Re: xsrc/59555: new pixman crashes on macppc

["Martin Husemann via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR xsrc/59555; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: xsrc/59555: new pixman crashes on macppc
Date: Fri, 25 Jul 2025 10:54:13 +0200

 The faulting instruction is:
 
 (gdb) x/16i $pc-24
    0xf9a7a148 <_pixman_implementation_create_vmx+40>:   lwz     r10,-32744(r30)
    0xf9a7a14c <_pixman_implementation_create_vmx+44>:   lwz     r4,-32768(r30)
    0xf9a7a150 <_pixman_implementation_create_vmx+48>:   lwz     r5,-32740(r30)
    0xf9a7a154 <_pixman_implementation_create_vmx+52>:   lwz     r6,-32736(r30)
    0xf9a7a158 <_pixman_implementation_create_vmx+56>:   lwz     r7,-32732(r30)
    0xf9a7a15c <_pixman_implementation_create_vmx+60>:   lwz     r8,-32728(r30)
 => 0xf9a7a160 <_pixman_implementation_create_vmx+64>:   lxvw4x  vs0,0,r10
    0xf9a7a164 <_pixman_implementation_create_vmx+68>:   lwz     r10,-32724(r30)
    0xf9a7a168 <_pixman_implementation_create_vmx+72>:   lwz     r0,-32716(r30)
    0xf9a7a16c <_pixman_implementation_create_vmx+76>:   lwz     r11,-32712(r30)
    0xf9a7a170 <_pixman_implementation_create_vmx+80>:   lwz     r12,-32720(r30)
    0xf9a7a174 <_pixman_implementation_create_vmx+84>:   stxvw4x vs0,0,r4
    0xf9a7a178 <_pixman_implementation_create_vmx+88>:   stw     r5,36(r3)
    0xf9a7a17c <_pixman_implementation_create_vmx+92>:   lwz     r4,-32708(r30)
    0xf9a7a180 <_pixman_implementation_create_vmx+96>:   lwz     r5,-32704(r30)
    0xf9a7a184 <_pixman_implementation_create_vmx+100>:  stw     r6,40(r3)
 
 According to gcc manuals this is only valid on CPUs implementing
 ISA 2.06 or newer, which this G5 probably does not implement.
 
 It is enabled by -mvsx:
 
 src/external/mit/xorg/lib/pixman/Makefile has that:
 --------
 revision 1.44
 date: 2025-07-23 00:35:06 +0200;  author: mrg;  state: Exp;  lines: +3 -3;  comm
 itid: LD8Ufi1K7ytPgN3G;
 also pass -mvsx for pixman-vmx.c on PPC.
 
 fixes ppc build.
 --------
 
 I can not reproduce any build issue with this change:
 
 Index: Makefile
 ===================================================================
 RCS file: /cvsroot/src/external/mit/xorg/lib/pixman/Makefile,v
 retrieving revision 1.45
 diff -u -r1.45 Makefile
 --- Makefile    24 Jul 2025 00:37:03 -0000      1.45
 +++ Makefile    25 Jul 2025 08:50:45 -0000
 @@ -66,8 +66,8 @@
  
  .if ${MACHINE_ARCH} == "powerpc"
  SRCS+= pixman-vmx.c
 -COPTS.pixman-vmx.c=    -maltivec -mvsx
 -MKDEPFLAGS+=           -maltivec -mvsx
 +COPTS.pixman-vmx.c=    -maltivec # -mvsx
 +MKDEPFLAGS+=           -maltivec # -mvsx
  .endif
  
  .if !empty(MACHINE_ARCH:Mearm*)
 
 
 Matt, do you remember details?
 
 Martin