py/emit: Remove logic to detect last-emit-was-return-value.
This optimisation to remove dead code is not as good as it could be. Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George
parent
0db046b67b
commit
e85a096302
24
py/compile.c
24
py/compile.c
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@ -1330,12 +1330,8 @@ STATIC void compile_if_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
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goto done;
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}
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if (
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// optimisation: don't jump over non-existent elif/else blocks
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!(MP_PARSE_NODE_IS_NULL(pns->nodes[2]) && MP_PARSE_NODE_IS_NULL(pns->nodes[3]))
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// optimisation: don't jump if last instruction was return
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&& !EMIT(last_emit_was_return_value)
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) {
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// optimisation: don't jump over non-existent elif/else blocks
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if (!(MP_PARSE_NODE_IS_NULL(pns->nodes[2]) && MP_PARSE_NODE_IS_NULL(pns->nodes[3]))) {
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// jump over elif/else blocks
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EMIT_ARG(jump, l_end);
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}
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@ -1362,10 +1358,7 @@ STATIC void compile_if_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
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goto done;
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}
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// optimisation: don't jump if last instruction was return
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if (!EMIT(last_emit_was_return_value)) {
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EMIT_ARG(jump, l_end);
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}
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EMIT_ARG(jump, l_end);
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EMIT_ARG(label_assign, l_fail);
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}
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}
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@ -1580,9 +1573,7 @@ STATIC void compile_for_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
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EMIT_ARG(for_iter, pop_label);
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c_assign(comp, pns->nodes[0], ASSIGN_STORE); // variable
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compile_node(comp, pns->nodes[2]); // body
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if (!EMIT(last_emit_was_return_value)) {
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EMIT_ARG(jump, continue_label);
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}
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EMIT_ARG(jump, continue_label);
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EMIT_ARG(label_assign, pop_label);
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EMIT(for_iter_end);
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@ -3048,11 +3039,8 @@ STATIC bool compile_scope(compiler_t *comp, scope_t *scope, pass_kind_t pass) {
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}
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compile_node(comp, pns->nodes[3]); // 3 is function body
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// emit return if it wasn't the last opcode
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if (!EMIT(last_emit_was_return_value)) {
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EMIT_ARG(load_const_tok, MP_TOKEN_KW_NONE);
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EMIT(return_value);
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}
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EMIT_ARG(load_const_tok, MP_TOKEN_KW_NONE);
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EMIT(return_value);
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} else if (scope->kind == SCOPE_LAMBDA) {
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assert(MP_PARSE_NODE_IS_STRUCT(scope->pn));
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mp_parse_node_struct_t *pns = (mp_parse_node_struct_t *)scope->pn;
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@ -115,7 +115,6 @@ typedef struct _emit_method_table_t {
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void (*start_pass)(emit_t *emit, pass_kind_t pass, scope_t *scope);
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bool (*end_pass)(emit_t *emit);
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bool (*last_emit_was_return_value)(emit_t *emit);
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void (*adjust_stack_size)(emit_t *emit, mp_int_t delta);
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void (*set_source_line)(emit_t *emit, mp_uint_t line);
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@ -227,7 +226,6 @@ void emit_native_xtensawin_free(emit_t *emit);
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void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope);
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bool mp_emit_bc_end_pass(emit_t *emit);
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bool mp_emit_bc_last_emit_was_return_value(emit_t *emit);
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void mp_emit_bc_adjust_stack_size(emit_t *emit, mp_int_t delta);
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void mp_emit_bc_set_source_line(emit_t *emit, mp_uint_t line);
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@ -47,7 +47,6 @@ struct _emit_t {
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byte dummy_data[DUMMY_DATA_SIZE];
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pass_kind_t pass : 8;
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mp_uint_t last_emit_was_return_value : 8;
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int stack_size;
