Re: [PATCH] FIx PR48508, alternate fix for PR48437

[Richard Guenther <rguenther at suse dot de>]

On Wed, 14 Dec 2011, Richard Guenther wrote:

> 
> The following patch avoids streaming extern var and function decls
> into the global decls and types section when streaming a tree
> chain list (effectively only when processing BLOCK_VARS).  This
> avoids the last LTO debug-info ICE I know of (knocks on wood)
> and provides a cleaner (well ...) fix for PR48437 as well.
> 
> LTO bootstrapped on x86_64-unknown-linux-gnu, testing in progress,
> so is SPEC 2k6 build with -g (hopefully now without ICEs as well).

Incrementally better.  Reducing a different remaining ICE on
483.xalancbmk right now.  At least we'll get some more testcases.

> I plan to commit this tomorrow if all goes well and declare
> LTO debug-info perfect for 4.7.

Done, but not perfect yet ;)

Richard.

> 2011-12-14  Richard Guenther  <rguenther@suse.de>
> 
> 	Revert
> 	PR lto/48437
> 	* lto-streamer-out.c (tree_is_indexable): Exclude block-local
> 	extern declarations.
> 
> 	PR lto/48508
> 	PR lto/48437
> 	* tree-streamer-out.c (streamer_write_chain): Stream DECL_EXTERNAL
> 	VAR_DECLs and FUNCTION_DECLs locally.
> 
> 	* g++.dg/lto/pr48508-1_0.C: New testcase.
> 	* g++.dg/lto/pr48508-1_1.C: Likewise.
> 
> Index: gcc/lto-streamer-out.c
> ===================================================================
> *** gcc/lto-streamer-out.c	(revision 182335)
> --- gcc/lto-streamer-out.c	(working copy)
> *************** tree_is_indexable (tree t)
> *** 129,144 ****
>     else if (TREE_CODE (t) == VAR_DECL && decl_function_context (t)
>   	   && !TREE_STATIC (t))
>       return false;
> -   /* If this is a decl generated for block local externs for
> -      debug info generation, stream it unshared alongside BLOCK_VARS.  */
> -   else if (VAR_OR_FUNCTION_DECL_P (t)
> - 	   /* ???  The following tests are a literal match on what
> - 	      c-decl.c:pop_scope does.  */
> - 	   && TREE_PUBLIC (t)
> - 	   && DECL_EXTERNAL (t)
> - 	   && DECL_CONTEXT (t)
> - 	   && TREE_CODE (DECL_CONTEXT (t)) == FUNCTION_DECL)
> -     return false;
>     /* Variably modified types need to be streamed alongside function
>        bodies because they can refer to local entities.  Together with
>        them we have to localize their members as well.
> --- 129,134 ----
> Index: gcc/tree-streamer-out.c
> ===================================================================
> *** gcc/tree-streamer-out.c	(revision 182335)
> --- gcc/tree-streamer-out.c	(working copy)
> *************** streamer_write_chain (struct output_bloc
> *** 405,411 ****
>         saved_chain = TREE_CHAIN (t);
>         TREE_CHAIN (t) = NULL_TREE;
>   
> !       stream_write_tree (ob, t, ref_p);
>   
>         TREE_CHAIN (t) = saved_chain;
>         t = TREE_CHAIN (t);
> --- 405,417 ----
>         saved_chain = TREE_CHAIN (t);
>         TREE_CHAIN (t) = NULL_TREE;
>   
> !       /* We avoid outputting external vars or functions by reference
> !          to the global decls section as we do not want to have them
> ! 	 enter decl merging.  This is, of course, only for the call
> ! 	 for streaming BLOCK_VARS, but other callers are safe.  */
> !       stream_write_tree (ob, t,
> ! 			 ref_p && !(VAR_OR_FUNCTION_DECL_P (t)
> ! 				    && DECL_EXTERNAL (t)));
>   
>         TREE_CHAIN (t) = saved_chain;
>         t = TREE_CHAIN (t);
> Index: gcc/testsuite/g++.dg/lto/pr48508-1_0.C
> ===================================================================
> *** gcc/testsuite/g++.dg/lto/pr48508-1_0.C	(revision 0)
> --- gcc/testsuite/g++.dg/lto/pr48508-1_0.C	(revision 0)
> ***************
> *** 0 ****
> --- 1,7 ----
> + // { dg-lto-do link }
> + // { dg-lto-options { { -g -O2 -flto -flto-partition=none } } }
> + 
> + void __attribute__((externally_visible))
> + foo (int i)
> + {
> + }
> Index: gcc/testsuite/g++.dg/lto/pr48508-1_1.C
> ===================================================================
> *** gcc/testsuite/g++.dg/lto/pr48508-1_1.C	(revision 0)
> --- gcc/testsuite/g++.dg/lto/pr48508-1_1.C	(revision 0)
> ***************
> *** 0 ****
> --- 1,10 ----
> + static void
> + bar (void)
> + {
> +   extern void foo (int);
> +   foo (0);
> + }
> + int main()
> + {
> +   bar ();
> + }
> 

-- 
Richard Guenther <rguenther@suse.de>
SUSE / SUSE Labs
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