More efficient version of Jul 10 bugfix of mine, as discussed on egcs-patches.

More efficient version of Jul 10 bugfix of mine, as
discussed on egcs-patches.
	* regclass.c (reg_scan_mark_refs): New arg min_regno.  Only update
	regscan information for REGs with numbers greater than or equal to
	this.  All callers changed.
	(reg_scan_update): New function to efficiently update regscan
	information on the fly.
	* rtl.h: Add prototype.
	* jump.c (jump_optimize): Call it when we make a transformation
	which generates new pseudo-REGs.

From-SVN: r21096

gcc/ChangeLog

+Mon Jul 13 02:24:08 1998  David S. Miller  <davem@pierdol.cobaltmicro.com>
+
+	* regclass.c (reg_scan_mark_refs): New arg min_regno.  Only update
+	regscan information for REGs with numbers greater than or equal to
+	this.  All callers changed.
+	(reg_scan_update): New function to efficiently update regscan
+	information on the fly.
+	* rtl.h: Add prototype.
+	* jump.c (jump_optimize): Call it when we make a transformation
+	which generates new pseudo-REGs.
+
 Sun Jul 12 13:08:14 1998  Jeffrey A Law  (law@cygnus.com)
 
 	* collect2.c (main): Use "-x c" instead of "-lang-c" for force the

gcc/jump.c

@@ -605,15 +605,6 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 	  int this_is_simplejump, this_is_condjump, reversep = 0;
 	  int this_is_condjump_in_parallel;
 
-	  /* If one of our transformations has created more REGs we
-	     must rerun reg_scan or else we risk missed optimizations,
-	     erroneous optimizations, or even worse a crash.  */
-	  if (after_regscan &&
-	      old_max_reg < max_reg_num ())
-	    {
-	      reg_scan (f, max_reg_num (), 0);
-	      old_max_reg = max_reg_num ();
-	    }
 #if 0
 	  /* If NOT the first iteration, if this is the last jump pass
 	     (just before final), do the special peephole optimizations.
@@ -987,7 +978,7 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 	     We set:
 
 	     TEMP to the "x = exp;" insn.
-	     TEMP1 to the single set in the "x = exp; insn.
+	     TEMP1 to the single set in the "x = exp;" insn.
 	     TEMP2 to "x".  */
 
 	  if (! reload_completed
@@ -1021,6 +1012,12 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 						   PREV_INSN (temp3), temp);
 		  delete_insn (temp);
 		  reallabelprev = prev_active_insn (JUMP_LABEL (insn));
+
+		  if (after_regscan)
+		    {
+		      reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
+		      old_max_reg = max_reg_num ();
+		    }
 		}
 	    }
 
@@ -1073,6 +1070,12 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 		  delete_insn (temp);
 		  delete_insn (temp3);
 		  reallabelprev = prev_active_insn (JUMP_LABEL (insn));
+
+		  if (after_regscan)
+		    {
+		      reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
+		      old_max_reg = max_reg_num ();
+		    }
 		}
 	    }
 
@@ -1133,6 +1136,12 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 		  delete_insn (temp);
 		  delete_insn (temp3);
 		  reallabelprev = prev_active_insn (JUMP_LABEL (insn));
+
+		  if (after_regscan)
+		    {
+		      reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
+		      old_max_reg = max_reg_num ();
+		    }
 		}
 	    }
 #endif /* HAVE_cc0 */
@@ -1244,7 +1253,7 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 
 		if (target)
 		  {
-		    rtx seq1,seq2;
+		    rtx seq1,seq2,last;
 
 		    /* Save the conditional move sequence but don't emit it
 		       yet.  On some machines, like the alpha, it is possible
@@ -1266,13 +1275,20 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 		    emit_insns_before (seq1, temp5);
 		    /* Insert conditional move after insn, to be sure that
 		       the jump and a possible compare won't be separated */
-		    emit_insns_after (seq2, insn);
+		    last = emit_insns_after (seq2, insn);
 
