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| author | Marius Hillenbrand <mhillen@linux.ibm.com> | 2020-12-01 11:02:27 +0100 |
|---|---|---|
| committer | Andreas Krebbel <krebbel@linux.ibm.com> | 2020-12-01 11:29:09 +0100 |
| commit | a5dd6b69fcbe74c02d4821ac2daf2b8c9f819f6e (patch) | |
| tree | 78b146b12ca2fe39d2170da0e04c2eb9d1f9da52 /gcc/doc | |
| parent | cffd725c0eb44daa0234f3af39cd94ad97f2833d (diff) | |
| download | gcc-a5dd6b69fcbe74c02d4821ac2daf2b8c9f819f6e.zip gcc-a5dd6b69fcbe74c02d4821ac2daf2b8c9f819f6e.tar.gz gcc-a5dd6b69fcbe74c02d4821ac2daf2b8c9f819f6e.tar.bz2 | |
IBM Z: Configure excess precision for float at compile-time
Historically, float_t has been defined as double on s390 and gcc would
emit double precision insns for evaluating float expressions when in
standard-compliant mode. Configure that behavior at compile-time as prep
for changes in glibc: When glibc ties float_t to double, keep the old
behavior; when glibc derives float_t from FLT_EVAL_METHOD (as on most
other archs), revert to the default behavior (i.e.,
FLT_EVAL_METHOD_PROMOTE_TO_FLOAT). Provide a configure option
--enable-s390-excess-float-precision to override the check.
gcc/ChangeLog:
2020-12-01 Marius Hillenbrand <mhillen@linux.ibm.com>
* configure.ac: Add configure option
--enable-s390-excess-float-precision and check to derive default
from glibc.
* config/s390/s390.c: Guard s390_excess_precision with an ifdef
for ENABLE_S390_EXCESS_FLOAT_PRECISION.
* doc/install.texi: Document --enable-s390-excess-float-precision.
* configure: Regenerate.
* config.in: Regenerate.
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/install.texi | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi index 021c347..a38ca3e 100644 --- a/gcc/doc/install.texi +++ b/gcc/doc/install.texi @@ -2270,6 +2270,16 @@ information in object. The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) target if target binutils supported. + +@item --enable-s390-excess-float-precision +@itemx --disable-s390-excess-float-precision +On s390(x) targets, enable treatment of float expressions with double precision +when in standards-compliant mode (e.g., when @code{--std=c99} or +@code{-fexcess-precision=standard} are given). + +For a native build, the option's default is derived from glibc's behavior. When +glibc clamps float_t to double, gcc follows and enables the option. In all other +cases, it defaults to off. @end table @subheading Cross-Compiler-Specific Options |