https://gcc.gnu.org/g:622c367a5fc67ebbda55c02aba391d86738dc6ad
commit 622c367a5fc67ebbda55c02aba391d86738dc6ad
Author: Ondřej Machota <ondrejmach...@gmail.com>
Date: Wed Mar 12 13:12:43 2025 +0100
rtl-ssa-dce: improve marking, but still not correct
Diff:
---
gcc/dce.cc | 211 +++++++++++++++++++++++++++++++++----------------------------
1 file changed, 113 insertions(+), 98 deletions(-)
diff --git a/gcc/dce.cc b/gcc/dce.cc
index d1558f2a9798..cfa58f21dc03 100644
--- a/gcc/dce.cc
+++ b/gcc/dce.cc
@@ -1390,10 +1390,12 @@ bool side_effects_with_mem (const_rtx x)
return true;
case MEM: // We might want tu return true iff volatile or mem is a
destination
+ // write or possible null read
case ASM_INPUT:
case ASM_OPERANDS:
return true;
+ // This should rather by RTX_BODY in is_rtx_insn_prelive - like global
clobber
case USE:
return true;
@@ -1471,6 +1473,9 @@ bool is_rtx_insn_prelive(rtx_insn *insn) {
return true;
rtx body = PATTERN(insn);
+ if (GET_CODE(body) == CLOBBER) //
~/Documents/gcc/gcc/testsuite/gcc.c-torture/compile/20000605-1.c
+ return true;
+
if (side_effects_with_mem(body) || can_throw_internal(body))
return true;
@@ -1588,6 +1593,7 @@ rtl_ssa_dce_mark()
auto_vec<set_info *> worklist_new{};
for (auto && item : worklist) {
insn_info * insn = item;
+ std::cerr << "cp Current: " << insn->uid() << '\n';
for (auto&& use : insn->uses()) {
set_info* set = use->def();
if (set) {
@@ -1603,118 +1609,119 @@ rtl_ssa_dce_mark()
continue;
}
- if (!(marked.count(insn) > 0))
- {
- marked.emplace(insn);
- }
+ /*
+ * TODO : a phi insn might be visited more times due to having more phi
nodes
+ * Either we have to mark phi nodes or do not mark phi insn
+ */
+ std::cerr << "Current: " << insn->uid() << '\n';
+ // if (insn->uid() == -21) {
+ // std::cerr << "Insn -21 phi? " << insn->is_phi() << '\n';
+ // }
- // use_array uses = insn->uses();
- if (insn->is_phi()) {
- phi_info* pi = as_a<phi_info *> (set);
-
- for (auto && input : pi->inputs()) {
- use_info* use = input;
- set_info* parent_set = use->def();
- if (!parent_set) { // Clobber...
- continue;
- }
-
- worklist_new.safe_push(parent_set);
- }
- } else {
- if (dump_file)
- fprintf(dump_file, " Adding insn %d to worklist - mark\n",
insn->uid());
-
- for (auto && use__ : insn->uses()) {
- use_info * use = use__;
- set_info* parent_set = use->def();
- if (!parent_set) {
- continue;
- }
-
- worklist_new.safe_push(parent_set);
- }
+ if ((marked.count(insn) > 0)) {
+ continue;
}
- }
- if (dump_file)
- fprintf(dump_file, "Finished inherently live, marking parents\n");
- while (!worklist.is_empty())
- {
- insn_info *insn = worklist.pop();
+ marked.emplace(insn);
+
use_array uses = insn->uses();
if (insn->is_phi()) {
- std::cerr << "Phi : "<< insn->uid() << " - uses: " << insn->num_uses()
<< ", defs:" << insn->num_defs() << '\n';
- for (auto&& use : uses) {
- debug(use);
- std::cerr << '\n';
- }
- } else if (insn->is_artificial()) {
- std::cerr << "Artificial " << insn->uid() << " - uses: " <<
insn->num_uses() << ", defs:" << insn->num_defs() << '\n';
- for (auto&& use : uses) {
- debug(use);
- std::cerr << '\n';
- }
+ phi_info* pi = as_a<phi_info *> (set);
+ uses = pi->inputs();
}
