params.def (PARAM_MAX_COMBINE_INSNS): New.

2014-07-23  Richard Biener  <rguenther@suse.de>

	* params.def (PARAM_MAX_COMBINE_INSNS): New.
	* combine.c: Include statistics.h and params.h.
	(combine_instructions): Guard three and four insn combines
	with max-combine-insns value.  Record statistics for combines
	performed.
	* doc/invoke.texi (max-combine-insns): Document new param.

From-SVN: r212923

gcc/ChangeLog

+2014-07-23  Richard Biener  <rguenther@suse.de>
+
+	* params.def (PARAM_MAX_COMBINE_INSNS): New.
+	* combine.c: Include statistics.h and params.h.
+	(combine_instructions): Guard three and four insn combines
+	with max-combine-insns value.  Record statistics for combines
+	performed.
+	* doc/invoke.texi (max-combine-insns): Document new param.
+
 2014-07-23  Roman Gareev  <gareevroman@gmail.com>
 
 	* graphite-isl-ast-to-gimple.c:

gcc/combine.c

@@ -104,6 +104,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "valtrack.h"
 #include "cgraph.h"
 #include "obstack.h"
+#include "statistics.h"
+#include "params.h"
 
 /* Number of attempts to combine instructions in this function.  */
 
@@ -1209,6 +1211,7 @@ combine_instructions (rtx f, unsigned int nregs)
   init_reg_last ();
   setup_incoming_promotions (first);
   last_bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
+  int max_combine = PARAM_VALUE (PARAM_MAX_COMBINE_INSNS);
 
   FOR_EACH_BB_FN (this_basic_block, cfun)
     {
@@ -1229,8 +1232,9 @@ combine_instructions (rtx f, unsigned int nregs)
 	   insn = next ? next : NEXT_INSN (insn))
 	{
 	  next = 0;
-	  if (NONDEBUG_INSN_P (insn))
-	    {
+	  if (!NONDEBUG_INSN_P (insn))
+	    continue;
+
 	  while (last_combined_insn
 		 && INSN_DELETED_P (last_combined_insn))
 	    last_combined_insn = PREV_INSN (last_combined_insn);
@@ -1255,10 +1259,14 @@ combine_instructions (rtx f, unsigned int nregs)
 	    if ((next = try_combine (insn, links->insn, NULL_RTX,
 				     NULL_RTX, &new_direct_jump_p,
 				     last_combined_insn)) != 0)
+	      {
+		statistics_counter_event (cfun, "two-insn combine", 1);
 		goto retry;
+	      }
 
 	  /* Try each sequence of three linked insns ending with this one.  */
 
+	  if (max_combine >= 3)
 	    FOR_EACH_LOG_LINK (links, insn)
 	      {
 		rtx link = links->insn;
@@ -1272,8 +1280,11 @@ combine_instructions (rtx f, unsigned int nregs)
 		  if ((next = try_combine (insn, link, nextlinks->insn,
 					   NULL_RTX, &new_direct_jump_p,
 					   last_combined_insn)) != 0)
+		    {
+		      statistics_counter_event (cfun, "three-insn combine", 1);
 		      goto retry;
 		    }
+	      }
 
 #ifdef HAVE_cc0
 	  /* Try to combine a jump insn that uses CC0
@@ -1338,6 +1349,7 @@ combine_instructions (rtx f, unsigned int nregs)
 
 	  /* Try combining an insn with two different insns whose results it
 	     uses.  */
+	  if (max_combine >= 3)
 	    FOR_EACH_LOG_LINK (links, insn)
 	      for (nextlinks = links->next; nextlinks;
 		   nextlinks = nextlinks->next)
@@ -1345,9 +1357,14 @@ combine_instructions (rtx f, unsigned int nregs)
 					 nextlinks->insn, NULL_RTX,
 					 &new_direct_jump_p,
 					 last_combined_insn)) != 0)
+
+		  {
+		    statistics_counter_event (cfun, "three-insn combine", 1);
 		    goto retry;
+		  }
 
