The first level is ordinary clone, corresponding to a non-self caller,
and the param_ipa_cp_max_recursive_depth-1 is for recursive cloning.
Then it's ok that the least value is 1, with which disabling does happen.
Feng
________________________________________
From: luoxhu <luo...@linux.ibm.com>
Sent: Tuesday, December 31, 2019 3:43 PM
To: Feng Xue OS; Jan Hubicka; Martin Jambor
Cc: Martin Liška; gcc-patches@gcc.gnu.org; seg...@kernel.crashing.org;
wschm...@linux.ibm.com; guoji...@linux.ibm.com; li...@gcc.gnu.org
Subject: Re: [PATCH v2] ipa-cp: Fix PGO regression caused by r278808
On 2019/12/31 14:43, Feng Xue OS wrote:
> One comment: it's better to allow zero value for
> param_ipa_cp_max_recursive_depth,
> this can be used to disable recursive cloning.
Thanks, "1" means no recursive cloning but only constant propagation from
caller to callee in your code?
ipa-cp.c, line 2019:
/* Recursively generate lattice values with a limited count. */
FOR_EACH_VEC_ELT (val_seeds, i, src_val)
{
for (int j = 1; j < param_ipa_cp_max_recursive_depth; j++)
{
tree cstval = get_val_across_arith_op (opcode, opnd1_type, opnd2,
src_val, res_type);
if (!cstval)
break;
ret |= dest_lat->add_value (cstval, cs, src_val, src_idx,
src_offset, &src_val, true);
gcc_checking_assert (src_val);
}
}
XiongHu
>
> Feng
> ________________________________________
> From: luoxhu <luo...@linux.ibm.com>
> Sent: Monday, December 30, 2019 4:11 PM
> To: Jan Hubicka; Martin Jambor
> Cc: Martin Liška; gcc-patches@gcc.gnu.org; seg...@kernel.crashing.org;
> wschm...@linux.ibm.com; guoji...@linux.ibm.com; li...@gcc.gnu.org; Feng Xue OS
> Subject: [PATCH v2] ipa-cp: Fix PGO regression caused by r278808
>
> v2 Changes:
> 1. Enable proportion orig_sum to the new nodes for self recursive node:
> new_sum = (orig_sum + new_sum) \
> * self_recursive_probability * (1 / param_ipa_cp_max_recursive_depth).
> 2. Add value range for param_ipa_cp_max_recursive_depth.
>
> The performance of exchange2 built with PGO will decrease ~28% by r278808
> due to profile count set incorrectly. The cloned nodes are updated to a
> very small count caused later pass cunroll fail to unroll the recursive
> function in exchange2.
>
> digits_2 ->
> digits_2.constprop.0, digits_2.constprop.1, etc.
>
> gcc/ChangeLog:
>
> 2019-12-26 Luo Xiong Hu <luo...@linux.ibm.com>
>
> * ipa-cp.c (update_profiling_info): Check self_scc node.
> * params.opt (ipa-cp-max-recursive-depth): Set param range.
> ---
> gcc/ipa-cp.c | 25 +++++++++++++++++++++++++
> gcc/params.opt | 2 +-
> 2 files changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c
> index 14064ae0034..947bf7c7199 100644
> --- a/gcc/ipa-cp.c
> +++ b/gcc/ipa-cp.c
> @@ -4272,6 +4272,31 @@ update_profiling_info (struct cgraph_node *orig_node,
> false);
> new_sum = stats.count_sum;
>
> + class ipa_node_params *info = IPA_NODE_REF (orig_node);
> + if (info && info->node_is_self_scc)
> + {
> + profile_count self_recursive_count;
> +
> + /* The self recursive edge is on the orig_node. */
> + for (cs = orig_node->callees; cs; cs = cs->next_callee)
> + if (ipa_edge_within_scc (cs))
> + {
> + cgraph_node *callee = cs->callee->function_symbol ();
> + if (callee && cs->caller == cs->callee)
> + {
> + self_recursive_count = cs->count;
> + break;
> + }
> + }
> +
> + /* Proportion count for self recursive node from all callers. */
> + new_sum
> + = (orig_sum + new_sum).apply_scale (self_recursive_count, orig_sum);
> +
> + /* Proportion count for specialized cloned node. */
> + new_sum = new_sum.apply_scale (1, param_ipa_cp_max_recursive_depth);
> + }
> +
> if (orig_node_count < orig_sum + new_sum)
> {
> if (dump_file)
> diff --git a/gcc/params.opt b/gcc/params.opt
> index d88ae0c468b..40a03b04580 100644
> --- a/gcc/params.opt
> +++ b/gcc/params.opt
> @@ -199,7 +199,7 @@ Common Joined UInteger Var(param_ipa_cp_loop_hint_bonus)
> Init(64) Param
> Compile-time bonus IPA-CP assigns to candidates which make loop bounds or
> strides known.
>
> -param=ipa-cp-max-recursive-depth=
> -Common Joined UInteger Var(param_ipa_cp_max_recursive_depth) Init(8) Param
> +Common Joined UInteger Var(param_ipa_cp_max_recursive_depth) Init(8)
> IntegerRange(1, 10) Param
> Maximum depth of recursive cloning for self-recursive function.
>
> -param=ipa-cp-min-recursive-probability=
> --
> 2.21.0.777.g83232e3864
>
