Original bug ID: 772
Reporter: administrator
Status: closed
Resolution: fixed
Priority: normal
Severity: minor
Category: ~DO NOT USE (was: OCaml general)

Bug description

Hello, ...

I got the following bug report, it is said to be against version 3.02-3, but
the directory listed shows that this is the 3.04 ocaml.

Could you have a look at it, and see if this is really a problem. I don't know
the bug reporter, but from his message, he seems well informed and did
appropriate research of the bug.

I hope you all well for this new year,

Friendly,

Sven Luther

----- Forwarded message from Mark Brown broonie@sirena.org.uk -----

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Subject: Bug#127347: ocaml: Out of range branches in assembler output
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From: Mark Brown broonie@sirena.org.uk
To: Debian Bug Tracking System submit@bugs.debian.org
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Date: Tue, 01 Jan 2002 20:01:27 +0000
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Package: ocaml
Version: 3.02-3
Severity: serious
Tags: patch

ocaml currently fails to build on PowerPC. The failing portion of
output is:

make[3]: Entering directory `/tmp/ocaml/ocaml-3.04/camlp4/meta'
../../boot/ocamlrun ../boot/camlp4r -nolib -I ../boot pa_extend.cmo
q_MLast.cmo -o pa_r.ppo pa_r.ml
../../boot/ocamlrun ../../ocamlopt -I ../../stdlib -I ../camlp4 -I
../boot -I ../../utils -c -impl pa_r.ppo
/tmp/camlasm0.s: Assembler messages:
/tmp/camlasm0.s:26869: Error: operand out of range (54196 not between
-32768 and 32767)
/tmp/camlasm0.s:27246: Error: operand out of range (52688 not between
-32768 and 32767)

and so on. Looking at the assembler output the failures appear to be
branch instructions attempting to call into what looks like a garbage
collector:

| .L1145: bltl .L1144

...

| .L1144:
| b caml_call_gc
| .section ".text"
| .globl Pa_r_code_end
| .type Pa_r_code_end, @object

Grovelling around in asmcomp/power it appears that the only place where
a bltl is emitted is:

| | Lop(Ialloc n) ->
| if !call_gc_label = 0 then call_gc_label := new_label();
| addi {emit_gpr 31}, {emit_gpr 31}, {emit_int(-n)}\n;
| cmplw {emit_gpr 31}, {emit_gpr 30}\n;
| addi {emit_reg i.res.(0)}, {emit_gpr 31}, 4\n;
| record_frame i.live;
| bltl {emit_label !call_gc_label}\n

The compiler either needs to be smarter about how it branches into the
GC routine (perhaps inserting the hooks at a higher level) or it needs
to assume that call_gc_label will be out of the range of a local jump.
This patch takes the latter approach:

--- ocaml-3.04/asmcomp/power/emit.mlp.orig Tue Jan 1 19:40:55 2002
+++ ocaml-3.04/asmcomp/power/emit.mlp Tue Jan 1 19:40:19 2002
@@ -545,12 +545,15 @@
| _ -> "stw" in
emit_load_store storeinstr addr i.arg 1 i.arg.(0)
| Lop(Ialloc n) ->

• let skip_label = new_label() in
  if !call_gc_label = 0 then call_gc_label := new_label();
  addi {emit_gpr 31}, {emit_gpr 31}, {emit_int(-n)}\n;
  cmplw {emit_gpr 31}, {emit_gpr 30}\n;
  addi {emit_reg i.res.(0)}, {emit_gpr 31}, 4\n;
• bgt {emit_label skip_label}\n;
  record_frame i.live;

•    `	bltl	{emit_label !call_gc_label}\n`
  

•    `	bl 	{emit_label !call_gc_label}\n`;
  

• {emit_label skip_label}:\n;
  | Lop(Iintop Isub) -> (* subf has swapped arguments )
  ( Use subfc instead of subf for RS6000 compatibility. *)
  subfc {emit_reg i.res.(0)}, {emit_reg i.arg.(1)}, {emit_reg i.arg.(0)}\n

It appears to work well enough to allow ocaml to build, though I've not
done more testing than that.

A full build log can be found at:

http://buildd.debian.org/fetch.php?&pkg=ocaml&ver=3.04-2&arch=powerpc&stamp=1009063512&file=log&as=raw

-- System Information
Debian Release: 3.0
Architecture: powerpc
Kernel: Linux raphaela 2.4.17-ben0 #8 Sun Dec 30 16:27:59 GMT 2001 ppc
Locale: LANG=en_GB, LC_CTYPE=en_GB

Versions of packages ocaml depends on:
ii libc6 2.2.4-7 GNU C Library: Shared libraries an
ii libncurses5 5.2.20010318-3 Shared libraries for terminal hand
ii libncurses5-dev 5.2.20010318-3 Developer's libraries and docs for
ii tcl8.3 8.3.3-5 The Tool Command Language (TCL) v8
ii tk8.3 8.3.3-7 The Tk toolkit for TCL and X11 v8.
ii xlibs 4.1.0-11 X Window System client libraries

----- End forwarded message -----