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Re: RFA: give the return column a size (Was: Re: RFA: Use _Unwind_Ptr)

From: Jim Wilson <wilson at tuliptree dot org>
To: Joern Rennecke <joern dot rennecke at superh dot com>
Cc: gcc-patches at gcc dot gnu dot org
Date: Mon, 14 Jul 2003 22:06:03 -0700
Subject: Re: RFA: give the return column a size (Was: Re: RFA: Use _Unwind_Ptr)
References: <20030711021547.GB1592@redhat.com> <200307111508.h6BF8SU16204@linsvr1.uk.superh.com>

Joern Rennecke wrote:

	* dwarf2out.c (expand_builtin_init_dwarf_reg_sizes):
	If DWARF_FRAME_RETURN_COLUMN doesn't have a register mode,
	look at RETURN_ADDR_RTX.

It isn't safe to use RETURN_ADDR_RTX this way. Not all ports define it. m68k for instance does not. All ports define INCOMING_RETURN_ADDR_RTX, but they don't define it with a usable mode, so you can't use that either.

I'd suggest just using Pmode here. Any port which doesn't use a Pmode return address is probably either broken, or shouldn't be sharing the return address column with another register.

So I suggest hardcoding save_mode to Pmode, and getting rid of all of the stuff that calls RETURN_ADDR_RTX. The patch is OK with that change. -- Jim Wilson, GNU Tools Support, http://www.specifix.com

Follow-Ups:
- Re: RFA: give the return column a size (Was: Re: RFA: Use _Unwind_Ptr)
  - From: Richard Sandiford

References:
- Re: RFA: Use _Unwind_Ptr (Was: Re: RFC / RFA: dwarf2 unwinding for targets with call-part-clobbered registers)
  - From: Richard Henderson
- RFA: give the return column a size (Was: Re: RFA: Use _Unwind_Ptr)
  - From: Joern Rennecke

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