simplify-rtx.c (mode_signbit_p): New function to check whether an RTX is an immediate constant that represents...

	* simplify-rtx.c (mode_signbit_p): New function to check whether
	an RTX is an immediate constant that represents the most significant
	bit of a given machine mode.
	(simplify_unary_operation) <NOT>: Optimize ~(X+C) as X ^ ~C, where
	C is the sign bit.
	(simplify_binary_operation) <PLUS>: Optimize (X^C1) + C2 as X^(C1^C2)
	when C2 is the sign bit.
	(simplify_binary_operation) <XOR>: Canonicalize X^C as X+C when C
	is the sign bit.  Optimize (X+C1) ^ C2 as X^(C1^C2) when C1 is the
	sign bit.

	* gcc.c-torture/execute/20040409-1.c: New test case.
	* gcc.c-torture/execute/20040409-2.c: New test case.
	* gcc.c-torture/execute/20040409-3.c: New test case.

From-SVN: r80568

6 files changed, 620 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f96a2b4..3a41ae9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2004-04-09  Roger Sayle  <roger@eyesopen.com>
+
+	* simplify-rtx.c (mode_signbit_p): New function to check whether
+	an RTX is an immediate constant that represents the most significant
+	bit of a given machine mode.
+	(simplify_unary_operation) <NOT>: Optimize ~(X+C) as X ^ ~C, where
+	C is the sign bit.
+	(simplify_binary_operation) <PLUS>: Optimize (X^C1) + C2 as X^(C1^C2)
+	when C2 is the sign bit.
+	(simplify_binary_operation) <XOR>: Canonicalize X^C as X+C when C
+	is the sign bit.  Optimize (X+C1) ^ C2 as X^(C1^C2) when C1 is the
+	sign bit.
+
 2004-04-09  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* builtins.c (mathfn_built_in): Check TYPE_MAIN_VARIANT, not
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 0d283cd..49f2d37 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -50,6 +50,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  ((((HOST_WIDE_INT) low) < 0) ? ((HOST_WIDE_INT) -1) : ((HOST_WIDE_INT) 0))
 
 static rtx neg_const_int (enum machine_mode, rtx);
+static bool mode_signbit_p (enum machine_mode, rtx);
 static int simplify_plus_minus_op_data_cmp (const void *, const void *);
 static rtx simplify_plus_minus (enum rtx_code, enum machine_mode, rtx,
 				rtx, int);
@@ -66,6 +67,39 @@ neg_const_int (enum machine_mode mode, rtx i)
   return gen_int_mode (- INTVAL (i), mode);
 }
 
+/* Test whether expression, X, is an immediate constant that represents
+   the most significant bit of machine mode MODE.  */
+
+static bool
+mode_signbit_p (enum machine_mode mode, rtx x)
+{
+  unsigned HOST_WIDE_INT val;
+  unsigned int width;
+
+  if (GET_MODE_CLASS (mode) != MODE_INT)
+    return false;
+
+  width = GET_MODE_BITSIZE (mode);
+  if (width == 0)
+    return false;
+  
+  if (width <= HOST_BITS_PER_WIDE_INT
+      && GET_CODE (x) == CONST_INT)
+    val = INTVAL (x);
+  else if (width <= 2 * HOST_BITS_PER_WIDE_INT
+	   && GET_CODE (x) == CONST_DOUBLE
+	   && CONST_DOUBLE_LOW (x) == 0)
+    {
+      val = CONST_DOUBLE_HIGH (x);
+      width -= HOST_BITS_PER_WIDE_INT;
+    }
+  else
+    return false;
+
+  if (width < HOST_BITS_PER_WIDE_INT)
+    val &= ((unsigned HOST_WIDE_INT) 1 << width) - 1;
+  return val == ((unsigned HOST_WIDE_INT) 1 << (width - 1));
+}
 
 /* Make a binary operation by properly ordering the operands and
    seeing if the expression folds.  */
@@ -912,6 +946,16 @@ simplify_unary_operation (enum rtx_code code, enum machine_mode mode,
 						   mode)) != 0)
 	    return simplify_gen_binary (XOR, mode, XEXP (op, 0), temp);
 
