深入jvm虚拟机--第一篇 void TemplateInterpreterGenerator::generate_and_dispatch(Template* t, TosState tos_out) 函数

阅读原文时间：2023年07月10日阅读：3

今天第一次使用虚拟姐打断点,断点设置在了void TemplateInterpreterGenerator::generate_and_dispatch(Template* t, TosState tos_out) 了

在TemplateInterpreterGenerator.cpp中,这个函数之前看书就不太懂,现在debug时候就能分析的比较清楚了,这个函数的介绍在解密jvm的528页中有具体介绍

void TemplateInterpreterGenerator::generate_and_dispatch(Template* t, TosState tos_out) {
if (PrintBytecodeHistogram) histogram_bytecode(t);
#ifndef PRODUCT
// debugging code
if (CountBytecodes || TraceBytecodes || StopInterpreterAt > 0) count_bytecode();
if (PrintBytecodePairHistogram) histogram_bytecode_pair(t);
if (TraceBytecodes) trace_bytecode(t);
if (StopInterpreterAt > 0) stop_interpreter_at();
__ verify_FPU(1, t->tos_in());
#endif // !PRODUCT
int step = 0;
if (!t->does_dispatch()) {
step = t->is_wide() ? Bytecodes::wide_length_for(t->bytecode()) : Bytecodes::length_for(t->bytecode());
if (tos_out == ilgl) tos_out = t->tos_out();
// compute bytecode size
assert(step > 0, "just checkin'");
// setup stuff for dispatching next bytecode
if (ProfileInterpreter && VerifyDataPointer
&& MethodData::bytecode_has_profile(t->bytecode())) {
__ verify_method_data_pointer();
}
__ dispatch_prolog(tos_out, step);
}
// generate template
t->generate(_masm);
// advance
if (t->does_dispatch()) {
#ifdef ASSERT
// make sure execution doesn't go beyond this point if code is broken
__ should_not_reach_here();
#endif // ASSERT
} else {
// dispatch to next bytecode
__ dispatch_epilog(tos_out, step);
}
}

先看这个入参函数Template

这个是一个对象,在哪里定义的呢?得往上边查看

void TemplateInterpreterGenerator::set_entry_points(Bytecodes::Code code) {
CodeletMark cm(_masm, Bytecodes::name(code), code);
// initialize entry points
assert(_unimplemented_bytecode != NULL, "should have been generated before");
assert(_illegal_bytecode_sequence != NULL, "should have been generated before");
address bep = _illegal_bytecode_sequence;
address zep = _illegal_bytecode_sequence;
address cep = _illegal_bytecode_sequence;
address sep = _illegal_bytecode_sequence;
address aep = _illegal_bytecode_sequence;
address iep = _illegal_bytecode_sequence;
address lep = _illegal_bytecode_sequence;
address fep = _illegal_bytecode_sequence;
address dep = _illegal_bytecode_sequence;
address vep = _unimplemented_bytecode;
address wep = _unimplemented_bytecode;
// code for short & wide version of bytecode
if (Bytecodes::is_defined(code)) {
Template* t = TemplateTable::template_for(code);
assert(t->is_valid(), "just checking");
set_short_entry_points(t, bep, cep, sep, aep, iep, lep, fep, dep, vep);
}
if (Bytecodes::wide_is_defined(code)) {
Template* t = TemplateTable::template_for_wide(code);
assert(t->is_valid(), "just checking");
set_wide_entry_point(t, wep);
}
// set entry points
EntryPoint entry(bep, zep, cep, sep, aep, iep, lep, fep, dep, vep);
Interpreter::_normal_table.set_entry(code, entry);
Interpreter::_wentry_point[code] = wep;
}

是通过: Template* t = TemplateTable::template_for(code); 得到的; TemplateTable的定义

需要知道的是这个是个静态类,理解是类似于java,能在全局通过类:成员,类:方法来调用(引用)

class TemplateTable: AllStatic {
public:
enum Operation { add, sub, mul, div, rem, _and, _or, _xor, shl, shr, ushr };
enum Condition { equal, not_equal, less, less_equal, greater, greater_equal };
enum CacheByte { f1_byte = 1, f2_byte = 2, f1_oop = 0x11 }; // byte_no codes

private:
static bool _is_initialized; // true if TemplateTable has been initialized
static Template _template_table [Bytecodes::number_of_codes];
static Template _template_table_wide[Bytecodes::number_of_codes];

static Template* _desc; // the current template to be generated
static Bytecodes::Code bytecode() { return _desc->bytecode(); }

static BarrierSet* _bs; // Cache the barrier set.
public:
//%note templates_1
static InterpreterMacroAssembler* _masm; // the assembler used when generating templates

private:

// special registers
static inline Address at_bcp(int offset);

// helpers
static void unimplemented_bc();
static void patch_bytecode(Bytecodes::Code bc, Register bc_reg,
Register temp_reg, bool load_bc_into_bc_reg = true, int byte_no = -1);

// C calls
static void call_VM(Register oop_result, address entry_point);
static void call_VM(Register oop_result, address entry_point, Register arg_1);
static void call_VM(Register oop_result, address entry_point, Register arg_1, Register arg_2);
static void call_VM(Register oop_result, address entry_point, Register arg_1, Register arg_2, Register arg_3);

// these overloadings are not presently used on SPARC:
static void call_VM(Register oop_result, Register last_java_sp, address entry_point);
static void call_VM(Register oop_result, Register last_java_sp, address entry_point, Register arg_1);
static void call_VM(Register oop_result, Register last_java_sp, address entry_point, Register arg_1, Register arg_2);
static void call_VM(Register oop_result, Register last_java_sp, address entry_point, Register arg_1, Register arg_2, Register arg_3);