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@ -272,7 +271,6 @@ STATIC void emit_write_bytecode_byte_label(emit_t *emit, int stack_adj, byte b1,
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void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) {
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emit->pass = pass;
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emit->stack_size = 0;
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emit->last_emit_was_return_value = false;
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emit->scope = scope;
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emit->last_source_line_offset = 0;
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emit->last_source_line = 1;
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@ -397,10 +395,6 @@ bool mp_emit_bc_end_pass(emit_t *emit) {
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return true;
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}
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bool mp_emit_bc_last_emit_was_return_value(emit_t *emit) {
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return emit->last_emit_was_return_value;
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}
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void mp_emit_bc_adjust_stack_size(emit_t *emit, mp_int_t delta) {
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if (emit->pass == MP_PASS_SCOPE) {
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return;
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@ -410,7 +404,6 @@ void mp_emit_bc_adjust_stack_size(emit_t *emit, mp_int_t delta) {
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if (emit->stack_size > emit->scope->stack_size) {
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emit->scope->stack_size = emit->stack_size;
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}
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emit->last_emit_was_return_value = false;
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}
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void mp_emit_bc_set_source_line(emit_t *emit, mp_uint_t source_line) {
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@ -773,7 +766,6 @@ void mp_emit_bc_call_method(emit_t *emit, mp_uint_t n_positional, mp_uint_t n_ke
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void mp_emit_bc_return_value(emit_t *emit) {
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emit_write_bytecode_byte(emit, -1, MP_BC_RETURN_VALUE);
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emit->last_emit_was_return_value = true;
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}
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void mp_emit_bc_raise_varargs(emit_t *emit, mp_uint_t n_args) {
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@ -806,7 +798,6 @@ const emit_method_table_t emit_bc_method_table = {
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mp_emit_bc_start_pass,
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mp_emit_bc_end_pass,
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mp_emit_bc_last_emit_was_return_value,
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mp_emit_bc_adjust_stack_size,
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mp_emit_bc_set_source_line,
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@ -276,8 +276,6 @@ struct _emit_t {
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uint16_t n_info;
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uint16_t n_cell;
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bool last_emit_was_return_value;
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scope_t *scope;
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ASM_T *as;
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@ -370,7 +368,6 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
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emit->pass = pass;
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emit->do_viper_types = scope->emit_options == MP_EMIT_OPT_VIPER;
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emit->stack_size = 0;
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emit->last_emit_was_return_value = false;
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emit->scope = scope;
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// allocate memory for keeping track of the types of locals
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@ -733,10 +730,6 @@ STATIC bool emit_native_end_pass(emit_t *emit) {
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return true;
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}
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STATIC bool emit_native_last_emit_was_return_value(emit_t *emit) {
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return emit->last_emit_was_return_value;
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}
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STATIC void ensure_extra_stack(emit_t *emit, size_t delta) {
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if (emit->stack_size + delta > emit->stack_info_alloc) {
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size_t new_alloc = (emit->stack_size + delta + 8) & ~3;
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@ -793,7 +786,7 @@ STATIC void emit_native_set_source_line(emit_t *emit, mp_uint_t source_line) {
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// this must be called at start of emit functions
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STATIC void emit_native_pre(emit_t *emit) {
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emit->last_emit_was_return_value = false;
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(void)emit;
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}
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// depth==0 is top, depth==1 is before top, etc
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@ -917,7 +910,6 @@ STATIC void emit_fold_stack_top(emit_t *emit, int reg_dest) {
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// If stacked value is in a register and the register is not r1 or r2, then
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// *reg_dest is set to that register. Otherwise the value is put in *reg_dest.