if (dump_file)
- fprintf(dump_file, "Looking at: %d, uses: %d\n", insn->uid(),
uses.size());
-
- //std::cerr << "Insn: " << insn->uid() << ", uses: " << uses.size() <<
'\n';
- std::cerr << "Current: " << insn->uid() << '\n';
- for (size_t i = 0; i < uses.size(); i++)
- {
- // debug(uses[i]);
- use_info* use = uses[i];
- // debug(use->def());
- // if (use->def() != nullptr) {
- // std::cerr << use->def()->insn()->uid() << '\n';
- // }
- // std::cerr << '\n';
- // debug(use);
- // std::cerr << '\n';
-
- set_info* set = use->def();
- if (!set) {
+ fprintf(dump_file, " Adding insn %d to worklist - mark\n", insn->uid());
+
+ for (auto && use__ : uses) {
+ use_info * use = use__;
+ set_info* parent_set = use->def();
+ if (!parent_set) {
continue;
}
- insn_info *parent_insn = set->insn();
- if (!parent_insn) {
- continue;
- }
- // if (parent_insn->is_phi()) { // this is weird...
- // // debug(use->def());
- // phi_info * pi = as_a<phi_info *> (use->def());
- // // std::cerr << "phi inputs: " << pi->num_inputs() << '\n';
- // for (auto&& input: pi->inputs()) {
- // use_info* phi_use = input;
- // std::cerr << "Via phi insn: " << phi_use->def()->insn()->uid() <<
'\n';
- // }
- // }
- int parent_insn_uid = parent_insn->uid();
- // propage that some instruction in chain is live from bottom to top
- if (dump_file)
- fprintf(dump_file, "Trying to add: %d\n", parent_insn_uid);
- // not yet marked
- if (!(marked.count(parent_insn) > 0))
- {
- //std::cerr << "Adding: " << parent_insn_uid << " to worklist";
- if (dump_file)
- fprintf(dump_file, " Adding insn %d to worklist - mark\n",
parent_insn_uid);
-
- worklist.safe_push(parent_insn);
- marked.emplace(parent_insn);
- }
+ worklist_new.safe_push(parent_set);
}
+ }
+
+ // if (dump_file)
+ // fprintf(dump_file, "Finished inherently live, marking parents\n");
+ // while (!worklist.is_empty())
+ // {
+ // insn_info *insn = worklist.pop();
+ // use_array uses = insn->uses();
+ // if (insn->is_phi()) {
+ // std::cerr << "Phi : "<< insn->uid() << " - uses: " <<
insn->num_uses() << ", defs:" << insn->num_defs() << '\n';
+ // for (auto&& use : uses) {
+ // debug(use);
+ // std::cerr << '\n';
+ // }
+ // } else if (insn->is_artificial()) {
+ // std::cerr << "Artificial " << insn->uid() << " - uses: " <<
insn->num_uses() << ", defs:" << insn->num_defs() << '\n';
+ // for (auto&& use : uses) {
+ // debug(use);
+ // std::cerr << '\n';
+ // }
+ // }
+
+ // if (dump_file)
+ // fprintf(dump_file, "Looking at: %d, uses: %d\n", insn->uid(),
uses.size());
+
+ // //std::cerr << "Insn: " << insn->uid() << ", uses: " << uses.size() <<
'\n';
+ // std::cerr << "Current: " << insn->uid() << '\n';
+ // for (size_t i = 0; i < uses.size(); i++)
+ // {
+ // // debug(uses[i]);
+ // use_info* use = uses[i];
+ // // debug(use->def());
+ // // if (use->def() != nullptr) {
+ // // std::cerr << use->def()->insn()->uid() << '\n';
+ // // }
+ // // std::cerr << '\n';
+ // // debug(use);
+ // // std::cerr << '\n';
+
+ // set_info* set = use->def();
+ // if (!set) {
+ // continue;
+ // }
+ // insn_info *parent_insn = set->insn();
+ // if (!parent_insn) {
+ // continue;
+ // }
+ // // if (parent_insn->is_phi()) { // this is weird...
