[PATCH] Introduce TV_INITIALIZE_RTL

[David Malcolm]

Before this patch, jit.dg/test-benchmark.c at optlevel 0, 100 iterations
showed "rest of compilation" as taking a significant chunk of time:

rest of compilation     :   1.53 (64%) usr   0.06 (32%) sys   1.60 (27%) wall    1388 kB ( 6%) ggc

This turned out to be almost entirely spent inside initialize_rtl; adding a
TV_INITIALIZE_RTL for this indicates this cost clearly:

initialize rtl          :   1.46 (61%) usr   0.01 ( 5%) sys   1.42 (24%) wall    1156 kB ( 5%) ggc
rest of compilation     :   0.05 ( 2%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall     232 kB ( 1%) ggc

I'm experimenting with a followup patch to amortize this away by making RTL
initialization a one-time deal, but in the meantime, this patch adds
accounting for it.

OK for trunk? (assuming bootstrap and testing)

gcc/ChangeLog:
	* timevar.def (TV_INITIALIZE_RTL): New.
	* toplev.c (initialize_rtl): Use an auto_timevar to account this
	function's time to TV_INITIALIZE_RTL.
---
 gcc/timevar.def | 1 +
 gcc/toplev.c    | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/gcc/timevar.def b/gcc/timevar.def
index 711bbed..cf8f37d 100644
--- a/gcc/timevar.def
+++ b/gcc/timevar.def
@@ -268,6 +268,7 @@ DEFTIMEVAR (TV_PLUGIN_RUN            , "plugin execution")
 DEFTIMEVAR (TV_GIMPLE_SLSR           , "straight-line strength reduction")
 DEFTIMEVAR (TV_VTABLE_VERIFICATION   , "vtable verification")
 DEFTIMEVAR (TV_TREE_UBSAN            , "tree ubsan")
+DEFTIMEVAR (TV_INITIALIZE_RTL        , "initialize rtl")
 
 /* Everything else in rest_of_compilation not included above.  */
 DEFTIMEVAR (TV_EARLY_LOCAL	     , "early local passes")
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 3c1ba38..54eefcd 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1818,6 +1818,8 @@ static int rtl_initialized;
 void
 initialize_rtl (void)
 {
+  auto_timevar tv (TV_INITIALIZE_RTL);
+
   /* Initialization done just once per compilation, but delayed
      till code generation.  */
   if (!rtl_initialized)
-- 
1.8.5.3