+	  /* (not (plus X C)) for signbit C is (xor X D) with D = ~C.  */
+	  if (GET_CODE (op) == PLUS
+	      && GET_CODE (XEXP (op, 1)) == CONST_INT
+	      && mode_signbit_p (mode, XEXP (op, 1))
+	      && (temp = simplify_unary_operation (NOT, mode,
+						   XEXP (op, 1),
+						   mode)) != 0)
+	    return simplify_gen_binary (XOR, mode, XEXP (op, 0), temp);
+
+
 
 	  /* (not (ashift 1 X)) is (rotate ~1 X).  We used to do this for
 	     operands other than 1, but that is not valid.  We could do a
@@ -1514,6 +1558,17 @@ simplify_binary_operation (enum rtx_code code, enum machine_mode mode,
 		}
 	    }
 
+	  /* (plus (xor X C1) C2) is (xor X (C1^C2)) if C2 is signbit.  */
+	  if ((GET_CODE (op1) == CONST_INT
+	       || GET_CODE (op1) == CONST_DOUBLE)
+	      && GET_CODE (op0) == XOR
+	      && (GET_CODE (XEXP (op0, 1)) == CONST_INT
+		  || GET_CODE (XEXP (op0, 1)) == CONST_DOUBLE)
+	      && mode_signbit_p (mode, op1))
+	    return simplify_gen_binary (XOR, mode, XEXP (op0, 0),
+					simplify_gen_binary (XOR, mode, op1,
+							     XEXP (op0, 1)));
+
 	  /* If one of the operands is a PLUS or a MINUS, see if we can
 	     simplify this by the associative law.
 	     Don't use the associative law for floating point.
@@ -1797,9 +1852,27 @@ simplify_binary_operation (enum rtx_code code, enum machine_mode mode,
 	      && ((INTVAL (trueop1) & GET_MODE_MASK (mode))
 		  == GET_MODE_MASK (mode)))
 	    return simplify_gen_unary (NOT, mode, op0, mode);
-	  if (trueop0 == trueop1 && ! side_effects_p (op0)
+	  if (trueop0 == trueop1
+	      && ! side_effects_p (op0)
 	      && GET_MODE_CLASS (mode) != MODE_CC)
 	    return const0_rtx;
+
+	  /* Canonicalize XOR of the most significant bit to PLUS.  */
+	  if ((GET_CODE (op1) == CONST_INT
+	       || GET_CODE (op1) == CONST_DOUBLE)
+	      && mode_signbit_p (mode, op1))
+	    return simplify_gen_binary (PLUS, mode, op0, op1);
+	  /* (xor (plus X C1) C2) is (xor X (C1^C2)) if C1 is signbit.  */
+	  if ((GET_CODE (op1) == CONST_INT
+	       || GET_CODE (op1) == CONST_DOUBLE)
+	      && GET_CODE (op0) == PLUS
+	      && (GET_CODE (XEXP (op0, 1)) == CONST_INT
+		  || GET_CODE (XEXP (op0, 1)) == CONST_DOUBLE)
+	      && mode_signbit_p (mode, XEXP (op0, 1)))
+	    return simplify_gen_binary (XOR, mode, XEXP (op0, 0),
+					simplify_gen_binary (XOR, mode, op1,
+							     XEXP (op0, 1)));
+	      
 	  tem = simplify_associative_operation (code, mode, op0, op1);
 	  if (tem)
 	    return tem;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1161a0d..40d5e47 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2004-04-09  Roger Sayle  <roger@eyesopen.com>
+
+	* gcc.c-torture/execute/20040409-1.c: New test case.
+	* gcc.c-torture/execute/20040409-2.c: New test case.
+	* gcc.c-torture/execute/20040409-3.c: New test case.
+
 2004-04-09  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	* gcc.dg/20040409-1.c: New test.
diff --git a/gcc/testsuite/gcc.c-torture/execute/20040409-1.c b/gcc/testsuite/gcc.c-torture/execute/20040409-1.c
new file mode 100644
