Initial SIMDBC interpreter.

runtime/vm/constants_dbc.h

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef VM_CONSTANTS_DBC_H_
+#define VM_CONSTANTS_DBC_H_
+
+#include "platform/globals.h"
+#include "platform/assert.h"
+#include "platform/utils.h"
+
+
+namespace dart {
+
+// List of Dart Bytecode instructions.
+//
+// INTERPRETER STATE
+//
+//      current frame info (see stack_frame_dbc.h for layout)
+//        v-----^-----v
+//   ~----+----~ ~----+-------+-------+-~ ~-+-------+-------+-~
+//   ~    |    ~ ~    | FP[0] | FP[1] | ~ ~ | SP[-1]| SP[0] |
+//   ~----+----~ ~----+-------+-------+-~ ~-+-------+-------+-~
+//                    ^                             ^
+//                    FP                            SP
+//
+//
+// The state of execution is captured in few interpreter registers:
+//
+//   FP - base of the cFurrent frame

[zra, 2016/04/08 22:37:34]

cFurrent -> current

[Vyacheslav Egorov (Google), 2016/04/11 10:49:10]

Done.

+//   SP - top of the stack (TOS) for the current frame
+//   PP - object pool for the currently execution function
+//
+// Frame info stored below FP additionally contains pointers to the currently
+// executing function and code (see stack_frame_dbc.h for more information).
+//
+// In the unoptimized code most of bytecodes take operands implicitly from
+// stack and store results again on the stack. Constant operands are usually
+// taken from the object pool by index.
+//
+// ENCODING
+//
+// Each instruction is a 32-bit integer with opcode stored in the least
+// significant byte. The following operand encodings are used:
+//
+//   0........8.......16.......24.......32
+//   +--------+--------+--------+--------+
+//   | opcode |~~~~~~~~~~~~~~~~~~~~~~~~~~|   0: no operands
+//   +--------+--------+--------+--------+
+//
+//   +--------+--------+--------+--------+
+//   | opcode |    A   |~~~~~~~~~~~~~~~~~|   A: single unsigned 8-bit operand
+//   +--------+--------+--------+--------+
+//
+//   +--------+--------+--------+--------+
+//   | opcode |    A   |        D        | A_D: unsigned 8-bit operand and
+//   +--------+--------+--------+--------+      unsigned 16-bit operand
+//
+//   +--------+--------+--------+--------+
+//   | opcode |    A   |        X        | A_X: unsigned 8-bit operand and
+//   +--------+--------+--------+--------+      signed 16-bit operand
+//
+//   +--------+--------+--------+--------+
+//   | opcode |~~~~~~~~|        D        |   D: unsigned 16-bit operand
+//   +--------+--------+--------+--------+
+//
+//   +--------+--------+--------+--------+
+//   | opcode |~~~~~~~~|        X        |   X: signed 16-bit operand
+//   +--------+--------+--------+--------+
+//
+//   +--------+--------+--------+--------+
+//   | opcode |    A   |    B   |    C   | A_B_C: 3 unsigned 8-bit operands
+//   +--------+--------+--------+--------+
+//
+//   +--------+--------+--------+--------+
+//   | opcode |             T            |   T: signed 24-bit operand
+//   +--------+--------+--------+--------+
+//
+//
+// INSTRUCTIONS
+//
+//  - Trap
+//
+//    Unreachable instruction.
+//
+//  - Compile
+//
+//    Compile current function and start executing newly produced code
+//    (used to implement LazyCompileStub);
+//
+//  - Intrinsic id
+//
+//    Execute intrinsic with the given id. If intrinsic returns true then
+//    return from the current function to the caller passing value produced
+//    by the intrinsic as a result;
+//
+//  - Drop1; DropR n; Drop n
+//
+//    Drop 1 or n values from the stack, if instruction is DropR push the first
+//    dropped value to the stack;
+//
+//  - Jump target
+//
+//    Jump to the given target. Target is specified as offset from the PC of the
+//    jump instruction.
+//
+//  - Return R; ReturnTOS
+//
+//    Return to the caller using either a value from the given register or a
+//    value from the top-of-stack as a result.
+//
+//    Note: return instruction knows how many arguments to remove from the
+//    stack because it can look at the call instruction at caller's PC and
+//    take argument count from it.
+//
+//  - Move rA, rX
+//
+//    FP[rA] <- FP[rX]
+//    Note: rX is singed so it can be used to address parameters which are
+//    at negative indices with respect to FP.
+//
+//  - Push rX
+//
+//    Push FP[rX] to the stack.
+//
+//  - LoadConstant rA, D; PushConstant D
+//
+//    Load value at index D from constant pool into rA or push it onto the

