------- Additional Comments From amacleod at redhat dot com 2005-08-15 17:15
-------
TER isnt doing anything with this because there are no virtual operands. It
sees:
# BLOCK 0
# PRED: ENTRY [100.0%] (fallthru,exec)
D.1279 = &var + 1B;
__asm__ __volatile__(""::"i" D.1279);
return 0;
so the stmt:
D.1279 = &var + 1B;
isnt considered for replacvement since there are no dependancies whatsoever on
it. TER operates on the assumptions that if a stmt has no USES and no VUSES,
then one of the other optimizations would have done the substitution if it were
possible.
There use to be a good reason for this, and there was a comment to that effect,
but it seems to have been removed. Perhaps the original reason is gone, but the
code hasnt been properly updated to fix the issue.
A quick hack to TER to add a "NO_DEPEND_PARTITION" for such statements appears
to do what you are looking for here:
# BLOCK 0
# PRED: ENTRY [100.0%] (fallthru,exec)
__asm__ __volatile__(""::"i" &var + 1B);
return 0;
I will run it through the test suites to see if it reintroduces whatever
the original problem with these types of replacements was.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23200
