simplify-rtx.c (simplify_unary_operation_1): We can strip zero_extend, bswap and rotates from POCOUNT's argument.

* simplify-rtx.c (simplify_unary_operation_1) <POPCOUNT>: We can
	strip zero_extend, bswap and rotates from POCOUNT's argument.
	<PARITY>: Likewise, we can strip not, bswap, sign_extend,
	zero_extend and rotates from PARITY's argument.
	<BSWAP>: A byte-swap followed by a byte-swap is an identity.
	(simplify_const_unary_operation) <BSWAP>: Evaluate the byte-swap
	of an integer constant at compile-time.

	* gcc.target/i386/builtin-bswap-2.c: New test case.

From-SVN: r121716

gcc/ChangeLog

@@ -1,3 +1,13 @@
+2007-02-08  Roger Sayle  <roger@eyesopen.com>
+
+	* simplify-rtx.c (simplify_unary_operation_1) <POPCOUNT>: We can
+	strip zero_extend, bswap and rotates from POCOUNT's argument.
+	<PARITY>: Likewise, we can strip not, bswap, sign_extend,
+	zero_extend and rotates from PARITY's argument.
+	<BSWAP>: A byte-swap followed by a byte-swap is an identity.
+	(simplify_const_unary_operation) <BSWAP>: Evaluate the byte-swap
+	of an integer constant at compile-time.
+
 2007-02-08  Diego Novillo  <dnovillo@redhat.com>
 
 	PR 30562

gcc/simplify-rtx.c

@@ -790,11 +790,54 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
       break;
 
     case POPCOUNT:
+      switch (GET_CODE (op))
+	{
+	case BSWAP:
+	case ZERO_EXTEND:
+	  /* (popcount (zero_extend <X>)) = (popcount <X>) */
+	  return simplify_gen_unary (POPCOUNT, mode, XEXP (op, 0),
+				     GET_MODE (XEXP (op, 0)));
+
+	case ROTATE:
+	case ROTATERT:
+	  /* Rotations don't affect popcount.  */
+	  if (!side_effects_p (XEXP (op, 1)))
+	    return simplify_gen_unary (POPCOUNT, mode, XEXP (op, 0),
+				       GET_MODE (XEXP (op, 0)));
+	  break;
+
+	default:
+	  break;
+	}
+      break;
+
     case PARITY:
-      /* (pop* (zero_extend <X>)) = (pop* <X>) */
+      switch (GET_CODE (op))
-      if (GET_CODE (op) == ZERO_EXTEND)
+	{
-	return simplify_gen_unary (code, mode, XEXP (op, 0),
+	case NOT:
-				   GET_MODE (XEXP (op, 0)));
+	case BSWAP:
+	case ZERO_EXTEND:
+	case SIGN_EXTEND:
+	  return simplify_gen_unary (PARITY, mode, XEXP (op, 0),
+				     GET_MODE (XEXP (op, 0)));
+
+	case ROTATE:
+	case ROTATERT:
+	  /* Rotations don't affect parity.  */
+	  if (!side_effects_p (XEXP (op, 1)))
+	    return simplify_gen_unary (PARITY, mode, XEXP (op, 0),
+				       GET_MODE (XEXP (op, 0)));
+	  break;
+
+	default:
+	  break;
+	}
+      break;
+
+    case BSWAP:
+      /* (bswap (bswap x)) -> x.  */
+      if (GET_CODE (op) == BSWAP)
+	return XEXP (op, 0);
       break;
 
     case FLOAT:
@@ -1047,7 +1090,19 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
 	  break;
 
 	case BSWAP:
-	  return 0;
+	  {
+	    unsigned int s;
+
+	    val = 0;
+	    for (s = 0; s < width; s += 8)
+	      {
+		unsigned int d = width - s - 8;
+		unsigned HOST_WIDE_INT byte;
+		byte = (arg0 >> s) & 0xff;
+		val |= byte << d;
+	      }
+	  }
+	  break;
 
 	case TRUNCATE:
 	  val = arg0;
@@ -1195,6 +1250,30 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
 	  lv &= 1;
 	  break;
 
+	case BSWAP:
+	  {
+	    unsigned int s;
+
+	    hv = 0;
+	    lv = 0;
+	    for (s = 0; s < width; s += 8)
+	      {
+		unsigned int d = width - s - 8;
+		unsigned HOST_WIDE_INT byte;
+
+		if (s < HOST_BITS_PER_WIDE_INT)
+		  byte = (l1 >> s) & 0xff;
+		else
+		  byte = (h1 >> (s - HOST_BITS_PER_WIDE_INT)) & 0xff;
+
+		if (d < HOST_BITS_PER_WIDE_INT)
+		  lv |= byte << d;
+		else
+		  hv |= byte << (d - HOST_BITS_PER_WIDE_INT);
+	      }
+	  }
+	  break;
+
 	case TRUNCATE:
 	  /* This is just a change-of-mode, so do nothing.  */
 	  lv = l1, hv = h1;

gcc/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2007-02-08  Roger Sayle  <roger@eyesopen.com>
+
+	* gcc.target/i386/builtin-bswap-2.c: New test case.
+
 2007-02-08  Roger Sayle  <roger@eyesopen.com>
 
 	* gfortran.dg/forall_8.f90: New test case.

gcc/testsuite/gcc.target/i386/builtin-bswap-2.c

@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=nocona" } */
+/* { dg-final { scan-assembler-not "bswap\[ \t\]" } } */
+
+int foo(int x)
+{
+  int t = __builtin_bswap32 (x);
+  return __builtin_bswap32 (t);
+}
+