[PATCH, rtl-optimization]: Fix PR37997: ICE shifting byte to the right with constant > 7FFFFFFF

[Eric Botcazou]

> 0x7fffffff is signed, 0x80000000 unsigned; other than that, no.

OK, the (int) v1 >> 0x80000000 is shortened to "char" in build_binary_op:

	  if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
	      /* We can shorten only if the shift count is less than the
		 number of bits in the smaller type size.  */
	      && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
	      /* We cannot drop an unsigned shift after sign-extension.  */
	      && (!TYPE_UNSIGNED (final_type) || unsigned_arg))
	    {
	      /* Do an unsigned shift if the operand was zero-extended.  */
	      result_type
		= c_common_signed_or_unsigned_type (unsigned_arg,
						    TREE_TYPE (arg0));
	      /* Convert value-to-be-shifted to that type.  */
	      if (TREE_TYPE (op0) != result_type)
		op0 = convert (result_type, op0);
	      converted = 1;
	    }

because

  compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0

return true since op1 is -2147483648.

It seems to me that the problem should be fixed there.

-- 
Eric Botcazou