[Bug c/30595] New: gcc3.4.6 generates incorrect ppc32 code for combination of bitfields and shifts
The code generated for a ppc32 for the 1 line function f below is incorrect.
Not that it should matter but this is a cross compiler, built with cross-tool.
typedef struct {
unsigned char c;
unsigned int i:24;
} e_t;
f(e_t *p)
{
p->i<<= 8;
}
#include
int
main(int argc, char *argv[])
{
e_t x = { .c='a', .i=0x12345 };
f(&x);
printf("(0x12345 << 8 ) & 0xff = %x\n", x.i);
}
Compiled with "-O".
The output is
(0x12345 << 8 ) & 0xff = 234561
The bottom 8 bits should be zero, not the contents of x.c.
If one comments out the driver function, so all that you are left with is the f
function, one gets the following assembler. I have added pseudo-C comments.
.file "t.c"
.section".text"
.align 2
.globl f
.type f, @function
f:
lwz 9,0(3) ;; r9 = *p
mr 0,9 ;; r0 = r9
rlwimi 0,9,8,8,31 ;; low24(r0) = low24(rotate8(r9)) ** Wrong
stw 0,0(3) ;; *p = r0
blr ;; return
.size f, .-f
.section.note.GNU-stack,"",@progbits
.ident "GCC: (GNU) 3.4.6"
gcc2.95 generates the correct code, and answer
(0x12345 << 8 ) & 0xff = 234500
--
Summary: gcc3.4.6 generates incorrect ppc32 code for combination
of bitfields and shifts
Product: gcc
Version: 3.4.6
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: ISPARRY at BROCADE dot COM
GCC build triplet: i686-host_pc-linux-gnu
GCC host triplet: i686-host_pc-linux-gnu
GCC target triplet: powerpc-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30595
[Bug c/19541] need another option to support what -I- did just besides -iquote
--- Comment #9 from ISPARRY at BROCADE dot COM 2008-01-19 00:53 --- (In reply to comment #8) > Changing component; the patch here doesn't touch the preprocessor at all. > If you are changing the component, would not a better choice be "driver" than "c"? I agree the patch does not touch the preprocessor code, but from a user point of view it is a preprocessor issue. The 4.2.2 manuals say in section 3.11 that "The preprocessor's direct interface is undocumented and subject to change, so whenever possible you should avoid using -Wp and let the driver handle the options instead." A user could reasonably (but wrongly) assume that the driver passes options like -I to the preprocessor. If you are changing the component, then can you change the severity to something more suitable than "enhancment" at the same time? Whilst I am all in favour of emitting warnings about obsolete features, until there is a working replacement for -I- it is a bug to complain that it is deprecated. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19541
[Bug preprocessor/34855] New: Bug 19541 is still not resolved in 4.3.0
This is bug 19541, but being reported against 4.3.0.
Still a problem in 4.3.using Debian unstable packages
gcc --version gives gcc-4.3 (Debian 4.3-20080116-1) 4.3.0 20080116
(experimental) [trunk revision 131577]
Can we either get the "ignore-source-dir" patch added to the mainline, or else
remove the "-I- is deprecated" warning? Clearly there are uses for -I-, as the
mailing list thread shows.
--
Summary: Bug 19541 is still not resolved in 4.3.0
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: ISPARRY at BROCADE dot COM
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34855
[Bug preprocessor/34857] New: Bug 19541 is still not resolved in 4.3.0
This is bug 19541, but being reported against 4.3.0.
Still a problem in 4.3.using Debian unstable packages
gcc --version gives gcc-4.3 (Debian 4.3-20080116-1) 4.3.0 20080116
(experimental) [trunk revision 131577]
Can we either get the "ignore-source-dir" patch added to the mainline, or else
remove the "-I- is deprecated" warning? Clearly there are uses for -I-, as the
mailing list thread shows.
--
Summary: Bug 19541 is still not resolved in 4.3.0
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: ISPARRY at BROCADE dot COM
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34857
[Bug preprocessor/34855] Bug 19541 is still not resolved in 4.3.0
--- Comment #3 from ISPARRY at BROCADE dot COM 2008-01-18 19:59 --- (In reply to comment #2) > And that bug is still opened. > > *** This bug has been marked as a duplicate of 19541 *** > Yes. 3 years after a fix is available, and 3 releases of gcc, the bug is still open. Can we get it closed please? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34855
[Bug preprocessor/34855] Bug 19541 is still not resolved in 4.3.0
--- Comment #5 from ISPARRY at BROCADE dot COM 2008-01-18 20:12 --- (In reply to comment #4) > Patches welcome. > Ceratinly. I can either up-rev the patch posted in http://gcc.gnu.org/ml/gcc-patches/2006-03/msg01197.html or I can do a patch to undo the deprecation of -I-. Which stands any chance of being accepted? My preference is to undo the deprecation of -I-, as it is used by other compilers. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34855
[Bug middle-end/30595] gcc3.4.6 generates incorrect ppc32 code for combination of bitfields and shifts
--- Comment #3 from ISPARRY at BROCADE dot COM 2009-02-06 21:25 --- Subject: RE: gcc3.4.6 generates incorrect ppc32 code for combination of bitfields and shifts Whilst I am not complaining about 3.4 not being supported, I think it is a pretty poor show that you are not able to reproduce it. Did anyone even try? > -Original Message- > From: steven at gcc dot gnu dot org [mailto:gcc-bugzi...@gcc.gnu.org] > Sent: Friday, February 06, 2009 1:16 PM > To: Icarus Sparry > Subject: [Bug middle-end/30595] gcc3.4.6 generates incorrect > ppc32 code for combination of bitfields and shifts > > > > --- Comment #2 from steven at gcc dot gnu dot org > 2009-02-06 21:15 --- Not reproducible, and gcc 3.4 is not > supported anymore. > > > -- > > steven at gcc dot gnu dot org changed: > >What|Removed |Added > -- > -- > Status|UNCONFIRMED |RESOLVED > Resolution||WONTFIX > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30595 > > --- You are receiving this mail because: --- You > reported the bug, or are watching the reporter. > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30595
