[Bug target/23450] local functions should not sign extend results (and arguments) for speed reasons

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=23450

Martin Sebor  changed:

   What|Removed |Added

 CC||carrot at google dot com

--- Comment #4 from Martin Sebor  ---
*** Bug 65010 has been marked as a duplicate of this bug. ***

[Bug target/23450] local functions should not sign extend results (and arguments) for speed reasons

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=23450

Martin Sebor  changed:

   What|Removed |Added

   Last reconfirmed|2007-07-01 00:47:09 |2016-1-27
 CC||msebor at gcc dot gnu.org
  Known to fail||4.9.3, 5.3.0, 6.0

--- Comment #3 from Martin Sebor  ---
Even though the generated code has changed, this is still a problem with 6.0
and in all supported versions prior to it as noted in bug 65010, for both
powerpc64 and powerpc64le, where GCC emits:

f:
addi 3,3,1
extsw 3,3
blr

g:
addi 3,3,1
extsw 3,3
b f

[Bug target/23450] local functions should not sign extend results (and arguments) for speed reasons

[pinskia at gcc dot gnu dot org]

--- Comment #2 from pinskia at gcc dot gnu dot org  2005-10-23 00:05 ---
I don't have time to work on this.


-- 

pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

 AssignedTo|pinskia at gcc dot gnu dot  |unassigned at gcc dot gnu
   |org |dot org
 Status|ASSIGNED|NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23450

[Bug target/23450] local functions should not sign extend results (and arguments) for speed reasons

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-18 
03:48 ---
I will be looking into this after working a libjava patch.

Note the current asm is:
_f:
addi r3,r3,1
extsw r3,r3
blr
.align 2
.p2align 4,,15
.globl _g
_g:
addi r3,r3,1
extsw r3,r3
b _f

This is most likely can apply to x86_64 also so if someone over there should 
look into it.

This also applies to all non-register sized types really and 32bit.
for another example:
static char f(char a) __attribute__((noinline));

static char f(char a)
{
  return a+1;
}

char g(char a)
{
  return f(a+1);
}


(this is much worse) (at -O2 -m32):
_f:
addi r3,r3,1
extsb r3,r3
blr
.align 2
.globl _g
_g:
mflr r0
addi r3,r3,1
extsb r3,r3
stw r0,8(r1)
stwu r1,-80(r1)
bl _f
addi r1,r1,80
lwz r0,8(r1)
mtlr r0
blr

-- 
   What|Removed |Added

 AssignedTo|unassigned at gcc dot gnu   |pinskia at gcc dot gnu dot
   |dot org |org
 Status|UNCONFIRMED |ASSIGNED
 Ever Confirmed||1
   Last reconfirmed|-00-00 00:00:00 |2005-08-18 03:48:22
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23450