Re: port-macppc/54827: alloca() is broken in gcc 8 on powerpc

[christos%zoulas.com@localhost (Christos Zoulas)]

On Jan 6,  8:45pm, david%gutteridge.ca@localhost ("David H. Gutteridge") wrote:
-- Subject: Re: port-macppc/54827: alloca() is broken in gcc 8 on powerpc

| The following reply was made to PR port-macppc/54827; it has been noted by GNATS.
| 
| From: "David H. Gutteridge" <david%gutteridge.ca@localhost>
| To: gnats-bugs%netbsd.org@localhost
| Cc: 
| Subject: Re: port-macppc/54827: alloca() is broken in gcc 8 on powerpc
| Date: Mon, 06 Jan 2020 15:40:42 -0500
| 
|  I'm not sure there is an upstream GCC fix for this, as I've found the
|  issue is isolated to the GCC built as part of the NetBSD tooling. That
|  is, I tested by building the following natively on a G4 Mac:
|  
|  GCC 8.3 from the NetBSD tree
|  GCC 8.3 from pkgsrc
|  GCC 9-snapshot from pkgsrc-wip
|  
|  The two GCCs from pkgsrc generate the correct instruction (as
|  previously detailed), where the one from the NetBSD src tree does not,
|  e.g.:
|  
|  --- alloca-ppc8.s       2020-01-06 08:49:43.908981299 -0500
|  +++ alloca-ppc8native.s 2020-01-06 11:21:06.732122549 -0500
|  @@ -7,17 +7,17 @@
|   foo:
|   .LFB0:
|          .cfi_startproc
|  -       stwu 1,-32(1)
|  -       .cfi_def_cfa_offset 32
|  +       stwu 1,-48(1)
|  +       .cfi_def_cfa_offset 48
|          mflr 0
|  -       stw 0,36(1)
|  -       stw 31,28(1)
|  +       stw 0,52(1)
|  +       stw 31,44(1)
|          .cfi_offset 65, 4
|          .cfi_offset 31, -4
|          mr 31,1
|          .cfi_def_cfa_register 31
|          lwz 9,0(1)
|  -       stwu 9,-32(1)
|  +       stwu 9,-16(1)
|          addi 9,1,8
|          addi 9,9,15
|          srwi 9,9,4
|  @@ -30,7 +30,7 @@
|          lwz 3,8(31)
|          bl bar
|          nop
|  -       addi 11,31,32
|  +       addi 11,31,48
|          lwz 0,4(11)
|          mtlr 0
|          lwz 31,-4(11)
|  @@ -42,4 +42,4 @@
|          .cfi_endproc
|   .LFE0:
|          .size   foo, .-foo
|  -       .ident  "GCC: (GNU) 8.3.0"
|  +       .ident  "GCC: (NetBSD nb1 20190930) 8.3.0"
|  
|  I also looked through GCC PRs and commit entries, but didn't find
|  anything that seemed to directly relate to this. (Having said that, I'm
|  out of my depths here, so I could well have missed something!)

I think that perhaps the order of the include files is affecting some
of the stack related macros?

christos