source: src/CodeGen/LinkOnce.cc @ eb779d5

//
// Cforall Version 1.0.0 Copyright (C) 2021 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// LinkOnce.cc -- Translate the cfa_linkonce attribute.
//
// Author           : Andrew Beach
// Created On       : Thur May 13 10:10:00 2021
// Last Modified By : Andrew Beach
// Last Modified On : Wed Oct  4 10:52:00 2023
// Update Count     : 1
//

#include "LinkOnce.h"

#include <algorithm>

#include "AST/Attribute.hpp"
#include "AST/Decl.hpp"
#include "AST/Expr.hpp"
#include "AST/Pass.hpp"
#include "Common/PassVisitor.h"       // for PassVisitor, WithShortCircuiting

namespace CodeGen {

namespace {

bool is_cfa_linkonce_old( Attribute const * attr ) {
        return std::string("cfa_linkonce") == attr->name;
}

bool is_section_attribute_old( Attribute const * attr ) {
        return std::string("section") == attr->name;
}

class LinkOnceVisitorCore : public WithShortCircuiting {
public:
        void previsit( Declaration * ) {
                visit_children = false;
        }

        void previsit( DeclarationWithType * decl ) {
                std::list< Attribute * > & attributes = decl->attributes;
                // See if we can find the element:
                auto found = std::find_if(attributes.begin(), attributes.end(), is_cfa_linkonce_old );
                if ( attributes.end() != found ) {
                        // Remove any other sections:
                        attributes.remove_if( is_section_attribute_old );
                        // Iterator to the cfa_linkonce attribute should still be valid.
                        Attribute * attribute = *found;
                        assert( attribute->parameters.empty() );
                        assert( !decl->mangleName.empty() );
                        // Overwrite the attribute in place.
                        const std::string section_name = ".gnu.linkonce." + decl->mangleName;
                        attribute->name = "section";
                        attribute->parameters.push_back(
                                new ConstantExpr( Constant::from_string( section_name ) )
                        );

                        // Unconditionnaly add "visibility(default)" to anything with gnu.linkonce
                        // visibility is a mess otherwise
                        attributes.push_back(new Attribute("visibility", {new ConstantExpr( Constant::from_string( "default" ) )}));

                }
                visit_children = false;
        }
};

bool is_cfa_linkonce( ast::Attribute const * attr ) {
        return "cfa_linkonce" == attr->name;
}

bool is_section_attribute( ast::Attribute const * attr ) {
        return "section" == attr->name;
}

struct LinkOnceCore : public ast::WithShortCircuiting {
        void previsit( ast::Decl const * ) {
                visit_children = false;
        }

        ast::DeclWithType const * postvisit( ast::DeclWithType const * decl ) {
                // Check to see if we have to mutate, because should be uncommon.
                {
                        auto & attributes = decl->attributes;
                        auto found = std::find_if( attributes.begin(), attributes.end(),
                                        is_cfa_linkonce );
                        if ( attributes.end() == found ) return decl;
                }
                auto mutDecl = mutate( decl );
                auto & attributes = mutDecl->attributes;

                // Remove all conflicting section attributes.
                erase_if( attributes, is_section_attribute );

                // Get the attribute, and overwrite it as a section attribute.
                auto found = std::find_if( attributes.begin(), attributes.end(),
                                is_cfa_linkonce );
                assert( attributes.end() != found );
                ast::Attribute * attribute = found->get_and_mutate();
                assert( attribute->params.empty() );
                assert( !decl->mangleName.empty() );

                attribute->name = "section";
                attribute->params.push_back(
                        ast::ConstantExpr::from_string( mutDecl->location,
                                ".gnu.linkonce." + decl->mangleName
                        )
                );

                // Unconditionnaly add "visibility(default)" to anything with
                // .gnu.linkonce visibility is a mess otherwise.
                attributes.push_back( new ast::Attribute( "visibility", {
                        ast::ConstantExpr::from_string( mutDecl->location, "default" )
                } ) );
                return mutDecl;
        }
};

} // namespace

void translateLinkOnce( std::list< Declaration *> & translationUnit ) {
        PassVisitor<LinkOnceVisitorCore> translator;
        acceptAll( translationUnit, translator );
}

void translateLinkOnce( ast::TranslationUnit & translationUnit ) {
        ast::Pass<LinkOnceCore>::run( translationUnit );
}

} // namespace CodeGen