From: juzhe.zhong@rivai.ai
To: gcc-patches@gcc.gnu.org
Cc: kito.cheng@gmail.com, palmer@dabbelt.com,
Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
Subject: [PATCH] RISC-V: Add probability model of each block to prevent endless loop of Phase 3
Date: Tue, 10 Jan 2023 07:17:20 +0800 [thread overview]
Message-ID: <20230109231720.155773-1-juzhe.zhong@rivai.ai> (raw)
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
next reply other threads:[~2023-01-09 23:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-09 23:17 juzhe.zhong [this message]
2023-01-26 19:16 ` Kito Cheng
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