[PATCH, preapproved] Disable DF_VERIFY_SCHEDULED at end of df_verify (PR72855)

[PATCH, preapproved] Disable DF_VERIFY_SCHEDULED at end of df_verify (PR72855)

[Bill Schmidt]

Hi,

PR72855 reports a compile-time problem with df_verify being called once per loop.
The compile time drops from about 2 hours to 9 minutes for the reported test case
when we disable the DF_VERIFY_SCHEDULED flag after df_verify runs.  That's all
this patch does.

Bin Cheng has a separate patch to factor some code in loop-doloop.c that will also
provide benefit.

There is a separate issue that this compile-time problem should not occur at all
with release checking, and yet it is.  That is still under investigation.

Bootstrapped and tested on powerpc64le-unknown-linux-gnu with no regressions.
Preapproved, committed.

Thanks,
Bill


2016-08-11  Richard Biener  <rguenther@suse.de>
	    Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR rtl-optimization/72855
	* df-core.c (df_verify): Turn off DF_VERIFY_SCHEDULED at end.


Index: gcc/df-core.c
===================================================================
--- gcc/df-core.c	(revision 239394)
+++ gcc/df-core.c	(working copy)
@@ -1833,6 +1833,7 @@ df_verify (void)
   if (df_live)
     df_live_verify_transfer_functions ();
 #endif
+  df->changeable_flags &= ~DF_VERIFY_SCHEDULED;
 }
 
 #ifdef DF_DEBUG_CFG