On Tue, Jan 02, 2018 at 05:39:17PM +0530, Prathamesh Kulkarni wrote:
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr82665.c
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +void f1 (char *p, __SIZE_TYPE__ sz)
> +{
> + char *q = __builtin_memchr (p, 0, sz);
> + long n = q - p;
Please use __PTRDIFF_TYPE__ instead of long, here and in other spots.
> --- a/gcc/vr-values.c
> +++ b/gcc/vr-values.c
> @@ -793,6 +793,42 @@ vr_values::extract_range_from_binary_expr (value_range
> *vr,
>
> extract_range_from_binary_expr_1 (vr, code, expr_type, &vr0, &vr1);
>
> + /* Set value_range for n in following sequence:
> + def = __builtin_memchr (arg, 0, sz)
> + n = def - arg
> + Here the range for n can be set to [0, PTRDIFF_MAX - 1]. */
> +
> + if (vr->type == VR_VARYING
> + && (code == POINTER_DIFF_EXPR)
> + && (TREE_CODE (op0) == SSA_NAME)
> + && (TREE_CODE (op1) == SSA_NAME))
Please drop the useless ()s around the comparisons. They are needed
only if the condition is multi-line and needed for emacs indentation,
or around assignments tested as conditions.
> + gcall *call_stmt = NULL;
> + if (def && arg
> + && (TREE_CODE (def) == SSA_NAME)
Likewise (many times).
> + && ((TREE_CODE (TREE_TYPE (def)) == POINTER_TYPE)
> + && (TREE_TYPE (TREE_TYPE (def)) == char_type_node))
> + && (TREE_CODE (arg) == SSA_NAME)
> + && ((TREE_CODE (TREE_TYPE (arg)) == POINTER_TYPE)
> + && (TREE_TYPE (TREE_TYPE (arg)) == char_type_node))
What is so special about char_type_node? Why e.g. unsigned char or signed
char pointer shouldn't be handled the same?
> + && (call_stmt = dyn_cast<gcall *>(SSA_NAME_DEF_STMT (def)))
> + && (gimple_call_combined_fn (call_stmt) == CFN_BUILT_IN_MEMCHR)
We don't have an ifn for memchr, so why this? On the other side, it should
be making sure one doesn't use unprototyped memchr with weirdo argument
types, so you need gimple_call_builtin_p.
> + && operand_equal_p (def, gimple_call_lhs (call_stmt), 0)
> + && operand_equal_p (arg, gimple_call_arg (call_stmt, 0), 0)
> + && integer_zerop (gimple_call_arg (call_stmt, 1)))
> + {
> + tree max = vrp_val_max (ptrdiff_type_node);
> + wide_int wmax = wi::to_wide (max, TYPE_PRECISION (TREE_TYPE
> (max)));
> + tree range_min = build_zero_cst (expr_type);
> + tree range_max = wide_int_to_tree (expr_type, wmax - 1);
> + set_value_range (vr, VR_RANGE, range_min, range_max, NULL);
> + return;
> + }
> + }
> +
> /* Try harder for PLUS and MINUS if the range of one operand is symbolic
> and based on the other operand, for example if it was deduced from a
> symbolic comparison. When a bound of the range of the first operand
Jakub
