https://gcc.gnu.org/g:3a067ae712e98d5ead1d565ad3b3dd32dc6ac37a
commit 3a067ae712e98d5ead1d565ad3b3dd32dc6ac37a
Author: David Balek <davca.ba...@gmail.com>
Date: Tue Sep 23 14:14:26 2025 +0200
Fixes merged switch creation
Diff:
---
gcc/gimple-flatten-switch.cc | 173 +++++++++++++++++++++----------------------
1 file changed, 84 insertions(+), 89 deletions(-)
diff --git a/gcc/gimple-flatten-switch.cc b/gcc/gimple-flatten-switch.cc
index 3d3e5c8a7695..133e87593dc8 100644
--- a/gcc/gimple-flatten-switch.cc
+++ b/gcc/gimple-flatten-switch.cc
@@ -28,27 +28,17 @@
#include <vector>
#include <algorithm>
-/* The struct holding the info about outer switch and all inner switches it
- points to. */
+/* The struct holding the info about outer and inenr switch pair. */
struct switch_info
{
- switch_info(gswitch *outer_switch, gswitch *inner_switch) :
- m_outer_switch(outer_switch), m_inner_switches()
- {
- m_inner_switches.create (1);
- m_inner_switches.safe_push (inner_switch);
- }
+ switch_info (gswitch *outer_switch, gswitch *inner_switch) :
+ m_outer_switch (outer_switch), m_inner_switch (inner_switch)
+ {}
- void add_inner_switch (gswitch *inner_switch);
gswitch *m_outer_switch;
- auto_vec<gswitch*> m_inner_switches;
+ gswitch *m_inner_switch;
};
-void
-switch_info::add_inner_switch (gswitch *inner_switch)
-{
- m_inner_switches.safe_push(inner_switch);
-}
void
print_nested_switches (basic_block bb, gswitch *sw1, gswitch *sw2)
@@ -591,58 +581,40 @@ repair_cfg (case_informations &merged_case_infos,
basic_block merged_switch_bb)
make_edge (info->m_this_bb, info->m_dest_bb, 0);
}
- /* Add the missing phi arguments */
- for (auto info : merged_case_infos)
- {
- edge e = (info->m_forwarder_bb == NULL)
- ? find_edge(info->m_this_bb, info->m_dest_bb)
- : find_edge(info->m_forwarder_bb, info->m_dest_bb);
-
- for (auto item : info->m_phi_mapping)
- {
- add_phi_arg (item.first, item.second, e, UNKNOWN_LOCATION);
- }
- }
+ /* Add the missing phi arguments */
+ for (auto info : merged_case_infos)
+ {
+ edge e = (info->m_forwarder_bb == NULL)
+ ? find_edge(info->m_this_bb, info->m_dest_bb)
+ : find_edge(info->m_forwarder_bb, info->m_dest_bb);
+
+ for (auto item : info->m_phi_mapping)
+ add_phi_arg (item.first, item.second, e, UNKNOWN_LOCATION);
+ }
}
/* Adjusts the outer switch to be merged switch */
static void
-change_outer_switch_to_merged_switch (gswitch *outer,
- case_informations &merged_case_infos)
+create_merged_switch (gswitch *outer,
+ case_informations &merged_case_infos)
{
gcc_assert (merged_case_infos.size () > 0);
gcc_assert (merged_case_infos[0]->is_default ());
- gimple_switch_set_num_labels (outer, merged_case_infos.size ());
- for (unsigned i = 0; i < merged_case_infos.size (); ++i)
+ gimple_stmt_iterator gsi = gsi_for_stmt (outer);
+ auto_vec<tree> labels;
+ for (unsigned i = 1; i < merged_case_infos.size (); ++i)
{
case_info_ptr info = merged_case_infos[i];
tree label = info->build_case ();
- gimple_switch_set_label (outer, i, label);
+ labels.safe_push (label);
}
-}
-/* Merges nested switches */
-static void
-merge_nested_switches (function *fun, switch_info *info)
-{
- gswitch* outer = info->m_outer_switch;
- for (gswitch* inner : info->m_inner_switches)
- {
- case_informations outer_case_info{}, inner_case_info{};
- outer_switch_case_informations (fun, outer, inner, outer_case_info);
- inner_switch_case_informations (fun, inner, inner_case_info);
-
- if (!check_if_switches_mergeable (outer_case_info, inner_case_info))
- continue;
-
- case_informations merged_case_info{};
- dump_function_to_file (fun->decl, stderr, TDF_DETAILS);
- merge_case_infos (outer_case_info, inner_case_info, merged_case_info);