// bytecodes
static void nop();

static void aconst_null();
static void iconst(int value);
static void lconst(int value);
static void fconst(int value);
static void dconst(int value);

static void bipush();
static void sipush();
static void ldc(bool wide);
static void ldc2_w();
static void fast_aldc(bool wide);

static void locals_index(Register reg, int offset = 1);
static void iload();
static void fast_iload();
static void fast_iload2();
static void fast_icaload();
static void lload();
static void fload();
static void dload();
static void aload();

static void locals_index_wide(Register reg);
static void wide_iload();
static void wide_lload();
static void wide_fload();
static void wide_dload();
static void wide_aload();

static void iaload();
static void laload();
static void faload();
static void daload();
static void aaload();
static void baload();
static void caload();
static void saload();

static void iload(int n);
static void lload(int n);
static void fload(int n);
static void dload(int n);
static void aload(int n);
static void aload_0();

static void istore();
static void lstore();
static void fstore();
static void dstore();
static void astore();

};

那么试着摸索能看到 _template_table,这个是一个数组,一共有239个,对应了239个字节码指令

static Template* template_for (Bytecodes::Code code) { Bytecodes::check (code); return &_template_table [code]; }

此时code值为01则返回对应的为_nop的指令,意思就是t=一个_nop字节码的信息,还接着看

step = t->is_wide() ? Bytecodes::wide_length_for(t->bytecode()) : Bytecodes::length_for(t->bytecode());

此为generate_and_dispatch函数中的,分析 t->bytecode(),值==01

//share/vm/interpreter/templateTable.cpp文件中
Bytecodes::Code Template::bytecode() const {
int i = this - TemplateTable::_template_table;
if (i < 0 || i >= Bytecodes::number_of_codes)
　　　　 i = this - TemplateTable::_template_table_wide;
return Bytecodes::cast(i);
}

那么看_template_table,还是上面已经介绍的那个,接着分析

Bytecodes::wide_length_for(01)

这里的用法就是静态方法调用,查看Bytecodes类

class Bytecodes: AllStatic {
public:
enum Code {
_illegal = -1,

// Java bytecodes  
\_nop                  =   0, // 0x00  
\_aconst\_null          =   1, // 0x01  
\_iconst\_m1            =   2, // 0x02  
\_iconst\_0             =   3, // 0x03  
\_iconst\_1             =   4, // 0x04  
\_iconst\_2             =   5, // 0x05  
\_iconst\_3             =   6, // 0x06  
\_iconst\_4             =   7, // 0x07  
\_iconst\_5             =   8, // 0x08  
\_lconst\_0             =   9, // 0x09  
\_lconst\_1             =  10, // 0x0a  
\_fconst\_0             =  11, // 0x0b  
\_fconst\_1             =  12, // 0x0c  
\_fconst\_2             =  13, // 0x0d  
\_dconst\_0             =  14, // 0x0e  
\_dconst\_1             =  15, // 0x0f  
\_bipush               =  16, // 0x10  
\_sipush               =  17, // 0x11  
\_ldc                  =  18, // 0x12  
\_ldc\_w                =  19, // 0x13  
\_ldc2\_w               =  20, // 0x14  
\_iload                =  21, // 0x15  
\_lload                =  22, // 0x16  
\_fload                =  23, // 0x17  
\_dload                =  24, // 0x18  
\_aload                =  25, // 0x19  
\_iload\_0              =  26, // 0x1a  
\_iload\_1              =  27, // 0x1b  
\_iload\_2              =  28, // 0x1c  
\_iload\_3              =  29, // 0x1d  
\_lload\_0              =  30, // 0x1e  
\_lload\_1              =  31, // 0x1f  
\_lload\_2              =  32, // 0x20  
\_lload\_3              =  33, // 0x21  
\_fload\_0              =  34, // 0x22  
 number\_of\_codes

};

// Flag bits derived from format strings, can_trap, can_rewrite, etc.:
enum Flags {
// semantic flags:
_bc_can_trap = 1<<0, // bytecode execution can trap or block
_bc_can_rewrite = 1<<1, // bytecode execution has an alternate form

// format bits (determined only by the format string):  
\_fmt\_has\_c        = 1<<2,     // constant, such as sipush "bcc"  
\_fmt\_has\_j        = 1<<3,     // constant pool cache index, such as getfield "bjj"  
\_fmt\_has\_k        = 1<<4,     // constant pool index, such as ldc "bk"  
\_fmt\_has\_i        = 1<<5,     // local index, such as iload  
\_fmt\_has\_o        = 1<<6,     // offset, such as ifeq  
\_fmt\_has\_nbo      = 1<<7,     // contains native-order field(s)  
\_fmt\_has\_u2       = 1<<8,     // contains double-byte field(s)  
\_fmt\_has\_u4       = 1<<9,     // contains quad-byte field  
\_fmt\_not\_variable = 1<<10,    // not of variable length (simple or wide)  
\_fmt\_not\_simple   = 1<<11,    // either wide or variable length  
\_all\_fmt\_bits     = (\_fmt\_not\_simple\*2 - \_fmt\_has\_c),

// Example derived format syndromes:  
\_fmt\_b      = \_fmt\_not\_variable,  
\_fmt\_bc     = \_fmt\_b | \_fmt\_has\_c,  
\_fmt\_bi     = \_fmt\_b | \_fmt\_has\_i,  
\_fmt\_bkk    = \_fmt\_b | \_fmt\_has\_k | \_fmt\_has\_u2,  
\_fmt\_bJJ    = \_fmt\_b | \_fmt\_has\_j | \_fmt\_has\_u2 | \_fmt\_has\_nbo,  
\_fmt\_bo2    = \_fmt\_b | \_fmt\_has\_o | \_fmt\_has\_u2,  
\_fmt\_bo4    = \_fmt\_b | \_fmt\_has\_o | \_fmt\_has\_u4

};

private:
static bool _is_initialized;
static const char* _name [number_of_codes];
static BasicType _result_type [number_of_codes];
static s_char _depth [number_of_codes];
static u_char _lengths [number_of_codes];
static Code _java_code [number_of_codes];
static jchar _flags [(1<<BitsPerByte)*2]; // all second page for wide formats

static void def(Code code, const char* name, const char* format, const char* wide_format, BasicType result_type, int depth, bool can_trap);
static void def(Code code, const char* name, const char* format, const char* wide_format, BasicType result_type, int depth, bool can_trap, Code java_code);
static void pd_initialize(); // platform specific initialization
static Code pd_base_code_for(Code code); // platform specific base_code_for implementation

