94 lines
4.0 KiB
C++
94 lines
4.0 KiB
C++
#include "elna/backend/target.hpp"
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#include "elna/backend/riscv.hpp"
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#include <elfio/elfio.hpp>
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namespace elna::riscv
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{
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void riscv32_elf(source::block *ast, const std::filesystem::path& out_file)
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{
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auto _visitor = std::make_unique<visitor>();
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_visitor->visit(ast);
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ELFIO::elfio writer;
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const ELFIO::Elf_Word instructions_size = _visitor->instructions.size() * sizeof(instruction);
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writer.create(ELFIO::ELFCLASS32, ELFIO::ELFDATA2LSB);
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writer.set_os_abi(ELFIO::ELFOSABI_NONE);
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writer.set_type(ELFIO::ET_REL);
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writer.set_machine(ELFIO::EM_RISCV);
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// Create code section
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ELFIO::section* text_sec = writer.sections.add(".text");
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text_sec->set_type(ELFIO::SHT_PROGBITS);
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text_sec->set_flags(ELFIO::SHF_ALLOC | ELFIO::SHF_EXECINSTR);
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text_sec->set_addr_align(0x1);
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text_sec->set_data(reinterpret_cast<const char *>(_visitor->instructions.data()),
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instructions_size);
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// Create string table section
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ELFIO::section* str_sec = writer.sections.add(".strtab");
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str_sec->set_type(ELFIO::SHT_STRTAB);
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// Create string table writer
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ELFIO::string_section_accessor stra(str_sec);
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// Create read only data section
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ELFIO::section* ro_sec = writer.sections.add(".rodata");
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ro_sec->set_type(ELFIO::SHT_PROGBITS);
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ro_sec->set_flags(ELFIO::SHF_ALLOC);
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ro_sec->set_addr_align(0x4);
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ro_sec->set_data("%d\n");
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// Create symbol table section
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ELFIO::section* sym_sec = writer.sections.add(".symtab");
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sym_sec->set_type(ELFIO::SHT_SYMTAB);
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sym_sec->set_info(2);
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sym_sec->set_addr_align(0x4);
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sym_sec->set_entry_size(writer.get_default_entry_size(ELFIO::SHT_SYMTAB));
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sym_sec->set_link(str_sec->get_index());
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// Create relocation table section
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ELFIO::section* rel_sec = writer.sections.add(".rel.text");
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rel_sec->set_type(ELFIO::SHT_REL);
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rel_sec->set_info(text_sec->get_index());
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rel_sec->set_addr_align(0x4);
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rel_sec->set_entry_size(writer.get_default_entry_size(ELFIO::SHT_REL));
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rel_sec->set_link(sym_sec->get_index());
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rel_sec->set_flags(ELFIO::SHF_ALLOC);
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// Create symbol relocation table writers
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ELFIO::symbol_section_accessor syma(writer, sym_sec);
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ELFIO::relocation_section_accessor rela(writer, rel_sec);
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ELFIO::Elf_Word digit_symbol = syma.add_symbol(stra, ".CL0", 0x00000000, strlen("%d\n") + 1,
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ELFIO::STB_LOCAL, ELFIO::STT_NOTYPE, 0, ro_sec->get_index());
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ELFIO::Elf_Word printf_symbol = syma.add_symbol(stra, "printf", 0x00000000, 0,
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ELFIO::STB_GLOBAL, ELFIO::STT_NOTYPE, 0, ELFIO::SHN_UNDEF);
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for (auto& reference : _visitor->references)
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{
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// The loop assumes that address_t::lower12i always follows address_t::high20.
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switch (reference.target)
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{
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case address_t::high20:
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rela.add_entry(reference.offset, digit_symbol, 26 /* ELFIO::R_RISCV_HI20 */);
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rela.add_entry(reference.offset, digit_symbol, 51 /* ELFIO::R_RISCV_RELAX */);
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break;
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case address_t::lower12i:
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rela.add_entry(reference.offset, digit_symbol, 27 /* ELFIO::R_RISCV_LO12_I */);
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rela.add_entry(reference.offset, digit_symbol, 51 /* ELFIO::R_RISCV_RELAX */);
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break;
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case address_t::text:
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rela.add_entry(reference.offset, printf_symbol, 18 /* ELFIO::R_RISCV_CALL */);
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rela.add_entry(reference.offset, printf_symbol, 51 /* ELFIO::R_RISCV_RELAX */);
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break;
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}
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}
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syma.add_symbol(stra, "main", 0x00000000, instructions_size,
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ELFIO::STB_GLOBAL, ELFIO::STT_FUNC, 0, text_sec->get_index());
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// Create ELF object file
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writer.save(out_file);
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}
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}
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