Re: Preserve callee cgraph edges when callgraph profiles sections are requested. (issue5101042)

[Xinliang David Li <davidxl at google dot com>]

ok for google branches.

(Did a little digging -- the remove pass is added because ipa-inline
did not do a good job updating the call graph so there might be some
inconsistency. However the affinity information needs to be computed
after inline transformation, so some more work may be needed in the
future to fix those inconsistencies -- or perhaps rebuild cgraph edges
if profile-cgraph-section option is specified).

David

On Thu, Sep 22, 2011 at 4:01 PM, Sriraman Tallam <tmsriram@google.com> wrote:
> This patch preserves cgraph callee edges till pass_final if callgraph
> edge profiles sections are requested. ?It also renames callgraph edge
> profile sections to be .gnu.callgraph instead of .note.callgraph
>
>
> Index: cgraphbuild.c
> ===================================================================
> --- cgraphbuild.c ? ? ? (revision 179098)
> +++ cgraphbuild.c ? ? ? (working copy)
> @@ -697,10 +697,18 @@ struct gimple_opt_pass pass_rebuild_cgraph_edges =
> ?}
> ?};
>
> +/* Defined in tree-optimize.c ?*/
> +extern bool cgraph_callee_edges_final_cleanup;
>
> ?static unsigned int
> ?remove_cgraph_callee_edges (void)
> ?{
> + ?/* The -fcallgraph-profiles-sections flag needs the call-graph preserved
> + ? ? till pass_final. ?*/
> + ?if (cgraph_callee_edges_final_cleanup
> + ? ? ?&& flag_callgraph_profiles_sections)
> + ? ? ?return 0;
> +
> ? cgraph_node_remove_callees (cgraph_node (current_function_decl));
> ? return 0;
> ?}
> Index: final.c
> ===================================================================
> --- final.c ? ? (revision 179098)
> +++ final.c ? ? (working copy)
> @@ -4425,10 +4425,11 @@ rest_of_handle_final (void)
> ? ? ?profiling information. */
> ? if (flag_callgraph_profiles_sections
> ? ? ? && flag_profile_use
> - ? ? ?&& cgraph_node (current_function_decl) != NULL)
> + ? ? ?&& cgraph_node (current_function_decl) != NULL
> + ? ? ?&& (cgraph_node (current_function_decl))->callees != NULL)
> ? ? {
> ? ? ? flags = SECTION_DEBUG;
> - ? ? ?asprintf (&profile_fnname, ".note.callgraph.text.%s", fnname);
> + ? ? ?asprintf (&profile_fnname, ".gnu.callgraph.text.%s", fnname);
> ? ? ? switch_to_section (get_section (profile_fnname, flags, NULL));
> ? ? ? fprintf (asm_out_file, "\t.string \"Function %s\"\n", fnname);
> ? ? ? dump_cgraph_profiles ();
> Index: testsuite/g++.dg/tree-prof/callgraph-profiles.C
> ===================================================================
> --- testsuite/g++.dg/tree-prof/callgraph-profiles.C ? ? (revision 0)
> +++ testsuite/g++.dg/tree-prof/callgraph-profiles.C ? ? (revision 0)
> @@ -0,0 +1,29 @@
> +/* Verify if call-graph profile sections are created
> + ? with -fcallgraph-profiles-sections. */
> +/* { dg-options "-O2 -fcallgraph-profiles-sections -ffunction-sections --save-temps" } */
> +
> +int __attribute__ ((noinline))
> +foo ()
> +{
> + ?return 1;
> +}
> +
> +int __attribute__ ((noinline))
> +bar ()
> +{
> + ?return 0;
> +}
> +
> +int main ()
> +{
> + ?int sum;
> + ?for (int i = 0; i< 1000; i++)
> + ? ?{
> + ? ? ?sum = foo () + bar();
> + ? ?}
> + ?return sum * bar ();
> +}
> +
> +/* { dg-final-use { scan-assembler "\.gnu\.callgraph\.text\.main" } } */
> +/* { dg-final-use { scan-assembler "\.string \"1000\"" } } */
> +/* { dg-final-use { cleanup-saved-temps } } ?*/
> Index: tree-optimize.c
> ===================================================================
> --- tree-optimize.c ? ? (revision 179098)
> +++ tree-optimize.c ? ? (working copy)
> @@ -48,11 +48,17 @@ along with GCC; see the file COPYING3. ?If not see
> ?#include "plugin.h"
> ?#include "regset.h" ? ?/* FIXME: For reg_obstack. ?*/
>
> +/* Decides if the cgraph callee edges are being cleaned up for the
> + ? last time. ?*/
> +bool cgraph_callee_edges_final_cleanup = false;
> +
> ?/* Gate: execute, or not, all of the non-trivial optimizations. ?*/
>
> ?static bool
> ?gate_all_optimizations (void)
> ?{
> + ?/* The cgraph callee edges can be cleaned up for the last time. ?*/
> + ?cgraph_callee_edges_final_cleanup = true;
> ? return (optimize >= 1
> ? ? ? ? ?/* Don't bother doing anything if the program has errors.
> ? ? ? ? ? ? We have to pass down the queue if we already went into SSA */
>
> --
> This patch is available for review at http://codereview.appspot.com/5101042
>