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* target/9571: PowerPC -- problems with 'const', -msdata=eabi and sections.
@ 2003-02-04 14:06 osv
0 siblings, 0 replies; only message in thread
From: osv @ 2003-02-04 14:06 UTC (permalink / raw)
To: gcc-gnats
>Number: 9571
>Category: target
>Synopsis: PowerPC -- problems with 'const', -msdata=eabi and sections.
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Tue Feb 04 14:06:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: Sergei Organov
>Release: gcc version 3.3 20030203 (prerelease)
>Organization:
>Environment:
Linux 2.4.20 i686
>Description:
Given the code:
$ cat const.cc
extern double const d;
double const d = 3.14;
double f() { return d; }
$ ~/try/tools/bin/ppc-rtems-gcc -meabi -msdata=eabi -c -O4 -save-temps -mregnames const.cc -o const.o
const.s: Assembler messages:
const.s:3: Warning: setting incorrect section attributes for .sdata2
$ cat const.s
.file "const.cc"
.globl d
.section .sdata2,"aw",@progbits
.align 3
.type d, @object
.size d, 8
d:
.long 1074339512
.long 1374389535
.section .rodata.cst8,"aM",@progbits,8
.align 3
.LC0:
.long 1074339512
.long 1374389535
.section ".text"
.align 2
.globl _Z1fv
.type _Z1fv, @function
_Z1fv:
.LFB3:
lis %r3,.LC0@ha
lfd %f1,.LC0@l(%r3)
blr
.LFE3:
.size _Z1fv, .-_Z1fv
.ident "GCC: (GNU) 3.3 20030203 (prerelease)"
Problems:
1. Attempt to set "w" attribute for read-only section '.sdata2'.
2. A copy of value of 'd' is put into section '.rodata.cst8'.
The latter should better go away entirely or at least be
'.sdata2.cst8', I think.
3. As a consequence of (2) function f() needs 2 insns instead
of 1 to load the constant into register.
For comparison consider perfect code generated in this case:
$ cat var.cc
extern double d;
double d = 3.14;
double f() { return d; }
$ ~/try/tools/bin/ppc-rtems-gcc -meabi -msdata=eabi -c -O4 -save-temps -mregnames var.cc -o var.o
$ cat var.s
.file "var.cc"
.globl d
.section .sdata,"aw",@progbits
.align 3
.type d, @object
.size d, 8
d:
.long 1074339512
.long 1374389535
.section ".text"
.align 2
.globl _Z1fv
.type _Z1fv, @function
_Z1fv:
.LFB3:
lfd %f1,d@sda21(%r0)
blr
.LFE3:
.size _Z1fv, .-_Z1fv
.ident "GCC: (GNU) 3.3 20030203 (prerelease)"
>How-To-Repeat:
Refer to description.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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2003-02-04 14:06 target/9571: PowerPC -- problems with 'const', -msdata=eabi and sections osv
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