- repair_cfg (merged_case_info, outer->bb);
- change_outer_switch_to_merged_switch (outer, merged_case_info);
- delete_basic_block (inner->bb);
- }
+ gswitch *s = gimple_build_switch (gimple_switch_index(outer),
+ merged_case_infos[0]->build_case (),
+ labels);
+ gsi_remove (&gsi, true);
+ gsi_insert_before (&gsi, s, GSI_NEW_STMT);
}
@@ -666,18 +638,17 @@ bb_only_labels_and_switch (basic_block bb)
return true;
}
-/* Finds the pairs of outer and inner switches */
-static void
-find_nested_switches (hash_map<basic_block, switch_info *> *switch_in_bb,
- basic_block bb)
+/* Finds the pair of outer and inner switch */
+static switch_info *
+find_nested_switch (basic_block bb)
{
gimple_stmt_iterator gsi = gsi_last_nondebug_bb(bb);
if (gsi_end_p(gsi))
- return;
+ return NULL;
gswitch *outer_switch = dyn_cast<gswitch *>(gsi_stmt(gsi));
if (outer_switch == NULL)
- return;
+ return NULL;
edge e;
edge_iterator ei;
@@ -705,18 +676,51 @@ find_nested_switches (hash_map<basic_block, switch_info
*> *switch_in_bb,
continue;
print_nested_switches(bb, outer_switch, inner_switch);
-
- switch_info** info = switch_in_bb->get(bb);
- if (info == NULL)
- {
- switch_info *new_info = new switch_info (outer_switch, inner_switch);
- switch_in_bb->put(bb, new_info);
- continue;
- }
- (*info)->add_inner_switch(inner_switch);
+ return new switch_info (outer_switch, inner_switch);
}
+
+ return NULL;
}
+
+/* Merges nested switches and returns if any were even found */
+static bool
+merge_nested_switches (function *fun, basic_block bb)
+{
+ switch_info *info = find_nested_switch (bb);
+ if (info == NULL)
+ return false;
+
+ do {
+ gswitch* outer = info->m_outer_switch;
+ gswitch* inner = info->m_inner_switch;
+ case_informations outer_case_info{}, inner_case_info{};
+ outer_switch_case_informations (fun, outer, inner, outer_case_info);
+ inner_switch_case_informations (fun, inner, inner_case_info);
+
+ if (!check_if_switches_mergeable (outer_case_info, inner_case_info))
+ {
+ delete info;
+ info = find_nested_switch (bb);
+ continue;
+ }
+
+
+ case_informations merged_case_info{};
+ dump_function_to_file (fun->decl, stderr, TDF_DETAILS);
+ merge_case_infos (outer_case_info, inner_case_info, merged_case_info);
+ repair_cfg (merged_case_info, outer->bb);
+ create_merged_switch (outer, merged_case_info);
+ delete_basic_block (inner->bb);
+ delete info;
+ info = find_nested_switch (bb);
+ } while (info);
+
+ return true;
+}
+
+
+
namespace
{
const pass_data pass_data_flatten_switch =
@@ -747,20 +751,12 @@ namespace
unsigned int
pass_flatten_switch::execute(function *fun)
{
- hash_map<basic_block, switch_info *> switches_in_bbs;
-
- basic_block bb;
- FOR_EACH_BB_FN (bb, fun)
- find_nested_switches (&switches_in_bbs, bb);
-
-
- if (switches_in_bbs.is_empty ())
- return 0;
-
+ //*
int *rpo = XNEWVEC (int, n_basic_blocks_for_fn (fun));
unsigned n = pre_and_rev_post_order_compute_fn (fun, NULL, rpo, false);
+ bool seen_nested_switch = false;
auto_bitmap seen_bbs;
for (int i = n - 1; i >= 0; --i)
{
@@ -769,24 +765,23 @@ namespace
continue;
bitmap_set_bit (seen_bbs, bb->index);
- switch_info **info = switches_in_bbs.get (bb);
- if (info == NULL)
- continue;
- merge_nested_switches(fun, *info);
+ seen_nested_switch |= merge_nested_switches(fun, bb);
}
free (rpo);
-
-
- for (hash_map<basic_block, switch_info *>::iterator it
- = switches_in_bbs.begin (); it != switches_in_bbs.end (); ++it)
- delete (*it).second;
+ if (!seen_nested_switch)
+ return 0;
free_dominance_info (CDI_DOMINATORS);
dump_function_to_file (fun->decl, stderr, TDF_DETAILS);
- return 0;
+ /*/
+
+ if (dump_file)
+ fprintf (dump_file, "there are %d bbs\n", n_basic_blocks_for_fn(fun));
+ //*/
+ return 0;
}
