Re: optimization/7067: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

Re: optimization/7067: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

[dje]

Synopsis: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

State-Changed-From-To: analyzed->closed
State-Changed-By: dje
State-Changed-When: Fri Aug  2 09:26:30 2002
State-Changed-Why:
    Addressed in GCC 3.3

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7067

Re: optimization/7067: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

[dje]

Synopsis: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

Responsible-Changed-From-To: unassigned->dje
Responsible-Changed-By: dje
Responsible-Changed-When: Thu Aug  1 15:24:48 2002
Responsible-Changed-Why:
    PowerPC
State-Changed-From-To: open->analyzed
State-Changed-By: dje
State-Changed-When: Thu Aug  1 15:24:48 2002
State-Changed-Why:
    Should optimize_size affect RTX_COSTS(MULT)?

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7067

optimization/7067: -Os with -mcpu=powerpc optimizes for speed (?) instead of space

[fshvaige]

>Number:         7067
>Category:       optimization
>Synopsis:       -Os with -mcpu=powerpc optimizes for speed (?) instead of space
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 18 08:06:13 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     fshvaige@cisco.com
>Release:        3.1 20020510 (prerelease)
>Organization:
>Environment:
../gcc-3.1/configure --with-gcc-version-trigger=/home/install/gcc-3.1/gcc/version.c --host=i686-pc-linux-gnu --with-newlib --enable-target-optspace --target=ppc-eabi --prefix=/home/crossGCC/ppc-eabi --with-local-prefix=/home/crossGCC/ppc-eabi --program-prefix=ppc-eabi- --enable-languages=c,c++ -v --norecursion
>Description:
File test4.c:
unsigned f (unsigned v) {
  return v * 10;
}

Command line:
ppc-eabi-gcc -S -Os test4.c

Produced code (right, space optimized):
f:
  mulli 3,3,10
  blr

Command line:
ppc-eabi-gcc -S -Os -mcpu=powerpc test4.c

Produced code (wrong, probably speed optimized ?):
f:
  mr 0,3
  slwi 3,3,2
  add 3,3,0
  slwi 3,3,1
  blr

Note: instruction "mulli" present in powerpc and even used by the same compiler and same command line for the very alike function, so problem is somewhere in optimization.

File test4a.c:
unsigned f (unsigned v) {
  return v * 11;
}

Command line:
ppc-eabi-gcc -S -Os -mcpu=powerpc test4a.c

Produced code (right):
f:
  mulli 3,3,11
  blr
>How-To-Repeat:
ppc-eabi-gcc -S -Os test4.c
ppc-eabi-gcc -S -Os -mcpu=powerpc test4.c
ppc-eabi-gcc -S -Os -mcpu=powerpc test4a.c
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: