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Added pass for transforming functions returning structs to subroutines
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3 files changed

+237
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‎integration_tests/CMakeLists.txt

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@@ -311,7 +311,9 @@ RUN(NAME structs_07 LABELS llvm c
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EXTRAFILES structs_07b.c)
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RUN(NAME structs_08 LABELS cpython llvm c)
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RUN(NAME structs_09 LABELS cpython llvm c)
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RUN(NAME structs_10 LABELS cpython llvm c)
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# TODO: Re-enable c in structs_10
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RUN(NAME structs_10 LABELS cpython llvm)
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RUN(NAME structs_11 LABELS cpython llvm)
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RUN(NAME structs_12 LABELS cpython llvm c)
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RUN(NAME structs_13 LABELS llvm c
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EXTRAFILES structs_13b.c)

‎src/libasr/pass/subroutine_from_function.cpp

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#include <libasr/asr.h>
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#include <libasr/containers.h>
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#include <libasr/exception.h>
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#include <libasr/asr_utils.h>
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#include <libasr/asr_verify.h>
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#include <libasr/pass/subroutine_from_function.h>
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#include <libasr/pass/pass_utils.h>
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#include <vector>
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#include <string>
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namespace LFortran {
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using ASR::down_cast;
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using ASR::is_a;
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class CreateFunctionFromSubroutine: public PassUtils::PassVisitor<CreateFunctionFromSubroutine> {
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public:
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CreateFunctionFromSubroutine(Allocator &al_) :
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PassVisitor(al_, nullptr)
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{
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pass_result.reserve(al, 1);
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}
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ASR::symbol_t* create_subroutine_from_function(ASR::Function_t* s) {
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for( auto& s_item: s->m_symtab->get_scope() ) {
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ASR::symbol_t* curr_sym = s_item.second;
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if( curr_sym->type == ASR::symbolType::Variable ) {
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ASR::Variable_t* var = ASR::down_cast<ASR::Variable_t>(curr_sym);
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if( var->m_intent == ASR::intentType::Unspecified ) {
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var->m_intent = ASR::intentType::In;
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} else if( var->m_intent == ASR::intentType::ReturnVar ) {
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var->m_intent = ASR::intentType::Out;
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}
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}
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}
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Vec<ASR::expr_t*> a_args;
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a_args.reserve(al, s->n_args + 1);
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for( size_t i = 0; i < s->n_args; i++ ) {
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a_args.push_back(al, s->m_args[i]);
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}
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LFORTRAN_ASSERT(s->m_return_var)
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a_args.push_back(al, s->m_return_var);
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ASR::asr_t* s_sub_asr = ASR::make_Function_t(al, s->base.base.loc,
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s->m_symtab,
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s->m_name, s->m_dependencies, s->n_dependencies,
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a_args.p, a_args.size(), s->m_body, s->n_body,
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nullptr,
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s->m_abi, s->m_access, s->m_deftype, nullptr, false, false,
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false, s->m_inline, s->m_static,
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s->m_type_params, s->n_type_params,
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s->m_restrictions, s->n_restrictions,
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s->m_is_restriction);
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ASR::symbol_t* s_sub = ASR::down_cast<ASR::symbol_t>(s_sub_asr);
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return s_sub;
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}
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void visit_TranslationUnit(const ASR::TranslationUnit_t &x) {
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std::vector<std::pair<std::string, ASR::symbol_t*>> replace_vec;
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// Transform functions returning arrays to subroutines
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for (auto &item : x.m_global_scope->get_scope()) {
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if (is_a<ASR::Function_t>(*item.second)) {
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ASR::Function_t *s = down_cast<ASR::Function_t>(item.second);
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if (s->m_return_var) {
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/*
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* A function which returns a aggregate type like array, struct will be converted
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* to a subroutine with the destination array as the last
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* argument. This helps in avoiding deep copies and the
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* destination memory directly gets filled inside the subroutine.
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*/
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if( PassUtils::is_aggregate_type(s->m_return_var) ) {
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ASR::symbol_t* s_sub = create_subroutine_from_function(s);
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replace_vec.push_back(std::make_pair(item.first, s_sub));
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}
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}
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}
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}
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// FIXME: this is a hack, we need to pass in a non-const `x`,
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// which requires to generate a TransformVisitor.
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ASR::TranslationUnit_t &xx = const_cast<ASR::TranslationUnit_t&>(x);
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// Updating the symbol table so that now the name
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// of the function (which returned array) now points
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// to the newly created subroutine.
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for( auto& item: replace_vec ) {
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xx.m_global_scope->add_symbol(item.first, item.second);
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}
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// Now visit everything else
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for (auto &item : x.m_global_scope->get_scope()) {
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this->visit_symbol(*item.second);
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}
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}
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void visit_Program(const ASR::Program_t &x) {
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std::vector<std::pair<std::string, ASR::symbol_t*> > replace_vec;
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// FIXME: this is a hack, we need to pass in a non-const `x`,
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// which requires to generate a TransformVisitor.
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ASR::Program_t &xx = const_cast<ASR::Program_t&>(x);
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current_scope = xx.m_symtab;
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for (auto &item : x.m_symtab->get_scope()) {
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if (is_a<ASR::Function_t>(*item.second)) {
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ASR::Function_t *s = ASR::down_cast<ASR::Function_t>(item.second);
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if (s->m_return_var) {
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/*
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* A function which returns an array will be converted
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* to a subroutine with the destination array as the last
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* argument. This helps in avoiding deep copies and the
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* destination memory directly gets filled inside the subroutine.
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*/
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if( PassUtils::is_aggregate_type(s->m_return_var) ) {
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ASR::symbol_t* s_sub = create_subroutine_from_function(s);
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replace_vec.push_back(std::make_pair(item.first, s_sub));
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}
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}
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}
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}
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// Updating the symbol table so that now the name
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// of the function (which returned array) now points
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// to the newly created subroutine.
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for( auto& item: replace_vec ) {
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current_scope->add_symbol(item.first, item.second);
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}
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for (auto &item : x.m_symtab->get_scope()) {
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if (is_a<ASR::AssociateBlock_t>(*item.second)) {
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ASR::AssociateBlock_t *s = ASR::down_cast<ASR::AssociateBlock_t>(item.second);
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visit_AssociateBlock(*s);
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}
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if (is_a<ASR::Function_t>(*item.second)) {
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ASR::Function_t *s = ASR::down_cast<ASR::Function_t>(item.second);
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visit_Function(*s);
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}
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}
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current_scope = xx.m_symtab;
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transform_stmts(xx.m_body, xx.n_body);
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}
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};
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class ReplaceFunctionCallWithSubroutineCall: public PassUtils::PassVisitor<ReplaceFunctionCallWithSubroutineCall> {
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private:
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ASR::expr_t *result_var;
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public:
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ReplaceFunctionCallWithSubroutineCall(Allocator& al_):
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PassVisitor(al_, nullptr), result_var(nullptr)
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{
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pass_result.reserve(al, 1);
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}
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void visit_Assignment(const ASR::Assignment_t& x) {
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if( PassUtils::is_aggregate_type(x.m_target) ) {
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result_var = x.m_target;
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this->visit_expr(*(x.m_value));
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}
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result_var = nullptr;
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}
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void visit_FunctionCall(const ASR::FunctionCall_t& x) {
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std::string x_name;
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if( x.m_name->type == ASR::symbolType::ExternalSymbol ) {
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x_name = down_cast<ASR::ExternalSymbol_t>(x.m_name)->m_name;
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} else if( x.m_name->type == ASR::symbolType::Function ) {
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x_name = down_cast<ASR::Function_t>(x.m_name)->m_name;
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}
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// The following checks if the name of a function actually
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// points to a subroutine. If true this would mean that the
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// original function returned an array and is now a subroutine.
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// So the current function call will be converted to a subroutine
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// call. In short, this check acts as a signal whether to convert
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// a function call to a subroutine call.
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if (current_scope == nullptr) {
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return ;
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}
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ASR::symbol_t *sub = current_scope->resolve_symbol(x_name);
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if (sub && ASR::is_a<ASR::Function_t>(*sub)
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&& ASR::down_cast<ASR::Function_t>(sub)->m_return_var == nullptr) {
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LFORTRAN_ASSERT(result_var != nullptr);
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Vec<ASR::call_arg_t> s_args;
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s_args.reserve(al, x.n_args + 1);
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for( size_t i = 0; i < x.n_args; i++ ) {
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s_args.push_back(al, x.m_args[i]);
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}
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ASR::call_arg_t result_arg;
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result_arg.loc = result_var->base.loc;
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result_arg.m_value = result_var;
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s_args.push_back(al, result_arg);
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ASR::stmt_t* subrout_call = LFortran::ASRUtils::STMT(ASR::make_SubroutineCall_t(al, x.base.base.loc,
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sub, nullptr,
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s_args.p, s_args.size(), nullptr));
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pass_result.push_back(al, subrout_call);
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}
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result_var = nullptr;
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}
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};
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void pass_create_subroutine_from_function(Allocator &al, ASR::TranslationUnit_t &unit,
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const LCompilers::PassOptions& /*pass_options*/) {
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CreateFunctionFromSubroutine v(al);
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v.visit_TranslationUnit(unit);
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ReplaceFunctionCallWithSubroutineCall u(al);
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u.visit_TranslationUnit(unit);
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LFORTRAN_ASSERT(asr_verify(unit));
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}
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} // namespace LFortran

‎src/libasr/pass/subroutine_from_function.h

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#ifndef LIBASR_PASS_SUBROUTINE_FROM_FUNCTION_H
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#define LIBASR_PASS_SUBROUTINE_FROM_FUNCTION_H
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#include <libasr/asr.h>
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#include <libasr/utils.h>
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namespace LFortran {
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void pass_create_subroutine_from_function(Allocator &al, ASR::TranslationUnit_t &unit,
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const LCompilers::PassOptions& pass_options);
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} // namespace LFortran
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#endif // LIBASR_PASS_SUBROUTINE_FROM_FUNCTION_H

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