From: Fabian Schriever <fabian.schriever@gtd-gmbh.de>
To: newlib@sourceware.org
Cc: Fabian Schriever <fabian.schriever@gtd-gmbh.de>
Subject: [PATCH] Fix error in fdim/f for infinities
Date: Tue, 10 Mar 2020 11:24:12 +0100 [thread overview]
Message-ID: <20200310102412.391-1-fabian.schriever@gtd-gmbh.de> (raw)
The comparison c == FP_INFINITE causes the function to return +inf as it
expects x = +inf to always be larger than y. This shortcut causes
several issues as it also returns +inf for the following cases:
- fdim(+inf, +inf), expected (as per C99): +0.0
- fdim(-inf, any non NaN), expected: +0.0
I don't see a reason to keep the comparison as all the infinity cases
return the correct result using just the ternary operation.
---
newlib/libm/common/s_fdim.c | 5 +----
newlib/libm/common/sf_fdim.c | 5 +----
2 files changed, 2 insertions(+), 8 deletions(-)
diff --git a/newlib/libm/common/s_fdim.c b/newlib/libm/common/s_fdim.c
index 73a027953..61a4908f3 100644
--- a/newlib/libm/common/s_fdim.c
+++ b/newlib/libm/common/s_fdim.c
@@ -49,11 +49,8 @@ ANSI C, POSIX.
double y;
#endif
{
- int c = __fpclassifyd(x);
- if (c == FP_NAN) return(x);
+ if (__fpclassifyd(x) == FP_NAN) return(x);
if (__fpclassifyd(y) == FP_NAN) return(y);
- if (c == FP_INFINITE)
- return HUGE_VAL;
return x > y ? x - y : 0.0;
}
diff --git a/newlib/libm/common/sf_fdim.c b/newlib/libm/common/sf_fdim.c
index fe349098b..8fee57002 100644
--- a/newlib/libm/common/sf_fdim.c
+++ b/newlib/libm/common/sf_fdim.c
@@ -14,11 +14,8 @@
float y;
#endif
{
- int c = __fpclassifyf(x);
- if (c == FP_NAN) return(x);
+ if (__fpclassifyf(x) == FP_NAN) return(x);
if (__fpclassifyf(y) == FP_NAN) return(y);
- if (c == FP_INFINITE)
- return HUGE_VALF;
return x > y ? x - y : 0.0;
}
--
2.24.1.windows.2
next reply other threads:[~2020-03-10 10:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 10:24 Fabian Schriever [this message]
2020-03-10 14:47 ` Corinna Vinschen
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