 		    /* ??? We can also delete the insn that sets X to A.
 		       Flow will do it too though.  */
 		    delete_insn (temp);
 		    next = NEXT_INSN (insn);
 		    delete_jump (insn);
+
+		    if (after_regscan)
+		      {
+			reg_scan_update (seq1, NEXT_INSN (last), old_max_reg);
+			old_max_reg = max_reg_num ();
+		      }
+
 		    changed = 1;
 		    continue;
 		  }
@@ -1455,6 +1471,13 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 		      delete_insn (temp);
 		      next = NEXT_INSN (insn);
 		      delete_jump (insn);
+
+		      if (after_regscan)
+			{
+			  reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
+			  old_max_reg = max_reg_num ();
+			}
+
 		      changed = 1;
 		      continue;
 		    }
@@ -1574,6 +1597,13 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
 		  delete_insn (prev_nonnote_insn (insn));
 #endif
 		  delete_insn (insn);
+
+		  if (after_regscan)
+		    {
+		      reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
+		      old_max_reg = max_reg_num ();
+		    }
+
 		  changed = 1;
 		  continue;
 		}

gcc/regclass.c

@@ -673,7 +673,7 @@ static void record_address_regs	PROTO((rtx, enum reg_class, int));
 #ifdef FORBIDDEN_INC_DEC_CLASSES
 static int auto_inc_dec_reg_p	PROTO((rtx, enum machine_mode));
 #endif
-static void reg_scan_mark_refs	PROTO((rtx, rtx, int));
+static void reg_scan_mark_refs	PROTO((rtx, rtx, int, int));
 
 /* Return the reg_class in which pseudo reg number REGNO is best allocated.
    This function is sometimes called before the info has been computed.
@@ -1939,21 +1939,54 @@ reg_scan (f, nregs, repeat)
 	if (GET_CODE (PATTERN (insn)) == PARALLEL
 	    && XVECLEN (PATTERN (insn), 0) > max_parallel)
 	  max_parallel = XVECLEN (PATTERN (insn), 0);
-	reg_scan_mark_refs (PATTERN (insn), insn, 0);
+	reg_scan_mark_refs (PATTERN (insn), insn, 0, 0);
 
 	if (REG_NOTES (insn))
-	  reg_scan_mark_refs (REG_NOTES (insn), insn, 1);
+	  reg_scan_mark_refs (REG_NOTES (insn), insn, 1, 0);
+      }
+}
+
+/* Update 'regscan' information by looking at the insns
+   from FIRST to LAST.  Some new REGs have been created,
+   and any REG with number greater than OLD_MAX_REGNO is
+   such a REG.  We only update information for those.  */
+
+void
+reg_scan_update(first, last, old_max_regno)
+     rtx first;
+     rtx last;
+     int old_max_regno;
+{
+  register rtx insn;
+
+  allocate_reg_info (max_reg_num (), FALSE, FALSE);
+
+  for (insn = first; insn != last; insn = NEXT_INSN (insn))
+    if (GET_CODE (insn) == INSN
+	|| GET_CODE (insn) == CALL_INSN
+	|| GET_CODE (insn) == JUMP_INSN)
+      {
+	if (GET_CODE (PATTERN (insn)) == PARALLEL
+	    && XVECLEN (PATTERN (insn), 0) > max_parallel)
+	  max_parallel = XVECLEN (PATTERN (insn), 0);
+	reg_scan_mark_refs (PATTERN (insn), insn, 0, old_max_regno);
+
+	if (REG_NOTES (insn))
+	  reg_scan_mark_refs (REG_NOTES (insn), insn, 1, old_max_regno);
       }
 }
 
