[Bug rtl-optimization/60159] New: improve code for conditional sibcall

[Bug rtl-optimization/60159] New: improve code for conditional sibcall

[jay.foad at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60159

            Bug ID: 60159
           Summary: improve code for conditional sibcall
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jay.foad at gmail dot com

If I compile this code for x86-64 I get:

$ cat jcc.c
extern int f(int x);
int g(int x) { return x > 3 ? f(x) : x; }

$ cc1 -quiet -O3 jcc.c -o -
...
g:
.LFB0:
        .cfi_startproc
        cmpl    $3, %edi
        jg      .L4
        movl    %edi, %eax
        ret
        .p2align 4,,10
        .p2align 3
.L4:
        jmp     f
        .cfi_endproc

This code would be simpler and shorter if the jg-to-jmp sequence was replaced
with a single "jg f" instruction.

I'm using gcc built from svn trunk r207717.

[Bug rtl-optimization/60159] improve code for conditional sibcall

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60159

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Not sure if that is desirable though, it will mess up debug/unwind info.

[Bug rtl-optimization/60159] improve code for conditional sibcall

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60159

Jeffrey A. Law <law at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at redhat dot com

--- Comment #2 from Jeffrey A. Law <law at redhat dot com> ---
Lots of things mess up debug info :-)  This seems reasonably desirable to me
and shouldn't be terribly difficult to implement, possibly guarding it on -Og.

[Bug target/60159] improve code for conditional sibcall

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60159

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |i?86-*-* x86_64-*-*
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-02-09
          Component|rtl-optimization            |target
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is a target specific bug because most other targets don't have the range
for their conditional branches compared to their normal jumps.

Confirmed.

[Bug target/60159] improve code for conditional sibcall

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60159

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|NEW                         |RESOLVED

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 47253.

*** This bug has been marked as a duplicate of bug 47253 ***