qiurui
/
glibc
mirror of git://sourceware.org/git/glibc.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

[powerpc] libc_feupdateenv_test: optimize FPSCR access 

ROUND_TO_ODD and a couple of other places use libc_feupdateenv_test to
restore the rounding mode and exception enables, preserve exception flags,
and test whether given exception(s) were generated.

If the exception flags haven't changed, then it is sufficient and a bit
more efficient to just restore the rounding mode and enables, rather than
writing the full Floating-Point Status and Control Register (FPSCR).

Reviewed-by: Paul E. Murphy <murphyp@linux.ibm.com>
This commit is contained in:
Paul A. Clarke 2019-09-19 11:18:33 -05:00
parent e3d85df50b
commit 7413c188c7
3 changed files with 24 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
ChangeLog
View File

@ -1,3 +1,9 @@
2019-09-27 Paul A. Clarke <pc@us.ibm.com>
* sysdeps/powerpc/fpu/fenv_libc.h (FPSCR_EXCEPTIONS_MASK): New.
* sysdeps/powerpc/fpu/fenv_private.h (__libc_femergeenv_ppc): Optimize
to write FPSCR control only, if exceptions have not changed.
2019-09-27 Paul A. Clarke <pc@us.ibm.com>
* sysdeps/powerpc/fpu/fenv_libc.h:

4
sysdeps/powerpc/fpu/fenv_libc.h
View File

@ -256,6 +256,10 @@ enum {
(FPSCR_VE_MASK|FPSCR_OE_MASK|FPSCR_UE_MASK|FPSCR_ZE_MASK|FPSCR_XE_MASK)
#define FPSCR_BASIC_EXCEPTIONS_MASK \
(FPSCR_VX_MASK|FPSCR_OX_MASK|FPSCR_UX_MASK|FPSCR_ZX_MASK|FPSCR_XX_MASK)
#define FPSCR_EXCEPTIONS_MASK (FPSCR_BASIC_EXCEPTIONS_MASK| \
FPSCR_VXSNAN_MASK|FPSCR_VXISI_MASK|FPSCR_VXIDI_MASK|FPSCR_VXZDZ_MASK| \
FPSCR_VXIMZ_MASK|FPSCR_VXVC_MASK|FPSCR_VXSOFT_MASK|FPSCR_VXSQRT_MASK| \
FPSCR_VXCVI_MASK)
#define FPSCR_FPRF_MASK \
(FPSCR_FPRF_C_MASK|FPSCR_FPRF_FL_MASK|FPSCR_FPRF_FG_MASK| \
FPSCR_FPRF_FE_MASK|FPSCR_FPRF_FU_MASK)

16
sysdeps/powerpc/fpu/fenv_private.h
View File

@ -52,8 +52,20 @@ __libc_femergeenv_ppc (const fenv_t *envp, unsigned long long old_mask,
__TEST_AND_EXIT_NON_STOP (old.l, new.l);
__TEST_AND_ENTER_NON_STOP (old.l, new.l);
/* Atomically enable and raise (if appropriate) exceptions set in `new'. */
fesetenv_register (new.fenv);
/* If requesting to keep status, replace control, and merge exceptions,
and exceptions haven't changed, we can just set new control instead
of the whole FPSCR. */
if ((old_mask & (FPSCR_CONTROL_MASK|FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK))
== (FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK) &&
(new_mask & (FPSCR_CONTROL_MASK|FPSCR_STATUS_MASK|FPSCR_EXCEPTIONS_MASK))
== (FPSCR_CONTROL_MASK|FPSCR_EXCEPTIONS_MASK) &&
(old.l & FPSCR_EXCEPTIONS_MASK) == (new.l & FPSCR_EXCEPTIONS_MASK))
{
fesetenv_mode (new.fenv);
}
else
/* Atomically enable and raise (if appropriate) exceptions set in `new'. */
fesetenv_register (new.fenv);
return old.l;
}