// Verify that bcp points into method
#ifdef ASSERT
static bool check_method(const methodOopDesc* method, address bcp);
#endif
static bool check_must_rewrite(Bytecodes::Code bc);

public:
// Conversion
static void check (Code code) { assert(is_defined(code), "illegal code"); }
static void wide_check (Code code) { assert(wide_is_defined(code), "illegal code"); }
static Code cast (int code) { return (Code)code; }

static Code code_at(const methodOopDesc* method, address bcp) {
assert(method == NULL || check_method(method, bcp), "bcp must point into method");
Code code = cast(*bcp);
assert(code != _breakpoint || method != NULL, "need methodOop to decode breakpoint");
return (code != _breakpoint) ? code : non_breakpoint_code_at(method, bcp);
}
static Code java_code_at(const methodOopDesc* method, address bcp) {
return java_code(code_at(method, bcp));
}

// Fetch a bytecode or a breakpoint:
static Code code_or_bp_at(address bcp) { return (Code)cast(*bcp); }

static Code code_at(methodOop method, int bci);
static bool is_active_breakpoint_at(address bcp) { return (Code)*bcp == _breakpoint; }

// find a bytecode, behind a breakpoint if necessary:
static Code non_breakpoint_code_at(const methodOopDesc* method, address bcp);

// Bytecode attributes
static bool is_defined (int code) { return 0 <= code && code < number_of_codes && flags(code, false) != 0; } static bool wide_is_defined(int code) { return is_defined(code) && flags(code, true) != 0; } static const char* name (Code code) { check(code); return _name [code]; } static BasicType result_type (Code code) { check(code); return _result_type [code]; } static int depth (Code code) { check(code); return _depth [code]; } // Note: Length functions must return <=0 for invalid bytecodes. // Calling check(code) in length functions would throw an unwanted assert. static int length_for (Code code) { /*no check*/ return _lengths [code] & 0xF; } static int wide_length_for(Code code) { /*no check*/ return _lengths [code] >> 4; }
static bool can_trap (Code code) { check(code); return has_all_flags(code, _bc_can_trap, false); }
static Code java_code (Code code) { check(code); return _java_code [code]; }
static bool can_rewrite (Code code) { check(code); return has_all_flags(code, _bc_can_rewrite, false); }
static bool must_rewrite(Bytecodes::Code code) { return can_rewrite(code) && check_must_rewrite(code); }
static bool native_byte_order(Code code) { check(code); return has_all_flags(code, _fmt_has_nbo, false); }
static bool uses_cp_cache (Code code) { check(code); return has_all_flags(code, _fmt_has_j, false); }
// if 'end' is provided, it indicates the end of the code buffer which
// should not be read past when parsing.
static int special_length_at(Bytecodes::Code code, address bcp, address end = NULL);
static int special_length_at(methodOop method, address bcp, address end = NULL) { return special_length_at(code_at(method, bcp), bcp, end); }
static int raw_special_length_at(address bcp, address end = NULL);
static int length_for_code_at(Bytecodes::Code code, address bcp) { int l = length_for(code); return l > 0 ? l : special_length_at(code, bcp); }
static int length_at (methodOop method, address bcp) { return length_for_code_at(code_at(method, bcp), bcp); }
static int java_length_at (methodOop method, address bcp) { return length_for_code_at(java_code_at(method, bcp), bcp); }
static bool is_java_code (Code code) { return 0 <= code && code < number_of_java_codes; }

static bool is_aload (Code code) { return (code == _aload || code == _aload_0 || code == _aload_1
|| code == _aload_2 || code == _aload_3); }
static bool is_astore (Code code) { return (code == _astore || code == _astore_0 || code == _astore_1
|| code == _astore_2 || code == _astore_3); }

static bool is_zero_const (Code code) { return (code == _aconst_null || code == _iconst_0
|| code == _fconst_0 || code == _dconst_0); }
static bool is_invoke (Code code) { return (_invokevirtual <= code && code <= _invokedynamic); }

static int compute_flags (const char* format, int more_flags = 0); // compute the flags
static int flags (int code, bool is_wide) {
assert(code == (u_char)code, "must be a byte");
return _flags[code + (is_wide ? (1<<BitsPerByte) : 0)];
}
static int format_bits (Code code, bool is_wide) { return flags(code, is_wide) & _all_fmt_bits; }
static bool has_all_flags (Code code, int test_flags, bool is_wide) {
return (flags(code, is_wide) & test_flags) == test_flags;
}

// Initialization
static void initialize ();
};

#endif // SHARE_VM_INTERPRETER_BYTECODES_HPP

那么

static int wide_length_for(Code code) { /*no check*/ return _lengths [code] >> 4; }

这个静态类中的值

那么久能看到了 _lengths[01] 为1,

static int length_for (Code code) { /*no check*/ return _lengths [code] & 0xF; }

_lengths[01]为1 &1111111 还是为1;

今天先分析到这里,明天再续
现在准备执行

// generate template
t->generate(_masm);

还是要看Template这个东西,先看类的定义

//"interpreter/interpreterRuntime.hpp"
class Template VALUE_OBJ_CLASS_SPEC {
private:
enum Flags {
uses_bcp_bit, // set if template needs the bcp pointing to bytecode
does_dispatch_bit, // set if template dispatches on its own
calls_vm_bit, // set if template calls the vm
wide_bit // set if template belongs to a wide instruction
};

typedef void (*generator)(int arg);

int _flags; // describes interpreter template properties (bcp unknown)
TosState _tos_in; // tos cache state before template execution
TosState _tos_out; // tos cache state after template execution
generator _gen; // template code generator
int _arg; // argument for template code generator

void initialize(int flags, TosState tos_in, TosState tos_out, generator gen, int arg);

friend class TemplateTable;

public:
Bytecodes::Code bytecode() const;
bool is_valid() const { return _gen != NULL; }
bool uses_bcp() const { return (_flags & (1 << uses_bcp_bit )) != 0; }
bool does_dispatch() const { return (_flags & (1 << does_dispatch_bit)) != 0; }
bool calls_vm() const { return (_flags & (1 << calls_vm_bit )) != 0; }
bool is_wide() const { return (_flags & (1 << wide_bit )) != 0; }
TosState tos_in() const { return _tos_in; }
TosState tos_out() const { return _tos_out; }
void generate(InterpreterMacroAssembler* masm);
};

