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ipa-cp: Avoid long linear searches through DECL_ARGUMENTS

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There have been concerns that linear searches through DECL_ARGUMENTS
that are often necessary to compute the index of a particular
PARM_DECL which is the key to results of IPA-CP can happen often
enough to be a compile time issue, especially if we plug the results
into value numbering, as I intend to do with a follow-up patch.

This patch creates a vector sorted according to PARM_DECLs to do the look-up
for all functions which have some information discovered by IPA-CP and which
have 32 parameters or more.  32 is a hard-wired magical constant here to
capture the trade-off between the memory allocation overhead and length of the
linear search.  I do not think it is worth making it a --param but if people
think it appropriate, I can turn it into one.

gcc/ChangeLog:

2023-05-31  Martin Jambor  <mjambor@suse.cz>

	* ipa-prop.h (ipa_uid_to_idx_map_elt): New type.
	(struct ipcp_transformation): Rearrange members	according to
	C++ class coding convention, add m_uid_to_idx,
	get_param_index and maybe_create_parm_idx_map.
	* ipa-cp.cc (ipcp_transformation::get_param_index): New function.
	(compare_uids): Likewise.
	(ipcp_transformation::maype_create_parm_idx_map): Likewise.
	* ipa-prop.cc (ipcp_get_parm_bits): Use get_param_index.
	(ipcp_update_bits): Accept TS as a parameter, assume it is not NULL.
	(ipcp_update_vr): Likewise.
	(ipcp_transform_function): Call, maybe_create_parm_idx_map of TS, bail
	out quickly if empty, pass it to ipcp_update_bits and ipcp_update_vr.
This commit is contained in:
Martin Jambor 2023-06-20 18:15:22 +02:00
parent 86df278de1
commit 7f986e2ed9
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GPG key ID: BF63C1BC3FA43540
3 changed files with 131 additions and 33 deletions
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76
gcc/ipa-cp.cc
View file

@ -6779,3 +6779,79 @@ ipa_cp_cc_finalize (void)
orig_overall_size = 0;
ipcp_free_transformation_sum ();
}
/* Given PARAM which must be a parameter of function FNDECL described by THIS,
return its index in the DECL_ARGUMENTS chain, using a pre-computed
DECL_UID-sorted vector if available (which is pre-computed only if there are
many parameters). Can return -1 if param is static chain not represented
among DECL_ARGUMENTS. */
int
ipcp_transformation::get_param_index (const_tree fndecl, const_tree param) const
{
gcc_assert (TREE_CODE (param) == PARM_DECL);
if (m_uid_to_idx)
{
unsigned puid = DECL_UID (param);
const ipa_uid_to_idx_map_elt *res
= std::lower_bound (m_uid_to_idx->begin(), m_uid_to_idx->end (), puid,
[] (const ipa_uid_to_idx_map_elt &elt, unsigned uid)
{
return elt.uid < uid;
});
if (res == m_uid_to_idx->end ()
|| res->uid != puid)
{
gcc_assert (DECL_STATIC_CHAIN (fndecl));
return -1;
}
return res->index;
}
unsigned index = 0;
for (tree p = DECL_ARGUMENTS (fndecl); p; p = DECL_CHAIN (p), index++)
if (p == param)
return (int) index;
gcc_assert (DECL_STATIC_CHAIN (fndecl));
return -1;
}
/* Helper function to qsort a vector of ipa_uid_to_idx_map_elt elements
according to the uid. */
static int
compare_uids (const void *a, const void *b)
{
const ipa_uid_to_idx_map_elt *e1 = (const ipa_uid_to_idx_map_elt *) a;
const ipa_uid_to_idx_map_elt *e2 = (const ipa_uid_to_idx_map_elt *) b;
if (e1->uid < e2->uid)
return -1;
if (e1->uid > e2->uid)
return 1;
gcc_unreachable ();
}
/* Assuming THIS describes FNDECL and it has sufficiently many parameters to
justify the overhead, create a DECL_UID-sorted vector to speed up mapping
from parameters to their indices in DECL_ARGUMENTS chain. */
void
ipcp_transformation::maybe_create_parm_idx_map (tree fndecl)
{
int c = count_formal_params (fndecl);
if (c < 32)
return;
m_uid_to_idx = NULL;
vec_safe_reserve (m_uid_to_idx, c, true);
unsigned index = 0;
for (tree p = DECL_ARGUMENTS (fndecl); p; p = DECL_CHAIN (p), index++)
{
ipa_uid_to_idx_map_elt elt;
elt.uid = DECL_UID (p);
elt.index = index;
m_uid_to_idx->quick_push (elt);
}
m_uid_to_idx->qsort (compare_uids);
}

