- result - xy == z || /* exact */ ++ (result - xy == z && result - z == xy) || /* exact */ + fegetround() != FE_TONEAREST) /* not round-to-nearest */ + { + /* +-- +2.17.0 + |