Function getCallerSaveRegs

src/e9tool/e9codegen.cpp:708–788

* Get all callee-save registers. */

 * Get all callee-save registers.
 */
const int *getCallerSaveRegs(bool sysv, bool clean, bool state,
    bool conditional, size_t num_args)
{
    // If "state", then we must save the entire register state:
    static const int state_save[] =
    {
        RAX_IDX, RCX_IDX, RDX_IDX, RBX_IDX, RBP_IDX, RSI_IDX, RDI_IDX, R8_IDX,
        R9_IDX, R10_IDX, R11_IDX, R12_IDX, R13_IDX, R14_IDX, R15_IDX,
        FLAGS_IDX, RSP_IDX, RIP_IDX, -1
    };
    if (state)
        return state_save;
 
    // For clean calls, we must save all caller save registers according
    // to the corresponding ABI.  Notes:
    // - To support `conditional', %rcx must be saved first.
    // - %rax must be saved before %rflags.
    static const int clean_sysv_save[] =
    {
        RCX_IDX, RAX_IDX, FLAGS_IDX, R11_IDX, R10_IDX, R9_IDX, R8_IDX,
        RDX_IDX, RSI_IDX, RDI_IDX, -1
    };
    static const int clean_win64_save[] =
    {
        RCX_IDX, RAX_IDX, FLAGS_IDX, R11_IDX, R10_IDX, R9_IDX, R8_IDX,
        RDX_IDX, -1
    };
    const int *clean_save = (sysv? clean_sysv_save: clean_win64_save);
    if (clean)
        return clean_save;

    // For `naked' calls, we only save the number of registers actually used
    // by args.
    static const int naked_sysv_save[] =
    {
        R11_IDX, R10_IDX, R9_IDX, R8_IDX, RCX_IDX, RDX_IDX, RSI_IDX, RDI_IDX,
        -1
    };
    static const int naked_win64_save[] =
    {
        R11_IDX, R10_IDX, R9_IDX, R8_IDX, RDX_IDX, RCX_IDX, -1
    };
    const int *naked_save = (sysv? naked_sysv_save: naked_win64_save);
    unsigned naked_len    = (sysv? 8: 6);
    if (!conditional)
        return naked_save + (naked_len - num_args);

    // For `conditional+naked' calls. %rax must be saved first:
    if (sysv)
    {
        static const int conditional_save[][10] =
        {
            {RAX_IDX, -1},
            {RAX_IDX, RDI_IDX, -1},
            {RAX_IDX, RSI_IDX, RDI_IDX, -1},
            {RAX_IDX, RDX_IDX, RSI_IDX, RDI_IDX, -1},
            {RAX_IDX, RCX_IDX, RDX_IDX, RSI_IDX, RDI_IDX, -1},
            {RAX_IDX, R8_IDX, RCX_IDX, RDX_IDX, RSI_IDX, RDI_IDX, -1},