44
gcc/ipa-prop.cc
View file

@ -5778,16 +5778,9 @@ ipcp_get_parm_bits (tree parm, tree *value, widest_int *mask)
if (!ts || vec_safe_length (ts->bits) == 0)
return false;
int i = 0;
for (tree p = DECL_ARGUMENTS (current_function_decl);
p != parm; p = DECL_CHAIN (p))
{
i++;
/* Ignore static chain. */
if (!p)
return false;
}
int i = ts->get_param_index (current_function_decl, parm);
if (i < 0)
return false;
clone_info *cinfo = clone_info::get (cnode);
if (cinfo && cinfo->param_adjustments)
{
@ -5804,16 +5797,12 @@ ipcp_get_parm_bits (tree parm, tree *value, widest_int *mask)
return true;
}
/* Update bits info of formal parameters as described in
ipcp_transformation. */
/* Update bits info of formal parameters of NODE as described in TS. */
static void
ipcp_update_bits (struct cgraph_node *node)
ipcp_update_bits (struct cgraph_node *node, ipcp_transformation *ts)
{
ipcp_transformation *ts = ipcp_get_transformation_summary (node);
if (!ts || vec_safe_length (ts->bits) == 0)
if (vec_safe_is_empty (ts->bits))
return;
vec<ipa_bits *, va_gc> &bits = *ts->bits;
unsigned count = bits.length ();
@ -5915,14 +5904,12 @@ ipcp_update_bits (struct cgraph_node *node)
}
}
/* Update value range of formal parameters as described in
ipcp_transformation. */
/* Update value range of formal parameters of NODE as described in TS. */
static void
ipcp_update_vr (struct cgraph_node *node)
ipcp_update_vr (struct cgraph_node *node, ipcp_transformation *ts)
{
ipcp_transformation *ts = ipcp_get_transformation_summary (node);
if (!ts || vec_safe_length (ts->m_vr) == 0)
if (vec_safe_is_empty (ts->m_vr))
return;
const vec<ipa_vr, va_gc> &vr = *ts->m_vr;
unsigned count = vr.length ();
@ -5998,10 +5985,17 @@ ipcp_transform_function (struct cgraph_node *node)
fprintf (dump_file, "Modification phase of node %s\n",
node->dump_name ());
ipcp_update_bits (node);
ipcp_update_vr (node);
ipcp_transformation *ts = ipcp_get_transformation_summary (node);
if (!ts || vec_safe_is_empty (ts->m_agg_values))
if (!ts
|| (vec_safe_is_empty (ts->m_agg_values)
&& vec_safe_is_empty (ts->bits)
&& vec_safe_is_empty (ts->m_vr)))
return 0;
ts->maybe_create_parm_idx_map (cfun->decl);
ipcp_update_bits (node, ts);
ipcp_update_vr (node, ts);
if (vec_safe_is_empty (ts->m_agg_values))
return 0;
param_count = count_formal_params (node->decl);
if (param_count == 0)

44
gcc/ipa-prop.h
View file

@ -921,20 +921,24 @@ ipa_is_param_used_by_polymorphic_call (class ipa_node_params *info, int i)
return (*info->descriptors)[i].used_by_polymorphic_call;
}
/* GTY-marked structure used to map DECL_UIDs of APRAMs to their indices in
their DECL_ARGUMENTs chain. */
struct GTY(()) ipa_uid_to_idx_map_elt
{
/* DECL_UID of the PARAM. */
unsigned uid;
/* Its index in the DECL_ARGUMETs chain. */
unsigned index;
};
/* Structure holding information for the transformation phase of IPA-CP. */
struct GTY(()) ipcp_transformation
{
/* Known aggregate values. */
vec<ipa_argagg_value, va_gc> *m_agg_values;
/* Known bits information. */
vec<ipa_bits *, va_gc> *bits;
/* Value range information. */
vec<ipa_vr, va_gc> *m_vr;
/* Default constructor. */
ipcp_transformation ()
: m_agg_values (NULL), bits (NULL), m_vr (NULL)
: m_agg_values (nullptr), bits (nullptr), m_vr (nullptr),
m_uid_to_idx (nullptr)
{ }
/* Default destructor. */
@ -944,6 +948,30 @@ struct GTY(()) ipcp_transformation
vec_free (bits);
vec_free (m_vr);
}
/* Given PARAM which must be a parameter of function FNDECL described by
THIS, return its index in the DECL_ARGUMENTS chain, using a pre-computed
DECL_UID-sorted vector if available (which is pre-computed only if there
are many parameters). Can return -1 if param is static chain not
represented among DECL_ARGUMENTS. */
int get_param_index (const_tree fndecl, const_tree param) const;
/* Assuming THIS describes FNDECL and it has sufficiently many parameters to
justify the overhead, create a DECL_UID-sorted vector to speed up mapping
from parameters to their indices in DECL_ARGUMENTS chain. */
void maybe_create_parm_idx_map (tree fndecl);
/* Known aggregate values. */
vec<ipa_argagg_value, va_gc> *m_agg_values;
/* Known bits information. */
vec<ipa_bits *, va_gc> *bits;
/* Value range information. */
vec<ipa_vr, va_gc> *m_vr;
/* If there are many parameters, this is a vector sorted by their DECL_UIDs
to map them to their indices in the DECL_ARGUMENT chain. */
vec<ipa_uid_to_idx_map_elt, va_gc> *m_uid_to_idx;
};
inline