alias.c (canon_rtx): Make it global.

	* alias.c (canon_rtx): Make it global.
	(rtx_equal_for_memref_p): CONST_INT equality is now pointer
	equality.
	* cse.c (struct table_elt): Add canon_exp.
	(insert): Clear it.
	(invalidate): Canonicalize expressions only once.
	* rtl.h (canon_rtx): Declare.

From-SVN: r32845

gcc/ChangeLog

+2000-03-31  Mark Mitchell  <mark@codesourcery.com>
+
+	* alias.c (canon_rtx): Make it global.
+	(rtx_equal_for_memref_p): CONST_INT equality is now pointer
+	equality.
+	* cse.c (struct table_elt): Add canon_exp.
+	(insert): Clear it.
+	(invalidate): Canonicalize expressions only once.
+	* rtl.h (canon_rtx): Declare.
+
 2000-03-30  Mark Mitchell  <mark@codesourcery.com>
 
 	* Makefile.in (emit-rtl.o): Depend on HASHTAB_H.

gcc/alias.c

@@ -79,7 +79,6 @@ typedef struct alias_set_entry
   splay_tree children;
 } *alias_set_entry;
 
-static rtx canon_rtx			PARAMS ((rtx));
 static int rtx_equal_for_memref_p	PARAMS ((rtx, rtx));
 static rtx find_symbolic_term		PARAMS ((rtx));
 static rtx get_addr			PARAMS ((rtx));
@@ -544,7 +543,12 @@ record_base_value (regno, val, invariant)
   reg_base_value[regno] = find_base_value (val);
 }
 
-static rtx
+/* Returns a canonical version of X, from the point of view alias
+   analysis.  (For example, if X is a MEM whose address is a register,
+   and the register has a known value (say a SYMBOL_REF), then a MEM
+   whose address is the SYMBOL_REF is returned.)  */
+
+rtx
 canon_rtx (x)
      rtx x;
 {
@@ -627,24 +631,33 @@ rtx_equal_for_memref_p (x, y)
   if (GET_MODE (x) != GET_MODE (y))
     return 0;
 
-  /* REG, LABEL_REF, and SYMBOL_REF can be compared nonrecursively.  */
-
-  if (code == REG)
+  /* Some RTL can be compared without a recursive examination.  */
+  switch (code)
+    {
+    case REG:
       return REGNO (x) == REGNO (y);
-  if (code == LABEL_REF)
+
+    case LABEL_REF:
       return XEXP (x, 0) == XEXP (y, 0);
-  if (code == SYMBOL_REF)
+      
+    case SYMBOL_REF:
       return XSTR (x, 0) == XSTR (y, 0);
-  if (code == CONST_INT)
-    return INTVAL (x) == INTVAL (y);
-  /* There's no need to compare the contents of CONST_DOUBLEs because
-     they're unique. */
-  if (code == CONST_DOUBLE)
+
+    case CONST_INT:
+    case CONST_DOUBLE:
+      /* There's no need to compare the contents of CONST_DOUBLEs or
+	 CONST_INTs because pointer equality is a good enough
+	 comparison for these nodes.  */
       return 0;
-  if (code == ADDRESSOF)
+
+    case ADDRESSOF:
       return (REGNO (XEXP (x, 0)) == REGNO (XEXP (y, 0))
 	      && XINT (x, 1) == XINT (y, 1));
 
+    default:
+      break;
+    }
+
   /* For commutative operations, the RTX match if the operand match in any
      order.  Also handle the simple binary and unary cases without a loop.  */
   if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c')

gcc/cse.c

@@ -408,6 +408,9 @@ static int hash_arg_in_memory;
    each recording one expression's information.
    That expression is in the `exp' field.
 
+   The canon_exp field contains a canonical (from the point of view of
+   alias analysis) version of the `exp' field.
+
    Those elements with the same hash code are chained in both directions
    through the `next_same_hash' and `prev_same_hash' fields.
 
@@ -447,6 +450,7 @@ static int hash_arg_in_memory;
 struct table_elt
 {
   rtx exp;
+  rtx canon_exp;
   struct table_elt *next_same_hash;
   struct table_elt *prev_same_hash;
   struct table_elt *next_same_value;
@@ -1498,6 +1502,7 @@ insert (x, classp, hash, mode)
     }
 
   elt->exp = x;
+  elt->canon_exp = NULL_RTX;
   elt->cost = COST (x);
   elt->next_same_value = 0;
   elt->prev_same_value = 0;
@@ -1823,6 +1828,10 @@ invalidate (x, full_mode)
       return;
 
     case MEM:
+      /* Calculate the canonical version of X here so that
+	 true_dependence doesn't generate new RTL for X on each call.  */
+      x = canon_rtx (x);
+
       /* Remove all hash table elements that refer to overlapping pieces of
 	 memory.  */
       if (full_mode == VOIDmode)
@@ -1835,11 +1844,23 @@ invalidate (x, full_mode)
 	  for (p = table[i]; p; p = next)
 	    {
 	      next = p->next_same_hash;
-	      if (p->in_memory
-		  && (GET_CODE (p->exp) != MEM
-		      || true_dependence (x, full_mode, p->exp,
-					  cse_rtx_varies_p)))
+	      if (p->in_memory)
+		{
+		  if (GET_CODE (p->exp) != MEM)
 		    remove_from_table (p, i);
+		  else 
+		    {
+		      /* Just canonicalize the expression once;
+			 otherwise each time we call invalidate
+			 true_dependence will canonicalize the
+			 expression again.  */
+		      if (!p->canon_exp)
+			p->canon_exp = canon_rtx (p->exp);
+		      if (true_dependence (x, full_mode, p->canon_exp,
+					   cse_rtx_varies_p))
+			remove_from_table (p, i);
+		    }
+		}
 	    }
 	}
       return;

gcc/rtl.h

@@ -1761,6 +1761,7 @@ extern void fancy_abort PARAMS ((const char *, int, const char *))
 #endif
 
 /* In alias.c */
+extern rtx canon_rtx                    PARAMS ((rtx));
 extern int true_dependence		PARAMS ((rtx, enum machine_mode, rtx,
 						int (*)(rtx)));
 extern int read_dependence		PARAMS ((rtx, rtx));