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[FunC] Add pragma remove-unused-functions for simple dead code elimination

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Aleksandr Kirsanov 2024-05-06 18:36:37 +03:00
parent 0628e17c7d
commit acf0043342
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GPG key ID: B758BBAA01FFB3D3
4 changed files with 119 additions and 5 deletions
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67
crypto/func/func.cpp
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@ -40,6 +40,7 @@ bool stack_layout_comments, op_rewrite_comments, program_envelope, asm_preamble;
bool interactive = false;
GlobalPragma pragma_allow_post_modification{"allow-post-modification"};
GlobalPragma pragma_compute_asm_ltr{"compute-asm-ltr"};
GlobalPragma pragma_remove_unused_functions{"remove-unused-functions"};
std::string generated_from, boc_output_filename;
ReadCallback::Callback read_callback;
@ -62,6 +63,11 @@ const TypeExpr *SymValFunc::get_arg_type() const {
bool SymValCodeFunc::does_need_codegen() const {
// when a function is declared, but not referenced from code in any way, don't generate its body
if (!is_really_used && pragma_remove_unused_functions.enabled()) {
return false;
}
// when a function is referenced like `var a = some_fn;` (or in some other non-call way), its continuation should exist
if (flags & flagUsedAsNonCall) {
return true;
}
@ -69,7 +75,6 @@ bool SymValCodeFunc::does_need_codegen() const {
// since all its usages are inlined
return !is_just_wrapper_for_another_f();
// in the future, we may want to implement a true AST inlining for `inline` functions also
// in the future, unused functions may also be excluded from codegen
}
td::Result<std::string> fs_read_callback(ReadCallback::Kind kind, const char* query) {
@ -93,6 +98,55 @@ td::Result<std::string> fs_read_callback(ReadCallback::Kind kind, const char* qu
}
}
void mark_function_used_dfs(const std::unique_ptr<Op>& op);
void mark_function_used(SymValCodeFunc* func_val) {
if (!func_val->code || func_val->is_really_used) { // already handled
return;
}
func_val->is_really_used = true;
mark_function_used_dfs(func_val->code->ops);
}
void mark_global_var_used(SymValGlobVar* glob_val) {
glob_val->is_really_used = true;
}
void mark_function_used_dfs(const std::unique_ptr<Op>& op) {
if (!op) {
return;
}
// op->fun_ref, despite its name, may actually ref global var
// note, that for non-calls, e.g. `var a = some_fn` (Op::_Let), some_fn is Op::_GlobVar
// (in other words, fun_ref exists not only for direct Op::_Call, but for non-call references also)
if (op->fun_ref) {
if (auto* func_val = dynamic_cast<SymValCodeFunc*>(op->fun_ref->value)) {
mark_function_used(func_val);
} else if (auto* glob_val = dynamic_cast<SymValGlobVar*>(op->fun_ref->value)) {
mark_global_var_used(glob_val);
} else if (auto* asm_val = dynamic_cast<SymValAsmFunc*>(op->fun_ref->value)) {
} else {
func_assert(false);
}
}
mark_function_used_dfs(op->next);
mark_function_used_dfs(op->block0);
mark_function_used_dfs(op->block1);
}
void mark_used_symbols() {
for (SymDef* func_sym : glob_func) {
auto* func_val = dynamic_cast<SymValCodeFunc*>(func_sym->value);
std::string name = sym::symbols.get_name(func_sym->sym_idx);
if (func_val->method_id.not_null() ||
name == "main" || name == "recv_internal" || name == "recv_external" ||
name == "run_ticktock" || name == "split_prepare" || name == "split_install") {
mark_function_used(func_val);
}
}
}
/*
*
* OUTPUT CODE GENERATOR
@ -188,6 +242,7 @@ int generate_output(std::ostream &outs, std::ostream &errs) {
if (program_envelope) {
outs << "PROGRAM{\n";
}
mark_used_symbols();
for (SymDef* func_sym : glob_func) {
SymValCodeFunc* func_val = dynamic_cast<SymValCodeFunc*>(func_sym->value);
func_assert(func_val);
@ -207,7 +262,14 @@ int generate_output(std::ostream &outs, std::ostream &errs) {
}
}
for (SymDef* gvar_sym : glob_vars) {
func_assert(dynamic_cast<SymValGlobVar*>(gvar_sym->value));
auto* glob_val = dynamic_cast<SymValGlobVar*>(gvar_sym->value);
func_assert(glob_val);
if (!glob_val->is_really_used && pragma_remove_unused_functions.enabled()) {
if (verbosity >= 2) {
errs << gvar_sym->name() << ": variable not generated, it's unused\n";
}
continue;
}
std::string name = sym::symbols.get_name(gvar_sym->sym_idx);
outs << std::string(indent * 2, ' ') << "DECLGLOBVAR " << name << "\n";
}
@ -274,6 +336,7 @@ int func_proceed(const std::vector<std::string> &sources, std::ostream &outs, st
}
pragma_allow_post_modification.check_enable_in_libs();
pragma_compute_asm_ltr.check_enable_in_libs();
pragma_remove_unused_functions.check_enable_in_libs();
return funC::generate_output(outs, errs);
} catch (src::Fatal& fatal) {
errs << "fatal: " << fatal << std::endl;