Patch for PR 31850 and slow compilation of limits-fndefn.c

[Steve Ellcey <sje at cup dot hp dot com>]

The PR 31850 bug report actually talks about a slowdown in
limits-fnargs.c but while fixing that I found that limits-fndefn.c was
also very slow, but for a different reason.

This patch fixes the slowdown in the compilation of limits-fndefn.c.  On
my PA box complilation goes from 30 minutes to 2 minutes after applying
this patch.

The problem is that for each argument we pass into a function we look to
see if we need to create any conversion instructions and as part of this
we call push_to_sequence.  push_to_sequence takes the instruction passed
it and walks the sequence to the end in order to set last_insn.  As the
sequence gets longer and longer push_to_sequence gets slower and slower.

This patch fixes the problem by creating push_to_sequence2 which takes
the last instruction (as well as the first) as arguments so it doesn't
have to walk the list.  I added a field to the assign_parm_data_all
structure in function.c so we could save the first and last instructions
in the conversion sequence instead of just saving the first instruction.

Regression tested on IA64 HP-UX and Linux and on HPPA HP-UX.

OK to checkin?


2007-05-23  Steve Ellcey  <sje@cup.hp.com>

	PR target/31850
	* rtl.h (push_to_sequence2): New.
	* emit-rtl.c (push_to_sequence2): New.
	* function.c (assign_parm_data_all): Add new fields.
	(assign_parm_setup_block): Call push_to_sequence2 instead of 
	push_to_sequence.
	(assign_parm_setup_reg): Ditto.
	(assign_parm_setup_stack): Ditto.
	(assign_parms_unsplit_complex): Ditto.
	(assign_parms): Change field name.

Index: rtl.h
===================================================================
--- rtl.h	(revision 124974)
+++ rtl.h	(working copy)
@@ -1494,6 +1494,7 @@ extern rtx get_first_nonnote_insn (void)
 extern rtx get_last_nonnote_insn (void);
 extern void start_sequence (void);
 extern void push_to_sequence (rtx);
+extern void push_to_sequence2 (rtx, rtx);
 extern void end_sequence (void);
 extern rtx immed_double_const (HOST_WIDE_INT, HOST_WIDE_INT,
 			       enum machine_mode);
Index: emit-rtl.c
===================================================================
--- emit-rtl.c	(revision 124974)
+++ emit-rtl.c	(working copy)
@@ -4630,6 +4630,18 @@ push_to_sequence (rtx first)
   last_insn = last;
 }
 
+/* Like push_to_sequence, but take the last insn as an argument to avoid
+   looping through the list.  */
+
+void
+push_to_sequence2 (rtx first, rtx last)
+{
+  start_sequence ();
+
+  first_insn = first;
+  last_insn = last;
+}
+
 /* Set up the outer-level insn chain
    as the current sequence, saving the previously current one.  */
 
Index: function.c
===================================================================
--- function.c	(revision 124974)
+++ function.c	(working copy)
@@ -1895,7 +1895,8 @@ struct assign_parm_data_all
   struct args_size stack_args_size;
   tree function_result_decl;
   tree orig_fnargs;
-  rtx conversion_insns;
+  rtx first_conversion_insn;
+  rtx last_conversion_insn;
   HOST_WIDE_INT pretend_args_size;
   HOST_WIDE_INT extra_pretend_bytes;
   int reg_parm_stack_space;
@@ -2489,7 +2490,8 @@ assign_parm_setup_block (struct assign_p
 	{
 	  rtx parmreg = gen_reg_rtx (data->nominal_mode);
 
-	  push_to_sequence (all->conversion_insns);
+	  push_to_sequence2 (all->first_conversion_insn,
+			     all->last_conversion_insn);
 
 	  /* For values returned in multiple registers, handle possible
 	     incompatible calls to emit_group_store.
@@ -2514,7 +2516,8 @@ assign_parm_setup_block (struct assign_p
 	    emit_group_store (parmreg, entry_parm, data->nominal_type,
 			      int_size_in_bytes (data->nominal_type));
 
-	  all->conversion_insns = get_insns ();
+	  all->first_conversion_insn = get_insns ();
+	  all->last_conversion_insn = get_last_insn ();
 	  end_sequence ();
 
 	  SET_DECL_RTL (parm, parmreg);
@@ -2561,9 +2564,11 @@ assign_parm_setup_block (struct assign_p
       /* Handle values in multiple non-contiguous locations.  */
       if (GET_CODE (entry_parm) == PARALLEL)
 	{
-	  push_to_sequence (all->conversion_insns);
+	  push_to_sequence2 (all->first_conversion_insn,
+			     all->last_conversion_insn);
 	  emit_group_store (mem, entry_parm, data->passed_type, size);
-	  all->conversion_insns = get_insns ();
+	  all->first_conversion_insn = get_insns ();
+	  all->last_conversion_insn = get_last_insn ();
 	  end_sequence ();
 	}
 
