rtlanal.c (insn_dependant_p, [...]): New.

        * rtlanal.c (insn_dependant_p, insn_dependant_p_1): New.
        * rtl.h (insn_dependant_p): Declare it.
        * loop.c (strength_reduce): Use it.

From-SVN: r34010

gcc/ChangeLog

+2000-05-18  Richard Henderson  <rth@cygnus.com>
+
+	* rtlanal.c (insn_dependant_p, insn_dependant_p_1): New.
+	* rtl.h (insn_dependant_p): Declare it.
+	* loop.c (strength_reduce): Use it.
+
 2000-05-18  Alexandre Oliva  <aoliva@cygnus.com>
 
 	* config/mn10300/mn10300.c (expand_prologue, expand_epilogue):

gcc/loop.c

@@ -4119,10 +4119,9 @@ strength_reduce (loop, insn_count, flags)
 
 		  for (next = NEXT_INSN (dominator); ; next = NEXT_INSN (next))
 		    {
-		      if ((INSN_P (next)
-			   && (reg_mentioned_p (giv, PATTERN (next))
-			       || reg_set_p (bl2->biv->src_reg, next)))
-			  || GET_CODE (next) == JUMP_INSN)
+		      if (GET_CODE (next) == JUMP_INSN
+			  || (INSN_P (next)
+			      && insn_dependant_p (giv_insn, next)))
 			break;
 #ifdef HAVE_cc0
 		      if (! INSN_P (next)

gcc/rtl.h

@@ -1212,6 +1212,7 @@ extern int modified_between_p		PARAMS ((rtx, rtx, rtx));
 extern int no_labels_between_p		PARAMS ((rtx, rtx));
 extern int no_jumps_between_p		PARAMS ((rtx, rtx));
 extern int modified_in_p		PARAMS ((rtx, rtx));
+extern int insn_dependant_p		PARAMS ((rtx, rtx));
 extern int reg_set_p			PARAMS ((rtx, rtx));
 extern rtx single_set			PARAMS ((rtx));
 extern int multiple_sets		PARAMS ((rtx));

gcc/rtlanal.c

@@ -26,6 +26,7 @@ Boston, MA 02111-1307, USA.  */
 
 static int rtx_addr_can_trap_p	PARAMS ((rtx));
 static void reg_set_p_1		PARAMS ((rtx, rtx, void *));
+static void insn_dependant_p_1	PARAMS ((rtx, rtx, void *));
 static void reg_set_last_1	PARAMS ((rtx, rtx, void *));
 
 
@@ -688,6 +689,45 @@ modified_in_p (x, insn)
   return 0;
 }
 
+/* Return true if anything in insn X is (anti,output,true) dependant on
+   anything in insn Y.  */
+
+int
+insn_dependant_p (x, y)
+     rtx x, y;
+{
+  rtx tmp;
+
+  if (! INSN_P (x) || ! INSN_P (y))
+    abort ();
+
+  tmp = PATTERN (y);
+  note_stores (PATTERN (x), insn_dependant_p_1, &tmp);
+  if (tmp == NULL_RTX)
+    return 1;
+
+  tmp = PATTERN (x);
+  note_stores (PATTERN (y), insn_dependant_p_1, &tmp);
+  if (tmp == NULL_RTX)
+    return 1;
+
+  return 0;
+}
+
+/* A helper routine for insn_dependant_p called through note_stores.  */
+
+static void
+insn_dependant_p_1 (x, pat, data)
+     rtx x;
+     rtx pat ATTRIBUTE_UNUSED;
+     void *data;
+{
+  rtx * pinsn = (rtx *) data;
+
+  if (*pinsn && reg_mentioned_p (x, *pinsn))
+    *pinsn = NULL_RTX;
+}
+
 /* Given an INSN, return a SET expression if this insn has only a single SET.
    It may also have CLOBBERs, USEs, or SET whose output
    will not be used, which we ignore.  */