[PR43656] skip debug insns in -fsched-pressure

[PR43656] skip debug insns in -fsched-pressure

[Alexandre Oliva]

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We didn't take debug insns into account when initializing register
pressure computations, but updates would sometimes take reg uses in
debug insns into account.  This patch fixes this, so that we get the
same scheduling.

Bootstrapped the compiler, along with the just-posted patch for PR44181,
on x86_64-linux-gnu, with the following options:

-O2 -g -fschedule-insns -fsched-pressure -funroll-loops -fgraphite-identity

for stage2 and stage3 host, and for stage3 libs (also -fcompare-debug)

I got build failures on zlib and libada, presumably because of this
unusual combination of flags, but no -fcompare-debug errors.

Ok to install?


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for  gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR debug/43656
	* haifa-sched.c (setup_insn_reg_pressure_info,
	update_register_pressure): Reject debug insns.
	(ready_sort): Don't setup reg pressure for debug insns.
	(schedule_insn): Don't update reg pressure for debug insns.

Index: gcc/haifa-sched.c
===================================================================
--- gcc/haifa-sched.c.orig	2010-06-11 10:56:20.000000000 -0300
+++ gcc/haifa-sched.c	2010-06-11 10:56:21.000000000 -0300
@@ -1124,6 +1124,8 @@ setup_insn_reg_pressure_info (rtx insn)
   struct reg_use_data *use;
   static int death[N_REG_CLASSES];
 
+  gcc_checking_assert (!DEBUG_INSN_P (insn));
+
   excess_cost_change = 0;
   for (i = 0; i < ira_reg_class_cover_size; i++)
     death[ira_reg_class_cover[i]] = 0;
@@ -1500,7 +1502,8 @@ ready_sort (struct ready_list *ready)
   if (sched_pressure_p)
     {
       for (i = 0; i < ready->n_ready; i++)
-	setup_insn_reg_pressure_info (first[i]);
+	if (!DEBUG_INSN_P (first[i]))
+	  setup_insn_reg_pressure_info (first[i]);
     }
   SCHED_SORT (first, ready->n_ready);
 }
@@ -1564,6 +1567,8 @@ update_register_pressure (rtx insn)
   struct reg_use_data *use;
   struct reg_set_data *set;
 
+  gcc_checking_assert (!DEBUG_INSN_P (insn));
+
   for (use = INSN_REG_USE_LIST (insn); use != NULL; use = use->next_insn_use)
     if (dying_use_p (use) && bitmap_bit_p (curr_reg_live, use->regno))
       mark_regno_birth_or_death (use->regno, false);
@@ -1684,7 +1689,7 @@ schedule_insn (rtx insn)
       fputc ('\n', sched_dump);
     }
 
-  if (sched_pressure_p)
+  if (sched_pressure_p && !DEBUG_INSN_P (insn))
     update_reg_and_insn_max_reg_pressure (insn);
 
   /* Scheduling instruction should have all its dependencies resolved and

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-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer