Richard Kenner <kenner@vlsi1.ultra.nyu.edu>:

        * rtl.def (CONSTANT_P_RTX): Clarify commentary.
        * expr.c (expand_builtin, case BUILT_IN_CONSTANT_P): Rework to
        consider constant CONSTRUCTOR constant and to defer some cases
        to cse.
        * cse.c (fold_rtx, case CONST): Add handling for CONSTANT_P_RTX.
        * regclass.c (reg_scan_mark_refs, case CONST): Likewise.
Richard Henderson  <rth@cygnus.com>
        * expr.c (init_expr_once): Kill can_handle_constant_p recognition.
        * cse.c (fold_rtx, case 'x'): Remove standalone CONSTANT_P_RTX code.

From-SVN: r24439

1 files changed, 15 insertions, 6 deletions

diff --git a/gcc/cse.c b/gcc/cse.c
index 2ef26a5..9ca2931 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -4931,6 +4931,21 @@ fold_rtx (x, insn)
   switch (code)
     {
     case CONST:
+      /* If the operand is a CONSTANT_P_RTX, see if what's inside it
+	 is known to be constant and replace the whole thing with a
+	 CONST_INT of either zero or one.  Note that this code assumes
+	 that an insn that recognizes a CONST will also recognize a
+	 CONST_INT, but that seems to be a safe assumption.  */
+      if (GET_CODE (XEXP (x, 0)) == CONSTANT_P_RTX)
+	{
+	  x = equiv_constant (fold_rtx (XEXP (XEXP (x, 0), 0), 0));
+	  return (x != 0 && (GET_CODE (x) == CONST_INT
+			     || GET_CODE (x) == CONST_DOUBLE)
+		  ? const1_rtx : const0_rtx);
+	}
+
+      /* ... fall through ... */
+
     case CONST_INT:
     case CONST_DOUBLE:
     case SYMBOL_REF:
@@ -5850,12 +5865,6 @@ fold_rtx (x, insn)
 					const_arg1 ? const_arg1 : folded_arg1,
 					const_arg2 ? const_arg2 : XEXP (x, 2));
       break;
-
-    case 'x':
-      /* Always eliminate CONSTANT_P_RTX at this stage. */
-      if (code == CONSTANT_P_RTX)
-	return (const_arg0 ? const1_rtx : const0_rtx);
-      break;
     }
 
   return new ? new : x;