[zra, 2016/04/08 22:37:34]

FP[rA]?

[Vyacheslav Egorov (Google), 2016/04/11 10:49:10]

Done.

+//    stack.
+//
+//  - StoreLocal rX; PopLocal rX
+//
+//    Store top of the stack into FP[rX] and pop it if needed.
+//
+//  - StaticCall ArgC, D
+//
+//    Invoke function in SP[0] with arguments SP[-(1+ArgC)], ..., SP[-1] and
+//    argument descriptor PP[D].
+//
+//  - InstanceCall ArgC, D; InstanceCall2 ArgC, D; InstanceCall3 ArgC, D
+//
+//    Lookup and invoke method using ICData in PP[D] with arguments
+//    SP[-(1+ArgC)], ..., SP[-1].
+//
+//  - NativeCall, NativeBootstrapCall
+//
+//    Invoke native function SP[-1] with argc_tag SP[0].
+//
+//  - AddTOS; SubTOS; MulTOS; BitOrTOS; BitAndTOS; EqualTOS; LessThanTOS;
+//    GreaterThanTOS;
+//
+//    Smi fast-path for a corresponding method. Checks if SP[0] and SP[-1] are
+//    both smis and result of SP[0] <op> SP[-1] is a smi - if this is true
+//    then pops operands and pushes result on the stack and skips the next
+//    instruction (which implements a slow path fallback).
+//
+//  - StoreStaticTOS D
+//
+//    Stores TOS into the static field PP[D].
+//
+//  - PushStatic
+//
+//    Pushes value of the static field PP[D] on to the stack.
+//
+//  - InitStaticTOS
+//
+//    Takes static field from TOS and ensures that it is initialized.
+//
+//  - IfNeStrictTOS; IfEqStrictTOS; IfNeStrictNumTOS; IfEqStrictNumTOS

[zra, 2016/04/08 22:37:34]

What does Strict mean here? Will there be non-Strict variants?

[Vyacheslav Egorov (Google), 2016/04/11 10:49:10]

Strict means the same it means in Token::kEQ_STRICT :)

I don't think there'll be a non strict comparison in the bytecode.

