diff options
Diffstat (limited to 'py/emitbc.c')
| -rw-r--r-- | py/emitbc.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/py/emitbc.c b/py/emitbc.c index 9c0d78d79..70a4d8b12 100644 --- a/py/emitbc.c +++ b/py/emitbc.c @@ -48,6 +48,11 @@ struct _emit_t { pass_kind_t pass : 8; + // Set to true if the code generator should suppress emitted code due to it + // being dead code. This can happen when opcodes immediately follow an + // unconditional flow control (eg jump or raise). + bool suppress; + int stack_size; mp_emit_common_t *emit_common; @@ -140,6 +145,9 @@ STATIC void emit_write_code_info_bytes_lines(emit_t *emit, mp_uint_t bytes_to_sk // all functions must go through this one to emit byte code STATIC uint8_t *emit_get_cur_to_write_bytecode(void *emit_in, size_t num_bytes_to_write) { emit_t *emit = emit_in; + if (emit->suppress) { + return emit->dummy_data; + } if (emit->pass < MP_PASS_EMIT) { emit->bytecode_offset += num_bytes_to_write; return emit->dummy_data; @@ -222,6 +230,10 @@ STATIC void emit_write_bytecode_byte_child(emit_t *emit, int stack_adj, byte b, STATIC void emit_write_bytecode_byte_label(emit_t *emit, int stack_adj, byte b1, mp_uint_t label) { mp_emit_bc_adjust_stack_size(emit, stack_adj); + if (emit->suppress) { + return; + } + // Determine if the jump offset is signed or unsigned, based on the opcode. const bool is_signed = b1 <= MP_BC_POP_JUMP_IF_FALSE; @@ -271,6 +283,7 @@ STATIC void emit_write_bytecode_byte_label(emit_t *emit, int stack_adj, byte b1, void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) { emit->pass = pass; emit->stack_size = 0; + emit->suppress = false; emit->scope = scope; emit->last_source_line_offset = 0; emit->last_source_line = 1; @@ -426,6 +439,10 @@ void mp_emit_bc_set_source_line(emit_t *emit, mp_uint_t source_line) { } void mp_emit_bc_label_assign(emit_t *emit, mp_uint_t l) { + // Assiging a label ends any dead-code region, and all following opcodes + // should be emitted (until another unconditional flow control). + emit->suppress = false; + mp_emit_bc_adjust_stack_size(emit, 0); if (emit->pass == MP_PASS_SCOPE) { return; @@ -589,6 +606,7 @@ void mp_emit_bc_rot_three(emit_t *emit) { void mp_emit_bc_jump(emit_t *emit, mp_uint_t label) { emit_write_bytecode_byte_label(emit, 0, MP_BC_JUMP, label); + emit->suppress = true; } void mp_emit_bc_pop_jump_if(emit_t *emit, bool cond, mp_uint_t label) { @@ -622,6 +640,7 @@ void mp_emit_bc_unwind_jump(emit_t *emit, mp_uint_t label, mp_uint_t except_dept emit_write_bytecode_byte_label(emit, 0, MP_BC_UNWIND_JUMP, label & ~MP_EMIT_BREAK_FROM_FOR); emit_write_bytecode_raw_byte(emit, ((label & MP_EMIT_BREAK_FROM_FOR) ? 0x80 : 0) | except_depth); } + emit->suppress = true; } void mp_emit_bc_setup_block(emit_t *emit, mp_uint_t label, int kind) { @@ -663,6 +682,7 @@ void mp_emit_bc_for_iter_end(emit_t *emit) { void mp_emit_bc_pop_except_jump(emit_t *emit, mp_uint_t label, bool within_exc_handler) { (void)within_exc_handler; emit_write_bytecode_byte_label(emit, 0, MP_BC_POP_EXCEPT_JUMP, label); + emit->suppress = true; } void mp_emit_bc_unary_op(emit_t *emit, mp_unary_op_t op) { @@ -766,6 +786,7 @@ void mp_emit_bc_call_method(emit_t *emit, mp_uint_t n_positional, mp_uint_t n_ke void mp_emit_bc_return_value(emit_t *emit) { emit_write_bytecode_byte(emit, -1, MP_BC_RETURN_VALUE); + emit->suppress = true; } void mp_emit_bc_raise_varargs(emit_t *emit, mp_uint_t n_args) { @@ -773,6 +794,7 @@ void mp_emit_bc_raise_varargs(emit_t *emit, mp_uint_t n_args) { MP_STATIC_ASSERT(MP_BC_RAISE_LAST + 2 == MP_BC_RAISE_FROM); assert(n_args <= 2); emit_write_bytecode_byte(emit, -n_args, MP_BC_RAISE_LAST + n_args); + emit->suppress = true; } void mp_emit_bc_yield(emit_t *emit, int kind) { |