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

1 files changed, 40 insertions, 0 deletions

diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 891799b..e9a9816 100644
--- a/gcc/rtlanal.c
+++ b/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 *));
 
 
@@ -687,6 +688,45 @@ 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