scc/ccompiler/backend/riscv32/riscv32.c

#include "riscv32.h"
#include <assembler/riscv32/riscv32_instr.h>

typedef struct {
    ir_func_t* func;
    int stack_offset;
    int stack_base;
    int func_idx;
    int block_idx;
} gen_ctx_t;

static inline int stack_pos(ir_node_t* ptr, gen_ctx_t *ctx) {
    // ir_func_t *func, int stack_base, int stack_offset
    int offset = ctx->stack_base;
    for (int i = 0; i < ctx->func->bblocks.size; i ++) {
        ir_bblock_t* block = vector_at(ctx->func->bblocks, i);
        for (int i = 0; i < block->instrs.size; i++) {
            if (vector_at(block->instrs, i) == ptr) {
                offset += i * 4;
                Assert(offset >= 0 && offset < ctx->stack_offset);
                return offset;
            }
        }
        offset += block->instrs.size * 4;
    }
    Panic("stack pos got error");
    return 0;
}

static int system_func(const char* name) {
    static struct {
        const char* name;
        int ecall_num;
    } defined_func[] = {
        {"ecall_pnt_int", 1},
        {"ecall_pnt_char", 11},
        {"ecall_scan_int", 1025 + 4},
    };

    for (int i = 0; i < sizeof(defined_func)/sizeof(defined_func[0]); i++) {
        if (rt_strcmp(name, defined_func[i].name) == 0) {
            return defined_func[i].ecall_num;
        }
    }
    return -1;
}

static int get_node_val(rv32_prog_t* out_asm, gen_ctx_t* ctx, ir_node_t* ptr, int reg) {
    int len = 0;
    switch (ptr->tag) {
        case IR_NODE_CONST_INT: {
            // TODO
            rv32_li(out_asm, reg, ptr->data.const_int.val);
            // emit_rv32_instr(out_asm, RV_ADDI, reg, reg, 0, ptr->data.const_int.val);
            break;
        }
        default: {
            int offset = stack_pos(ptr, ctx);
            rv32_lw(out_asm, reg, REG_SP, offset);
            break;
        }
    }
    return len;
}

static int gen_instr(rv32_prog_t* out_asm, gen_ctx_t* ctx, ir_node_t* instr) {
    int idx = 0;
    int offset;
    char buf[1024];
    symasm_entry_t label;

    switch (instr->tag) {
        case IR_NODE_ALLOC: {
            // TODO
            break;
        }
        case IR_NODE_LOAD: {
            offset = stack_pos(instr->data.load.target, ctx);
            // t0 = M[sp + offset]
            rv32_lw(out_asm, REG_T0, REG_SP, offset);
            break;
        }
        case IR_NODE_STORE: {
            idx += get_node_val(out_asm, ctx, instr->data.store.value,  REG_T0);
            offset = stack_pos(instr->data.store.target, ctx);
            // M[sp + offset] = t0
            rv32_sw(out_asm, REG_T0, REG_SP, offset);
            break;
        }
        case IR_NODE_RET: {
            // A0 = S0
            if (instr->data.ret.ret_val != NULL) {
                idx += get_node_val(out_asm, ctx, instr->data.ret.ret_val, REG_A0);
            }
            // ra = M[sp + 0]
            rv32_lw(out_asm, REG_RA, REG_SP, 0);
            // sp = sp + stack_offset
            rv32_addi(out_asm, REG_SP, REG_SP, ctx->stack_offset);
            // ret == JALR(REG_X0, REG_RA, 0)
            rv32_ret(out_asm);
            break;
        }
        case IR_NODE_OP: {
            idx += get_node_val(out_asm, ctx, instr->data.op.lhs, REG_T1);
            idx += get_node_val(out_asm, ctx, instr->data.op.rhs, REG_T2);

            rv32_instr_t _instr = {
                .rd = REG_T0,
                .rs1 = REG_T1,
                .rs2 = REG_T2,
                .imm = 0
            };
            #define GEN_BIN_OP(type) _instr.instr_type = type, \
                emit_rv32_instr(out_asm, &_instr, EMIT_PUSH_BACK, NULL)
            switch (instr->data.op.op) {
            case IR_OP_ADD:
                GEN_BIN_OP(RV_ADD);
                break;
            case IR_OP_SUB:
                GEN_BIN_OP(RV_SUB);
                break;
            case IR_OP_MUL:
                GEN_BIN_OP(RV_MUL);
                break;
            case IR_OP_DIV:
                GEN_BIN_OP(RV_DIV);
                break;
            case IR_OP_MOD:
                GEN_BIN_OP(RV_REM);
                break;
            case IR_OP_EQ:
                GEN_BIN_OP(RV_XOR);
                rv32_seqz(out_asm, REG_T0, REG_T0);
                break;
            case IR_OP_GE:
                GEN_BIN_OP(RV_SLT);
                rv32_seqz(out_asm, REG_T0, REG_T0);
                break;
            case IR_OP_GT:
                // SGT(rd, rs1, rs2) SLT(rd, rs2, rs1)
                // GENCODE(SGT(REG_T0, REG_T1, REG_T2));
                rv32_slt(out_asm, REG_T0, REG_T2, REG_T1);
                break;
            case IR_OP_LE:
                // GENCODE(SGT(REG_T0, REG_T1, REG_T2));
                rv32_slt(out_asm, REG_T0, REG_T2, REG_T1);
                rv32_seqz(out_asm, REG_T0, REG_T0);
                break;
            case IR_OP_LT:
                rv32_slt(out_asm, REG_T0, REG_T1, REG_T2);
                break;
            case IR_OP_NEQ:
                GEN_BIN_OP(RV_XOR);
                break;
            default:
                LOG_ERROR("ERROR gen_instr op in riscv");
                break;
            }
            offset = stack_pos(instr, ctx);
            rv32_sw(out_asm, REG_T0, REG_SP, offset);
            break;
        }
        case IR_NODE_BRANCH: {
            get_node_val(out_asm, ctx, instr->data.branch.cond, REG_T0);

