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* [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax"
@ 2010-03-01 2:22 richardpku at gmail dot com
2010-03-01 9:56 ` [Bug target/43215] " ubizjak at gmail dot com
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: richardpku at gmail dot com @ 2010-03-01 2:22 UTC (permalink / raw)
To: gcc-bugs
#include <stdint.h>
uint64_t extract_double (double x)
{
union {
double dbl;
uint64_t u;
} t;
t.dbl = x;
return t.u;
}
Compile this function with "x86_64-pc-linux-gnu-gcc -O2 -march=core2 -S a.c",
and we get the following assembly codes:
extract_double:
.LFB0:
.cfi_startproc
movd %xmm0, %rax
ret
The instruction "movd %xmm0, %rax" is nonstandard. Movd should be replaced by
movq.
(GNU assembler silently accepts it as if it were "movq %xmm0, %rax", so it
probably has caused no practical problems.)
--
Summary: x86-64: Nonstandard instruction "movd %xmm0, %rax"
Product: gcc
Version: 4.4.3
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: richardpku at gmail dot com
GCC build triplet: x86_64-linux-gnu
GCC host triplet: i686-linux-gnu
GCC target triplet: x86_64-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
@ 2010-03-01 9:56 ` ubizjak at gmail dot com
2010-03-01 13:31 ` hjl dot tools at gmail dot com
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: ubizjak at gmail dot com @ 2010-03-01 9:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from ubizjak at gmail dot com 2010-03-01 09:56 -------
Indeed.
Following patch fixes the problem:
Index: i386.md
===================================================================
--- i386.md (revision 157132)
+++ i386.md (working copy)
@@ -3245,7 +3245,7 @@
case 9:
case 10:
- return "%vmovd\t{%1, %0|%0, %1}";
+ return "%vmovq\t{%1, %0|%0, %1}";
default:
gcc_unreachable();
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |ubizjak at gmail dot com
|dot org |
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2010-03-01 09:56:03
date| |
Target Milestone|--- |4.3.5
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
2010-03-01 9:56 ` [Bug target/43215] " ubizjak at gmail dot com
@ 2010-03-01 13:31 ` hjl dot tools at gmail dot com
2010-03-01 14:56 ` rguenth at gcc dot gnu dot org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2010-03-01 13:31 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from hjl dot tools at gmail dot com 2010-03-01 13:31 -------
This is done on purpose to provide backward compatibility
since vmovq isn't in original x86-64 spec and older assemblers
don't support it. From i386-opc.tbl in binutils:
// These really shouldn't allow for Reg64 (movq is the right mnemonic for
// copying between Reg64/Mem64 and RegXMM/RegMMX, as is mandated by Intel's
// spec). AMD's spec, having been in existence for much longer, failed to
// recognize that and specified movd for 32- and 64-bit operations.
// vmovd really shouldn't allow for 64bit operand (vmovq is the right
// mnemonic for copying between Reg64/Mem64 and RegXMM, as is mandated
// by Intel AVX spec). To avoid extra template in gcc x86 backend and
// support assembler for AMD64, we accept 64bit operand on vmovd so
// that we can use one template for both SSE and AVX instructions.
--
hjl dot tools at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |WONTFIX
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
2010-03-01 9:56 ` [Bug target/43215] " ubizjak at gmail dot com
2010-03-01 13:31 ` hjl dot tools at gmail dot com
@ 2010-03-01 14:56 ` rguenth at gcc dot gnu dot org
2010-03-01 15:42 ` hjl dot tools at gmail dot com
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2010-03-01 14:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rguenth at gcc dot gnu dot org 2010-03-01 14:55 -------
I fail to see why binutils accepting both version should be a reason to
not fix gcc.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|WONTFIX |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (2 preceding siblings ...)
2010-03-01 14:56 ` rguenth at gcc dot gnu dot org
@ 2010-03-01 15:42 ` hjl dot tools at gmail dot com
2010-03-01 20:30 ` ubizjak at gmail dot com
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2010-03-01 15:42 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from hjl dot tools at gmail dot com 2010-03-01 15:42 -------
(In reply to comment #3)
> I fail to see why binutils accepting both version should be a reason to
> not fix gcc.
>
What is the minimum binutils required by gcc? Does it support movq?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (3 preceding siblings ...)
2010-03-01 15:42 ` hjl dot tools at gmail dot com
@ 2010-03-01 20:30 ` ubizjak at gmail dot com
2010-03-01 20:36 ` ubizjak at gmail dot com
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: ubizjak at gmail dot com @ 2010-03-01 20:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from ubizjak at gmail dot com 2010-03-01 20:30 -------
(In reply to comment #4)
> What is the minimum binutils required by gcc? Does it support movq?
install.texi says that i?86-linux-gnu requires 2.13.1.