//进入函数内部

void Template::generate(InterpreterMacroAssembler* masm) {
// parameter passing
TemplateTable::_desc = this;
TemplateTable::_masm = masm;
// code generation
_gen(_arg); ///这个函数在 TemplateTable类中
masm->flush();
}

进入_gen(_arg)

//templateTable_x86.cpp
void TemplateTable::nop() {
transition(vtos, vtos);
// nothing to do
}

这里正是对应了templateTable

特别注意上边的类的调用: Template::generater ===>调用了 TemplateTable::nop函数

这nop函数啥也没做

void TemplateTable::transition(TosState tos_in, TosState tos_out) {
assert(_desc->tos_in() == tos_in , "inconsistent tos_in information");
assert(_desc->tos_out() == tos_out, "inconsistent tos_out information");
}

这样就结束了, t->generate(_masm);生成模板的函数调用,之前看过template是在哪里 Template TemplateTable::_template_table [Bytecodes::number_of_codes];保存

那么他是怎么创造的呢?

//templateTable.cpp
void TemplateTable::initialize() {
if (_is_initialized) return;

// Initialize table
TraceTime timer("TemplateTable initialization", TraceStartupTime);

_bs = Universe::heap()->barrier_set();

// For better readability
const char _ = ' ';
const int ____ = 0;
const int ubcp const int disp const int clvm const int iswd // // Java spec bytecodes def(Bytecodes::_nop def(Bytecodes::_aconst_null def(Bytecodes::_iconst_m1 def(Bytecodes::_iconst_0 def(Bytecodes::_iconst_1 def(Bytecodes::_iconst_2 def(Bytecodes::_iconst_3 def(Bytecodes::_iconst_4 def(Bytecodes::_iconst_5 def(Bytecodes::_lconst_0 def(Bytecodes::_lconst_1 def(Bytecodes::_fconst_0 def(Bytecodes::_fconst_1 def(Bytecodes::_fconst_2 def(Bytecodes::_dconst_0 def(Bytecodes::_dconst_1 def(Bytecodes::_bipush def(Bytecodes::_sipush def(Bytecodes::_ldc def(Bytecodes::_ldc_w def(Bytecodes::_ldc2_w def(Bytecodes::_iload def(Bytecodes::_lload def(Bytecodes::_fload def(Bytecodes::_dload def(Bytecodes::_aload def(Bytecodes::_iload_0 def(Bytecodes::_iload_1 def(Bytecodes::_iload_2 def(Bytecodes::_iload_3 def(Bytecodes::_lload_0 def(Bytecodes::_lload_1 def(Bytecodes::_lload_2 def(Bytecodes::_lload_3 def(Bytecodes::_fload_0 def(Bytecodes::_fload_1 def(Bytecodes::_fload_2 def(Bytecodes::_fload_3 def(Bytecodes::_dload_0 def(Bytecodes::_dload_1 def(Bytecodes::_dload_2 def(Bytecodes::_dload_3 def(Bytecodes::_aload_0 def(Bytecodes::_aload_1 def(Bytecodes::_aload_2 def(Bytecodes::_aload_3 def(Bytecodes::_iaload def(Bytecodes::_laload def(Bytecodes::_faload def(Bytecodes::_daload def(Bytecodes::_aaload def(Bytecodes::_baload def(Bytecodes::_caload def(Bytecodes::_saload def(Bytecodes::_istore def(Bytecodes::_lstore def(Bytecodes::_fstore def(Bytecodes::_dstore def(Bytecodes::_astore def(Bytecodes::_istore_0 def(Bytecodes::_istore_1 def(Bytecodes::_istore_2 def(Bytecodes::_istore_3 def(Bytecodes::_lstore_0 def(Bytecodes::_lstore_1 def(Bytecodes::_lstore_2 def(Bytecodes::_lstore_3 def(Bytecodes::_fstore_0 def(Bytecodes::_fstore_1 def(Bytecodes::_fstore_2 def(Bytecodes::_fstore_3 def(Bytecodes::_dstore_0 def(Bytecodes::_dstore_1 def(Bytecodes::_dstore_2 def(Bytecodes::_dstore_3 def(Bytecodes::_astore_0 def(Bytecodes::_astore_1 def(Bytecodes::_astore_2 def(Bytecodes::_astore_3 def(Bytecodes::_iastore def(Bytecodes::_lastore def(Bytecodes::_fastore def(Bytecodes::_dastore def(Bytecodes::_aastore def(Bytecodes::_bastore def(Bytecodes::_castore def(Bytecodes::_sastore def(Bytecodes::_pop def(Bytecodes::_pop2 def(Bytecodes::_dup def(Bytecodes::_dup_x1 def(Bytecodes::_dup_x2 def(Bytecodes::_dup2 def(Bytecodes::_dup2_x1 def(Bytecodes::_dup2_x2 def(Bytecodes::_swap def(Bytecodes::_iadd def(Bytecodes::_ladd def(Bytecodes::_fadd def(Bytecodes::_dadd def(Bytecodes::_isub def(Bytecodes::_lsub def(Bytecodes::_fsub def(Bytecodes::_dsub def(Bytecodes::_imul def(Bytecodes::_lmul def(Bytecodes::_fmul def(Bytecodes::_dmul def(Bytecodes::_idiv def(Bytecodes::_ldiv def(Bytecodes::_fdiv def(Bytecodes::_ddiv def(Bytecodes::_irem def(Bytecodes::_lrem def(Bytecodes::_frem def(Bytecodes::_drem def(Bytecodes::_ineg def(Bytecodes::_lneg def(Bytecodes::_fneg def(Bytecodes::_dneg def(Bytecodes::_ishl def(Bytecodes::_lshl def(Bytecodes::_ishr def(Bytecodes::_lshr def(Bytecodes::_iushr def(Bytecodes::_lushr def(Bytecodes::_iand def(Bytecodes::_land def(Bytecodes::_ior def(Bytecodes::_lor def(Bytecodes::_ixor def(Bytecodes::_lxor def(Bytecodes::_iinc def(Bytecodes::_i2l def(Bytecodes::_i2f def(Bytecodes::_i2d def(Bytecodes::_l2i def(Bytecodes::_l2f def(Bytecodes::_l2d def(Bytecodes::_f2i def(Bytecodes::_f2l def(Bytecodes::_f2d def(Bytecodes::_d2i def(Bytecodes::_d2l def(Bytecodes::_d2f def(Bytecodes::_i2b def(Bytecodes::_i2c def(Bytecodes::_i2s def(Bytecodes::_lcmp def(Bytecodes::_fcmpl def(Bytecodes::_fcmpg def(Bytecodes::_dcmpl def(Bytecodes::_dcmpg def(Bytecodes::_ifeq def(Bytecodes::_ifne def(Bytecodes::_iflt def(Bytecodes::_ifge def(Bytecodes::_ifgt def(Bytecodes::_ifle def(Bytecodes::_if_icmpeq def(Bytecodes::_if_icmpne def(Bytecodes::_if_icmplt def(Bytecodes::_if_icmpge def(Bytecodes::_if_icmpgt def(Bytecodes::_if_icmple def(Bytecodes::_if_acmpeq def(Bytecodes::_if_acmpne def(Bytecodes::_goto def(Bytecodes::_jsr def(Bytecodes::_ret def(Bytecodes::_tableswitch def(Bytecodes::_lookupswitch def(Bytecodes::_ireturn def(Bytecodes::_lreturn def(Bytecodes::_freturn def(Bytecodes::_dreturn def(Bytecodes::_areturn def(Bytecodes::_return def(Bytecodes::_getstatic def(Bytecodes::_putstatic def(Bytecodes::_getfield def(Bytecodes::_putfield def(Bytecodes::_invokevirtual def(Bytecodes::_invokespecial def(Bytecodes::_invokestatic def(Bytecodes::_invokeinterface def(Bytecodes::_invokedynamic def(Bytecodes::_new def(Bytecodes::_newarray def(Bytecodes::_anewarray def(Bytecodes::_arraylength def(Bytecodes::_athrow def(Bytecodes::_checkcast def(Bytecodes::_instanceof def(Bytecodes::_monitorenter def(Bytecodes::_monitorexit def(Bytecodes::_wide def(Bytecodes::_multianewarray def(Bytecodes::_ifnull def(Bytecodes::_ifnonnull def(Bytecodes::_goto_w def(Bytecodes::_jsr_w = 1 << Template::uses_bcp_bit;
