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Re: [RFA][PATCH] Improve VRP of COND_EXPR_CONDs -- v2
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 9 Apr 2013 11:03:08 +0200
- Subject: Re: [RFA][PATCH] Improve VRP of COND_EXPR_CONDs -- v2
- References: <516374E3 dot 8080800 at redhat dot com>
On Tue, Apr 9, 2013 at 3:54 AM, Jeff Law <law@redhat.com> wrote:
>
> This incorporates the concrete suggestions from Steven & Richi -- it doesn't
> do any refactoring of the VRP code. There's still stuff I'm looking at that
> might directly lead to some refactoring. In the mean time I'm submitting
> the obvious small improvements.
>
> Bootstrapped and regression tested on x86_64-unknown-linux-gnu.
>
> OK for trunk?
Ok.
Thanks,
Richard.
> Jeff
>
> commit d6d1e36561b9022bbcdf157a886895f5bb0ef2ae
> Author: Jeff Law <law@redhat.com>
> Date: Sat Apr 6 06:46:58 2013 -0600
>
> * tree-vrp.c (simplify_cond_using_ranges): Simplify test of
> boolean
> when the boolean was created by converting a wider object which
> had a boolean range.
>
> * gcc.dg/tree-ssa/vrp87.c: New test
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 6ee7d9c..110f61e 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -16,8 +16,14 @@
>
> 2013-04-08 Jeff Law <law@redhat.com>
>
> + * tree-vrp.c (simplify_cond_using_ranges): Simplify test of boolean
> + when the boolean was created by converting a wider object which
> + had a boolean range.
> +
> +2013-04-08 Jeff Law <law@redhat.com>
> +
> * gimple.c (canonicalize_cond_expr_cond): Rewrite x ^ y into x != y.
> -
> +
> 2013-04-08 Richard Biener <rguenther@suse.de>
>
> * gimple-pretty-print.c (debug_gimple_stmt): Do not print
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp87.c
> b/gcc/testsuite/gcc.dg/tree-ssa/vrp87.c
> new file mode 100644
> index 0000000..7feff81
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp87.c
> @@ -0,0 +1,81 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-vrp2-details -fdump-tree-cddce2-details" }
> */
> +
> +struct bitmap_head_def;
> +typedef struct bitmap_head_def *bitmap;
> +typedef const struct bitmap_head_def *const_bitmap;
> +
> +
> +typedef unsigned long BITMAP_WORD;
> +typedef struct bitmap_element_def
> +{
> + struct bitmap_element_def *next;
> + unsigned int indx;
> + BITMAP_WORD bits[((128 + (8 * 8 * 1u) - 1) / (8 * 8 * 1u))];
> +} bitmap_element;
> +
> +
> +
> +
> +
> +
> +typedef struct bitmap_head_def
> +{
> + bitmap_element *first;
> +
> +} bitmap_head;
> +
> +
> +
> +static __inline__ unsigned char
> +bitmap_elt_ior (bitmap dst, bitmap_element * dst_elt,
> + bitmap_element * dst_prev, const bitmap_element * a_elt,
> + const bitmap_element * b_elt, unsigned char changed)
> +{
> +
> + if (a_elt)
> + {
> +
> + if (!changed && dst_elt)
> + {
> + changed = 1;
> + }
> + }
> + else
> + {
> + changed = 1;
> + }
> + return changed;
> +}
> +
> +unsigned char
> +bitmap_ior_into (bitmap a, const_bitmap b)
> +{
> + bitmap_element *a_elt = a->first;
> + const bitmap_element *b_elt = b->first;
> + bitmap_element *a_prev = ((void *) 0);
> + unsigned char changed = 0;
> +
> + while (b_elt)
> + {
> +
> + if (!a_elt || a_elt->indx == b_elt->indx)
> + changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt, b_elt, changed);
> + else if (a_elt->indx > b_elt->indx)
> + changed = 1;
> + b_elt = b_elt->next;
> +
> +
> + }
> +
> + return changed;
> +}
> +
> +/* Verify that VRP simplified an "if" statement. */
> +/* { dg-final { scan-tree-dump "Folded into: if.*" "vrp2"} } */
> +/* Verify that DCE after VRP2 eliminates a dead conversion
> + to a (Bool). */
> +/* { dg-final { scan-tree-dump "Deleting.*_Bool.*;" "cddce2"} } */
> +/* { dg-final { cleanup-tree-dump "vrp2" } } */
> +/* { dg-final { cleanup-tree-dump "cddce2" } } */
> +
> diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
> index 250a506..4520c89 100644
> --- a/gcc/tree-vrp.c
> +++ b/gcc/tree-vrp.c
> @@ -8584,6 +8584,45 @@ simplify_cond_using_ranges (gimple stmt)
> }
> }
>
> + /* If we have a comparison of a SSA_NAME boolean against
> + a constant (which obviously must be [0..1]), see if the
> + SSA_NAME was set by a type conversion where the source
> + of the conversion is another SSA_NAME with a range [0..1].
> +
> + If so, we can replace the SSA_NAME in the comparison with
> + the RHS of the conversion. This will often make the type
> + conversion dead code which DCE will clean up. */
> + if (TREE_CODE (op0) == SSA_NAME
> + && (TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
> + || (INTEGRAL_TYPE_P (TREE_TYPE (op))
> + && TYPE_PRECISION (TREE_TYPE (op0)) == 1))
> + && TREE_CODE (op1) == INTEGER_CST)
> + {
> + gimple def_stmt = SSA_NAME_DEF_STMT (op0);
> + tree innerop;
> +
> + if (!is_gimple_assign (def_stmt)
> + || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
> + return false;
> +
> + innerop = gimple_assign_rhs1 (def_stmt);
> +
> + if (TREE_CODE (innerop) == SSA_NAME)
> + {
> + value_range_t *vr = get_value_range (innerop);
> +
> + if (range_int_cst_p (vr)
> + && operand_equal_p (vr->min, integer_zero_node, 0)
> + && operand_equal_p (vr->max, integer_one_node, 0))
> + {
> + tree newconst = fold_convert (TREE_TYPE (innerop), op1);
> + gimple_cond_set_lhs (stmt, innerop);
> + gimple_cond_set_rhs (stmt, newconst);
> + return true;
> + }
> + }
> + }
> +
> return false;
> }
>
>