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STATIC void emit_pre_pop_reg_flexible(emit_t *emit, vtype_kind_t *vtype, int *reg_dest, int not_r1, int not_r2) {
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emit->last_emit_was_return_value = false;
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stack_info_t *si = peek_stack(emit, 0);
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if (si->kind == STACK_REG && si->data.u_reg != not_r1 && si->data.u_reg != not_r2) {
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*vtype = si->vtype;
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@ -930,12 +922,10 @@ STATIC void emit_pre_pop_reg_flexible(emit_t *emit, vtype_kind_t *vtype, int *re
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}
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STATIC void emit_pre_pop_discard(emit_t *emit) {
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emit->last_emit_was_return_value = false;
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adjust_stack(emit, -1);
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}
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STATIC void emit_pre_pop_reg(emit_t *emit, vtype_kind_t *vtype, int reg_dest) {
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emit->last_emit_was_return_value = false;
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emit_access_stack(emit, 1, vtype, reg_dest);
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adjust_stack(emit, -1);
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}
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@ -2771,7 +2761,6 @@ STATIC void emit_native_return_value(emit_t *emit) {
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// Do the unwinding jump to get to the return handler
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emit_native_unwind_jump(emit, emit->exit_label, emit->exc_stack_size);
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emit->last_emit_was_return_value = true;
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return;
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}
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@ -2809,7 +2798,6 @@ STATIC void emit_native_return_value(emit_t *emit) {
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ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_RET_VAL(emit), REG_PARENT_RET);
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}
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emit_native_unwind_jump(emit, emit->exit_label, emit->exc_stack_size);
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emit->last_emit_was_return_value = true;
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}
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STATIC void emit_native_raise_varargs(emit_t *emit, mp_uint_t n_args) {
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@ -2928,7 +2916,6 @@ const emit_method_table_t EXPORT_FUN(method_table) = {
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emit_native_start_pass,
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emit_native_end_pass,
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emit_native_last_emit_was_return_value,
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emit_native_adjust_stack_size,
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emit_native_set_source_line,
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@ -48,12 +48,12 @@ arg names:
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43 LOAD_CONST_NONE
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44 RETURN_VALUE
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File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ 45\[46\] bytes)
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Raw bytecode (code_info_size=8\[46\], bytecode_size=370):
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Raw bytecode (code_info_size=8\[46\], bytecode_size=372):
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a8 12 9\[bf\] 03 05 60 60 26 22 24 64 22 24 25 25 24
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26 23 63 22 22 25 23 23 2f 6c 25 65 25 25 69 68
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26 65 27 6a 62 20 23 62 2a 29 69 24 25 28 67 26
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########
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\.\+81 63
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\.\+51 63
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arg names:
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(N_STATE 22)
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(N_EXC_STACK 2)
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@ -403,6 +403,8 @@ arg names:
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367 RETURN_VALUE
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368 LOAD_CONST_SMALL_INT 1
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369 RETURN_VALUE
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370 LOAD_CONST_NONE
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371 RETURN_VALUE
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File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ 59 bytes)
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Raw bytecode (code_info_size=8, bytecode_size=51):
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a8 10 0a 05 80 82 34 38 81 57 c0 57 c1 57 c2 57
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@ -621,9 +623,9 @@ arg names: *
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08 DELETE_DEREF 0
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10 LOAD_CONST_NONE
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11 RETURN_VALUE
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File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ 13 bytes)
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Raw bytecode (code_info_size=8, bytecode_size=5):
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9a 01 0a 05 03 08 80 8b b1 25 00 f2 63
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File cmdline/cmd_showbc.py, code block 'f' (descriptor: \.\+, bytecode @\.\+ 15 bytes)
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Raw bytecode (code_info_size=8, bytecode_size=7):
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9a 01 0a 05 03 08 80 8b b1 25 00 f2 63 51 63
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arg names: * b
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(N_STATE 4)
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(N_EXC_STACK 0)
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@ -633,6 +635,8 @@ arg names: * b
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01 LOAD_DEREF 0
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03 BINARY_OP 27 __add__
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04 RETURN_VALUE
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05 LOAD_CONST_NONE
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06 RETURN_VALUE
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mem: total=\\d\+, current=\\d\+, peak=\\d\+
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stack: \\d\+ out of \\d\+
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GC: total: \\d\+, used: \\d\+, free: \\d\+
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