From: Kito Cheng <kito.cheng@gmail.com>
To: juzhe.zhong@rivai.ai
Cc: gcc-patches@gcc.gnu.org, palmer@dabbelt.com
Subject: Re: [PATCH] RISC-V: Add probability model of each block to prevent endless loop of Phase 3
Date: Fri, 27 Jan 2023 03:16:48 +0800 [thread overview]
Message-ID: <CA+yXCZAuJQ35zC_HJUhmUMx_MGbX4OufRtPdq56TzEPpnVyLFQ@mail.gmail.com> (raw)
In-Reply-To: <20230109231720.155773-1-juzhe.zhong@rivai.ai>
[-- Attachment #1: Type: text/plain, Size: 3857 bytes --]
committed, thanks.
On Tue, Jan 10, 2023 at 7:17 AM <juzhe.zhong@rivai.ai> wrote:
> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
>
> Notice that the PASS is just simpily pick the probability >= 50%
> to do the backward fusion which will create endless loop on Phase 3.
>
> Adding this probability to fix this bug.
> gcc/ChangeLog:
>
> * config/riscv/riscv-vsetvl.cc
> (vector_infos_manager::vector_infos_manager): Add probability.
> (vector_infos_manager::dump): Ditto.
> (pass_vsetvl::compute_probabilities): Ditto.
> * config/riscv/riscv-vsetvl.h (struct vector_block_info): Ditto.
>
> ---
> gcc/config/riscv/riscv-vsetvl.cc | 39 ++++++++++++++++++++++++++++++++
> gcc/config/riscv/riscv-vsetvl.h | 3 +++
> 2 files changed, 42 insertions(+)
>
> diff --git a/gcc/config/riscv/riscv-vsetvl.cc
> b/gcc/config/riscv/riscv-vsetvl.cc
> index 0f12d4ddb23..7d8c3a32aaa 100644
> --- a/gcc/config/riscv/riscv-vsetvl.cc
> +++ b/gcc/config/riscv/riscv-vsetvl.cc
> @@ -1465,6 +1465,7 @@ vector_infos_manager::vector_infos_manager ()
> vector_block_infos[bb->index ()].reaching_out = vector_insn_info
> ();
> for (insn_info *insn : bb->real_insns ())
> vector_insn_infos[insn->uid ()].parse_insn (insn);
> + vector_block_infos[bb->index ()].probability =
> profile_probability ();
> }
> }
> }
> @@ -1642,6 +1643,8 @@ vector_infos_manager::dump (FILE *file) const
> }
> fprintf (file, "<FOOTER>=");
> vector_block_infos[cfg_bb->index].reaching_out.dump (file);
> + fprintf (file, "<Probability>=");
> + vector_block_infos[cfg_bb->index].probability.dump (file);
> fprintf (file, "\n\n");
> }
>
> @@ -1764,6 +1767,7 @@ private:
>
> void init (void);
> void done (void);
> + void compute_probabilities (void);
>
> public:
> pass_vsetvl (gcc::context *ctxt) : rtl_opt_pass (pass_data_vsetvl,
> ctxt) {}
> @@ -2629,6 +2633,41 @@ pass_vsetvl::done (void)
> m_vector_manager = nullptr;
> }
>
> +/* Compute probability for each block. */
> +void
> +pass_vsetvl::compute_probabilities (void)
> +{
> + /* Don't compute it in -O0 since we don't need it. */
> + if (!optimize)
> + return;
> + edge e;
> + edge_iterator ei;
> +
> + for (const bb_info *bb : crtl->ssa->bbs ())
> + {
> + basic_block cfg_bb = bb->cfg_bb ();
> + auto &curr_prob
> + = m_vector_manager->vector_block_infos[cfg_bb->index].probability;
> + if (ENTRY_BLOCK_PTR_FOR_FN (cfun) == cfg_bb)
> + curr_prob = profile_probability::always ();
> + gcc_assert (curr_prob.initialized_p ());
> + FOR_EACH_EDGE (e, ei, cfg_bb->succs)
> + {
> + auto &new_prob
> + =
> m_vector_manager->vector_block_infos[e->dest->index].probability;
> + if (!new_prob.initialized_p ())
> + new_prob = curr_prob * e->probability;
> + else if (new_prob == profile_probability::always ())
> + continue;
> + else
> + new_prob += curr_prob * e->probability;
> + }
> + }
> + auto &exit_block
> + = m_vector_manager->vector_block_infos[EXIT_BLOCK_PTR_FOR_FN
> (cfun)->index];
> + exit_block.probability = profile_probability::always ();
> +}
> +
> /* Lazy vsetvl insertion for optimize > 0. */
> void
> pass_vsetvl::lazy_vsetvl (void)
> diff --git a/gcc/config/riscv/riscv-vsetvl.h
> b/gcc/config/riscv/riscv-vsetvl.h
> index 563ad3084ed..fb3ebb9db79 100644
> --- a/gcc/config/riscv/riscv-vsetvl.h
> +++ b/gcc/config/riscv/riscv-vsetvl.h
> @@ -291,6 +291,9 @@ struct vector_block_info
> /* The reaching_out vector insn_info of the block. */
> vector_insn_info reaching_out;
>
> + /* The static execute probability of the demand info. */
> + profile_probability probability;
> +
> vector_block_info () = default;
> };
>
> --
> 2.36.1
>
>
prev parent reply other threads:[~2023-01-26 19:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-09 23:17 juzhe.zhong
2023-01-26 19:16 ` Kito Cheng [this message]
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