Since you are listed as x86 binutils maintainer, I would expect that you can
provide the information if it includes correct movq support.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (4 preceding siblings ...)
2010-03-01 20:30 ` ubizjak at gmail dot com
@ 2010-03-01 20:36 ` ubizjak at gmail dot com
2010-03-01 23:16 ` hjl dot tools at gmail dot com
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: ubizjak at gmail dot com @ 2010-03-01 20:36 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from ubizjak at gmail dot com 2010-03-01 20:36 -------
(In reply to comment #5)
> install.texi says that i?86-linux-gnu requires 2.13.1.
binutils-2.13.1.tar.bz2 07-Nov-2002 23:45 9.5M
binutils-2.13.1.tar.gz 07-Nov-2002 23:45 12M
IMNSHO, I really can't see the reason why we should support *eight* years old
toolchain part with a new compiler. Does it even build with gcc-4.5?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (5 preceding siblings ...)
2010-03-01 20:36 ` ubizjak at gmail dot com
@ 2010-03-01 23:16 ` hjl dot tools at gmail dot com
2010-03-01 23:18 ` hjl dot tools at gmail dot com
2010-05-03 9:01 ` ubizjak at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2010-03-01 23:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from hjl dot tools at gmail dot com 2010-03-01 23:16 -------
(In reply to comment #5)
> (In reply to comment #4)
>
> > What is the minimum binutils required by gcc? Does it support movq?
>
> install.texi says that i?86-linux-gnu requires 2.13.1.
>
> Since you are listed as x86 binutils maintainer, I would expect that you can
> provide the information if it includes correct movq support.
"movq" was added by
http://sourceware.org/ml/binutils/2005-07/msg00134.html
in binutils-2.17.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (6 preceding siblings ...)
2010-03-01 23:16 ` hjl dot tools at gmail dot com
@ 2010-03-01 23:18 ` hjl dot tools at gmail dot com
2010-05-03 9:01 ` ubizjak at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: hjl dot tools at gmail dot com @ 2010-03-01 23:18 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from hjl dot tools at gmail dot com 2010-03-01 23:18 -------
(In reply to comment #6)
> (In reply to comment #5)
>
> > install.texi says that i?86-linux-gnu requires 2.13.1.
>
> binutils-2.13.1.tar.bz2 07-Nov-2002 23:45 9.5M
> binutils-2.13.1.tar.gz 07-Nov-2002 23:45 12M
>
> IMNSHO, I really can't see the reason why we should support *eight* years old
> toolchain part with a new compiler. Does it even build with gcc-4.5?
>
It may be a good idea by itself. However, since AMD64 uses movd instead
of movq, some non-GNU assemblers may not support movq. Why change it
when nothing is broken?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug target/43215] x86-64: Nonstandard instruction "movd %xmm0, %rax"
2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
` (7 preceding siblings ...)
2010-03-01 23:18 ` hjl dot tools at gmail dot com
@ 2010-05-03 9:01 ` ubizjak at gmail dot com
8 siblings, 0 replies; 10+ messages in thread
From: ubizjak at gmail dot com @ 2010-05-03 9:01 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from ubizjak at gmail dot com 2010-05-03 09:01 -------
(In reply to comment #8)
> It may be a good idea by itself. However, since AMD64 uses movd instead
> of movq, some non-GNU assemblers may not support movq. Why change it
> when nothing is broken?
Indeed.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution| |WONTFIX
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43215
^ permalink raw reply [flat|nested] 10+ messages in thread
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2010-03-01 2:22 [Bug target/43215] New: x86-64: Nonstandard instruction "movd %xmm0, %rax" richardpku at gmail dot com
2010-03-01 9:56 ` [Bug target/43215] " ubizjak at gmail dot com
2010-03-01 13:31 ` hjl dot tools at gmail dot com
2010-03-01 14:56 ` rguenth at gcc dot gnu dot org
2010-03-01 15:42 ` hjl dot tools at gmail dot com
2010-03-01 20:30 ` ubizjak at gmail dot com
2010-03-01 20:36 ` ubizjak at gmail dot com
2010-03-01 23:16 ` hjl dot tools at gmail dot com
2010-03-01 23:18 ` hjl dot tools at gmail dot com
2010-05-03 9:01 ` ubizjak at gmail dot com
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