161 lines
4.5 KiB
C++
161 lines
4.5 KiB
C++
#include "CodeGenerator.hpp"
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#include "gen_context_struct.hpp"
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#include "settings.hpp"
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using namespace std;
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static const char* PRELUDE =
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"#include <assert.h>\n"
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"\n"
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;
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CodeGenerator::CodeGenerator(
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const SimpleDwarf& dwarf,
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std::ostream& os,
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NamingScheme naming_scheme):
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dwarf(dwarf), os(os), naming_scheme(naming_scheme)
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{}
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void CodeGenerator::generate() {
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gen_of_dwarf();
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}
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void CodeGenerator::gen_of_dwarf() {
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os << CONTEXT_STRUCT_STR << '\n'
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<< PRELUDE << '\n' << endl;
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switch(settings::switch_generation_policy) {
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case settings::SGP_SwitchPerFunc:
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{
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vector<LookupEntry> lookup_entries;
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// A function per FDE
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for(const auto& fde: dwarf.fde_list) {
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LookupEntry cur_entry;
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cur_entry.name = naming_scheme(fde);
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cur_entry.beg = fde.beg_ip;
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cur_entry.end = fde.end_ip;
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lookup_entries.push_back(cur_entry);
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gen_function_of_fde(fde);
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os << endl;
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}
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gen_lookup(lookup_entries);
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break;
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}
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case settings::SGP_GlobalSwitch:
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{
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gen_unwind_func_header("_eh_elf");
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for(const auto& fde: dwarf.fde_list) {
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gen_switchpart_of_fde(fde);
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}
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gen_unwind_func_footer();
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break;
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}
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}
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}
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void CodeGenerator::gen_unwind_func_header(const std::string& name) {
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os << "unwind_context_t "
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<< name
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<< "(unwind_context_t ctx, uintptr_t pc) {\n"
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<< "\tunwind_context_t out_ctx;\n"
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<< "\tswitch(pc) {" << endl;
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}
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void CodeGenerator::gen_unwind_func_footer() {
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os << "\t\tdefault: assert(0);\n"
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<< "\t}\n"
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<< "}" << endl;
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}
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void CodeGenerator::gen_function_of_fde(const SimpleDwarf::Fde& fde) {
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gen_unwind_func_header(naming_scheme(fde));
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gen_switchpart_of_fde(fde);
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gen_unwind_func_footer();
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}
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void CodeGenerator::gen_switchpart_of_fde(const SimpleDwarf::Fde& fde) {
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os << "\t\t/********** FDE: 0x" << std::hex << fde.fde_offset
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<< ", PC = 0x" << fde.beg_ip << std::dec << " */" << std::endl;
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for(size_t fde_row_id=0; fde_row_id < fde.rows.size(); ++fde_row_id)
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{
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uintptr_t up_bound = fde.end_ip - 1;
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if(fde_row_id != fde.rows.size() - 1)
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up_bound = fde.rows[fde_row_id + 1].ip - 1;
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gen_of_row(fde.rows[fde_row_id], up_bound);
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}
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}
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void CodeGenerator::gen_of_row(
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const SimpleDwarf::DwRow& row,
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uintptr_t row_end)
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{
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os << "\t\tcase " << std::hex << "0x" << row.ip
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<< " ... 0x" << row_end << ":" << std::dec << endl;
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os << "\t\t\t" << "out_ctx.rsp = ";
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gen_of_reg(row.cfa);
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os << ';' << endl;
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os << "\t\t\t" << "out_ctx.rbp = ";
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gen_of_reg(row.rbp);
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os << ';' << endl;
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os << "\t\t\t" << "out_ctx.rip = ";
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gen_of_reg(row.ra);
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os << ';' << endl;
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os << "\t\t\treturn " << "out_ctx" << ";" << endl;
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}
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static const char* ctx_of_dw_name(SimpleDwarf::MachineRegister reg) {
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switch(reg) {
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case SimpleDwarf::REG_RIP:
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throw CodeGenerator::NotImplementedCase();
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case SimpleDwarf::REG_RSP:
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return "ctx.rsp";
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case SimpleDwarf::REG_RBP:
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return "ctx.rbp";
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case SimpleDwarf::REG_RA:
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throw CodeGenerator::NotImplementedCase();
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}
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return "";
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}
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void CodeGenerator::gen_of_reg(const SimpleDwarf::DwRegister& reg) {
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switch(reg.type) {
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case SimpleDwarf::DwRegister::REG_UNDEFINED:
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os << "0"; // FIXME do better?
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break;
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case SimpleDwarf::DwRegister::REG_REGISTER:
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os << ctx_of_dw_name(reg.reg)
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<< " + (" << reg.offset << ")";
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break;
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case SimpleDwarf::DwRegister::REG_CFA_OFFSET:
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os << "*((uintptr_t*)(out_ctx.rsp + ("
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<< reg.offset
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<< ")))";
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break;
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case SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED:
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os << "0; assert(0)";
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break;
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}
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}
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void CodeGenerator::gen_lookup(const std::vector<LookupEntry>& entries) {
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os << "_fde_func_t _fde_lookup(uintptr_t pc) {\n"
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<< "\tswitch(pc) {" << endl;
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for(const auto& entry: entries) {
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os << "\t\tcase " << std::hex << "0x" << entry.beg
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<< " ... 0x" << entry.end - 1 << ":\n" << std::dec
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<< "\t\t\treturn &" << entry.name << ";" << endl;
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}
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os << "\t\tdefault: assert(0);\n"
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<< "\t}\n"
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<< "}" << endl;
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}
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