= 1 << Template::does_dispatch_bit;
= 1 << Template::calls_vm_bit;
= 1 << Template::wide_bit;
interpr. templates
ubcp|disp|clvm|iswd in out generator argument
, ____|____|____|____, vtos, vtos, nop , _ );
, ____|____|____|____, vtos, atos, aconst_null , _ );
, ____|____|____|____, vtos, itos, iconst , -1 );
, ____|____|____|____, vtos, itos, iconst , 0 );
, ____|____|____|____, vtos, itos, iconst , 1 );
, ____|____|____|____, vtos, itos, iconst , 2 );
, ____|____|____|____, vtos, itos, iconst , 3 );
, ____|____|____|____, vtos, itos, iconst , 4 );
, ____|____|____|____, vtos, itos, iconst , 5 );
, ____|____|____|____, vtos, ltos, lconst , 0 );
, ____|____|____|____, vtos, ltos, lconst , 1 );
, ____|____|____|____, vtos, ftos, fconst , 0 );
, ____|____|____|____, vtos, ftos, fconst , 1 );
, ____|____|____|____, vtos, ftos, fconst , 2 );
, ____|____|____|____, vtos, dtos, dconst , 0 );
, ____|____|____|____, vtos, dtos, dconst , 1 );
, ubcp|____|____|____, vtos, itos, bipush , _ );
, ubcp|____|____|____, vtos, itos, sipush , _ );
, ubcp|____|clvm|____, vtos, vtos, ldc , false );
, ubcp|____|clvm|____, vtos, vtos, ldc , true );
, ubcp|____|____|____, vtos, vtos, ldc2_w , _ );
, ubcp|____|clvm|____, vtos, itos, iload , _ );
, ubcp|____|____|____, vtos, ltos, lload , _ );
, ubcp|____|____|____, vtos, ftos, fload , _ );
, ubcp|____|____|____, vtos, dtos, dload , _ );
, ubcp|____|clvm|____, vtos, atos, aload , _ );
, ____|____|____|____, vtos, itos, iload , 0 );
, ____|____|____|____, vtos, itos, iload , 1 );
, ____|____|____|____, vtos, itos, iload , 2 );
, ____|____|____|____, vtos, itos, iload , 3 );
, ____|____|____|____, vtos, ltos, lload , 0 );
, ____|____|____|____, vtos, ltos, lload , 1 );
, ____|____|____|____, vtos, ltos, lload , 2 );
, ____|____|____|____, vtos, ltos, lload , 3 );
, ____|____|____|____, vtos, ftos, fload , 0 );
, ____|____|____|____, vtos, ftos, fload , 1 );
, ____|____|____|____, vtos, ftos, fload , 2 );
, ____|____|____|____, vtos, ftos, fload , 3 );
, ____|____|____|____, vtos, dtos, dload , 0 );
, ____|____|____|____, vtos, dtos, dload , 1 );
, ____|____|____|____, vtos, dtos, dload , 2 );
, ____|____|____|____, vtos, dtos, dload , 3 );
, ubcp|____|clvm|____, vtos, atos, aload_0 , _ );
, ____|____|____|____, vtos, atos, aload , 1 );
, ____|____|____|____, vtos, atos, aload , 2 );
, ____|____|____|____, vtos, atos, aload , 3 );
, ____|____|____|____, itos, itos, iaload , _ );
, ____|____|____|____, itos, ltos, laload , _ );
, ____|____|____|____, itos, ftos, faload , _ );
, ____|____|____|____, itos, dtos, daload , _ );
, ____|____|____|____, itos, atos, aaload , _ );
, ____|____|____|____, itos, itos, baload , _ );
, ____|____|____|____, itos, itos, caload , _ );
, ____|____|____|____, itos, itos, saload , _ );
, ubcp|____|clvm|____, itos, vtos, istore , _ );
, ubcp|____|____|____, ltos, vtos, lstore , _ );
, ubcp|____|____|____, ftos, vtos, fstore , _ );
, ubcp|____|____|____, dtos, vtos, dstore , _ );
, ubcp|____|clvm|____, vtos, vtos, astore , _ );
, ____|____|____|____, itos, vtos, istore , 0 );
, ____|____|____|____, itos, vtos, istore , 1 );
, ____|____|____|____, itos, vtos, istore , 2 );
, ____|____|____|____, itos, vtos, istore , 3 );
, ____|____|____|____, ltos, vtos, lstore , 0 );
, ____|____|____|____, ltos, vtos, lstore , 1 );
, ____|____|____|____, ltos, vtos, lstore , 2 );
, ____|____|____|____, ltos, vtos, lstore , 3 );
, ____|____|____|____, ftos, vtos, fstore , 0 );
, ____|____|____|____, ftos, vtos, fstore , 1 );
, ____|____|____|____, ftos, vtos, fstore , 2 );
, ____|____|____|____, ftos, vtos, fstore , 3 );
, ____|____|____|____, dtos, vtos, dstore , 0 );
, ____|____|____|____, dtos, vtos, dstore , 1 );
, ____|____|____|____, dtos, vtos, dstore , 2 );
, ____|____|____|____, dtos, vtos, dstore , 3 );
, ____|____|____|____, vtos, vtos, astore , 0 );
, ____|____|____|____, vtos, vtos, astore , 1 );
, ____|____|____|____, vtos, vtos, astore , 2 );
, ____|____|____|____, vtos, vtos, astore , 3 );
, ____|____|____|____, itos, vtos, iastore , _ );
, ____|____|____|____, ltos, vtos, lastore , _ );
, ____|____|____|____, ftos, vtos, fastore , _ );
, ____|____|____|____, dtos, vtos, dastore , _ );
, ____|____|clvm|____, vtos, vtos, aastore , _ );
, ____|____|____|____, itos, vtos, bastore , _ );
, ____|____|____|____, itos, vtos, castore , _ );
, ____|____|____|____, itos, vtos, sastore , _ );
, ____|____|____|____, vtos, vtos, pop , _ );
, ____|____|____|____, vtos, vtos, pop2 , _ );
, ____|____|____|____, vtos, vtos, dup , _ );
, ____|____|____|____, vtos, vtos, dup_x1 , _ );
, ____|____|____|____, vtos, vtos, dup_x2 , _ );
, ____|____|____|____, vtos, vtos, dup2 , _ );
, ____|____|____|____, vtos, vtos, dup2_x1 , _ );
, ____|____|____|____, vtos, vtos, dup2_x2 , _ );
, ____|____|____|____, vtos, vtos, swap , _ );
, ____|____|____|____, itos, itos, iop2 , add );
, ____|____|____|____, ltos, ltos, lop2 , add );
