[Bug regression/29248] New: Stack pointer is modified in functions that don't use the stack

[Bug regression/29248] New: Stack pointer is modified in functions that don't use the stack

[atgraham at gmail dot com]

Consider the following two functions:

int foo() { return 1; }
void bar() {}

Disassembly when compiled with gcc 2.95.2: (-Os)
  00000000 <foo(void)>:
     0:   38 60 00 01     li      r3,1
     4:   4e 80 00 20     blr
  00000008 <bar(void)>:
     8:   4e 80 00 20     blr

Disassembly when compiled with gcc 4.1.1: (-Os)
  00000000 <foo()>:
     0:   94 21 ff f0     stwu    r1,-16(r1)
     4:   38 60 00 01     li      r3,1
     8:   38 21 00 10     addi    r1,r1,16
     c:   4e 80 00 20     blr
  00000010 <bar()>:
    10:   94 21 ff f0     stwu    r1,-16(r1)
    14:   38 21 00 10     addi    r1,r1,16
    18:   4e 80 00 20     blr


-- 
           Summary: Stack pointer is modified in functions that don't use
                    the stack
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: atgraham at gmail dot com
  GCC host triplet: i686
GCC target triplet: powerpc-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug middle-end/29248] Stack pointer is modified in functions that don't use the stack

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-09-27 03:26 -------
How did you configure 4.1.1?
I bet this is really a dup of bug 28966.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
          Component|regression                  |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug middle-end/29248] Stack pointer is modified in functions that don't use the stack

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-09-27 03:59 -------
This works for me on the mainline:
[pinskia@celery gcc]$ ./cc1 -m32 -Os t.c -o - -quiet
        .file   "t.c"
        .section        ".text"
        .align 2
        .globl foo
        .type   foo, @function
foo:
        li 3,1
        blr
        .size   foo,.-foo
        .align 2
        .globl bar
        .type   bar, @function
bar:
        blr
        .size   bar,.-bar
        .ident  "GCC: (GNU) 4.2.0 20060909 (experimental)"
        .section        .note.GNU-stack,"",@progbits




Are you sure you did not add -maltivec somewhere or --with-cpu=970 ?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug regression/29248] Stack pointer is modified in functions that don't use the stack

[atgraham at gmail dot com]

------- Comment #3 from atgraham at gmail dot com  2006-09-27 04:28 -------
Ack!  Sorry--I had indicated the wrong target on that one.  The target is
vxworks, not linux.  My 4.1.1 powerpc-linux compiler *does* get this
optimization right.  So something in the vxworks-specific code is causing this:

/opt/vxppc/libexec/gcc/powerpc-wrs-vxworks/4.1.1> ./cc1 -m32 -Os ~/foo.c -o -
-quiet
        .file   "foo.c"
        .section        ".text"
        .align 2
        .globl foo
        .type   foo, @function
foo:
        stwu 1,-16(1)
        li 3,1
        addi 1,1,16
        blr
        .size   foo, .-foo
        .align 2
        .globl bar
        .type   bar, @function
bar:
        stwu 1,-16(1)
        addi 1,1,16
        blr
        .size   bar, .-bar
        .ident  "GCC: (GNU) 4.1.1"

In my opinion, this is a very low priority problem, despite that this is one of
my primary development environments.  Sorry for wasting your time with the
wrong target.


-- 

atgraham at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |regression
 GCC target triplet|powerpc-linux               |powerpc-wrs-vxworks


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug regression/29248] Stack pointer is modified in functions that don't use the stack

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-09-27 04:42 -------
Can you give the output of gcc -v for powerpc-wrs-vxworks?  I bet vxworks
enables altivec by default which means it is a dup still.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug target/29248] Stack pointer is modified in functions that don't use the stack

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2006-09-27 05:14 -------
#define STACK_BOUNDARY (16*BITS_PER_UNIT)

This is a target issue.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
          Component|regression                  |target
     Ever Confirmed|0                           |1
      Known to work|2.95.2                      |
   Last reconfirmed|0000-00-00 00:00:00         |2006-09-27 05:14:43
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug target/29248] Stack pointer is modified in functions that don't use the stack

[nathan at gcc dot gnu dot org]

------- Comment #6 from nathan at gcc dot gnu dot org  2006-12-18 18:36 -------
this is really a duplicate of 28966.  Like vxworks has an unconditional 128 bit
stack alignment, unlike other targets where it is only 128bit when altivec
comes into play.

*** This bug has been marked as a duplicate of 28966 ***


-- 

nathan at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248

[Bug target/29248] Stack pointer is modified in functions that don't use the stack

[pthaugen at gcc dot gnu dot org]

------- Comment #7 from pthaugen at gcc dot gnu dot org  2007-10-31 19:48 -------
Subject: Bug 29248

Author: pthaugen
Date: Wed Oct 31 19:48:19 2007
New Revision: 129806

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=129806
Log:
2007-10-01  Pat Haugen  <pthaugen@us.ibm.com>

        Backport the following patches:

        2007-09-04  Daniel Jacobowitz  <dan@codesourcery.com>

        * config/rs6000/rs6000.c (rs6000_stack_info): Allocate space for the
        GOT pointer only if there is a constant pool.  Use the allocated space
        for SPE also.

        2006-12-21  Nathan Sidwell  <nathan@codesourcery.com>

        PR target/28966
        PR target/29248
        * reload1.c (reload): Realign stack after it changes size.


Modified:
    branches/ibm/gcc-4_1-branch/gcc/ChangeLog
    branches/ibm/gcc-4_1-branch/gcc/config/rs6000/rs6000.c
    branches/ibm/gcc-4_1-branch/gcc/reload1.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29248