index 0000000..1e81edb
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20040409-1.c
@@ -0,0 +1,142 @@
+#include <limits.h>
+
+extern void abort ();
+
+int test1(int x)
+{
+  return x ^ INT_MIN;
+}
+
+unsigned int test1u(unsigned int x)
+{
+  return x ^ (unsigned int)INT_MIN;
+}
+
+int test2(int x)
+{
+  return x + INT_MIN;
+}
+
+unsigned int test2u(unsigned int x)
+{
+  return x + (unsigned int)INT_MIN;
+}
+
+int test3(int x)
+{
+  return x - INT_MIN;
+}
+
+unsigned int test3u(unsigned int x)
+{
+  return x - (unsigned int)INT_MIN;
+}
+
+int test4(int x)
+{
+  int y = INT_MIN;
+  return x ^ y;
+}
+
+unsigned int test4u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return x ^ y;
+}
+
+int test5(int x)
+{
+  int y = INT_MIN;
+  return x + y;
+}
+
+unsigned int test5u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return x + y;
+}
+
+int test6(int x)
+{
+  int y = INT_MIN;
+  return x - y;
+}
+
+unsigned int test6u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return x - y;
+}
+
+
+
+void test(int a, int b)
+{
+  if (test1(a) != b)
+    abort();
+  if (test2(a) != b)
+    abort();
+  if (test3(a) != b)
+    abort();
+  if (test4(a) != b)
+    abort();
+  if (test5(a) != b)
+    abort();
+  if (test6(a) != b)
+    abort();
+}
+
+void testu(unsigned int a, unsigned int b)
+{
+  if (test1u(a) != b)
+    abort();
+  if (test2u(a) != b)
+    abort();
+  if (test3u(a) != b)
+    abort();
+  if (test4u(a) != b)
+    abort();
+  if (test5u(a) != b)
+    abort();
+  if (test6u(a) != b)
+    abort();
+}
+
+
+int main()
+{
+#if INT_MAX == 2147483647
+  test(0x00000000,0x80000000);
+  test(0x80000000,0x00000000);
+  test(0x12345678,0x92345678);
+  test(0x92345678,0x12345678);
+  test(0x7fffffff,0xffffffff);
+  test(0xffffffff,0x7fffffff);
+
+  testu(0x00000000,0x80000000);
+  testu(0x80000000,0x00000000);
+  testu(0x12345678,0x92345678);
+  testu(0x92345678,0x12345678);
+  testu(0x7fffffff,0xffffffff);
+  testu(0xffffffff,0x7fffffff);
+#endif
+
+#if INT_MAX == 32767
+  test(0x0000,0x8000);
+  test(0x8000,0x0000);
+  test(0x1234,0x9234);
+  test(0x9234,0x1234);
+  test(0x7fff,0xffff);
+  test(0xffff,0x7fff);
+
+  testu(0x0000,0x8000);
+  testu(0x8000,0x0000);
+  testu(0x1234,0x9234);
+  testu(0x9234,0x1234);
+  testu(0x7fff,0xffff);
+  testu(0xffff,0x7fff);
+#endif
+
+  return 0;
+}
+
diff --git a/gcc/testsuite/gcc.c-torture/execute/20040409-2.c b/gcc/testsuite/gcc.c-torture/execute/20040409-2.c
new file mode 100644
index 0000000..5bec7ee
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20040409-2.c
@@ -0,0 +1,243 @@
+#include <limits.h>
+
+extern void abort ();
+
+int test1(int x)
+{
+  return (x ^ INT_MIN) ^ 0x1234;
+}
+
+unsigned int test1u(unsigned int x)
+{
+  return (x ^ (unsigned int)INT_MIN) ^ 0x1234;
+}
+
+int test2(int x)
+{
+  return (x ^ 0x1234) ^ INT_MIN;
+}
+
+unsigned int test2u(unsigned int x)
+{
+  return (x ^ 0x1234) ^ (unsigned int)INT_MIN;
+}
+
+int test3(int x)
+{
+  return (x + INT_MIN) ^ 0x1234;
+}
+
+unsigned int test3u(unsigned int x)
+{
+  return (x + (unsigned int)INT_MIN) ^ 0x1234;