, ____|____|____|____, ftos, ftos, fop2 , add );
, ____|____|____|____, dtos, dtos, dop2 , add );
, ____|____|____|____, itos, itos, iop2 , sub );
, ____|____|____|____, ltos, ltos, lop2 , sub );
, ____|____|____|____, ftos, ftos, fop2 , sub );
, ____|____|____|____, dtos, dtos, dop2 , sub );
, ____|____|____|____, itos, itos, iop2 , mul );
, ____|____|____|____, ltos, ltos, lmul , _ );
, ____|____|____|____, ftos, ftos, fop2 , mul );
, ____|____|____|____, dtos, dtos, dop2 , mul );
, ____|____|____|____, itos, itos, idiv , _ );
, ____|____|____|____, ltos, ltos, ldiv , _ );
, ____|____|____|____, ftos, ftos, fop2 , div );
, ____|____|____|____, dtos, dtos, dop2 , div );
, ____|____|____|____, itos, itos, irem , _ );
, ____|____|____|____, ltos, ltos, lrem , _ );
, ____|____|____|____, ftos, ftos, fop2 , rem );
, ____|____|____|____, dtos, dtos, dop2 , rem );
, ____|____|____|____, itos, itos, ineg , _ );
, ____|____|____|____, ltos, ltos, lneg , _ );
, ____|____|____|____, ftos, ftos, fneg , _ );
, ____|____|____|____, dtos, dtos, dneg , _ );
, ____|____|____|____, itos, itos, iop2 , shl );
, ____|____|____|____, itos, ltos, lshl , _ );
, ____|____|____|____, itos, itos, iop2 , shr );
, ____|____|____|____, itos, ltos, lshr , _ );
, ____|____|____|____, itos, itos, iop2 , ushr );
, ____|____|____|____, itos, ltos, lushr , _ );
, ____|____|____|____, itos, itos, iop2 , _and );
, ____|____|____|____, ltos, ltos, lop2 , _and );
, ____|____|____|____, itos, itos, iop2 , _or );
, ____|____|____|____, ltos, ltos, lop2 , _or );
, ____|____|____|____, itos, itos, iop2 , _xor );
, ____|____|____|____, ltos, ltos, lop2 , _xor );
, ubcp|____|clvm|____, vtos, vtos, iinc , _ );
, ____|____|____|____, itos, ltos, convert , _ );
, ____|____|____|____, itos, ftos, convert , _ );
, ____|____|____|____, itos, dtos, convert , _ );
, ____|____|____|____, ltos, itos, convert , _ );
, ____|____|____|____, ltos, ftos, convert , _ );
, ____|____|____|____, ltos, dtos, convert , _ );
, ____|____|____|____, ftos, itos, convert , _ );
, ____|____|____|____, ftos, ltos, convert , _ );
, ____|____|____|____, ftos, dtos, convert , _ );
, ____|____|____|____, dtos, itos, convert , _ );
, ____|____|____|____, dtos, ltos, convert , _ );
, ____|____|____|____, dtos, ftos, convert , _ );
, ____|____|____|____, itos, itos, convert , _ );
, ____|____|____|____, itos, itos, convert , _ );
, ____|____|____|____, itos, itos, convert , _ );
, ____|____|____|____, ltos, itos, lcmp , _ );
, ____|____|____|____, ftos, itos, float_cmp , -1 );
, ____|____|____|____, ftos, itos, float_cmp , 1 );
, ____|____|____|____, dtos, itos, double_cmp , -1 );
, ____|____|____|____, dtos, itos, double_cmp , 1 );
, ubcp|____|clvm|____, itos, vtos, if_0cmp , equal );
, ubcp|____|clvm|____, itos, vtos, if_0cmp , not_equal );
, ubcp|____|clvm|____, itos, vtos, if_0cmp , less );
, ubcp|____|clvm|____, itos, vtos, if_0cmp , greater_equal);
, ubcp|____|clvm|____, itos, vtos, if_0cmp , greater );
, ubcp|____|clvm|____, itos, vtos, if_0cmp , less_equal );
, ubcp|____|clvm|____, itos, vtos, if_icmp , equal );
, ubcp|____|clvm|____, itos, vtos, if_icmp , not_equal );
, ubcp|____|clvm|____, itos, vtos, if_icmp , less );
, ubcp|____|clvm|____, itos, vtos, if_icmp , greater_equal);
, ubcp|____|clvm|____, itos, vtos, if_icmp , greater );
, ubcp|____|clvm|____, itos, vtos, if_icmp , less_equal );
, ubcp|____|clvm|____, atos, vtos, if_acmp , equal );
, ubcp|____|clvm|____, atos, vtos, if_acmp , not_equal );
, ubcp|disp|clvm|____, vtos, vtos, _goto , _ );
, ubcp|disp|____|____, vtos, vtos, jsr , _ ); // result is not an oop, so do not transition to atos
, ubcp|disp|____|____, vtos, vtos, ret , _ );
, ubcp|disp|____|____, itos, vtos, tableswitch , _ );
, ubcp|disp|____|____, itos, itos, lookupswitch , _ );
, ____|disp|clvm|____, itos, itos, _return , itos );
, ____|disp|clvm|____, ltos, ltos, _return , ltos );
, ____|disp|clvm|____, ftos, ftos, _return , ftos );
, ____|disp|clvm|____, dtos, dtos, _return , dtos );
, ____|disp|clvm|____, atos, atos, _return , atos );
, ____|disp|clvm|____, vtos, vtos, _return , vtos );
, ubcp|____|clvm|____, vtos, vtos, getstatic , f1_byte );
, ubcp|____|clvm|____, vtos, vtos, putstatic , f2_byte );
, ubcp|____|clvm|____, vtos, vtos, getfield , f1_byte );
, ubcp|____|clvm|____, vtos, vtos, putfield , f2_byte );
, ubcp|disp|clvm|____, vtos, vtos, invokevirtual , f2_byte );
, ubcp|disp|clvm|____, vtos, vtos, invokespecial , f1_byte );
, ubcp|disp|clvm|____, vtos, vtos, invokestatic , f1_byte );
, ubcp|disp|clvm|____, vtos, vtos, invokeinterface , f1_byte );
, ubcp|disp|clvm|____, vtos, vtos, invokedynamic , f1_oop );
, ubcp|____|clvm|____, vtos, atos, _new , _ );
, ubcp|____|clvm|____, itos, atos, newarray , _ );
, ubcp|____|clvm|____, itos, atos, anewarray , _ );
, ____|____|____|____, atos, itos, arraylength , _ );
, ____|disp|____|____, atos, vtos, athrow , _ );
, ubcp|____|clvm|____, atos, atos, checkcast , _ );
, ubcp|____|clvm|____, atos, itos, instanceof , _ );
, ____|disp|clvm|____, atos, vtos, monitorenter , _ );
, ____|____|clvm|____, atos, vtos, monitorexit , _ );
, ubcp|disp|____|____, vtos, vtos, wide , _ );
, ubcp|____|clvm|____, vtos, atos, multianewarray , _ );
, ubcp|____|clvm|____, atos, vtos, if_nullcmp , equal );
, ubcp|____|clvm|____, atos, vtos, if_nullcmp , not_equal );
, ubcp|____|clvm|____, vtos, vtos, goto_w , _ );
, ubcp|____|____|____, vtos, vtos, jsr_w , _ );

