https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
Uroš Bizjak changed:
What|Removed |Added
Status|UNCONFIRMED |RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #17 from Jeremy ---
Did you mean "stc" rather than "setc" ???
But yes, it looks like its working well.
On 20 July 2015 at 10:05, gccbugzilla at limegreensocks dot com <
gcc-bugzi...@gcc.gnu.org> wrote:
> https://gcc.gnu.org/bugzill
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #16 from David ---
I've tried it now and it seems to do good things. This code:
int main(int argc, char *argv[])
{
char x;
asm("setc" : "=@ccc"(x));
if (!x)
return 6;
else
return argc;
}
produces this outp
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #15 from Jeremy ---
Perhaps the optimizer can reduce "seta; test; jnz" to "ja" since the
compiler now knows the intention. In which case this is a great solution.
On 17 July 2015 at 22:24, gccbugzilla at limegreensocks dot com <
gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #14 from David ---
(In reply to Jeremy from comment #12)
> It probably does a setcc on x86 which doesn't really gain much
I don't have a 6.0 build to test with yet, but I don't believe that's quite
correct. Looking at the testsuite
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #13 from Andrew Pinski ---
(In reply to Jeremy from comment #12)
> Hi David,
> That's very interesting. Its not in gcc 5.2.0 released yesterday though.
That is because 5.2 is a patch release off of the 5 branch. It was added to gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #12 from Jeremy ---
Hi David,
That's very interesting. Its not in gcc 5.2.0 released yesterday though.
It probably does a setcc on x86 which doesn't really gain much, but on ARM
it could be useful.
More useful (as of gcc 5.0) is the
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #11 from David ---
Apparently this feature has been checked in:
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#FlagOutputOperands
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #10 from David ---
There was some discussion of this on the gcc mailing list. Not sure what
became of it: https://gcc.gnu.org/ml/gcc/2015-05/msg6.html
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #9 from Ryan Johnson ---
(In reply to Andi Kleen from comment #7)
> You can do many of these things these days with asm goto, however it
> typically requires non-structured control flow (goto labels).
I filed this bug after determinin
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #8 from Jeremy ---
Asm goto does not allow any outputs, which does limit its usefulness.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
Andi Kleen changed:
What|Removed |Added
CC||andi-gcc at firstfloor dot org
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #6 from Ryan Johnson ---
(In reply to Jeremy from comment #5)
> It may not be possible, but perhaps a simpler thing might be for
> the asm() to notionally "return" a single boolean value which
> reflects ONE flag only.
Interesting!
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
Jeremy changed:
What|Removed |Added
CC||gcc.hall at gmail dot com
--- Comment #5 from J
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
Jeroen van Bemmel changed:
What|Removed |Added
CC||jbemmel at zonnet dot nl
--- Comment
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #3 from Ryan Johnson 2012-04-12 16:39:32
UTC ---
FYI: based on a discussion from quite some time ago [1], it seems that the
Linux kernel folks would be "tickled pink" to have this feature, and discussed
several potential ways to imple
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #2 from Ryan Johnson 2011-07-04 20:32:01
UTC ---
(In reply to comment #1)
> Making this work reliably is probably more work than making GCC use the flags
> from more cases from regular C code.
Does that mean each such case would need
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49611
--- Comment #1 from Richard Guenther 2011-07-02
12:36:44 UTC ---
Making this work reliably is probably more work than making GCC use the flags
from more cases from regular C code.
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