combine.c (simplify_comparison <AND>): Check TRULY_NOOP_TRUNCATION before start using a subreg.

	* combine.c (simplify_comparison <AND>): Check
	TRULY_NOOP_TRUNCATION before start using a subreg.
	
	* config/mips/mips.md (*branch_zero<mode>, 
	*branch_zero<mode>_inverted, *branch_equality<mode>, 
	*branch_equality<mode>_inverted, *branch_equality<mode>_mips16): 
	Remove mode check from comparisons.

From-SVN: r110358

gcc/ChangeLog

+2006-01-28  Adam Nemet  <anemet@caviumnetworks.com>
+
+	* combine.c (simplify_comparison <AND>): Check
+	TRULY_NOOP_TRUNCATION before start using a subreg.
+	
+	* config/mips/mips.md (*branch_zero<mode>, 
+	*branch_zero<mode>_inverted, *branch_equality<mode>, 
+	*branch_equality<mode>_inverted, *branch_equality<mode>_mips16): 
+	Remove mode check from comparisons. 
+
 2006-01-28  Kenneth Zadeck <zadeck@naturalbridge.com>
 
 	* config/mips/mips-protos.h (mips_set_live_on_entry): Deleted.

gcc/combine.c

@@ -10295,14 +10295,27 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
 	  /* If this AND operation is really a ZERO_EXTEND from a narrower
 	     mode, the constant fits within that mode, and this is either an
 	     equality or unsigned comparison, try to do this comparison in
-	     the narrower mode.  */
+	     the narrower mode.
+
+	     Note that in:
+
+	     (ne:DI (and:DI (reg:DI 4) (const_int 0xffffffff)) (const_int 0))
+	     -> (ne:DI (reg:SI 4) (const_int 0))
+
+	     unless TRULY_NOOP_TRUNCATION allows it or the register is
+	     known to hold a value of the required mode the
+	     transformation is invalid.  */
 	  if ((equality_comparison_p || unsigned_comparison_p)
 	      && GET_CODE (XEXP (op0, 1)) == CONST_INT
 	      && (i = exact_log2 ((INTVAL (XEXP (op0, 1))
 				   & GET_MODE_MASK (mode))
 				  + 1)) >= 0
 	      && const_op >> i == 0
-	      && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode)
+	      && (tmode = mode_for_size (i, MODE_INT, 1)) != BLKmode
+	      && (TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (tmode),
+					 GET_MODE_BITSIZE (GET_MODE (op0)))
+		  || (REG_P (XEXP (op0, 0))
+		      && reg_truncated_to_mode (tmode, XEXP (op0, 0)))))
 	    {
 	      op0 = gen_lowpart (tmode, XEXP (op0, 0));
 	      continue;

gcc/config/mips/mips.md

@@ -4316,9 +4316,9 @@
 (define_insn "*branch_zero<mode>"
   [(set (pc)
 	(if_then_else
-	 (match_operator:GPR 0 "comparison_operator"
-			     [(match_operand:GPR 2 "register_operand" "d")
-			      (const_int 0)])
+	 (match_operator 0 "comparison_operator"
+			 [(match_operand:GPR 2 "register_operand" "d")
+			  (const_int 0)])
 	 (label_ref (match_operand 1 "" ""))
 	 (pc)))]
   "!TARGET_MIPS16"
@@ -4336,9 +4336,9 @@
 (define_insn "*branch_zero<mode>_inverted"
   [(set (pc)
 	(if_then_else
-	 (match_operator:GPR 0 "comparison_operator"
-			     [(match_operand:GPR 2 "register_operand" "d")
-			      (const_int 0)])
+	 (match_operator 0 "comparison_operator"
+			 [(match_operand:GPR 2 "register_operand" "d")
+			  (const_int 0)])
 	 (pc)
 	 (label_ref (match_operand 1 "" ""))))]
   "!TARGET_MIPS16"
@@ -4358,9 +4358,9 @@
 (define_insn "*branch_equality<mode>"
   [(set (pc)
 	(if_then_else
-	 (match_operator:GPR 0 "equality_operator"
-			     [(match_operand:GPR 2 "register_operand" "d")
-			      (match_operand:GPR 3 "register_operand" "d")])
+	 (match_operator 0 "equality_operator"
+			 [(match_operand:GPR 2 "register_operand" "d")
+			  (match_operand:GPR 3 "register_operand" "d")])
 	 (label_ref (match_operand 1 "" ""))
 	 (pc)))]
   "!TARGET_MIPS16"
@@ -4378,9 +4378,9 @@
 (define_insn "*branch_equality<mode>_inverted"
   [(set (pc)
 	(if_then_else
-	 (match_operator:GPR 0 "equality_operator"
-			     [(match_operand:GPR 2 "register_operand" "d")
-			      (match_operand:GPR 3 "register_operand" "d")])
+	 (match_operator 0 "equality_operator"
+			 [(match_operand:GPR 2 "register_operand" "d")
+			  (match_operand:GPR 3 "register_operand" "d")])
 	 (pc)
 	 (label_ref (match_operand 1 "" ""))))]
   "!TARGET_MIPS16"
@@ -4400,9 +4400,9 @@
 (define_insn "*branch_equality<mode>_mips16"
   [(set (pc)
 	(if_then_else
-	 (match_operator:GPR 0 "equality_operator"
-			     [(match_operand:GPR 1 "register_operand" "d,t")
-			      (const_int 0)])
+	 (match_operator 0 "equality_operator"
+			 [(match_operand:GPR 1 "register_operand" "d,t")
+			  (const_int 0)])
 	 (match_operand 2 "pc_or_label_operand" "")
 	 (match_operand 3 "pc_or_label_operand" "")))]
   "TARGET_MIPS16"