Makefile.in (reorg.o): Add params.h dependence.

2001-02-21  Jeffrey Oldham  <oldham@codesourcery.com>

	* Makefile.in (reorg.o): Add params.h dependence.
	* params.def: Fix typographical error in comment.
	(MAX_DELAY_SLOT_INSN_SEARCH): New parameter.
	* params.h: Modify introductory comment.
	(MAX_DELAY_SLOT_INSN_SEARCH): New parameter.
	* reorg.c: Add dependence on params.h.
	(redundant_insn): Add parameterized throttle for search.
	(fill_simple_delay_slots): Add a comment explaining a variable.
	Move conditional out of loop, simplifying code.
	(fill_eager_delay_slots): Fix typographical error in comment.

From-SVN: r39948

5 files changed, 100 insertions, 82 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b4bd206..9461dca 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2001-02-21  Jeffrey Oldham  <oldham@codesourcery.com>
+
+	* Makefile.in (reorg.o): Add params.h dependence.
+	* params.def: Fix typographical error in comment.
+	(MAX_DELAY_SLOT_INSN_SEARCH): New parameter.
+	* params.h: Modify introductory comment.
+	(MAX_DELAY_SLOT_INSN_SEARCH): New parameter.
+	* reorg.c: Add dependence on params.h.
+	(redundant_insn): Add parameterized throttle for search.
+	(fill_simple_delay_slots): Add a comment explaining a variable.
+	Move conditional out of loop, simplifying code.
+	(fill_eager_delay_slots): Fix typographical error in comment.
+
 2001-02-20  Aldy Hernandez  <aldyh@redhat.com>
 
         * tm.texi (REVERSE_CONDEXEC_PREDICATES_P): New macro documentation.
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index b71ca64..ba41875 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1481,7 +1481,7 @@ caller-save.o : caller-save.c $(CONFIG_H) system.h $(RTL_H) flags.h \
    $(RECOG_H) reload.h $(EXPR_H) toplev.h
 reorg.o : reorg.c $(CONFIG_H) system.h $(RTL_H) conditions.h hard-reg-set.h \
    $(BASIC_BLOCK_H) $(REGS_H) insn-config.h $(INSN_ATTR_H) insn-flags.h \
-   $(RECOG_H) function.h flags.h output.h $(EXPR_H) toplev.h
+   $(RECOG_H) function.h flags.h output.h $(EXPR_H) toplev.h params.h
 alias.o : alias.c $(CONFIG_H) system.h $(RTL_H) flags.h hard-reg-set.h \
    $(BASIC_BLOCK_H) $(REGS_H) toplev.h output.h $(EXPR_H) insn-flags.h \
    $(GGC_H) function.h cselib.h $(TREE_H)
diff --git a/gcc/params.def b/gcc/params.def
index f96a89f..61c3600 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -24,7 +24,7 @@ Boston, MA 02111-1307, USA.
 /* This file contains definitions for language-independent
    parameters.  The DEFPARAM macro takes 4 arguments:
 
-     - The enumeral corresonding to this parameter.
+     - The enumeral corresponding to this parameter.
 
      - The name that can be used to set this parameter using the 
        command-line option `--param <name>=<value>'.
@@ -44,6 +44,17 @@ DEFPARAM (PARAM_MAX_INLINE_INSNS,
 	  "The maximum number of instructions in a function that is eligible for inlining",
 	  10000)
 
+/* The maximum number of instructions to consider when looking for an
+   instruction to fill a delay slot.  If more than this arbitrary
+   number of instructions is searched, the time savings from filling
+   the delay slot will be minimal so stop searching.  Increasing
+   values mean more aggressive optimization, making the compile time
+   increase with probably small improvement in executable run time.  */
+DEFPARAM (PARAM_MAX_DELAY_SLOT_INSN_SEARCH,
+	  "max-delay-slot-insn-search",
+	  "The maximum number of instructions to consider to fill a delay slot",
+	  100)
+
 /*
 Local variables:
 mode:c
diff --git a/gcc/params.h b/gcc/params.h
index c097ad1..b60d29d 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -27,7 +27,10 @@ Boston, MA 02111-1307, USA.
    place.  The values of the parameters can be set on the
    command-line, thereby providing a way to control the amount of
    effort spent on particular optimization passes, or otherwise tune
-   the behavior of the compiler.  */
+   the behavior of the compiler.
+
+   Since their values can be set on the command-line, these parameters
+   should not be used for non-dynamic memory allocation.  */
 
