cse.c (count_reg_usage): Correctly handle REG_NONNEG notes.

        * cse.c (count_reg_usage): Correctly handle REG_NONNEG notes.
        (delete_trivially_dead_insns): Renamed from delete_dead_from_cse.
        * toplev.c (rest_of_compilation): Call delete_trivially_dead_insns
        instead of delete_dead_from_cse.  Also call delete_trivially_dead_insns
        between loop optimization passes.
        * rtl.h: Updated appropriately.

From-SVN: r19100

gcc/ChangeLog

+Sat Apr 11 01:24:28 1998  Jeffrey A Law  (law@cygnus.com)
+
+	* cse.c (count_reg_usage): Correctly handle REG_NONNEG notes.
+	(delete_trivially_dead_insns): Renamed from delete_dead_from_cse.
+	* toplev.c (rest_of_compilation): Call delete_trivially_dead_insns		instead of delete_dead_from_cse.  Also call delete_trivially_dead_insns
+	between loop optimization passes.
+	* rtl.h: Updated appropriately.
+
 Fri Apr 10 22:28:32 1998  Jeffrey A Law  (law@cygnus.com)
 
 	Reinstall this patch from Jason.

gcc/cse.c

@@ -8731,7 +8731,7 @@ count_reg_usage (x, counts, dest, incr)
     case EXPR_LIST:
     case INSN_LIST:
       if (REG_NOTE_KIND (x) == REG_EQUAL
-	  || GET_CODE (XEXP (x,0)) == USE)
+	  || (REG_NOTE_KIND (x) != REG_NONNEG && GET_CODE (XEXP (x,0)) == USE))
 	count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr);
       count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr);
       return;
@@ -8754,13 +8754,13 @@ count_reg_usage (x, counts, dest, incr)
 /* Scan all the insns and delete any that are dead; i.e., they store a register
    that is never used or they copy a register to itself.
 
-   This is used to remove insns made obviously dead by cse.  It improves the
-   heuristics in loop since it won't try to move dead invariants out of loops
-   or make givs for dead quantities.  The remaining passes of the compilation
-   are also sped up.  */
+   This is used to remove insns made obviously dead by cse, loop or other
+   optimizations.  It improves the heuristics in loop since it won't try to
+   move dead invariants out of loops or make givs for dead quantities.  The
+   remaining passes of the compilation are also sped up.  */
 
 void
-delete_dead_from_cse (insns, nreg)
+delete_trivially_dead_insns (insns, nreg)
      rtx insns;
      int nreg;
 {

gcc/rtl.h

@@ -1115,7 +1115,7 @@ extern int read_skip_spaces		PROTO ((FILE *));
 /* In cse.c */
 struct cse_basic_block_data;
 extern int rtx_cost			PROTO ((rtx, enum rtx_code));
-extern void delete_dead_from_cse	PROTO ((rtx, int));
+extern void delete_trivially_dead_insns	PROTO ((rtx, int));
 #ifdef BUFSIZ
 extern int cse_main			PROTO ((rtx, int, int, FILE *));
 #endif

gcc/toplev.c

@@ -3211,7 +3211,7 @@ rest_of_compilation (decl)
 
       TIMEVAR (cse_time, tem = cse_main (insns, max_reg_num (),
 					 0, rtl_dump_file));
-      TIMEVAR (cse_time, delete_dead_from_cse (insns, max_reg_num ()));
+      TIMEVAR (cse_time, delete_trivially_dead_insns (insns, max_reg_num ()));
 
       if (tem || optimize > 1)
 	TIMEVAR (jump_time, jump_optimize (insns, 0, 0, 0));
@@ -3244,8 +3244,15 @@ rest_of_compilation (decl)
 	       
 	       loop_optimize (insns, rtl_dump_file, 0);
 	       
-	       /* The regscan pass may not be necessary, but let's
-		  be safe until we can prove otherwise.  */
+	
+	       /* The first call to loop_optimize makes some instructions
+		  trivially dead.  We delete those instructions now in the
+		  hope that doing so will make the heuristics in loop work
+		  better and possibly speed up compilation.  */
+	       delete_trivially_dead_insns (insns, max_reg_num ());
+
+	       /* The regscan pass is currently necessary as the alias
+		  analysis code depends on this information.  */
 	       reg_scan (insns, max_reg_num (), 1);
 	     }
 	   loop_optimize (insns, rtl_dump_file, flag_unroll_loops);