Method process_unary_op

LiveRecomp/live_generator.cpp:893–1167

}

void N64Recomp::LiveGenerator::process_unary_op(const UnaryOp& op, const InstructionContext& ctx) const {
    // Skip instructions that output to $zero
    if (outputs_to_zero(op.output, ctx)) {
        return;
    }

    // A unary op may have a float u32l as the source or destination, but not both.
    if (is_fpr_u32l(op.input) && is_fpr_u32l(op.output)) {
        assert(false);
        errored = true;
        return;
    }

    sljit_sw dst;
    sljit_sw dstw;
    sljit_sw src;
    sljit_sw srcw;
    bool output_good = get_operand_values(op.output, ctx, dst, dstw, compiler, Registers::arithmetic_temp3);
    bool input_good = get_operand_values(op.input, ctx, src, srcw, compiler, Registers::arithmetic_temp3);

    if (!output_good || !input_good) {
        assert(false);
        errored = true;
        return;
    }

    // If a relocation is needed for the input operand, perform the relocation and store the result directly.
    if (ctx.reloc_type != RelocType::R_MIPS_NONE) {
        // Only allow relocation of lui with an immediate.
        if (op.operation != UnaryOpType::Lui || op.input != Operand::ImmU16) {
            assert(false);
            errored = true;
            return;
        }
        // Only allow HI16 relocs.
        if (ctx.reloc_type != RelocType::R_MIPS_HI16) {
            assert(false);
            errored = true;
            return;
        }
        // Load the relocated address into temp1.
        load_relocated_address(ctx, Registers::arithmetic_temp1);

        // HI16 reloc on a lui
        // The 32-bit address (a) is equal to section address + section offset
        // The 16-bit immediate is equal to (a - (int16_t)a) >> 16
        // Therefore, the register should be set to (int32_t)(a - (int16_t)a) as the shifts cancel out and the lower 16 bits are zero.

        // Extract a sign extended 16-bit value from the lower half of the relocated address and put it in temp2.
        sljit_emit_op1(compiler, SLJIT_MOV_S16, Registers::arithmetic_temp2, 0, Registers::arithmetic_temp1, 0);

        // Subtract the sign extended 16-bit value from the full address to get the HI16 value and place it in the destination.
        sljit_emit_op2(compiler, SLJIT_SUB, dst, dstw, Registers::arithmetic_temp1, 0, Registers::arithmetic_temp2, 0);
        return;
    }

    sljit_s32 jit_op = SLJIT_BREAKPOINT;