            rt.snprintf(buf, sizeof(buf), "L%s%p", instr->data.branch.true_bblock->label, instr->data.branch.true_bblock);
            label.name = strpool_intern(out_asm->strpool, buf);
            label.attr = LOCAL;
            rv32_bne_l(out_asm, REG_T0, REG_X0, &label);

            rt.snprintf(buf, sizeof(buf), "L%s%p", instr->data.branch.false_bblock->label, instr->data.branch.false_bblock);
            label.name = strpool_intern(out_asm->strpool, buf);
            label.attr = LOCAL;
            rv32_jal_l(out_asm, REG_X0, &label);
            break;
        }
        case IR_NODE_JUMP: {
            // TODO
            rt.snprintf(buf, sizeof(buf), "L%s%p", instr->data.jump.target_bblock->label, instr->data.jump.target_bblock);
            label.name = strpool_intern(out_asm->strpool, buf);
            label.attr = LOCAL;
            rv32_jal_l(out_asm, REG_X0, &label);
            break;
        }
        case IR_NODE_CALL: {
            if (instr->data.call.args.size > 8) {
                LOG_ERROR("can't add so much params");
            }
            int param_regs[8] = {
                REG_A0, REG_A1, REG_A2, REG_A3,
                REG_A4, REG_A5, REG_A6, REG_A7
            };
            for (int i = 0; i < instr->data.call.args.size; i++) {
                ir_node_t* param = vector_at(instr->data.call.args, i);
                idx += get_node_val(out_asm, ctx, param, param_regs[i]);
            }

            int system_func_idx = system_func(instr->data.call.callee->name);
            if (system_func_idx != -1) {
                rv32_li(out_asm, REG_A7, system_func_idx);
                rv32_ecall(out_asm);
                goto CALL_END;
            }

            /*            
            // GENCODES(CALL(0));
            // AUIPC(REG_X1, REG_X0), \
            // JALR(REG_X1, REG_X1, offset)
            */
            // TODO CALL
            label.name = strpool_intern(out_asm->strpool, instr->data.call.callee->name);
            label.attr = GLOBAL;
            rv32_call_l(out_asm, &label);
        CALL_END:
            offset = stack_pos(instr, ctx);
            rv32_sw(out_asm, REG_A0, REG_SP, offset);
            break;
        }
        default:
            LOG_ERROR("ERROR gen_instr in riscv");
    }
    return idx;
}

static int gen_block(rv32_prog_t* out_asm, gen_ctx_t* ctx, ir_bblock_t* block) {
    symasm_entry_t label;
    char buf[1024];
    rt.snprintf(buf, sizeof(buf), "L%s%p", block->label, block);
    label.name = strpool_intern(out_asm->strpool, buf);
    label.attr = LOCAL;
    rv32_append_label(out_asm, &label, out_asm->text.size);

    for (int i = 0; i < block->instrs.size; i ++) {
        gen_instr(out_asm, ctx, vector_at(block->instrs, i));
    }
    return 0;
}

static int gen_func(rv32_prog_t* out_asm, ir_func_t* func) {
    gen_ctx_t ctx;

    symasm_entry_t label = {
        .name = strpool_intern(out_asm->strpool, func->name),
        .attr = GLOBAL,
    };
    rv32_append_label(out_asm, &label, out_asm->text.size);

    int stack_base = 4;
    int stack_offset = stack_base;
    for (int i = 0; i < func->bblocks.size; i++) {
        // TODO every instr push ret val to stack
        stack_offset += 4 * (*vector_at(func->bblocks, i)).instrs.size;
    }
    ctx.func = func;
    ctx.stack_base = stack_base;
    ctx.stack_offset = stack_offset;
    ctx.func_idx = 0;
    ctx.block_idx = 0;
    // TODO Alignment by 16
    
    // sp = sp - stack_offset;
    rv32_addi(out_asm, REG_SP, REG_SP, -stack_offset);
    // M[sp] = ra;
    rv32_sw(out_asm, REG_RA, REG_SP, 0);

    int param_regs[8] = {
        REG_A0, REG_A1, REG_A2, REG_A3,
        REG_A4, REG_A5, REG_A6, REG_A7
    };
    if (func->params.size > 8) {
        LOG_ERROR("can't add so much params");
    }
    for (int i = 0; i < func->params.size; i++) {
        int offset = stack_pos(vector_at(func->params, i), &ctx);
        // M[sp + offset] = param[idx];
        rv32_sw(out_asm, param_regs[i], REG_SP, offset);
    }
    
    for(int i = 0; i < func->bblocks.size; i ++) {
        gen_block(out_asm, &ctx ,vector_at(func->bblocks, i));
    }
    return 0;
}


int gen_rv32_from_ir(ir_prog_t* ir, rv32_prog_t* out_asm) {
    init_rv32_prog(out_asm, NULL);

    for(int i = 0; i < ir->funcs.size; i ++) {
        gen_func(out_asm, vector_at(ir->funcs, i));
    }
    return 0;

    // // Got Main pos;
    // for (int i = 0; i < prog->funcs.size; i++) {
    //     if (strcmp(vector_at(prog->funcs, i)->name, "main") == 0) {
    //         return jmp_cache[i];
    //     }
    // }
    // LOG_ERROR("main not found");
}