 #ifndef PARAMS_H
 #define PARAMS_H
@@ -81,5 +84,7 @@ typedef enum compiler_param
 /* Macros for the various parameters.  */
 #define MAX_INLINE_INSNS \
   PARAM_VALUE (PARAM_MAX_INLINE_INSNS)
+#define MAX_DELAY_SLOT_INSN_SEARCH \
+  PARAM_VALUE (PARAM_MAX_DELAY_SLOT_INSN_SEARCH)
 
 #endif /* PARAMS_H */
diff --git a/gcc/reorg.c b/gcc/reorg.c
index 6d3b26a..142ecdf 100644
--- a/gcc/reorg.c
+++ b/gcc/reorg.c
@@ -139,6 +139,7 @@ Boston, MA 02111-1307, USA.  */
 #include "obstack.h"
 #include "insn-attr.h"
 #include "resource.h"
+#include "params.h"
 
 #ifdef DELAY_SLOTS
 
@@ -1635,6 +1636,7 @@ redundant_insn (insn, target, delay_list)
   rtx trial, pat;
   struct resources needed, set;
   int i;
+  unsigned insns_to_search;
 
   /* If INSN has any REG_UNUSED notes, it can't match anything since we
      are allowed to not actually assign to such a register.  */
@@ -1642,7 +1644,10 @@ redundant_insn (insn, target, delay_list)
     return 0;
 
   /* Scan backwards looking for a match.  */
-  for (trial = PREV_INSN (target); trial; trial = PREV_INSN (trial))
+  for (trial = PREV_INSN (target),
+	 insns_to_search = MAX_DELAY_SLOT_INSN_SEARCH;
+       trial && insns_to_search > 0;
+       trial = PREV_INSN (trial), --insns_to_search)
     {
       if (GET_CODE (trial) == CODE_LABEL)
 	return 0;
@@ -1743,9 +1748,10 @@ redundant_insn (insn, target, delay_list)
   /* Scan backwards until we reach a label or an insn that uses something
      INSN sets or sets something insn uses or sets.  */
 
-  for (trial = PREV_INSN (target);
-       trial && GET_CODE (trial) != CODE_LABEL;
-       trial = PREV_INSN (trial))
+  for (trial = PREV_INSN (target),
+	 insns_to_search = MAX_DELAY_SLOT_INSN_SEARCH;
+       trial && GET_CODE (trial) != CODE_LABEL && insns_to_search > 0;
+       trial = PREV_INSN (trial), --insns_to_search)
     {
       if (GET_CODE (trial) != INSN && GET_CODE (trial) != CALL_INSN
 	  && GET_CODE (trial) != JUMP_INSN)
@@ -2223,9 +2229,11 @@ fill_simple_delay_slots (non_jumps_p)
 		  && ! simplejump_p (insn)
 		  && JUMP_LABEL (insn) != 0)))
 	{
+	  /* Invariant: If insn is a JUMP_INSN, the insn's jump
+	     label.  Otherwise, zero.  */
 	  rtx target = 0;
 	  int maybe_never = 0;
-	  struct resources needed_at_jump;
+	  rtx pat, trial_delay;
 
 	  CLEAR_RESOURCE (&needed);
 	  CLEAR_RESOURCE (&set);
@@ -2244,92 +2252,73 @@ fill_simple_delay_slots (non_jumps_p)
 		target = JUMP_LABEL (insn);
 	    }
 
-	  for (trial = next_nonnote_insn (insn); trial; trial = next_trial)
-	    {
-	      rtx pat, trial_delay;
-
-	      next_trial = next_nonnote_insn (trial);
-
-	      if (GET_CODE (trial) == CODE_LABEL
-		  || GET_CODE (trial) == BARRIER)
-		break;
+	  if (target == 0)
+	    for (trial = next_nonnote_insn (insn); trial; trial = next_trial)
+	      {
+		next_trial = next_nonnote_insn (trial);
 
-	      /* We must have an INSN, JUMP_INSN, or CALL_INSN.  */
-	      pat = PATTERN (trial);
+		if (GET_CODE (trial) == CODE_LABEL
+		    || GET_CODE (trial) == BARRIER)
+		  break;
 
-	      /* Stand-alone USE and CLOBBER are just for flow.  */
-	      if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER)
-		continue;
+		/* We must have an INSN, JUMP_INSN, or CALL_INSN.  */
+		pat = PATTERN (trial);
 
