RISC-V: Fix bugs for refine vsetvl a5, zero into vsetvl zero, zero incorrectly

From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

Currently we support this optimization:

bb 0:
 vsetvli a5,zero,e32,mf2
bb 1:
 vsetvli a5,zero,e64,m1 --> vsetvli zero,zero,e64,m1

According RVV ISA, we can do this optimization only if both RATIO and AVL are equal.
However, current VSETVL PASS missed the check of AVL. This patch add this condition
check to fix bugs.

gcc/ChangeLog:

        * config/riscv/riscv-vsetvl.cc (vector_infos_manager::all_same_avl_p): New function.
        (pass_vsetvl::can_refine_vsetvl_p): Add AVL check.
        (pass_vsetvl::commit_vsetvls): Ditto.
        * config/riscv/riscv-vsetvl.h: New function declaration.
 
---
 gcc/config/riscv/riscv-vsetvl.cc | 35 ++++++++++++++++++++++++++++----
 gcc/config/riscv/riscv-vsetvl.h  |  3 +++
 2 files changed, 34 insertions(+), 4 deletions(-)

committed, thanks.

On Tue, Jan 3, 2023 at 2:56 PM <juzhe.zhong@rivai.ai> wrote:

> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
>
> Currently we support this optimization:
>
> bb 0:
>  vsetvli a5,zero,e32,mf2
> bb 1:
>  vsetvli a5,zero,e64,m1 --> vsetvli zero,zero,e64,m1
>
> According RVV ISA, we can do this optimization only if both RATIO and AVL
> are equal.
> However, current VSETVL PASS missed the check of AVL. This patch add this
> condition
> check to fix bugs.
>
> gcc/ChangeLog:
>
>         * config/riscv/riscv-vsetvl.cc
> (vector_infos_manager::all_same_avl_p): New function.
>         (pass_vsetvl::can_refine_vsetvl_p): Add AVL check.
>         (pass_vsetvl::commit_vsetvls): Ditto.
>         * config/riscv/riscv-vsetvl.h: New function declaration.
>
> ---
>  gcc/config/riscv/riscv-vsetvl.cc | 35 ++++++++++++++++++++++++++++----
>  gcc/config/riscv/riscv-vsetvl.h  |  3 +++
>  2 files changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/config/riscv/riscv-vsetvl.cc
> b/gcc/config/riscv/riscv-vsetvl.cc
> index ce1e9e3609f..1afe76304fb 100644
> --- a/gcc/config/riscv/riscv-vsetvl.cc
> +++ b/gcc/config/riscv/riscv-vsetvl.cc
> @@ -1440,6 +1440,29 @@ vector_infos_manager::all_same_ratio_p (sbitmap
> bitdata) const
>    return true;
>  }
>
> +bool
> +vector_infos_manager::all_same_avl_p (const basic_block cfg_bb,
> +                                     sbitmap bitdata) const
> +{
> +  if (bitmap_empty_p (bitdata))
> +    return false;
> +
> +  const auto &block_info = vector_block_infos[cfg_bb->index];
> +  if (!block_info.local_dem.demand_p (DEMAND_AVL))
> +    return true;
> +
> +  avl_info avl = block_info.local_dem.get_avl_info ();
> +  unsigned int bb_index;
> +  sbitmap_iterator sbi;
> +
> +  EXECUTE_IF_SET_IN_BITMAP (bitdata, 0, bb_index, sbi)
> +  {
> +    if (vector_exprs[bb_index]->get_avl_info () != avl)
> +      return false;
> +  }
> +  return true;
> +}
> +
>  size_t
>  vector_infos_manager::expr_set_num (sbitmap bitdata) const
>  {
> @@ -2113,6 +2136,10 @@ pass_vsetvl::can_refine_vsetvl_p (const basic_block
> cfg_bb, uint8_t ratio) const
>         m_vector_manager->vector_avin[cfg_bb->index]))
>      return false;
>
> +  if (!m_vector_manager->all_same_avl_p (
> +       cfg_bb, m_vector_manager->vector_avin[cfg_bb->index]))
> +    return false;
> +
>    size_t expr_id
>      = bitmap_first_set_bit (m_vector_manager->vector_avin[cfg_bb->index]);
>    if (m_vector_manager->vector_exprs[expr_id]->get_ratio () != ratio)
> @@ -2227,11 +2254,11 @@ pass_vsetvl::commit_vsetvls (void)
>
>               insn_info *insn = require->get_insn ();
>               vector_insn_info prev_info = vector_insn_info ();
> -             if (m_vector_manager->all_same_ratio_p (
> -                   m_vector_manager->vector_avout[eg->src->index]))
> +             sbitmap bitdata =
> m_vector_manager->vector_avout[eg->src->index];
> +             if (m_vector_manager->all_same_ratio_p (bitdata)
> +                 && m_vector_manager->all_same_avl_p (eg->dest, bitdata))
>                 {
> -                 size_t first = bitmap_first_set_bit (
> -                   m_vector_manager->vector_avout[eg->src->index]);
> +                 size_t first = bitmap_first_set_bit (bitdata);
>                   prev_info = *m_vector_manager->vector_exprs[first];
>                 }
>
> diff --git a/gcc/config/riscv/riscv-vsetvl.h
> b/gcc/config/riscv/riscv-vsetvl.h
> index 6f27004fab1..c8218a6ff00 100644
> --- a/gcc/config/riscv/riscv-vsetvl.h
> +++ b/gcc/config/riscv/riscv-vsetvl.h
> @@ -333,6 +333,9 @@ public:
>    /* Get all relaxer expression id for corresponding vector info.  */
>    auto_vec<size_t> get_all_available_exprs (const vector_insn_info &)
> const;
>
> +  /* Return true if all expression set in bitmap are same AVL.  */
> +  bool all_same_avl_p (const basic_block, sbitmap) const;
> +
>    /* Return true if all expression set in bitmap are same ratio.  */
>    bool all_same_ratio_p (sbitmap) const;
>
> --
> 2.36.3
>
>