 /* X is the expression to scan.  INSN is the insn it appears in.
-   NOTE_FLAG is nonzero if X is from INSN's notes rather than its body.  */
+   NOTE_FLAG is nonzero if X is from INSN's notes rather than its body.
+   We should only record information for REGs with numbers
+   greater than or equal to MIN_REGNO.  */
 
 static void
-reg_scan_mark_refs (x, insn, note_flag)
+reg_scan_mark_refs (x, insn, note_flag, min_regno)
      rtx x;
      rtx insn;
      int note_flag;
+     int min_regno;
 {
   register enum rtx_code code = GET_CODE (x);
   register rtx dest;
@@ -1976,24 +2009,27 @@ reg_scan_mark_refs (x, insn, note_flag)
       {
 	register int regno = REGNO (x);
 
+	if (regno >= min_regno)
+	  {
 	    REGNO_LAST_NOTE_UID (regno) = INSN_UID (insn);
 	    if (!note_flag)
 	      REGNO_LAST_UID (regno) = INSN_UID (insn);
 	    if (REGNO_FIRST_UID (regno) == 0)
 	      REGNO_FIRST_UID (regno) = INSN_UID (insn);
 	  }
+      }
       break;
 
     case EXPR_LIST:
       if (XEXP (x, 0))
-	reg_scan_mark_refs (XEXP (x, 0), insn, note_flag);
+	reg_scan_mark_refs (XEXP (x, 0), insn, note_flag, min_regno);
       if (XEXP (x, 1))
-	reg_scan_mark_refs (XEXP (x, 1), insn, note_flag);
+	reg_scan_mark_refs (XEXP (x, 1), insn, note_flag, min_regno);
       break;
 
     case INSN_LIST:
       if (XEXP (x, 1))
-	reg_scan_mark_refs (XEXP (x, 1), insn, note_flag);
+	reg_scan_mark_refs (XEXP (x, 1), insn, note_flag, min_regno);
       break;
 
     case SET:
@@ -2004,7 +2040,8 @@ reg_scan_mark_refs (x, insn, note_flag)
 	   dest = XEXP (dest, 0))
 	;
 
-      if (GET_CODE (dest) == REG)
+      if (GET_CODE (dest) == REG
+	  && REGNO (dest) >= min_regno)
 	REG_N_SETS (REGNO (dest))++;
 
       /* If this is setting a pseudo from another pseudo or the sum of a
@@ -2021,6 +2058,7 @@ reg_scan_mark_refs (x, insn, note_flag)
 
       if (GET_CODE (SET_DEST (x)) == REG
 	  && REGNO (SET_DEST (x)) >= FIRST_PSEUDO_REGISTER
+	  && REGNO (SET_DEST (x)) >= min_regno
 	  /* If the destination pseudo is set more than once, then other
 	     sets might not be to a pointer value (consider access to a
 	     union in two threads of control in the presense of global
@@ -2063,12 +2101,12 @@ reg_scan_mark_refs (x, insn, note_flag)
 	for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
 	  {
 	    if (fmt[i] == 'e')
-	      reg_scan_mark_refs (XEXP (x, i), insn, note_flag);
+	      reg_scan_mark_refs (XEXP (x, i), insn, note_flag, min_regno);
 	    else if (fmt[i] == 'E' && XVEC (x, i) != 0)
 	      {
 		register int j;
 		for (j = XVECLEN (x, i) - 1; j >= 0; j--)
-		  reg_scan_mark_refs (XVECEXP (x, i, j), insn, note_flag);
+		  reg_scan_mark_refs (XVECEXP (x, i, j), insn, note_flag, min_regno);
 	      }
 	  }
       }

gcc/rtl.h

@@ -1449,6 +1449,7 @@ extern void regset_release_memory	PROTO ((void));
 extern void regclass_init		PROTO ((void));
 extern void regclass			PROTO ((rtx, int));
 extern void reg_scan			PROTO ((rtx, int, int));
+extern void reg_scan_update		PROTO ((rtx, rtx, int));
 extern void fix_register		PROTO ((char *, int, int));
 
 /* In regmove.c */