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* Re: other/7329: fixed or forbidden register bug (and test case)
@ 2002-12-09 16:12 ehrhardt
0 siblings, 0 replies; 2+ messages in thread
From: ehrhardt @ 2002-12-09 16:12 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, lupus, nobody
Synopsis: fixed or forbidden register bug (and test case)
State-Changed-From-To: open->closed
State-Changed-By: cae
State-Changed-When: Mon Dec 9 16:12:52 2002
State-Changed-Why:
The code is wrong. Your are not allowed to globber %ebx or use it
as an asm operand if compiling PIC code. %ebx is used by the pic code
itself to address pc relative data. I think a workaround could be
to do something like this:
__asm__ __volatile__ ("xchg %edi,%ebx\n\tcpuid\n\txchg %edi,%ebx":...)
and use edi for the output operand. gcc probably can't detect the
save and restore of ebx, however, this might still be illegal code.
regards Christian
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7329
^ permalink raw reply [flat|nested] 2+ messages in thread
* other/7329: fixed or forbidden register bug (and test case)
@ 2002-07-16 8:26 lupus
0 siblings, 0 replies; 2+ messages in thread
From: lupus @ 2002-07-16 8:26 UTC (permalink / raw)
To: gcc-gnats, debian-gcc
>Number: 7329
>Category: other
>Synopsis: fixed or forbidden register bug (and test case)
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: rejects-legal
>Submitter-Id: net
>Arrival-Date: Tue Jul 16 08:26:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Paolo Molaro
>Release: 3.1.1 20020703 (Debian prerelease) (Debian testing/unstable)
>Organization:
Ximian
>Environment:
System: Linux luna 2.4.19-pre5 #1 Tue Apr 2 11:33:31 CEST 2002 i686 unknown unknown GNU/Linux
Architecture: i686
host: i386-pc-linux-gnu
build: i386-pc-linux-gnu
target: i386-pc-linux-gnu
configured with: /mnt/data/gcc-3.1/gcc-3.1-3.1.1ds2/src/configure -v --enable-languages=c,c++,java,f77,proto,objc,ada --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/g++-v3-3.1 --enable-shared --with-system-zlib --enable-long-long --enable-nls --without-included-gettext --enable-clocale=gnu --enable-__cxa_atexit --enable-threads=posix --enable-java-gc=boehm --enable-objc-gc i386-linux
The same happens also with gcc 2.7.2 and gcc 2.95.4:
gcc -v
Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs
gcc version 2.95.4 20011002 (Debian prerelease)
gcc272 -v
Reading specs from /usr/lib/gcc-lib/i386-linux/2.7.2.3/specs
gcc version 2.7.2.3
>Description:
As part of the mono project we build a library that
needs to detect the x86 processor features. The provided function
is compiled correctly when building a static library, but the compilation
fails when building a shared library.
Until the bug is fixed it would be nce to know if there is a different
workaround. Thanks.
>How-To-Repeat:
Save the following code to a file name cp.c and compile enabling PIC:
static int
cpuid (int id, int* p_eax, int* p_ebx, int* p_ecx, int* p_edx)
{
__asm__ __volatile__ ("cpuid"
: "=a" (*p_eax), "=b" (*p_ebx), "=c" (*p_ecx), "=d" (*p_edx)
: "a" (id));
return 1;
}
and compile it with:
gcc272 -c -fPIC cp.c
error:
cp.c: In function `cpuid':
cp.c:9: fixed or forbidden register was spilled.
This may be due to a compiler bug or to impossible asm
statements or clauses.
gcc-3.1 -c -fPIC cp.c
error:
cp.c: In function `cpuid':
cp.c:5: can't find a register in class `BREG' while reloading `asm'
gcc-2.95 -c -fPIC cp.c
error:
cp.c: In function `cpuid':
cp.c:7: Invalid `asm' statement:
cp.c:7: fixed or forbidden register 3 (bx) was spilled for class BREG.
>Fix:
Compile without -fPIC and it builds fine. I tryed compiling with different
-O options to no avail.
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 2+ messages in thread
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2002-12-09 16:12 other/7329: fixed or forbidden register bug (and test case) ehrhardt
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2002-07-16 8:26 lupus
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