// wide Java spec bytecodes
def(Bytecodes::_iload , ubcp|____|____|iswd, vtos, itos, wide_iload , _ );
def(Bytecodes::_lload , ubcp|____|____|iswd, vtos, ltos, wide_lload , _ );
def(Bytecodes::_fload , ubcp|____|____|iswd, vtos, ftos, wide_fload , _ );
def(Bytecodes::_dload , ubcp|____|____|iswd, vtos, dtos, wide_dload , _ );
def(Bytecodes::_aload , ubcp|____|____|iswd, vtos, atos, wide_aload , _ );
def(Bytecodes::_istore , ubcp|____|____|iswd, vtos, vtos, wide_istore , _ );
def(Bytecodes::_lstore , ubcp|____|____|iswd, vtos, vtos, wide_lstore , _ );
def(Bytecodes::_fstore , ubcp|____|____|iswd, vtos, vtos, wide_fstore , _ );
def(Bytecodes::_dstore , ubcp|____|____|iswd, vtos, vtos, wide_dstore , _ );
def(Bytecodes::_astore , ubcp|____|____|iswd, vtos, vtos, wide_astore , _ );
def(Bytecodes::_iinc , ubcp|____|____|iswd, vtos, vtos, wide_iinc , _ );
def(Bytecodes::_ret , ubcp|disp|____|iswd, vtos, vtos, wide_ret , _ );
def(Bytecodes::_breakpoint , ubcp|disp|clvm|____, vtos, vtos, _breakpoint , _ );

