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John Bampton
11 KiB
11 KiB
The new bytecode
We will reimplement the VM to use 8bit instruction code. By bytecode, we mean real byte code. The whole purpose is reducing the memory consumption of mruby VM.
Instructions
Instructions are bytes. There can be 256 instructions. Currently, we have 94 instructions. Instructions can take 0 to 3 operands.
operands
The size of operands can be either 8bits, 16bits or 24bits. In the table.1 below, the second field describes the size (and sign) of operands.
- B: 8bit
- S: 16bit
- sS: signed 16bit
- W: 24bit
table.1 Instruction Table
| Instruction Name | Operand type | Semantics |
|---|---|---|
| OP_NOP | - | no operation |
| OP_MOVE | BB | R(a) = R(b) |
| OP_LOADL | BB | R(a) = Pool(b) |
| OP_LOADL16 | BS | R(a) = Pool(b) |
| OP_LOADI | BB | R(a) = mrb_int(b) |
| OP_LOADINEG | BB | R(a) = mrb_int(-b) |
| OP_LOADI__1 | B | R(a) = mrb_int(-1) |
| OP_LOADI_0 | B | R(a) = mrb_int(0) |
| OP_LOADI_1 | B | R(a) = mrb_int(1) |
| OP_LOADI_2 | B | R(a) = mrb_int(2) |
| OP_LOADI_3 | B | R(a) = mrb_int(3) |
| OP_LOADI_4 | B | R(a) = mrb_int(4) |
| OP_LOADI_5 | B | R(a) = mrb_int(5) |
| OP_LOADI_6 | B | R(a) = mrb_int(6) |
| OP_LOADI_7 | B | R(a) = mrb_int(7) |
| OP_LOADI16 | BS | R(a) = mrb_int(b) |
| OP_LOADI32 | BSS | R(a) = mrb_int((b<<16)+c) |
| OP_LOADSYM | BB | R(a) = Syms(b) |
| OP_LOADSYM16 | BS | R(a) = Syms(b) |
| OP_LOADNIL | B | R(a) = nil |
| OP_LOADSELF | B | R(a) = self |
| OP_LOADT | B | R(a) = true |
| OP_LOADF | B | R(a) = false |
| OP_GETGV | BB | R(a) = getglobal(Syms(b)) |
| OP_SETGV | BB | setglobal(Syms(b), R(a)) |
| OP_GETSV | BB | R(a) = Special[Syms(b)] |
| OP_SETSV | BB | Special[Syms(b)] = R(a) |
| OP_GETIV | BB | R(a) = ivget(Syms(b)) |
| OP_SETIV | BB | ivset(Syms(b),R(a)) |
| OP_GETCV | BB | R(a) = cvget(Syms(b)) |
| OP_SETCV | BB | cvset(Syms(b),R(a)) |
| OP_GETCONST | BB | R(a) = constget(Syms(b)) |
| OP_SETCONST | BB | constset(Syms(b),R(a)) |
| OP_GETMCNST | BB | R(a) = R(a)::Syms(b) |
| OP_SETMCNST | BB | R(a+1)::Syms(b) = R(a) |
| OP_GETUPVAR | BBB | R(a) = uvget(b,c) |
| OP_SETUPVAR | BBB | uvset(b,c,R(a)) |
| OP_JMP | S | pc+=a |
| OP_JMPIF | BS | if R(a) pc+=b |
| OP_JMPNOT | BS | if !R(a) pc+=b |
| OP_JMPNIL | BS | if R(a)==nil pc+=b |
| OP_JMPUW | S | unwind_and_jump_to(a) |
| OP_EXCEPT | B | R(a) = exc |
| OP_RESCUE | BB | R(b) = R(a).isa?(R(b)) |
| OP_RAISEIF | B | raise(R(a)) if R(a) |
| OP_SENDV | BB | R(a) = call(R(a),Syms(b),*R(a+1)) |
| OP_SENDVB | BB | R(a) = call(R(a),Syms(b),*R(a+1),&R(a+2)) |
| OP_SEND | BBB | R(a) = call(R(a),Syms(b),R(a+1),...,R(a+c)) |
| OP_SENDB | BBB | R(a) = call(R(a),Syms(b),R(a+1),...,R(a+c),&R(a+c+1)) |
| OP_SENDVK | BB | R(a) = call(R(a),Syms(b),*R(a+1),**(a+2),&R(a+3)) |