+ // // // debug(use->def());
+ // // phi_info * pi = as_a<phi_info *> (use->def());
+ // // // std::cerr << "phi inputs: " << pi->num_inputs() << '\n';
+ // // for (auto&& input: pi->inputs()) {
+ // // use_info* phi_use = input;
+ // // std::cerr << "Via phi insn: " << phi_use->def()->insn()->uid()
<< '\n';
+ // // }
+ // // }
+ // int parent_insn_uid = parent_insn->uid();
+ // // propage that some instruction in chain is live from bottom to top
+ // if (dump_file)
+ // fprintf(dump_file, "Trying to add: %d\n", parent_insn_uid);
+ // // not yet marked
+ // if (!(marked.count(parent_insn) > 0))
+ // {
+ // //std::cerr << "Adding: " << parent_insn_uid << " to worklist";
+ // if (dump_file)
+ // fprintf(dump_file, " Adding insn %d to worklist - mark\n",
parent_insn_uid);
+
+
+ // worklist.safe_push(parent_insn);
+ // marked.emplace(parent_insn);
+ // }
+ // }
// auto bb = insn->bb();
- }
+ // }
- for (auto&& insn : marked) {
- if (dump_file)
- fprintf(dump_file, " Marked insn: %d\n", insn->uid());
- }
+ // for (auto&& insn : marked) {
+ // if (dump_file)
+ // fprintf(dump_file, " Marked insn: %d\n", insn->uid());
+ // }
// TODO : control dependence
return marked;
@@ -1729,6 +1736,7 @@ rtl_ssa_dce_sweep(std::unordered_set<insn_info *> marked)
// we can get the number of items in the set and create an array of changes
// which will hopefully have constructor for array_slice<insn_info *>
auto attempt = crtl->ssa->new_change_attempt ();
+ std::cerr << "Change attempt created successfully" << std::endl;
for (insn_info *insn = crtl->ssa->first_insn(); insn; insn = next)
{
if (dump_file)
@@ -1746,6 +1754,7 @@ rtl_ssa_dce_sweep(std::unordered_set<insn_info *> marked)
// Skip artificial insns (or uid() < 0)
if (insn->is_real())
{
+ std::cerr << "Insn: " << insn->uid() << " will be deleted\n";
auto change = insn_change::delete_insn(insn);
// crtl->ssa->possibly_queue_changes(change);
to_delete.safe_push(change);
@@ -1753,14 +1762,18 @@ rtl_ssa_dce_sweep(std::unordered_set<insn_info *>
marked)
}
}
}
+
+ std::cerr << "Selected unmarked insns" << std::endl;
auto_vec<insn_change*> changes(to_delete.length());
for (size_t i = 0; i != to_delete.length(); ++i) {
changes.safe_push(&to_delete[i]);
}
+ std::cerr << "Verification" << std::endl;
if (crtl->ssa->verify_insn_changes(changes)) {
- //std::cerr << "Changes are correct\n";
+ std::cerr << "Changes are correct" << std::endl;
+ // segfault: gcc.c-torture/execute/20000224-1.c
crtl->ssa->change_insns(changes);
} else {
std::cerr << "Changes are not correct\n";
@@ -1775,7 +1788,9 @@ rtl_ssa_dce()
//std::cerr << "Next phase: prelive + mark: \n";
std::unordered_set<insn_info *> marked = rtl_ssa_dce_mark();
+ std::cerr << "Marking done\n";
rtl_ssa_dce_sweep(marked);
+ std::cerr << "Sweeping done\n";
rtl_ssa_dce_done();
return 0;
