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* [Bug c++/13413] New: need "o" inline asm constraint
@ 2003-12-16 17:17 melkov at comptek dot ru
2003-12-16 17:50 ` [Bug inline-asm/13413] " bangerth at dealii dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: melkov at comptek dot ru @ 2003-12-16 17:17 UTC (permalink / raw)
To: gcc-bugs
I think that having no "o" constraint is asm for i386 target is unfair, because
in effect all the "m" values are actually offsetable.
For example, when I write:
movl 4+%5, %2
- I always get correct code.
The only problem here is that I get gas warning each time %5 happens to be a
base register without an offset, i.e. something like (%ebx) turns the above
line into
movl 4+(%ebx), %eax
If there was "o" constraing that behaves like "m" in most cases but prints zero
in case of zero offset, some people like me would be happy.
What I want, once again:
%5 == (%ebx)
"m" prints (%ebx)
"o" prints 0(%ebx)
-> quite correct movl 4+0(%ebx), %eax in "o" case.
%5 == 12(%ebx)
both "m" and "o" print (%ebx)
-> still correct movl 4+12(%ebx), %eax code.
I hope that's easy to do. Thanks in advance :)
--
Summary: need "o" inline asm constraint
Product: gcc
Version: 3.3.2
Status: UNCONFIRMED
Severity: enhancement
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: melkov at comptek dot ru
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-freebsd-gnu
GCC host triplet: i686-freebsd-gnu
GCC target triplet: i686-freebsd-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13413
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug inline-asm/13413] need "o" inline asm constraint
2003-12-16 17:17 [Bug c++/13413] New: need "o" inline asm constraint melkov at comptek dot ru
@ 2003-12-16 17:50 ` bangerth at dealii dot org
2003-12-16 20:07 ` [Bug target/13413] " pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: bangerth at dealii dot org @ 2003-12-16 17:50 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Component|c++ |inline-asm
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13413
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/13413] need "o" inline asm constraint
2003-12-16 17:17 [Bug c++/13413] New: need "o" inline asm constraint melkov at comptek dot ru
2003-12-16 17:50 ` [Bug inline-asm/13413] " bangerth at dealii dot org
@ 2003-12-16 20:07 ` pinskia at gcc dot gnu dot org
2003-12-19 8:06 ` pinskia at gcc dot gnu dot org
2003-12-20 0:45 ` melkov at comptek dot ru
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2003-12-16 20:07 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Component|inline-asm |target
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13413
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/13413] need "o" inline asm constraint
2003-12-16 17:17 [Bug c++/13413] New: need "o" inline asm constraint melkov at comptek dot ru
2003-12-16 17:50 ` [Bug inline-asm/13413] " bangerth at dealii dot org
2003-12-16 20:07 ` [Bug target/13413] " pinskia at gcc dot gnu dot org
@ 2003-12-19 8:06 ` pinskia at gcc dot gnu dot org
2003-12-20 0:45 ` melkov at comptek dot ru
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2003-12-19 8:06 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2003-12-19 07:36 -------
So this is what you want:
int f(int *i){int t; asm("a %1":"=r"(t):"o"(*i)); return t;}
0(%eax) and not (%eax) which it currently is now, right?
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2003-12-19 07:36:29
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13413
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/13413] need "o" inline asm constraint
2003-12-16 17:17 [Bug c++/13413] New: need "o" inline asm constraint melkov at comptek dot ru
` (2 preceding siblings ...)
2003-12-19 8:06 ` pinskia at gcc dot gnu dot org
@ 2003-12-20 0:45 ` melkov at comptek dot ru
3 siblings, 0 replies; 5+ messages in thread
From: melkov at comptek dot ru @ 2003-12-20 0:45 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From melkov at comptek dot ru 2003-12-19 21:35 -------
(In reply to comment #1)
> So this is what you want:
> int f(int *i){int t; asm("a %1":"=r"(t):"o"(*i)); return t;}
> 0(%eax) and not (%eax) which it currently is now, right?
Yes, that's right.
But that's not enough. Nowadays gcc doesn't like "o" at all, it says: "error:
impossible constraint in `asm'".
/usr/local/egcs-3/bin/c++ -O -Wall mo.cpp
mo.cpp: In function `int main(int, char**)':
mo.cpp:3: error: impossible constraint in `asm'
==> mo.cpp <==
int main(int argc, char *[]) {
long long A = argc;
asm volatile(
""
: "=o" (A)
:
: "cc"
);
return A;
}
With "m", it compiles fine. (note -O switch)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13413
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2003-12-19 21:35 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-12-16 17:17 [Bug c++/13413] New: need "o" inline asm constraint melkov at comptek dot ru
2003-12-16 17:50 ` [Bug inline-asm/13413] " bangerth at dealii dot org
2003-12-16 20:07 ` [Bug target/13413] " pinskia at gcc dot gnu dot org
2003-12-19 8:06 ` pinskia at gcc dot gnu dot org
2003-12-20 0:45 ` melkov at comptek dot ru
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