[PATCH][4.1]: Fix PR28772: Compile time explosion in the scheduler

[Maxim Kuvyrkov <mkuvyrkov at ispras dot ru>]

Hi,

The attached patch is a port to gcc-4_1-branch of a fix written by Eric 
Botcazou.  As there is a PR hanging in the bugzilla I ask Eric to check 
in the attached patch and close the PR.

Here is the link to the original patch: 
http://gcc.gnu.org/ml/gcc-patches/2006-04/msg00445.html

The patch was bootstrapped and tested on ia64-linux-gnu with no regressions.

:ADDPATCH scheduler:


Thanks,

Maxim

2007-02-13  Eric Botcazou  <ebotcazou@adacore.com>

	* params.def (PARAM_MAX_SCHED_READY_INSNS): New parameter,
	defaulting to 100.
	* params.h (MAX_SCHED_READY_INSNS): New macro.
	* haifa-sched.c (params.h): New include.
	(queue_to_ready): Re-queue insns for the next cycle past
	MAX_SCHED_READY_INSNS during the first scheduling pass.
	(schedule_block): Delay insns past MAX_SCHED_READY_INSNS in
	the ready list for 1 cycle during the first scheduling pass.
	* Makefile.in (haifa-sched.o): Add a dependency from new include.
	* doc/invoke.texi (--param): New parameter max-sched-ready-insns.

Only in gcc-4_1-branch-patched/gcc/: ChangeLog.orig
Only in gcc-4_1-branch-patched/gcc/: ChangeLog.rej
diff -rup gcc-4_1-branch/gcc/doc/invoke.texi gcc-4_1-branch-patched/gcc/doc/invoke.texi
--- gcc-4_1-branch/gcc/doc/invoke.texi	2007-02-09 10:24:00.000000000 +0300
+++ gcc-4_1-branch-patched/gcc/doc/invoke.texi	2007-02-09 10:33:20.000000000 +0300
@@ -6082,6 +6082,12 @@ feedback is available and may be set to 
 @option{reorder-block-duplicate} since information about the hot spots is more
 accurate.
 
+@item max-sched-ready-insns
+The maximum number of instructions ready to be issued the scheduler should
+consider at any given time during the first scheduling pass.  Increasing
+values mean more thorough searches, making the compilation time increase
+with probably little benefit.  The default value is 100.
+
 @item max-sched-region-blocks
 The maximum number of blocks in a region to be considered for
 interblock scheduling.  The default value is 10.
Only in gcc-4_1-branch-patched/gcc/doc: invoke.texi.orig
diff -rup gcc-4_1-branch/gcc/haifa-sched.c gcc-4_1-branch-patched/gcc/haifa-sched.c
--- gcc-4_1-branch/gcc/haifa-sched.c	2007-02-09 10:25:05.000000000 +0300
+++ gcc-4_1-branch-patched/gcc/haifa-sched.c	2007-02-13 11:13:57.000000000 +0300
@@ -142,6 +142,7 @@ Software Foundation, 51 Franklin Street,
 #include "recog.h"
 #include "sched-int.h"
 #include "target.h"
+#include "params.h"
 
 #ifdef INSN_SCHEDULING
 
@@ -1379,9 +1380,22 @@ queue_to_ready (struct ready_list *ready
 	fprintf (sched_dump, ";;\t\tQ-->Ready: insn %s: ",
 		 (*current_sched_info->print_insn) (insn, 0));
 
-      ready_add (ready, insn);
-      if (sched_verbose >= 2)
-	fprintf (sched_dump, "moving to ready without stalls\n");
+      /* If the ready list is full, delay the insn for 1 cycle.
+	 See the comment in schedule_block for the rationale.  */
+      if (!reload_completed
+	  && ready->n_ready > MAX_SCHED_READY_INSNS
+	  && !SCHED_GROUP_P (insn))
+	{
+	  if (sched_verbose >= 2)
+	    fprintf (sched_dump, "requeued because ready full\n");
+	  queue_insn (insn, 1);
+	}
+      else
+	{
+	  ready_add (ready, insn);
+	  if (sched_verbose >= 2)
+	    fprintf (sched_dump, "moving to ready without stalls\n");
+        }
     }
   insn_queue[q_ptr] = 0;
 