| OP_CALL | - | R(0) = self.call(frame.argc, frame.argv) |
| OP_SUPER | BB | R(a) = super(R(a+1),... ,R(a+b+1)) |
| OP_ARGARY | BS | R(a) = argument array (16=5:1:5:1:4) |
| OP_ENTER | W | arg setup according to flags (23=5:5:1:5:5:1:1) |
| OP_KEY_P | BB | R(a) = kdict.key?(Syms(b)) |
| OP_KEYEND | - | raise unless kdict.empty? |
| OP_KARG | BB | R(a) = kdict[Syms(b)]; kdict.delete(Syms(b)) |
| OP_RETURN | B | return R(a) (normal) |
| OP_RETURN_BLK | B | return R(a) (in-block return) |
| OP_BREAK | B | break R(a) |
| OP_BLKPUSH | BS | R(a) = block (16=5:1:5:1:4) |
| OP_ADD | B | R(a) = R(a)+R(a+1) |
| OP_ADDI | BB | R(a) = R(a)+mrb_int(b) |
| OP_SUB | B | R(a) = R(a)-R(a+1) |
| OP_SUBI | BB | R(a) = R(a)-mrb_int(b) |
| OP_MUL | B | R(a) = R(a)*R(a+1) |
| OP_DIV | B | R(a) = R(a)/R(a+1) |
| OP_EQ | B | R(a) = R(a)==R(a+1) |
| OP_LT | B | R(a) = R(a)<R(a+1) |
| OP_LE | B | R(a) = R(a)<=R(a+1) |
| OP_GT | B | R(a) = R(a)>R(a+1) |
| OP_GE | B | R(a) = R(a)>=R(a+1) |
| OP_ARRAY | BB | R(a) = ary_new(R(a),R(a+1)..R(a+b)) |
| OP_ARRAY2 | BBB | R(a) = ary_new(R(b),R(b+1)..R(b+c)) |
| OP_ARYCAT | B | ary_cat(R(a),R(a+1)) |
| OP_ARYPUSH | B | ary_push(R(a),R(a+1)) |
| OP_ARYDUP | B | R(a) = ary_dup(R(a)) |
| OP_AREF | BBB | R(a) = R(b)[c] |
| OP_ASET | BBB | R(a)[c] = R(b) |
| OP_APOST | BBB | *R(a),R(a+1)..R(a+c) = R(a)[b..] |
| OP_INTERN | B | R(a) = intern(R(a)) |
| OP_STRING | BB | R(a) = str_dup(Lit(b)) |
| OP_STRING16 | BS | R(a) = str_dup(Lit(b)) |
| OP_STRCAT | B | str_cat(R(a),R(a+1)) |
| OP_HASH | BB | R(a) = hash_new(R(a),R(a+1)..R(a+b*2-1)) |
| OP_HASHADD | BB | R(a) = hash_push(R(a),R(a+1)..R(a+b*2)) |
| OP_HASHCAT | B | R(a) = hash_cat(R(a),R(a+1)) |
| OP_LAMBDA | BB | R(a) = lambda(SEQ[b],OP_L_LAMBDA) |
| OP_LAMBDA16 | BS | R(a) = lambda(SEQ[b],OP_L_LAMBDA) |
| OP_BLOCK | BB | R(a) = lambda(SEQ[b],OP_L_BLOCK) |
| OP_BLOCK16 | BS | R(a) = lambda(SEQ[b],OP_L_BLOCK) |
| OP_METHOD | BB | R(a) = lambda(SEQ[b],OP_L_METHOD) |
| OP_METHOD16 | BS | R(a) = lambda(SEQ[b],OP_L_METHOD) |
| OP_RANGE_INC | B | R(a) = range_new(R(a),R(a+1),FALSE) |
| OP_RANGE_EXC | B | R(a) = range_new(R(a),R(a+1),TRUE) |
| OP_OCLASS | B | R(a) = ::Object |
| OP_CLASS | BB | R(a) = newclass(R(a),Syms(b),R(a+1)) |
| OP_MODULE | BB | R(a) = newmodule(R(a),Syms(b)) |
| OP_EXEC | BB | R(a) = blockexec(R(a),SEQ[b]) |
| OP_EXEC16 | BS | R(a) = blockexec(R(a),SEQ[b]) |
| OP_DEF | BB | R(a).newmethod(Syms(b),R(a+1)) |
| OP_ALIAS | BB | alias_method(target_class,Syms(a),Syms(b)) |
| OP_UNDEF | B | undef_method(target_class,Syms(a)) |
| OP_SCLASS | B | R(a) = R(a).singleton_class |
| OP_TCLASS | B | R(a) = target_class |
| OP_DEBUG | BBB | print a,b,c |
| OP_ERR | B | raise(LocalJumpError, Lit(a)) |
| OP_STOP | - | stop VM |
| ------------------ | -------------- | -------------------------------------------------------- |