[Bug target/50289] New: [avr]: call-prologues saveing/restoring global register variables

[Bug target/50289] New: [avr]: call-prologues saveing/restoring global register variables

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50289

             Bug #: 50289
           Summary: [avr]: call-prologues saveing/restoring global
                    register variables
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: gjl@gcc.gnu.org
                CC: eric.weddington@atmel.com
            Target: avr


void bar (long long, long long, void*);

register char x asm ("7");

void foo (char a)
{
    asm volatile ("":::"6");
    bar (0, 0, &a);
}


This small program, compiles with
   avr-gcc-4.6.1 -mcall-prologues -S -Os -mmcu=atmega8 
to

foo:
    ldi r26,lo8(1)
    ldi r27,hi8(1)
    ldi r30,lo8(gs(1f))
    ldi r31,hi8(gs(1f))
    jmp __prologue_saves__+((18 - 13) * 2)
1:

This means that __prologue_saves__ from libgcc saves R7 (i.e. R6..R17 and Y)
even though R7 is a global register variable and must not saved/restored by
function prologue/epilogue.

The function to fix is avr.c:sequent_regs_live()

[Bug target/50289] [avr]: call-prologues saving/restoring global register variables

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50289

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-09-04
   Target Milestone|---                         |4.6.2
     Ever Confirmed|0                           |1

[Bug target/50289] [avr]: call-prologues saving/restoring global register variables

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50289

--- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-09-05 12:20:18 UTC ---
Author: gjl
Date: Mon Sep  5 12:20:03 2011
New Revision: 178528

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178528
Log:
    PR target/50289
    * config/avr/avr.c (sequent_regs_live): Don't recognize sequences
    that contain global register variable.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/avr/avr.c

[Bug target/50289] [avr]: call-prologues saving/restoring global register variables

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50289

--- Comment #2 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-09-05 12:24:17 UTC ---
Author: gjl
Date: Mon Sep  5 12:24:06 2011
New Revision: 178529

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178529
Log:
    PR target/50289
    Backport from mainline r178528
    * config/avr/avr.c (sequent_regs_live): Don't recognize sequences
    that contain global register variable.


Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/config/avr/avr.c

[Bug target/50289] [avr]: call-prologues saving/restoring global register variables

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50289

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
         AssignedTo|unassigned at gcc dot       |gjl at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #3 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-09-05 12:26:35 UTC ---
Fixed for the 4.6.2 Milestone.