@@ -1901,6 +1915,32 @@ schedule_block (int b, int rgn_n_insns)
 
   insn_queue = alloca ((max_insn_queue_index + 1) * sizeof (rtx));
   memset (insn_queue, 0, (max_insn_queue_index + 1) * sizeof (rtx));
+
+  /* The algorithm is O(n^2) in the number of ready insns at any given
+     time in the worst case.  Before reload we are more likely to have
+     big lists so truncate them to a reasonable size.  */
+  if (!reload_completed && ready.n_ready > MAX_SCHED_READY_INSNS)
+    {
+      ready_sort (&ready);
+
+      /* Find first free-standing insn past MAX_SCHED_READY_INSNS.  */
+      for (i = MAX_SCHED_READY_INSNS; i < ready.n_ready; i++)
+	if (!SCHED_GROUP_P (ready_element (&ready, i)))
+	  break;
+
+      if (sched_verbose >= 2)
+	{
+	  fprintf (sched_dump,
+		   ";;\t\tReady list on entry: %d insns\n", ready.n_ready);
+	  fprintf (sched_dump,
+		   ";;\t\t before reload => truncated to %d insns\n", i);
+	}
+
+      /* Delay all insns past it for 1 cycle.  */
+      while (i < ready.n_ready)
+	queue_insn (ready_remove (&ready, i), 1);
+    }
+
   last_clock_var = -1;
 
   /* Start just before the beginning of time.  */
Only in gcc-4_1-branch-patched/gcc/: haifa-sched.c~
Only in gcc-4_1-branch-patched/gcc/: haifa-sched.c.orig
Only in gcc-4_1-branch-patched/gcc/: haifa-sched.c.rej
diff -rup gcc-4_1-branch/gcc/Makefile.in gcc-4_1-branch-patched/gcc/Makefile.in
--- gcc-4_1-branch/gcc/Makefile.in	2007-02-09 10:25:39.000000000 +0300
+++ gcc-4_1-branch-patched/gcc/Makefile.in	2007-02-09 11:36:16.000000000 +0300
@@ -2420,7 +2420,8 @@ modulo-sched.o : modulo-sched.c $(DDG_H)
    cfghooks.h $(DF_H) $(GCOV_IO_H) hard-reg-set.h $(TM_H) timevar.h tree-pass.h
 haifa-sched.o : haifa-sched.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
    $(SCHED_INT_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h function.h \
-   $(INSN_ATTR_H) toplev.h $(RECOG_H) except.h $(TM_P_H) $(TARGET_H)
+   $(INSN_ATTR_H) toplev.h $(RECOG_H) except.h $(TM_P_H) $(TARGET_H) \
+   $(PARAMS_H)
 sched-deps.o : sched-deps.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(RTL_H) $(SCHED_INT_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
    function.h $(INSN_ATTR_H) toplev.h $(RECOG_H) except.h cselib.h \
Only in gcc-4_1-branch-patched/gcc/: Makefile.in~
diff -rup gcc-4_1-branch/gcc/params.def gcc-4_1-branch-patched/gcc/params.def
--- gcc-4_1-branch/gcc/params.def	2007-02-09 10:25:53.000000000 +0300
+++ gcc-4_1-branch-patched/gcc/params.def	2007-02-09 10:33:20.000000000 +0300
@@ -560,6 +560,12 @@ DEFPARAM (PARAM_MAX_FIELDS_FOR_FIELD_SEN
           "max-fields-for-field-sensitive",
 	  "Maximum number of fields in a structure before pointer analysis treats the structure as a single variable",
 	  100, 0, 0)
+
+DEFPARAM(PARAM_MAX_SCHED_READY_INSNS,
+	 "max-sched-ready-insns",
+	 "The maximum number of instructions ready to be issued to be considered by the scheduler during the first scheduling pass",
+	 100, 0, 0)
+
 /*
 Local variables:
 mode:c
Only in gcc-4_1-branch-patched/gcc/: params.def.orig
diff -rup gcc-4_1-branch/gcc/params.h gcc-4_1-branch-patched/gcc/params.h
--- gcc-4_1-branch/gcc/params.h	2007-02-09 10:24:03.000000000 +0300
+++ gcc-4_1-branch-patched/gcc/params.h	2007-02-09 10:33:20.000000000 +0300
@@ -147,4 +147,6 @@ typedef enum compiler_param
   PARAM_VALUE (PARAM_VIRTUAL_MAPPINGS_TO_SYMS_RATIO)
 #define MAX_FIELDS_FOR_FIELD_SENSITIVE \
   ((size_t) PARAM_VALUE (PARAM_MAX_FIELDS_FOR_FIELD_SENSITIVE))
+#define MAX_SCHED_READY_INSNS \
+  PARAM_VALUE (PARAM_MAX_SCHED_READY_INSNS)
 #endif /* ! GCC_PARAMS_H */
Only in gcc-4_1-branch-patched/gcc/: params.h.orig