[Bug middle-end/42590] unnecessary stack frame set up

[jamborm at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42590

Martin Jambor jamborm at gcc dot gnu.org changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution||FIXED

--- Comment #4 from Martin Jambor jamborm at gcc dot gnu.org 2010-12-16 
15:00:58 UTC ---
I guess it is.  Please re-open if not.

[Bug middle-end/42590] unnecessary stack frame set up

[jamborm at gcc dot gnu dot org]

--- Comment #1 from jamborm at gcc dot gnu dot org  2010-01-25 18:02 ---
Since PR 42585 is fixed, the optimized dump (at -O2) is

bb 2:
  _T2$curr_12 = sptr_1(D)-curr;
  D.1966_7 = _T2$curr_12 + -1;
  sptr_1(D)-curr = D.1966_7;
  return 0;
}

The generated assembly is:

Cyc_string_ungetc:
pushl   %ebp
movl%esp, %ebp
movl12(%ebp), %eax
subl$1, (%eax)
xorl%eax, %eax
popl%ebp
ret

With -O2 -fomit-frame-pointer it is:

Cyc_string_ungetc:
movl8(%esp), %eax
subl$1, (%eax)
xorl%eax, %eax
ret

(Which is weird because the manual says that -fomit-frame-pointer is
enabled at -O2 by default - maybe this is the actual bug here now?)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42590

[Bug middle-end/42590] unnecessary stack frame set up

[jakub at gcc dot gnu dot org]

--- Comment #2 from jakub at gcc dot gnu dot org  2010-01-25 18:24 ---
On i?86-linux -fomit-frame-pointer is not the default, on the contrary.
info gcc says:
 `-O' also turns on `-fomit-frame-pointer' on machines where doing
 so does not interfere with debugging.
and i?86-linux is not considered such machine (unlike e.g. x86_64-linux).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42590

[Bug middle-end/42590] unnecessary stack frame set up

[jamborm at gcc dot gnu dot org]

--- Comment #3 from jamborm at gcc dot gnu dot org  2010-01-25 18:30 ---
I have found the sentence you quoted in the manual too but it refers
only to -O1 (as far as I understand it).  And the description of
-fomit-frame-pointer simply states that Enabled at levels -O, -O2,
-O3, -Os.  So I'd say that at least the documentation is slightly
confusing.

Anyway, does this mean that this issue is also resolved now?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42590