On Wed, 21 Jun 2023, Richard Biener wrote:
> PR110243 shows strip_offset has some correctness issues, the following
> avoids using it from loop distribution which can use the more correct
> split_constant_offset from data-ref analysis instead. The patch then
> un-exports the function and refactors it to make it obvious the
> actual constant offset is only interesting in address-cases.
>
> The series is split, removing one strip_offset at a time for easier
> bisecting of code generation quality issues.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
>
> * tree-loop-distribution.cc (classify_builtin_st): Use
> split_constant_offset.
> * tree-ssa-loop-ivopts.h (strip_offset): Remove.
> * tree-ssa-loop-ivopts.cc (strip_offset): Make static.
> Refactor to make the offset operand optional and assert
> we are dealing with addresses if its required.
Just noticed this refactoring is a left-over and I edited it out of
this series, will push after re-bootstrapping.
Richard.
> ---
> gcc/tree-loop-distribution.cc | 9 +++++----
> gcc/tree-ssa-loop-ivopts.cc | 22 ++++++++++++++--------
> gcc/tree-ssa-loop-ivopts.h | 1 -
> 3 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/gcc/tree-loop-distribution.cc b/gcc/tree-loop-distribution.cc
> index 6291f941a21..cf7c197aaf7 100644
> --- a/gcc/tree-loop-distribution.cc
> +++ b/gcc/tree-loop-distribution.cc
> @@ -1756,11 +1756,12 @@ classify_builtin_st (loop_p loop, partition
> *partition, data_reference_p dr)
> return;
> }
>
> - poly_uint64 base_offset;
> - unsigned HOST_WIDE_INT const_base_offset;
> - tree base_base = strip_offset (base, &base_offset);
> - if (!base_offset.is_constant (&const_base_offset))
> + tree base_offset;
> + tree base_base;
> + split_constant_offset (base, &base_base, &base_offset);
> + if (!cst_and_fits_in_hwi (base_offset))
> return;
> + unsigned HOST_WIDE_INT const_base_offset = int_cst_value (base_offset);
>
> struct builtin_info *builtin;
> builtin = alloc_builtin (dr, NULL, base, NULL_TREE, size);
> diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc
> index 6fbd2d59318..7978c80b39e 100644
> --- a/gcc/tree-ssa-loop-ivopts.cc
> +++ b/gcc/tree-ssa-loop-ivopts.cc
> @@ -1175,6 +1175,9 @@ contain_complex_addr_expr (tree expr)
> return res;
> }
>
> +static tree
> +strip_offset (tree expr, poly_uint64_pod *offset = nullptr);
> +
> /* Allocates an induction variable with given initial value BASE and step
> STEP
> for loop LOOP. NO_OVERFLOW implies the iv doesn't overflow. */
>
> @@ -2942,12 +2945,16 @@ strip_offset_1 (tree expr, bool inside_addr, bool
> top_compref,
>
> /* Strips constant offsets from EXPR and stores them to OFFSET. */
>
> -tree
> +static tree
> strip_offset (tree expr, poly_uint64_pod *offset)
> {
> poly_int64 off;
> tree core = strip_offset_1 (expr, false, false, &off);
> - *offset = off;
> + if (offset)
> + {
> + gcc_assert (POINTER_TYPE_P (expr));
> + *offset = off;
> + }
> return core;
> }
>
> @@ -3512,7 +3519,6 @@ add_iv_candidate_derived_from_uses (struct ivopts_data
> *data)
> static void
> add_iv_candidate_for_use (struct ivopts_data *data, struct iv_use *use)
> {
> - poly_uint64 offset;
> tree base;
> struct iv *iv = use->iv;
> tree basetype = TREE_TYPE (iv->base);
> @@ -3563,8 +3569,8 @@ add_iv_candidate_for_use (struct ivopts_data *data,
> struct iv_use *use)
>
> /* Record common candidate with constant offset stripped in base.
> Like the use itself, we also add candidate directly for it. */
> - base = strip_offset (iv->base, &offset);
> - if (maybe_ne (offset, 0U) || base != iv->base)
> + base = strip_offset (iv->base);
> + if (base != iv->base)
> {
> record_common_cand (data, base, iv->step, use);
> add_candidate (data, base, iv->step, false, use);
> @@ -3582,9 +3588,9 @@ add_iv_candidate_for_use (struct ivopts_data *data,
> struct iv_use *use)
> step = fold_convert (sizetype, step);
> record_common_cand (data, base, step, use);
> /* Also record common candidate with offset stripped. */
> - base = strip_offset (base, &offset);
> - if (maybe_ne (offset, 0U))
> - record_common_cand (data, base, step, use);
> + tree alt_base = strip_offset (base);
> + if (alt_base != base)
> + record_common_cand (data, alt_base, step, use);
> }
>
> /* At last, add auto-incremental candidates. Make such variables
> diff --git a/gcc/tree-ssa-loop-ivopts.h b/gcc/tree-ssa-loop-ivopts.h
> index 95148616e70..7a53ce47f10 100644
> --- a/gcc/tree-ssa-loop-ivopts.h
> +++ b/gcc/tree-ssa-loop-ivopts.h
> @@ -28,7 +28,6 @@ extern void dump_cand (FILE *, struct iv_cand *);
> extern bool contains_abnormal_ssa_name_p (tree);
> extern class loop *outermost_invariant_loop_for_expr (class loop *, tree);
> extern bool expr_invariant_in_loop_p (class loop *, tree);
> -extern tree strip_offset (tree, poly_uint64_pod *);
> bool may_be_nonaddressable_p (tree expr);
> void tree_ssa_iv_optimize (void);
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
