On Mon, Jun 28, 2021 at 1:26 AM apinski--- via Gcc-patches
<[email protected]> wrote:
>
> From: Andrew Pinski <[email protected]>
>
> Since match_simplify_replacement uses gimple_simplify, there is a new
> ssa name created sometimes and then we go and replace the phi edge with
> this new ssa name, the range information on the phi is lost.
> Placing this in replace_phi_edge_with_variable is the best option instead
> of doing it in each time replace_phi_edge_with_variable is called which is
> what is done today.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.c (replace_phi_edge_with_variable): Duplicate range
> info if we're the only things setting the target PHI.
> (value_replacement): Don't duplicate range here.
> (minmax_replacement): Likewise.
> ---
> gcc/tree-ssa-phiopt.c | 43 ++++++++++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
> index 1777bff2f7c..ab12e85569d 100644
> --- a/gcc/tree-ssa-phiopt.c
> +++ b/gcc/tree-ssa-phiopt.c
> @@ -391,6 +391,32 @@ replace_phi_edge_with_variable (basic_block cond_block,
> basic_block bb = gimple_bb (phi);
> basic_block block_to_remove;
> gimple_stmt_iterator gsi;
> + tree phi_result = PHI_RESULT (phi);
> +
> + /* Duplicate range info if we're the only things setting the target PHI.
> + This is needed as later on, the new_tree will be replacing
> + The assignement of the PHI.
> + For an example:
> + bb1:
> + _4 = min<a_1, 255>
> + goto bb2
> +
> + range<-INF,255>
> + a_3 = PHI<_4(1)>
> + bb3:
> +
> + use(a_3)
> + And _4 gets prograted into the use of a_3 and losing the range info.
> + This can't be done for more than 2 incoming edges as the progration
> + won't happen. */
> + if (TREE_CODE (new_tree) == SSA_NAME
> + && EDGE_COUNT (gimple_bb (phi)->preds) == 2
> + && INTEGRAL_TYPE_P (TREE_TYPE (phi_result))
> + && !SSA_NAME_RANGE_INFO (new_tree)
> + && SSA_NAME_RANGE_INFO (phi_result))
> + duplicate_ssa_name_range_info (new_tree,
> + SSA_NAME_RANGE_TYPE (phi_result),
> + SSA_NAME_RANGE_INFO (phi_result));
>
> /* Change the PHI argument to new. */
> SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
> @@ -1385,16 +1411,6 @@ value_replacement (basic_block cond_bb, basic_block
> middle_bb,
> <bb 4>:
> # u_3 = PHI <u_6(3), 4294967295(2)> */
> reset_flow_sensitive_info (lhs);
> - if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
> - {
> - /* If available, we can use VR of phi result at least. */
> - tree phires = gimple_phi_result (phi);
> - struct range_info_def *phires_range_info
> - = SSA_NAME_RANGE_INFO (phires);
> - if (phires_range_info)
> - duplicate_ssa_name_range_info (lhs, SSA_NAME_RANGE_TYPE (phires),
> - phires_range_info);
> - }
> gimple_stmt_iterator gsi_from;
> for (int i = prep_cnt - 1; i >= 0; --i)
> {
> @@ -1794,13 +1810,6 @@ minmax_replacement (basic_block cond_bb, basic_block
> middle_bb,
> gimple_seq stmts = NULL;
> tree phi_result = PHI_RESULT (phi);
> result = gimple_build (&stmts, minmax, TREE_TYPE (phi_result), arg0, arg1);
> - /* Duplicate range info if we're the only things setting the target PHI.
> */
> - if (!gimple_seq_empty_p (stmts)
> - && EDGE_COUNT (gimple_bb (phi)->preds) == 2
> - && !POINTER_TYPE_P (TREE_TYPE (phi_result))
> - && SSA_NAME_RANGE_INFO (phi_result))
> - duplicate_ssa_name_range_info (result, SSA_NAME_RANGE_TYPE (phi_result),
> - SSA_NAME_RANGE_INFO (phi_result));
>
> gsi = gsi_last_bb (cond_bb);
> gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT);
> --
> 2.27.0
>