+}
+
+int test4(int x)
+{
+  return (x ^ 0x1234) + INT_MIN;
+}
+
+unsigned int test4u(unsigned int x)
+{
+  return (x ^ 0x1234) + (unsigned int)INT_MIN;
+}
+
+int test5(int x)
+{
+  return (x - INT_MIN) ^ 0x1234;
+}
+
+unsigned int test5u(unsigned int x)
+{
+  return (x - (unsigned int)INT_MIN) ^ 0x1234;
+}
+
+int test6(int x)
+{
+  return (x ^ 0x1234) - INT_MIN;
+}
+
+unsigned int test6u(unsigned int x)
+{
+  return (x ^ 0x1234) - (unsigned int)INT_MIN;
+}
+
+int test7(int x)
+{
+  int y = INT_MIN;
+  int z = 0x1234;
+  return (x ^ y) ^ z;
+}
+
+unsigned int test7u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  unsigned int z = 0x1234;
+  return (x ^ y) ^ z;
+}
+
+int test8(int x)
+{
+  int y = 0x1234;
+  int z = INT_MIN;
+  return (x ^ y) ^ z;
+}
+
+unsigned int test8u(unsigned int x)
+{
+  unsigned int y = 0x1234;
+  unsigned int z = (unsigned int)INT_MIN;
+  return (x ^ y) ^ z;
+}
+
+int test9(int x)
+{
+  int y = INT_MIN;
+  int z = 0x1234;
+  return (x + y) ^ z;
+}
+
+unsigned int test9u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  unsigned int z = 0x1234;
+  return (x + y) ^ z;
+}
+
+int test10(int x)
+{
+  int y = 0x1234;
+  int z = INT_MIN;
+  return (x ^ y) + z;
+}
+
+unsigned int test10u(unsigned int x)
+{
+  unsigned int y = 0x1234;
+  unsigned int z = (unsigned int)INT_MIN;
+  return (x ^ y) + z;
+}
+
+int test11(int x)
+{
+  int y = INT_MIN;
+  int z = 0x1234;
+  return (x - y) ^ z;
+}
+
+unsigned int test11u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  unsigned int z = 0x1234;
+  return (x - y) ^ z;
+}
+
+int test12(int x)
+{
+  int y = 0x1234;
+  int z = INT_MIN;
+  return (x ^ y) - z;
+}
+
+unsigned int test12u(unsigned int x)
+{
+  unsigned int y = 0x1234;
+  unsigned int z = (unsigned int)INT_MIN;
+  return (x ^ y) - z;
+}
+
+
+void test(int a, int b)
+{
+  if (test1(a) != b)
+    abort();
+  if (test2(a) != b)
+    abort();
+  if (test3(a) != b)
+    abort();
+  if (test4(a) != b)
+    abort();
+  if (test5(a) != b)
+    abort();
+  if (test6(a) != b)
+    abort();
+  if (test7(a) != b)
+    abort();
+  if (test8(a) != b)
+    abort();
+  if (test9(a) != b)
+    abort();
+  if (test10(a) != b)
+    abort();
+  if (test11(a) != b)
+    abort();
+  if (test12(a) != b)
+    abort();
+}
+
+void testu(unsigned int a, unsigned int b)
+{
+  if (test1u(a) != b)
+    abort();
+  if (test2u(a) != b)
+    abort();
+  if (test3u(a) != b)
+    abort();
+  if (test4u(a) != b)
+    abort();
+  if (test5u(a) != b)
+    abort();
+  if (test6u(a) != b)
+    abort();
+  if (test7u(a) != b)
+    abort();
+  if (test8u(a) != b)
+    abort();
+  if (test9u(a) != b)
+    abort();
+  if (test10u(a) != b)
+    abort();
+  if (test11u(a) != b)
+    abort();
+  if (test12u(a) != b)
+    abort();
+}
+
+
+int main()
+{
+#if INT_MAX == 2147483647
+  test(0x00000000,0x80001234);
+  test(0x00001234,0x80000000);
+  test(0x80000000,0x00001234);
+  test(0x80001234,0x00000000);
+  test(0x7fffffff,0xffffedcb);
+  test(0xffffffff,0x7fffedcb);
+
+  testu(0x00000000,0x80001234);