+//
+//    Skips the next instruction unless the given condition holds. 'Num'
+//    variants perform number check while non-Num variants just compare
+//    RawObject pointers.
+//
+//    Used to implement conditional jump:
+//
+//        IfNeStrictTOS
+//        Jump T         ;; jump if not equal
+//
+//  - CreateArrayTOS
+//
+//    Allocate array of length SP[0] with type arguments SP[-1].
+//
+//  - Allocate D
+//
+//    Allocate object of class PP[D] with no type arguments.
+//
+//  - AllocateT
+//
+//    Allocate object of class SP[0] with type arguments SP[-1].
+//
+//  - StoreIndexedTOS
+//
+//    Store SP[0] into array SP[-2] at index SP[-1]. No typechecking is done.
+//    SP[-2] is assumed to be a RawArray, SP[-1] to be a smi.
+//
+//  - StoreField rA, B, rC
+//
+//    Store value FP[rC] into object FP[rA] at offset (in words) B.
+//
+//  - StoreFieldTOS D
+//
+//    Store value SP[0] into object SP[-1] at offset (in words) D.
+//
+//  - LoadField rA, rB, C
+//
+//    Load value at offset (in words) C from object FP[rB] into FP[rA].
+//
+//  - LoadFieldTOS D
+//
+//    Push value at offset (in words) D from object SP[0].
+//
+//  - BooleanNegateTOS
+//
+//    SP[0] = !SP[0]
+//
+//  - Throw A
+//
+//    Throw (Rethrow if A != 0) exception. Exception object and stack object
+//    are taken from TOS.
+//
+//  - Entry A, B, rC
+//
+//    Function prologue for the function with no optional or named arguments:
+//        A - expected number of positional arguments;
+//        B - number of local slots to reserve;
+//        rC - specifies context register to initialize with empty context.
+//
+//  - EntryOpt A, B, C
+//
+//    Function prologue for the function with optional or named arguments:
+//        A - expected number of positional arguments;
+//        B - number of optional arguments;
+//        C - number of named arguments;
+//
+//    Only one of B and C can be not 0.
+//
+//    If B is not 0 then EntryOpt bytecode is followed by B LoadConstant
+//    bytecodes specifying default values for optional arguments.
+//
+//    If C is not 0 then EntryOpt is followed by 2 * B LoadConstant bytecodes.
+//    Bytecode at 2 * i specifies name of the i-th named argument and at
+//    2 * i + 1 default value. rA part of the LoadConsant bytecode specifies
+//    the location of the parameter on the stack. Here named arguments are
+//    sorted alphabetically to enable linear matching similar to how function
+//    prologues are implemented on other architectures.
+//
+//    Note: Unlike Entry bytecode EntryOpt does not setup the frame for
+//    local variables this is done by a separate bytecode Frame.
+//
+//  - Frame D
+//
+//    Reserve and initialize with null space for D local variables.
+//
+//  - SetFrame A
+//
+//    Reinitialize SP assuming that current frame has size A.
+//    Used to drop temporaries from the stack in the exception handler.
+//
+//  - AllocateContext D
+//
+//    Allocate Context object assuming for D context variables.
+//
+//  - CloneContext
+//
+//    Clone context stored in TOS.
+//
+//  - MoveSpecial rA, D
+//
+//    Copy special values from inside interpreter to FP[rA]. Currently only
+//    used to pass exception object (D = 0) and stack trace object (D = 1) to
+//    catch handler.
+//
+//  - InstantiateType D
+//
+//    Instantiate type PP[D] with instantiator type arguments SP[0].
+//
+//  - InstantiateTypeArgumentsTOS D
+//
+//    Instantiate type arguments PP[D] with instantiator SP[0].
+//
+//  - AssertAssignable D
+//
+//    Assert that SP[-3] is assignable to variable named SP[0] of type
+//    SP[-1] with type arguments SP[-2] using SubtypeTestCache PP[D].
+//
+//  - AssertBoolean A
+//
+//    Assert that TOS is a boolean (A = 1) or that TOS is not null (A = 0).
+//
+//  - CheckStack
+//
+//    Compare SP against isolate stack limit and call StackOverflow handler if
+//    necessary.
+//
+//  - DebugStep, DebugBreak A
+//
+//    Debugger support. DebugBreak is bytecode that can be patched into the
+//    instruction stream to trigger in place breakpoint.
+//
+//    When patching instance or static call with DebugBreak we set A to
+//    match patched call's argument count so that Return instructions continue
+//    to work.
+//
+// TODO(vegorov) the way we replace calls with DebugBreak does not work
+//               with our smi fast paths because DebugBreak is simply skipped.
+//
+// BYTECODE LIST FORMAT
+//
+// Bytecode list below is specified using the following format:
+//
+//     V(BytecodeName, OperandForm, Op1, Op2, Op3)
+//
+// - OperandForm specifies operand encoding and should be one of 0, A, T, A_D,
+//   A_X, X, D (see ENCODING section above).
+//
+// - Op1, Op2, Op2 specify operand meaning. Possible values:
+//
+//     ___ ignored / non-existent operand
+//     num immediate operand
+//     lit constant literal from object pool
+//     reg register (unsigned FP relative local)
+//     xeg x-register (signed FP relative local)
+//
+#define BYTECODES_LIST(V)                              \
+  V(Trap,                            0, ___, ___, ___) \
+  V(Compile,                         0, ___, ___, ___) \
+  V(Intrinsic,                       A, num, ___, ___) \
+  V(Drop1,                           0, ___, ___, ___) \
+  V(DropR,                           A, num, ___, ___) \
+  V(Drop,                            A, num, ___, ___) \
+  V(Jump,                            T, tgt, ___, ___) \

