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Re: PCH versus --enable-mapped-location

From: Per Bothner <per at bothner dot com>
To: Daniel Jacobowitz <drow at false dot org>
Cc: Geoff Keating <geoffk at geoffk dot org>, gcc at gcc dot gnu dot org, Zack Weinberg <zack at codesourcery dot com>
Date: Thu, 31 Mar 2005 14:05:19 -0800
Subject: Re: PCH versus --enable-mapped-location
References: <424B9A69.8020609@bothner.com> <02054ee455a079c19065bf2867104b48@geoffk.org> <424C6AD9.60407@bothner.com> <20050331213505.GA25053@nevyn.them.org>

Daniel Jacobowitz wrote:
 > That's exactly what Geoff said.  There are two relevant properties of

GCed memory here:
  - Anything in GCed memory will be saved to the PCH
  - Anything in GCed memory will be overwritten by loading the PCH.

So the corrollary: After a restore any pointers from non-gc'd memory to gc'd memory will be a dangling pointer, if we count static variables marked with GTY as "gc'd memory" in this context.

Right now, as far as I can tell, the filenames in the line_table are
allocated from non-gc'd memory.  This complicates using gc.
--
	--Per Bothner
per@bothner.com   http://per.bothner.com/

Follow-Ups:
- Re: PCH versus --enable-mapped-location
  - From: Geoffrey Keating

References:
- PCH versus --enable-mapped-location
  - From: Per Bothner
- Re: PCH versus --enable-mapped-location
  - From: Geoff Keating
- Re: PCH versus --enable-mapped-location
  - From: Per Bothner
- Re: PCH versus --enable-mapped-location
  - From: Daniel Jacobowitz

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