 	  /* Try four-instruction combinations.  */
+	  if (max_combine >= 4)
 	    FOR_EACH_LOG_LINK (links, insn)
 	      {
 		struct insn_link *next1;
@@ -1369,7 +1386,10 @@ combine_instructions (rtx f, unsigned int nregs)
 					       nextlinks->insn,
 					       &new_direct_jump_p,
 					       last_combined_insn)) != 0)
+			{
+			  statistics_counter_event (cfun, "four-insn combine", 1);
 			  goto retry;
+			}
 		    /* I0, I1 -> I2, I2 -> I3.  */
 		    for (nextlinks = next1->next; nextlinks;
 			 nextlinks = nextlinks->next)
@@ -1377,8 +1397,11 @@ combine_instructions (rtx f, unsigned int nregs)
 					       nextlinks->insn,
 					       &new_direct_jump_p,
 					       last_combined_insn)) != 0)
+			{
+			  statistics_counter_event (cfun, "four-insn combine", 1);
 			  goto retry;
 			}
+		  }
 
 		for (next1 = links->next; next1; next1 = next1->next)
 		  {
@@ -1391,16 +1414,22 @@ combine_instructions (rtx f, unsigned int nregs)
 					       nextlinks->insn,
 					       &new_direct_jump_p,
 					       last_combined_insn)) != 0)
+			{
+			  statistics_counter_event (cfun, "four-insn combine", 1);
 			  goto retry;
+			}
 		    /* I0 -> I1; I1, I2 -> I3.  */
 		    FOR_EACH_LOG_LINK (nextlinks, link1)
 		      if ((next = try_combine (insn, link, link1,
 					       nextlinks->insn,
 					       &new_direct_jump_p,
 					       last_combined_insn)) != 0)
+			{
+			  statistics_counter_event (cfun, "four-insn combine", 1);
 			  goto retry;
 			}
 		  }
+	      }
 
 	  /* Try this insn with each REG_EQUAL note it links back to.  */
 	  FOR_EACH_LOG_LINK (links, insn)
@@ -1430,7 +1459,10 @@ combine_instructions (rtx f, unsigned int nregs)
 				      last_combined_insn);
 		  i2mod = NULL_RTX;
 		  if (next)
+		    {
+		      statistics_counter_event (cfun, "insn-with-note combine", 1);
 		      goto retry;
+		    }
 		  SET_SRC (set) = orig;
 		}
 	    }
@@ -1438,11 +1470,10 @@ combine_instructions (rtx f, unsigned int nregs)
 	  if (!NOTE_P (insn))
 	    record_dead_and_set_regs (insn);
 
-	    retry:
+retry:
 	  ;
 	}
     }
-    }
 
   default_rtl_profile ();
   clear_bb_flags ();

gcc/doc/invoke.texi

@@ -10006,6 +10006,10 @@ The maximum size measured as number of RTLs that can be recorded in an expressio
 in combiner for a pseudo register as last known value of that register.  The default
 is 10000.
 
+@item max-combine-insns
+The maximum number of instructions the RTL combiner tries to combine.
+The default value is 2 at @option{-Og} and 4 otherwise.
+
 @item integer-share-limit
 Small integer constants can use a shared data structure, reducing the
 compiler's memory usage and increasing its speed.  This sets the maximum

gcc/params.def

@@ -673,6 +673,11 @@ DEFPARAM(PARAM_MAX_LAST_VALUE_RTL,
 	 "The maximum number of RTL nodes that can be recorded as combiner's last value",
 	 10000, 0, 0)
 
+DEFPARAM(PARAM_MAX_COMBINE_INSNS,
+	 "max-combine-insns",
+	 "The maximum number of insns combine tries to combine",
+	 4, 2, 4)
+
 /* INTEGER_CST nodes are shared for values [{-1,0} .. N) for
    {signed,unsigned} integral types.  This determines N.
    Experimentation shows 251 to be a good value that generates the