+  testu(0x00001234,0x80000000);
+  testu(0x80000000,0x00001234);
+  testu(0x80001234,0x00000000);
+  testu(0x7fffffff,0xffffedcb);
+  testu(0xffffffff,0x7fffedcb);
+#endif
+
+#if INT_MAX == 32767
+  test(0x0000,0x9234);
+  test(0x1234,0x8000);
+  test(0x8000,0x1234);
+  test(0x9234,0x0000);
+  test(0x7fff,0xffff);
+  test(0xffff,0x7fff);
+
+  testu(0x0000,0x8000);
+  testu(0x8000,0x0000);
+  testu(0x1234,0x9234);
+  testu(0x9234,0x1234);
+  testu(0x7fff,0xedcb);
+  testu(0xffff,0x6dcb);
+#endif
+
+  return 0;
+}
+
diff --git a/gcc/testsuite/gcc.c-torture/execute/20040409-3.c b/gcc/testsuite/gcc.c-torture/execute/20040409-3.c
new file mode 100644
index 0000000..07aa99c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20040409-3.c
@@ -0,0 +1,142 @@
+#include <limits.h>
+
+extern void abort ();
+
+int test1(int x)
+{
+  return ~(x ^ INT_MIN);
+}
+
+unsigned int test1u(unsigned int x)
+{
+  return ~(x ^ (unsigned int)INT_MIN);
+}
+
+int test2(int x)
+{
+  return ~(x + INT_MIN);
+}
+
+unsigned int test2u(unsigned int x)
+{
+  return ~(x + (unsigned int)INT_MIN);
+}
+
+int test3(int x)
+{
+  return ~(x - INT_MIN);
+}
+
+unsigned int test3u(unsigned int x)
+{
+  return ~(x - (unsigned int)INT_MIN);
+}
+
+int test4(int x)
+{
+  int y = INT_MIN;
+  return ~(x ^ y);
+}
+
+unsigned int test4u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return ~(x ^ y);
+}
+
+int test5(int x)
+{
+  int y = INT_MIN;
+  return ~(x + y);
+}
+
+unsigned int test5u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return ~(x + y);
+}
+
+int test6(int x)
+{
+  int y = INT_MIN;
+  return ~(x - y);
+}
+
+unsigned int test6u(unsigned int x)
+{
+  unsigned int y = (unsigned int)INT_MIN;
+  return ~(x - y);
+}
+
+
+
+void test(int a, int b)
+{
+  if (test1(a) != b)
+    abort();
+  if (test2(a) != b)
+    abort();
+  if (test3(a) != b)
+    abort();
+  if (test4(a) != b)
+    abort();
+  if (test5(a) != b)
+    abort();
+  if (test6(a) != b)
+    abort();
+}
+
+void testu(unsigned int a, unsigned int b)
+{
+  if (test1u(a) != b)
+    abort();
+  if (test2u(a) != b)
+    abort();
+  if (test3u(a) != b)
+    abort();
+  if (test4u(a) != b)
+    abort();
+  if (test5u(a) != b)
+    abort();
+  if (test6u(a) != b)
+    abort();
+}
+
+
+int main()
+{
+#if INT_MAX == 2147483647
+  test(0x00000000,0x7fffffff);
+  test(0x80000000,0xffffffff);
+  test(0x12345678,0x6dcba987);
+  test(0x92345678,0xedcba987);
+  test(0x7fffffff,0x00000000);
+  test(0xffffffff,0x80000000);
+
+  testu(0x00000000,0x7fffffff);
+  testu(0x80000000,0xffffffff);
+  testu(0x12345678,0x6dcba987);
+  testu(0x92345678,0xedcba987);
+  testu(0x7fffffff,0x00000000);
+  testu(0xffffffff,0x80000000);
+#endif
+
+#if INT_MAX == 32767
+  test(0x0000,0x7fff);
+  test(0x8000,0xffff);
+  test(0x1234,0x6dcb);
+  test(0x9234,0xedcb);
+  test(0x7fff,0x0000);
+  test(0xffff,0x8000);
+
+  testu(0x0000,0x7fff);
+  testu(0x8000,0xffff);
+  testu(0x1234,0x6dcb);
+  testu(0x9234,0xedcb);
+  testu(0x7fff,0x0000);
+  testu(0xffff,0x8000);
+#endif
+
+  return 0;
+}
+