combine.c (num_sign_bit_copies): In NEG...

        * combine.c (num_sign_bit_copies): In NEG, MULT, DIV and MOD cases,
        when a test can't be performed due to limited width of
        HOST_BITS_PER_WIDE_INT, use the more conservative approximation.
        Fix UDIV case for cases where the first operand has the highest bit
        set.

From-SVN: r24547

gcc/ChangeLog

+Thu Jan  7 00:29:25 199  Bernd Schmidt <crux@pool.informatik.rwth-aachen.de>
+
+	* combine.c (num_sign_bit_copies): In NEG, MULT, DIV and MOD cases,
+	when a test can't be performed due to limited width of
+	HOST_BITS_PER_WIDE_INT, use the more conservative approximation.
+	Fix UDIV case for cases where the first operand has the highest bit
+	set.
+
 Thu Jan  7 00:01:38 1999  Lutz Vieweg <lkv@mania.robin.de>
 
 	* pa.h (reg_class): Add FPUPPER_REGS.

gcc/combine.c

@@ -8020,13 +8020,15 @@ num_sign_bit_copies (x, mode)
 	 is known to be positive, the number of sign bit copies is the
 	 same as that of the input.  Finally, if the input has just one bit
 	 that might be nonzero, all the bits are copies of the sign bit.  */
+      num0 = num_sign_bit_copies (XEXP (x, 0), mode);
+      if (bitwidth > HOST_BITS_PER_WIDE_INT)
+	return num0 > 1 ? num0 - 1 : 1;
+
       nonzero = nonzero_bits (XEXP (x, 0), mode);
       if (nonzero == 1)
 	return bitwidth;
 
-      num0 = num_sign_bit_copies (XEXP (x, 0), mode);
       if (num0 > 1
-	  && bitwidth <= HOST_BITS_PER_WIDE_INT
 	  && (((HOST_WIDE_INT) 1 << (bitwidth - 1)) & nonzero))
 	num0--;
 
@@ -8070,19 +8072,27 @@ num_sign_bit_copies (x, mode)
 
       result = bitwidth - (bitwidth - num0) - (bitwidth - num1);
       if (result > 0
-	  && bitwidth <= HOST_BITS_PER_WIDE_INT
-	  && ((nonzero_bits (XEXP (x, 0), mode)
-	       & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
-	  && ((nonzero_bits (XEXP (x, 1), mode)
-	      & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
+	  && (bitwidth > HOST_BITS_PER_WIDE_INT
+	      || (((nonzero_bits (XEXP (x, 0), mode)
+		    & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
+		  && ((nonzero_bits (XEXP (x, 1), mode)
+		       & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))))
 	result--;
 
       return MAX (1, result);
 
     case UDIV:
-      /* The result must be <= the first operand.  */
-      return num_sign_bit_copies (XEXP (x, 0), mode);
-
+      /* The result must be <= the first operand.  If the first operand
+         has the high bit set, we know nothing about the number of sign
+         bit copies.  */
+      if (bitwidth > HOST_BITS_PER_WIDE_INT)
+	return 1;
+      else if ((nonzero_bits (XEXP (x, 0), mode)
+		& ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
+	return 1;
+      else
+	return num_sign_bit_copies (XEXP (x, 0), mode);
+				    
     case UMOD:
       /* The result must be <= the scond operand.  */
       return num_sign_bit_copies (XEXP (x, 1), mode);
@@ -8093,20 +8103,20 @@ num_sign_bit_copies (x, mode)
 	 to add 1.  */
       result = num_sign_bit_copies (XEXP (x, 0), mode);
       if (result > 1
-	  && bitwidth <= HOST_BITS_PER_WIDE_INT
-	  && (nonzero_bits (XEXP (x, 1), mode)
-	      & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
-	result --;
+	  && (bitwidth > HOST_BITS_PER_WIDE_INT
+	      || (nonzero_bits (XEXP (x, 1), mode)
+		  & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
+	result--;
 
       return result;
 
     case MOD:
       result = num_sign_bit_copies (XEXP (x, 1), mode);
       if (result > 1
-	  && bitwidth <= HOST_BITS_PER_WIDE_INT
-	  && (nonzero_bits (XEXP (x, 1), mode)
-	      & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0)
-	result --;
+	  && (bitwidth > HOST_BITS_PER_WIDE_INT
+	      || (nonzero_bits (XEXP (x, 1), mode)
+		  & ((HOST_WIDE_INT) 1 << (bitwidth - 1))) != 0))
+	result--;
 
       return result;