// JVM bytecodes
def(Bytecodes::_fast_agetfield , ubcp|____|____|____, atos, atos, fast_accessfield , atos );
def(Bytecodes::_fast_bgetfield , ubcp|____|____|____, atos, itos, fast_accessfield , itos );
def(Bytecodes::_fast_cgetfield , ubcp|____|____|____, atos, itos, fast_accessfield , itos );
def(Bytecodes::_fast_dgetfield , ubcp|____|____|____, atos, dtos, fast_accessfield , dtos );
def(Bytecodes::_fast_fgetfield , ubcp|____|____|____, atos, ftos, fast_accessfield , ftos );
def(Bytecodes::_fast_igetfield , ubcp|____|____|____, atos, itos, fast_accessfield , itos );
def(Bytecodes::_fast_lgetfield , ubcp|____|____|____, atos, ltos, fast_accessfield , ltos );
def(Bytecodes::_fast_sgetfield , ubcp|____|____|____, atos, itos, fast_accessfield , itos );

def(Bytecodes::_fast_aputfield , ubcp|____|____|____, atos, vtos, fast_storefield , atos );
def(Bytecodes::_fast_bputfield , ubcp|____|____|____, itos, vtos, fast_storefield , itos );
def(Bytecodes::_fast_zputfield , ubcp|____|____|____, itos, vtos, fast_storefield , itos );
def(Bytecodes::_fast_cputfield , ubcp|____|____|____, itos, vtos, fast_storefield , itos );
def(Bytecodes::_fast_dputfield , ubcp|____|____|____, dtos, vtos, fast_storefield , dtos );
def(Bytecodes::_fast_fputfield , ubcp|____|____|____, ftos, vtos, fast_storefield , ftos );
def(Bytecodes::_fast_iputfield , ubcp|____|____|____, itos, vtos, fast_storefield , itos );
def(Bytecodes::_fast_lputfield , ubcp|____|____|____, ltos, vtos, fast_storefield , ltos );
def(Bytecodes::_fast_sputfield , ubcp|____|____|____, itos, vtos, fast_storefield , itos );

def(Bytecodes::_fast_aload_0 , ____|____|____|____, vtos, atos, aload , 0 );
def(Bytecodes::_fast_iaccess_0 , ubcp|____|____|____, vtos, itos, fast_xaccess , itos );
def(Bytecodes::_fast_aaccess_0 , ubcp|____|____|____, vtos, atos, fast_xaccess , atos );
def(Bytecodes::_fast_faccess_0 , ubcp|____|____|____, vtos, ftos, fast_xaccess , ftos );

def(Bytecodes::_fast_iload , ubcp|____|____|____, vtos, itos, fast_iload , _ );
def(Bytecodes::_fast_iload2 , ubcp|____|____|____, vtos, itos, fast_iload2 , _ );
def(Bytecodes::_fast_icaload , ubcp|____|____|____, vtos, itos, fast_icaload , _ );

def(Bytecodes::_fast_invokevfinal , ubcp|disp|clvm|____, vtos, vtos, fast_invokevfinal , f2_byte );

def(Bytecodes::_return_register_finalizer , ____|disp|clvm|____, vtos, vtos, _return , vtos );

def(Bytecodes::_shouldnotreachhere , ____|____|____|____, vtos, vtos, shouldnotreachhere , _ );
// platform specific bytecodes
pd_initialize();

_is_initialized = true;
}

看这个函数:TemplateTable::initialize(),这里为每个字节码指令进行了一次def(….)命令,

def(Bytecodes::_nop , ____|____|____|____, vtos, vtos, nop , _ );

def就是定义的意思,关注这个nop参数,他是一个函数位于templateTable.cpp

void TemplateTable::nop() {
transition(vtos, vtos);
// nothing to do
}

看def函数

void TemplateTable::def(Bytecodes::Code code, int flags, TosState in, TosState out, void (*gen)(int arg), int arg) {
// should factor out these constants
const int ubcp = 1 << Template::uses_bcp_bit; const int disp = 1 << Template::does_dispatch_bit; const int clvm = 1 << Template::calls_vm_bit; const int iswd = 1 << Template::wide_bit; // determine which table to use bool is_wide = (flags & iswd) != 0; // make sure that wide instructions have a vtos entry point // (since they are executed extremely rarely, it doesn't pay out to have an // extra set of 5 dispatch tables for the wide instructions - for simplicity // they all go with one table) assert(in == vtos || !is_wide, "wide instructions have vtos entry point only"); Template* t = is_wide ? template_for_wide(code) : template_for(code); // setup entry t->initialize(flags, in, out, gen, arg);
assert(t->bytecode() == code, "just checkin'");
}

关键点就在 Template* t = is_wide ? template_for_wide(code) : template_for(code);

之前分析过t=? : template_for(code);是在 static Template _template_table [];数组中保存的

那么这句话就是获取一个得到数组中的一个引用,应该这个t不能是null,否则就会空指针异常了,应该在哪里初始化过了,那么接下了

生成具体内容 t->initialize(flags, in, out, gen, arg);

// Implementation of Template

void Template::initialize(int flags, TosState tos_in, TosState tos_out, generator gen, int arg) {
_flags = flags;
_tos_in = tos_in;
_tos_out = tos_out;
_gen = gen;
_arg = arg;
}

也没干别的就是把 templateTable中的函数指针,数据等赋值给了 Template对象(模板对象)

接着分析 dispatch_epilog(tos_out, step);

__ dispatch_epilog 其中的开头__ 代表 masm 这在揭秘虚拟机中有解释,

void InterpreterMacroAssembler::dispatch_epilog(TosState state, int step) {
dispatch_next(state, step);
}

void InterpreterMacroAssembler::dispatch_next(TosState state, int step, bool generate_poll) {
// load next bytecode (load before advancing _bcp_register to prevent AGI)
load_unsigned_byte(rbx, Address(_bcp_register, step));
// advance _bcp_register
increment(_bcp_register, step);
dispatch_base(state, Interpreter::dispatch_table(state), true, generate_poll);
}

对应的

那么今天就结束了,下次再续

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