65 lines
2.1 KiB
Diff
65 lines
2.1 KiB
Diff
From 672f05a903f2b3ef7144c8c92efdff5e766a0dba Mon Sep 17 00:00:00 2001
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From: XingLi <lixing@loongson.cn>
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Date: Thu, 2 Feb 2023 18:49:01 +0800
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Subject: [PATCH] math: Fix asin and acos invalid exception with old gcc
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This works around a gcc issue where it const folded inf/inf into nan,
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preventing the invalid exception to be signalled.
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(x-x)/(x-x) is more robust against optimizations and works for all
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out of bounds values including x==nan.
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The gcc issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95115
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should be fixed on release branches starting from gcc-10, but it is
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better to change the code in case glibc is built with older gcc.
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Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
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upstream commit 7363a9a9a097c455a7ddb9386b4c6f7bdf91065f
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Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
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---
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sysdeps/ieee754/dbl-64/e_asin.c | 20 +++-----------------
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1 file changed, 3 insertions(+), 17 deletions(-)
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diff --git a/sysdeps/ieee754/dbl-64/e_asin.c b/sysdeps/ieee754/dbl-64/e_asin.c
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index 4473ae5d..b03a0a94 100644
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--- a/sysdeps/ieee754/dbl-64/e_asin.c
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+++ b/sysdeps/ieee754/dbl-64/e_asin.c
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@@ -165,15 +165,8 @@ __ieee754_asin(double x){
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/*---------------------------- |x|>=1 -------------------------------*/
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else if (k==0x3ff00000 && u.i[LOW_HALF]==0) return (m>0)?hp0.x:-hp0.x;
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else
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- if (k>0x7ff00000 || (k == 0x7ff00000 && u.i[LOW_HALF] != 0)) return x + x;
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- else {
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- u.i[HIGH_HALF]=0x7ff00000;
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- v.i[HIGH_HALF]=0x7ff00000;
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- u.i[LOW_HALF]=0;
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- v.i[LOW_HALF]=0;
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- return u.x/v.x; /* NaN */
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- }
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-}
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+ return (x - x) / (x - x);
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+ }
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#ifndef __ieee754_asin
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libm_alias_finite (__ieee754_asin, __asin)
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#endif
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@@ -334,14 +327,7 @@ __ieee754_acos(double x)
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else
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if (k==0x3ff00000 && u.i[LOW_HALF]==0) return (m>0)?0:2.0*hp0.x;
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else
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- if (k>0x7ff00000 || (k == 0x7ff00000 && u.i[LOW_HALF] != 0)) return x + x;
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- else {
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- u.i[HIGH_HALF]=0x7ff00000;
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- v.i[HIGH_HALF]=0x7ff00000;
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- u.i[LOW_HALF]=0;
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- v.i[LOW_HALF]=0;
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- return u.x/v.x;
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- }
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+ return (x - x) / (x - x);
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}
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#ifndef __ieee754_acos
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libm_alias_finite (__ieee754_acos, __acos)
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--
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2.33.0
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