re PR rtl-optimization/48141 (DSE compile time hog)

	PR rtl-optimization/48141
	* params.def (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES): New.
	* dse.c: Include params.h.
	(active_local_stores_len): New variable.
	(add_wild_read, dse_step1): Clear it when setting active_local_stores
	to NULL.
	(record_store, check_mem_read_rtx): Decrease it when removing
	from the chain.
	(scan_insn): Likewise.  Increase it when adding to chain, if it
	reaches PARAM_MAX_DSE_ACTIVE_LOCAL_STORES limit, set to 1 and
	set active_local_stores to NULL before the addition.
	* Makefile.in (dse.o): Depend on $(PARAMS_H).

From-SVN: r171090

gcc/ChangeLog

 2011-03-17  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/48141
+	* params.def (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES): New.
+	* dse.c: Include params.h.
+	(active_local_stores_len): New variable.
+	(add_wild_read, dse_step1): Clear it when setting active_local_stores
+	to NULL.
+	(record_store, check_mem_read_rtx): Decrease it when removing
+	from the chain.
+	(scan_insn): Likewise.  Increase it when adding to chain, if it
+	reaches PARAM_MAX_DSE_ACTIVE_LOCAL_STORES limit, set to 1 and
+	set active_local_stores to NULL before the addition.
+	* Makefile.in (dse.o): Depend on $(PARAMS_H).
+
+	PR rtl-optimization/48141
 	* dse.c (record_store): If no positions are needed in an insn
 	that cannot be deleted, at least unchain it from active_local_stores.
 

gcc/Makefile.in

@@ -3070,7 +3070,7 @@ dse.o : dse.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
    $(TREE_H) $(TM_P_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
    $(RECOG_H) $(EXPR_H) $(DF_H) cselib.h $(DBGCNT_H) $(TIMEVAR_H) \
    $(TREE_PASS_H) alloc-pool.h $(ALIAS_H) dse.h $(OPTABS_H) $(TARGET_H) \
-   $(BITMAP_H)
+   $(BITMAP_H) $(PARAMS_H)
 fwprop.o : fwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
    $(DIAGNOSTIC_CORE_H) insn-config.h $(RECOG_H) $(FLAGS_H) $(OBSTACK_H) $(BASIC_BLOCK_H) \
    output.h $(DF_H) alloc-pool.h $(TIMEVAR_H) $(TREE_PASS_H) $(TARGET_H) \

gcc/dse.c

@@ -47,6 +47,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "optabs.h"
 #include "dbgcnt.h"
 #include "target.h"
+#include "params.h"
 
 /* This file contains three techniques for performing Dead Store
    Elimination (dse).
@@ -387,6 +388,7 @@ static alloc_pool insn_info_pool;
 /* The linked list of stores that are under consideration in this
    basic block.  */
 static insn_info_t active_local_stores;
+static int active_local_stores_len;
 
 struct bb_info
 {
@@ -947,6 +949,7 @@ add_wild_read (bb_info_t bb_info)
     }
   insn_info->wild_read = true;
   active_local_stores = NULL;
+  active_local_stores_len = 0;
 }
 
 
@@ -1537,6 +1540,7 @@ record_store (rtx body, bb_info_t bb_info)
 	{
 	  insn_info_t insn_to_delete = ptr;
 
+	  active_local_stores_len--;
 	  if (last)
 	    last->next_local_store = ptr->next_local_store;
 	  else
@@ -2074,6 +2078,7 @@ check_mem_read_rtx (rtx *loc, void *data)
 	      if (dump_file)
 		dump_insn_info ("removing from active", i_ptr);
 
+	      active_local_stores_len--;
 	      if (last)
 		last->next_local_store = i_ptr->next_local_store;
 	      else
@@ -2163,6 +2168,7 @@ check_mem_read_rtx (rtx *loc, void *data)
 	      if (dump_file)
 		dump_insn_info ("removing from active", i_ptr);
 
+	      active_local_stores_len--;
 	      if (last)
 		last->next_local_store = i_ptr->next_local_store;
 	      else
@@ -2222,6 +2228,7 @@ check_mem_read_rtx (rtx *loc, void *data)
 	      if (dump_file)
 		dump_insn_info ("removing from active", i_ptr);
 
+	      active_local_stores_len--;
 	      if (last)
 		last->next_local_store = i_ptr->next_local_store;
 	      else
@@ -2426,6 +2433,7 @@ scan_insn (bb_info_t bb_info, rtx insn)
 		  if (dump_file)
 		    dump_insn_info ("removing from active", i_ptr);
 
+		  active_local_stores_len--;
 		  if (last)
 		    last->next_local_store = i_ptr->next_local_store;
 		  else
@@ -2453,6 +2461,12 @@ scan_insn (bb_info_t bb_info, rtx insn)
 		    fprintf (dump_file, "handling memset as BLKmode store\n");
 		  if (mems_found == 1)
 		    {
+		      if (active_local_stores_len++
+			  >= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
+			{
+			  active_local_stores_len = 1;
+			  active_local_stores = NULL;
+			}
 		      insn_info->next_local_store = active_local_stores;
 		      active_local_stores = insn_info;
 		    }
@@ -2496,6 +2510,12 @@ scan_insn (bb_info_t bb_info, rtx insn)
      it as cannot delete.  This simplifies the processing later.  */
   if (mems_found == 1)
     {
+      if (active_local_stores_len++
+	  >= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
+	{
+	  active_local_stores_len = 1;
+	  active_local_stores = NULL;
+	}
       insn_info->next_local_store = active_local_stores;
       active_local_stores = insn_info;
     }
@@ -2534,6 +2554,7 @@ remove_useless_values (cselib_val *base)
 
       if (del)
 	{
+	  active_local_stores_len--;
 	  if (last)
 	    last->next_local_store = insn_info->next_local_store;
 	  else
@@ -2584,6 +2605,7 @@ dse_step1 (void)
 	    = create_alloc_pool ("cse_store_info_pool",
 				 sizeof (struct store_info), 100);
 	  active_local_stores = NULL;
+	  active_local_stores_len = 0;
 	  cselib_clear_table ();
 
 	  /* Scan the insns.  */

gcc/params.def

@@ -698,6 +698,12 @@ DEFPARAM(PARAM_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)
 
+/* This is the maximum number of active local stores RTL DSE will consider.  */
+DEFPARAM (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES,
+	  "max-dse-active-local-stores",
+	  "Maximum number of active local stores in RTL dead store elimination",
+	  5000, 0, 0)
+
 /* Prefetching and cache-optimizations related parameters.  Default values are
    usually set by machine description.  */