-	      /* If this already has filled delay slots, get the insn needing
-		 the delay slots.  */
-	      if (GET_CODE (pat) == SEQUENCE)
-		trial_delay = XVECEXP (pat, 0, 0);
-	      else
-		trial_delay = trial;
-
-	      /* If this is a jump insn to our target, indicate that we have
-		 seen another jump to it.  If we aren't handling a conditional
-		 jump, stop our search. Otherwise, compute the needs at its
-		 target and add them to NEEDED.  */
-	      if (GET_CODE (trial_delay) == JUMP_INSN)
-		{
-		  if (target == 0)
-		    break;
-		  else if (JUMP_LABEL (trial_delay) != target)
-		    {
-		      rtx ninsn =
-			next_active_insn (JUMP_LABEL (trial_delay));
-
-		      mark_target_live_regs (get_insns (), ninsn,
-					     &needed_at_jump);
-		      needed.memory |= needed_at_jump.memory;
-		      needed.unch_memory |= needed_at_jump.unch_memory;
-		      IOR_HARD_REG_SET (needed.regs, needed_at_jump.regs);
-		    }
-		}
+		/* Stand-alone USE and CLOBBER are just for flow.  */
+		if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER)
+		  continue;
 
-	      /* See if we have a resource problem before we try to
-		 split.   */
-	      if (target == 0
-		  && GET_CODE (pat) != SEQUENCE
-		  && ! insn_references_resource_p (trial, &set, 1)
-		  && ! insn_sets_resource_p (trial, &set, 1)
-		  && ! insn_sets_resource_p (trial, &needed, 1)
+		/* If this already has filled delay slots, get the insn needing
+		   the delay slots.  */
+		if (GET_CODE (pat) == SEQUENCE)
+		  trial_delay = XVECEXP (pat, 0, 0);
+		else
+		  trial_delay = trial;
+
+		/* Stop our search when seeing an unconditional jump.  */
+		if (GET_CODE (trial_delay) == JUMP_INSN)
+		  break;
+
+		/* See if we have a resource problem before we try to
+		   split.   */
+		if (GET_CODE (pat) != SEQUENCE
+		    && ! insn_references_resource_p (trial, &set, 1)
+		    && ! insn_sets_resource_p (trial, &set, 1)
+		    && ! insn_sets_resource_p (trial, &needed, 1)
 #ifdef HAVE_cc0
-		  && ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat))
+		    && ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat))
 #endif
-		  && ! (maybe_never && may_trap_p (pat))
-		  && (trial = try_split (pat, trial, 0))
-		  && eligible_for_delay (insn, slots_filled, trial, flags))
-		{
-		  next_trial = next_nonnote_insn (trial);
-		  delay_list = add_to_delay_list (trial, delay_list);
+		    && ! (maybe_never && may_trap_p (pat))
+		    && (trial = try_split (pat, trial, 0))
+		    && eligible_for_delay (insn, slots_filled, trial, flags))
+		  {
+		    next_trial = next_nonnote_insn (trial);
+		    delay_list = add_to_delay_list (trial, delay_list);
 
 #ifdef HAVE_cc0
-		  if (reg_mentioned_p (cc0_rtx, pat))
-		    link_cc0_insns (trial);
+		    if (reg_mentioned_p (cc0_rtx, pat))
+		      link_cc0_insns (trial);
 #endif
 
-		  delete_insn (trial);
-		  if (slots_to_fill == ++slots_filled)
-		    break;
-		  continue;
-		}
+		    delete_insn (trial);
+		    if (slots_to_fill == ++slots_filled)
+		      break;
+		    continue;
+		  }
 
-	      mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL);
-	      mark_referenced_resources (trial, &needed, 1);
+		mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL);
+		mark_referenced_resources (trial, &needed, 1);
 
-	      /* Ensure we don't put insns between the setting of cc and the
-		 comparison by moving a setting of cc into an earlier delay
-		 slot since these insns could clobber the condition code.  */
-	      set.cc = 1;
+		/* Ensure we don't put insns between the setting of cc and the
+		   comparison by moving a setting of cc into an earlier delay
+		   slot since these insns could clobber the condition code.  */
+		set.cc = 1;
 
-	      /* If this is a call or jump, we might not get here.  */
-	      if (GET_CODE (trial_delay) == CALL_INSN
-		  || GET_CODE (trial_delay) == JUMP_INSN)
-		maybe_never = 1;
-	    }
+		/* If this is a call or jump, we might not get here.  */
+		if (GET_CODE (trial_delay) == CALL_INSN
+		    || GET_CODE (trial_delay) == JUMP_INSN)
+		  maybe_never = 1;
+	      }
 
 	  /* If there are slots left to fill and our search was stopped by an
 	     unconditional branch, try the insn at the branch target.  We can
@@ -2982,7 +2971,7 @@ fill_eager_delay_slots ()
 	}
 
       /* If this insn is expected to branch, first try to get insns from our
-	 target, then our fallthrough insns.  If it is not, expected to branch,
+	 target, then our fallthrough insns.  If it is not expected to branch,
 	 try the other order.  */
 
       if (prediction > 0)