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authorMarius Hillenbrand <mhillen@linux.ibm.com>2020-11-30 15:53:59 +0100
committerStefan Liebler <stli@linux.ibm.com>2020-12-09 16:26:46 +0100
commitf88242af19dc970949806790f70c6fd6336944a6 (patch)
tree5dbc966ce8356ff8b3f5515f151f2c7de4e61f7e /sysdeps/s390
parentb5eeca8cfd9d0fd92b5633a88901d9ff27f2b496 (diff)
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S390: Derive float_t from FLT_EVAL_METHOD
float_t supposedly represents the type that is used to evaluate float
expressions internally. While the isa supports single-precision float
operations, the port of glibc to s390 incorrectly deferred to the
generic definitions which, back then, tied float_t to double. gcc by
default evaluates float in single precision, so that scenario violates
the C standard (sections 5.2.4.2.2 and 7.12 in C11/C17). With
-fexcess-precision=standard, gcc evaluates float in double precision,
which aligns with the standard yet at the cost of added conversion
instructions.

With this patch, we drop the s390-specific definition of float_t and
defer to the default behavior, which aligns float_t with the
compiler-defined FLT_EVAL_METHOD in a standard-compliant way.

Checked on s390x-linux-gnu with 31-bit and 64-bit builds.
Diffstat (limited to 'sysdeps/s390')
-rw-r--r--sysdeps/s390/bits/flt-eval-method.h24
1 files changed, 0 insertions, 24 deletions
diff --git a/sysdeps/s390/bits/flt-eval-method.h b/sysdeps/s390/bits/flt-eval-method.h
deleted file mode 100644
index 826bbfec2f..0000000000
--- a/sysdeps/s390/bits/flt-eval-method.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* Define __GLIBC_FLT_EVAL_METHOD.  S/390 version.
-   Copyright (C) 2016-2020 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _MATH_H
-# error "Never use <bits/flt-eval-method.h> directly; include <math.h> instead."
-#endif
-
-/* This value is used because of a historical mistake.  */
-#define __GLIBC_FLT_EVAL_METHOD	1