[zra, 2016/04/08 22:37:34]

tgt is not in the key above.

[Vyacheslav Egorov (Google), 2016/04/11 10:49:10]

Done.

+  V(Return,                          A, num, ___, ___) \
+  V(ReturnTOS,                       0, ___, ___, ___) \
+  V(Move,                          A_X, reg, xeg, ___) \
+  V(Push,                            X, xeg, ___, ___) \
+  V(LoadConstant,                  A_D, reg, lit, ___) \
+  V(PushConstant,                    D, lit, ___, ___) \
+  V(StoreLocal,                      X, xeg, ___, ___) \
+  V(PopLocal,                        X, xeg, ___, ___) \
+  V(StaticCall,                    A_D, num, num, ___) \
+  V(InstanceCall,                  A_D, num, num, ___) \
+  V(InstanceCall2,                 A_D, num, num, ___) \
+  V(InstanceCall3,                 A_D, num, num, ___) \
+  V(NativeCall,                      0, ___, ___, ___) \
+  V(NativeBootstrapCall,             0, ___, ___, ___) \
+  V(AddTOS,                          0, ___, ___, ___) \
+  V(SubTOS,                          0, ___, ___, ___) \
+  V(MulTOS,                          0, ___, ___, ___) \
+  V(BitOrTOS,                        0, ___, ___, ___) \
+  V(BitAndTOS,                       0, ___, ___, ___) \
+  V(EqualTOS,                        0, ___, ___, ___) \
+  V(LessThanTOS,                     0, ___, ___, ___) \
+  V(GreaterThanTOS,                  0, ___, ___, ___) \
+  V(StoreStaticTOS,                  D, lit, ___, ___) \
+  V(PushStatic,                      D, lit, ___, ___) \
+  V(InitStaticTOS,                   0, ___, ___, ___) \
+  V(IfNeStrictTOS,                   0, ___, ___, ___) \
+  V(IfEqStrictTOS,                   0, ___, ___, ___) \
+  V(IfNeStrictNumTOS,                0, ___, ___, ___) \
+  V(IfEqStrictNumTOS,                0, ___, ___, ___) \
+  V(CreateArrayTOS,                  0, ___, ___, ___) \
+  V(Allocate,                        D, lit, ___, ___) \
+  V(AllocateT,                       0, ___, ___, ___) \
+  V(StoreIndexedTOS,                 0, ___, ___, ___) \
+  V(StoreField,                  A_B_C, reg, reg, reg) \
+  V(StoreFieldTOS,                   D, num, ___, ___) \
+  V(LoadField,                   A_B_C, reg, reg, reg) \
+  V(LoadFieldTOS,                    D, num, ___, ___) \
+  V(BooleanNegateTOS,                0, ___, ___, ___) \
+  V(Throw,                           A, num, ___, ___) \
+  V(Entry,                       A_B_C, num, num, num) \
+  V(EntryOpt,                    A_B_C, num, num, num) \
+  V(Frame,                           D, num, ___, ___) \
+  V(SetFrame,                        A, num, ___, num) \
+  V(AllocateContext,                 D, num, ___, ___) \
+  V(CloneContext,                    0, ___, ___, ___) \
+  V(MoveSpecial,                   A_D, reg, num, ___) \
+  V(InstantiateType,                 D, lit, ___, ___) \
+  V(InstantiateTypeArgumentsTOS,   A_D, num, lit, ___) \
+  V(AssertAssignable,                D, num, lit, ___) \
+  V(AssertBoolean,                   A, num, ___, ___) \
+  V(CheckStack,                      0, ___, ___, ___) \
+  V(DebugStep,                       0, ___, ___, ___) \
+  V(DebugBreak,                      A, num, ___, ___) \
+
+class Bytecode {
+ public:
+  enum Opcode {
+#define DECLARE_BYTECODE(name, encoding, op1, op2, op3) k##name,
+BYTECODES_LIST(DECLARE_BYTECODE)
+#undef DECLARE_BYTECODE
+  };
+
+  static uint32_t Encode(Opcode op, uintptr_t a, uintptr_t b, uintptr_t c) {
+    ASSERT((a & 0xFF) == a);
+    ASSERT((b & 0xFF) == b);
+    ASSERT((c & 0xFF) == c);
+    return op | (a << 8) | (b << 16) | (c << 24);
+  }
+
+  static uint32_t Encode(Opcode op, uintptr_t a, uintptr_t d) {
+    ASSERT((a & 0x00FF) == a);
+    ASSERT((d & 0xFFFF) == d);
+    return op | (a << 8) | (d << 16);
+  }
+
+  static uint32_t Encode(Opcode op, uint32_t abc) {
+    return op | (abc << 8);
+  }
+
+  static uint32_t EncodeSigned(Opcode op, uintptr_t a, intptr_t x) {
+    ASSERT((a & 0x00FF) == a);
+    ASSERT((x << 16) >> 16 == x);
+    return op | (a << 8) | (x << 16);
+  }
+
+  static uint32_t EncodeSigned(Opcode op, intptr_t x) {
+    ASSERT((x << 8) >> 8 == x);
+    return op | (x << 8);
+  }
+
+  static uint32_t Encode(Opcode op) {
+    return op;
+  }
+
+  DART_FORCE_INLINE static Opcode DecodeOpcode(uint32_t bc) {
+    return static_cast<Opcode>(bc & 0xFF);
+  }
+
+  DART_FORCE_INLINE static uint8_t DecodeArgc(uint32_t call) {
+#if defined(DEBUG)
+    const Opcode op = DecodeOpcode(call);
+    ASSERT(op == Bytecode::kStaticCall ||

