re PR rtl-optimization/28173 (misses constant folding)

	PR rtl-optimization/28173
	* simplify-rtx.c (simplify_binary_operation_1) <IOR>:  Optimize
	(X & C1) | C2 as C2 when (C1 & C2) == C1 and X has no side-effects.
	Optimize (X & C1) | C2 as X | C2 when (C1 | C2) == ~0.
	Canonicalize (X & C1) | C2 as (X & (C1 & ~C2)) | C2.
	<AND>: Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2).

	* gcc.target/i386/andor-1.c: New test case.

From-SVN: r122116

gcc/ChangeLog

+2007-02-18  Roger Sayle  <roger@eyesopen.com>
+
+	PR rtl-optimization/28173
+	* simplify-rtx.c (simplify_binary_operation_1) <IOR>:  Optimize
+	(X & C1) | C2 as C2 when (C1 & C2) == C1 and X has no side-effects.
+	Optimize (X & C1) | C2 as X | C2 when (C1 | C2) == ~0.
+	Canonicalize (X & C1) | C2 as (X & (C1 & ~C2)) | C2.
+	<AND>: Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2).
+
 2007-02-18  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* builtins.c (fold_builtin_load_exponent): New.

gcc/simplify-rtx.c

@@ -2072,6 +2072,33 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
 	  && (nonzero_bits (op0, mode) & ~INTVAL (op1)) == 0)
 	return op1;
  
+      /* Canonicalize (X & C1) | C2.  */
+      if (GET_CODE (op0) == AND
+	  && GET_CODE (trueop1) == CONST_INT
+	  && GET_CODE (XEXP (op0, 1)) == CONST_INT)
+	{
+	  HOST_WIDE_INT mask = GET_MODE_MASK (mode);
+	  HOST_WIDE_INT c1 = INTVAL (XEXP (op0, 1));
+	  HOST_WIDE_INT c2 = INTVAL (trueop1);
+
+	  /* If (C1&C2) == C1, then (X&C1)|C2 becomes X.  */
+	  if ((c1 & c2) == c1
+	      && !side_effects_p (XEXP (op0, 0)))
+	    return trueop1;
+
+	  /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2.  */
+	  if (((c1|c2) & mask) == mask)
+	    return simplify_gen_binary (IOR, mode, XEXP (op0, 0), op1);
+
+	  /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2.  */
+	  if (((c1 & ~c2) & mask) != (c1 & mask))
+	    {
+	      tem = simplify_gen_binary (AND, mode, XEXP (op0, 0),
+					 gen_int_mode (c1 & ~c2, mode));
+	      return simplify_gen_binary (IOR, mode, tem, op1);
+	    }
+	}
+
       /* Convert (A & B) | A to A.  */
       if (GET_CODE (op0) == AND
 	  && (rtx_equal_p (XEXP (op0, 0), op1)
@@ -2312,6 +2339,18 @@ simplify_binary_operation_1 (enum rtx_code code, enum machine_mode mode,
 	  return simplify_gen_unary (ZERO_EXTEND, mode, tem, imode);
 	}
 
+      /* Canonicalize (A | C1) & C2 as (A & C2) | (C1 & C2).  */
+      if (GET_CODE (op0) == IOR
+	  && GET_CODE (trueop1) == CONST_INT
+	  && GET_CODE (XEXP (op0, 1)) == CONST_INT)
+	{
+	  HOST_WIDE_INT tmp = INTVAL (trueop1) & INTVAL (XEXP (op0, 1));
+	  return simplify_gen_binary (IOR, mode,
+				      simplify_gen_binary (AND, mode,
+							   XEXP (op0, 0), op1),
+				      gen_int_mode (tmp, mode));
+	}
+
       /* Convert (A ^ B) & A to A & (~B) since the latter is often a single
 	 insn (and may simplify more).  */
       if (GET_CODE (op0) == XOR

gcc/testsuite/ChangeLog

+2007-02-18  Roger Sayle  <roger@eyesopen.com>
+
+	PR rtl-optimization/28173
+	* gcc.target/i386/andor-1.c: New test case.
+
 2007-02-18  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* gcc.dg/torture/builtin-ldexp-1.c: New.

gcc/testsuite/gcc.target/i386/andor-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "andl" } } */
+
+unsigned int foo(unsigned int x)
+{
+  unsigned int t = x & ~1;
+  return t | 1;
+}
+