@@ -2622,10 +2627,11 @@ assign_parm_setup_block (struct assign_p
     }
   else if (data->stack_parm == 0)
     {
-      push_to_sequence (all->conversion_insns);
+      push_to_sequence2 (all->first_conversion_insn, all->last_conversion_insn);
       emit_block_move (stack_parm, data->entry_parm, GEN_INT (size),
 		       BLOCK_OP_NORMAL);
-      all->conversion_insns = get_insns ();
+      all->first_conversion_insn = get_insns ();
+      all->last_conversion_insn = get_last_insn ();
       end_sequence ();
     }
 
@@ -2698,7 +2704,7 @@ assign_parm_setup_reg (struct assign_par
 
       emit_move_insn (tempreg, validize_mem (data->entry_parm));
 
-      push_to_sequence (all->conversion_insns);
+      push_to_sequence2 (all->first_conversion_insn, all->last_conversion_insn);
       tempreg = convert_to_mode (data->nominal_mode, tempreg, unsignedp);
 
       if (GET_CODE (tempreg) == SUBREG
@@ -2719,7 +2725,8 @@ assign_parm_setup_reg (struct assign_par
       save_tree_used = TREE_USED (parm);
       expand_assignment (parm, make_tree (data->nominal_type, tempreg));
       TREE_USED (parm) = save_tree_used;
-      all->conversion_insns = get_insns ();
+      all->first_conversion_insn = get_insns ();
+      all->last_conversion_insn = get_last_insn ();
       end_sequence ();
 
       did_conversion = true;
@@ -2745,11 +2752,13 @@ assign_parm_setup_reg (struct assign_par
 	  rtx tempreg = gen_reg_rtx (GET_MODE (DECL_RTL (parm)));
 	  int unsigned_p = TYPE_UNSIGNED (TREE_TYPE (parm));
 
-	  push_to_sequence (all->conversion_insns);
+	  push_to_sequence2 (all->first_conversion_insn,
+			     all->last_conversion_insn);
 	  emit_move_insn (tempreg, DECL_RTL (parm));
 	  tempreg = convert_to_mode (GET_MODE (parmreg), tempreg, unsigned_p);
 	  emit_move_insn (parmreg, tempreg);
-	  all->conversion_insns = get_insns ();
+	  all->first_conversion_insn = get_insns ();
+	  all->last_conversion_insn = get_last_insn ();
 	  end_sequence ();
 
 	  did_conversion = true;
@@ -2835,7 +2844,7 @@ assign_parm_setup_stack (struct assign_p
 
       emit_move_insn (tempreg, validize_mem (data->entry_parm));
 
-      push_to_sequence (all->conversion_insns);
+      push_to_sequence2 (all->first_conversion_insn, all->last_conversion_insn);
       to_conversion = true;
 
       data->entry_parm = convert_to_mode (data->nominal_mode, tempreg,
@@ -2867,7 +2876,8 @@ assign_parm_setup_stack (struct assign_p
 	{
 	  /* Use a block move to handle potentially misaligned entry_parm.  */
 	  if (!to_conversion)
-	    push_to_sequence (all->conversion_insns);
+	    push_to_sequence2 (all->first_conversion_insn,
+			       all->last_conversion_insn);
 	  to_conversion = true;
 
 	  emit_block_move (dest, src,
@@ -2880,7 +2890,8 @@ assign_parm_setup_stack (struct assign_p
 
   if (to_conversion)
     {
-      all->conversion_insns = get_insns ();
+      all->first_conversion_insn = get_insns ();
+      all->last_conversion_insn = get_last_insn ();
       end_sequence ();
     }
 
@@ -2924,10 +2935,12 @@ assign_parms_unsplit_complex (struct ass
 	      set_mem_attributes (tmp, parm, 1);
 	      rmem = adjust_address_nv (tmp, inner, 0);
 	      imem = adjust_address_nv (tmp, inner, GET_MODE_SIZE (inner));
-	      push_to_sequence (all->conversion_insns);
+	      push_to_sequence2 (all->first_conversion_insn,
+				 all->last_conversion_insn);
 	      emit_move_insn (rmem, real);
 	      emit_move_insn (imem, imag);
-	      all->conversion_insns = get_insns ();
+	      all->first_conversion_insn = get_insns ();
+	      all->last_conversion_insn = get_last_insn ();
 	      end_sequence ();
 	    }
 	  else
@@ -3025,7 +3038,7 @@ assign_parms (tree fndecl)
 
   /* Output all parameter conversion instructions (possibly including calls)
      now that all parameters have been copied out of hard registers.  */
-  emit_insn (all.conversion_insns);
+  emit_insn (all.first_conversion_insn);
 
   /* If we are receiving a struct value address as the first argument, set up
      the RTL for the function result. As this might require code to convert