[zra, 2016/04/08 22:37:34]

parens around each 'a == b'

[Vyacheslav Egorov (Google), 2016/04/11 10:49:10]

Done.

+           op == Bytecode::kInstanceCall ||
+           op == Bytecode::kInstanceCall2 ||
+           op == Bytecode::kInstanceCall3 ||
+           op == Bytecode::kDebugBreak);
+#endif
+    return (call >> 8) & 0xFF;
+  }
+};
+
+// Various dummy declarations to make shared code compile.
+// TODO(vegorov) we need to prune away as much dead code as possible instead
+// of just making it compile.
+typedef int16_t Register;
+
+const int16_t FPREG = 0;
+const int16_t SPREG = 1;
+const intptr_t kNumberOfCpuRegisters = 20;
+const intptr_t kDartAvailableCpuRegs = 0;
+const intptr_t kNoRegister = -1;
+const intptr_t kReservedCpuRegisters = 0;
+const intptr_t ARGS_DESC_REG = 0;
+const intptr_t CODE_REG = 0;
+const intptr_t kExceptionObjectReg = 0;
+const intptr_t kStackTraceObjectReg = 0;
+const intptr_t CTX = 0;
+
+enum FpuRegister { kNoFpuRegister = -1, kFakeFpuRegister };
+const FpuRegister FpuTMP = kFakeFpuRegister;
+const intptr_t kNumberOfFpuRegisters = 1;
+
+enum Condition { EQ, NE };
+
+class Instr { };
+
+}  // namespace dart
+
+#endif  // VM_CONSTANTS_DBC_H_