[Bug target/28946] [4.0/4.1/4.2 Regression] assembler shifts set the flag ZF, no need to re-test to zero

uros at kss-loka dot si gcc-bugzilla@gcc.gnu.org
Tue Sep 5 06:20:00 GMT 2006



------- Comment #4 from uros at kss-loka dot si  2006-09-05 06:20 -------
(In reply to comment #2)
> It is entirely coincident. For some processors, it is an optimization to avoid
> partial flag register stall. When it is fixed, it should be reenabled with a
> new flag, something like TARGET_PARTIAL_FLAG_REG_STALL.

There is TARGET_USE_INCDEC flag that already implements your suggestion.

>From predicates.md:
  /* On Pentium4, the inc and dec operations causes extra dependency on flag
     registers, since carry flag is not set.  */
  if (!TARGET_USE_INCDEC && !optimize_size)

If used elsewhere, this flag should perhaps be renamed to proposed
TARGET_PARTIAL_FLAG_REG_STALL.


-- 

uros at kss-loka dot si changed:

           What    |Removed                     |Added
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                 CC|                            |uros at kss-loka dot si


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28946



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