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Bug 471713 - Part 2: Add documentation for control statements related opcodes. r=jorendorff

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Tooru Fujisawa 2014-04-30 10:06:00 -04:00
Родитель 539f7b5ac4
Коммит 6e351c744f
1 изменённых файлов: 258 добавлений и 21 удалений
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279
js/src/vm/Opcodes.h
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@ -100,7 +100,26 @@
*/ \
macro(JSOP_UNDEFINED, 1, js_undefined_str, "", 1, 0, 1, JOF_BYTE) \
macro(JSOP_UNUSED2, 2, "unused2", NULL, 1, 1, 0, JOF_BYTE) \
/*
* Pops the top of stack value, converts it to an object, and adds a
* 'DynamicWithObject' wrapping that object to the scope chain.
*
* There is a matching JSOP_LEAVEWITH instruction later. All name
* lookups between the two that may need to consult the With object
* are deoptimized.
* Category: Statements
* Type: With Statement
* Operands: uint32_t staticWithIndex
* Stack: val =>
*/ \
macro(JSOP_ENTERWITH, 3, "enterwith", NULL, 5, 1, 0, JOF_OBJECT) \
/*
* Pops the scope chain object pushed by JSOP_ENTERWITH.
* Category: Statements
* Type: With Statement
* Operands:
* Stack: =>
*/ \
macro(JSOP_LEAVEWITH, 4, "leavewith", NULL, 1, 0, 0, JOF_BYTE) \
/*
* Pops the top of stack value as 'rval', stops interpretation of current
@ -111,8 +130,35 @@
* Stack: rval =>
*/ \
macro(JSOP_RETURN, 5, "return", NULL, 1, 1, 0, JOF_BYTE) \
/*
* Jumps to a 32-bit offset from the current bytecode.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: =>
*/ \
macro(JSOP_GOTO, 6, "goto", NULL, 5, 0, 0, JOF_JUMP) \
/*
* Pops the top of stack value, converts it into a boolean, if the result is
* 'false', jumps to a 32-bit offset from the current bytecode.
*
* The idea is that a sequence like
* JSOP_ZERO; JSOP_ZERO; JSOP_EQ; JSOP_IFEQ; JSOP_RETURN;
* reads like a nice linear sequence that will execute the return.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: cond =>
*/ \
macro(JSOP_IFEQ, 7, "ifeq", NULL, 5, 1, 0, JOF_JUMP|JOF_DETECTING) \
/*
* Pops the top of stack value, converts it into a boolean, if the result is
* 'true', jumps to a 32-bit offset from the current bytecode.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: cond =>
*/ \
macro(JSOP_IFNE, 8, "ifne", NULL, 5, 1, 0, JOF_JUMP) \
\
/*
@ -491,10 +537,38 @@
*/ \
macro(JSOP_FALSE, 66, js_false_str, js_false_str, 1, 0, 1, JOF_BYTE) \
macro(JSOP_TRUE, 67, js_true_str, js_true_str, 1, 0, 1, JOF_BYTE) \
/*
* Converts the top of stack value into a boolean, if the result is 'true',
* jumps to a 32-bit offset from the current bytecode.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: cond => cond
*/ \
macro(JSOP_OR, 68, "or", NULL, 5, 1, 1, JOF_JUMP|JOF_DETECTING|JOF_LEFTASSOC) \
/*
* Converts the top of stack value into a boolean, if the result is 'false',
* jumps to a 32-bit offset from the current bytecode.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: cond => cond
*/ \
macro(JSOP_AND, 69, "and", NULL, 5, 1, 1, JOF_JUMP|JOF_DETECTING|JOF_LEFTASSOC) \
\
/* The switch bytecodes have variable length. */ \
/*
* Pops the top of stack value as 'i', if 'low <= i <= high',
* jumps to a 32-bit offset: 'offset[i - low]' from the current bytecode,
* jumps to a 32-bit offset: 'len' from the current bytecode if not.
*
* This opcode has variable length.
* Category: Statements
* Type: Switch Statement
* Operands: int32_t len, int32_t low, int32_t high,
* int32_t offset[0], ..., int32_t offset[high-low]
* Stack: i =>
* len: len
*/ \
macro(JSOP_TABLESWITCH, 70, "tableswitch", NULL, -1, 1, 0, JOF_TABLESWITCH|JOF_DETECTING) \
\
/*
@ -531,20 +605,48 @@
macro(JSOP_SETCALL, 74, "setcall", NULL, 1, 0, 0, JOF_BYTE) \
\
/*
* JSOP_ITER sets up a for-in or for-each-in loop using the JSITER_* flag bits
* in this op's uint8_t immediate operand. It replaces the top of stack value
* with an iterator for that value.
*
* JSOP_MOREITER stores the next iterated value into cx->iterValue and pushes
* true if another value is available, and false otherwise. It is followed
* immediately by JSOP_IFNE.
*
* JSOP_ENDITER cleans up after the loop. It uses the slot above the iterator
* for temporary GC rooting.
* Sets up a for-in or for-each-in loop using the JSITER_* flag bits in
* this op's uint8_t immediate operand. It pops the top of stack value as
* 'val' and pushes 'iter' which is an iterator for 'val'.
* Category: Statements
* Type: For-In Statement
* Operands: uint8_t flags
* Stack: val => iter
*/ \
macro(JSOP_ITER, 75, "iter", NULL, 2, 1, 1, JOF_UINT8) \
/*
* Stores the next iterated value into 'cx->iterValue' and pushes 'true'
* onto the stack if another value is available, and 'false' otherwise.
* It is followed immediately by JSOP_IFNE.
*
* This opcode increments iterator cursor if current iteration has
* JSITER_FOREACH flag.
* Category: Statements
* Type: For-In Statement
* Operands:
* Stack: iter => iter, cond
*/ \
macro(JSOP_MOREITER, 76, "moreiter", NULL, 1, 1, 2, JOF_BYTE) \
/*
* Pushes the value produced by the preceding JSOP_MOREITER operation
* ('cx->iterValue') onto the stack
*
* This opcode increments iterator cursor if current iteration does not have
* JSITER_FOREACH flag.
* Category: Statements
* Type: For-In Statement
* Operands:
* Stack: iter => iter, val
*/ \
macro(JSOP_ITERNEXT, 77, "iternext", "<next>", 1, 0, 1, JOF_BYTE) \
/*
* Exits a for-in loop by popping the iterator object from the stack and
* closing it.
* Category: Statements
* Type: For-In Statement
* Operands:
* Stack: iter =>
*/ \
macro(JSOP_ENDITER, 78, "enditer", NULL, 1, 1, 0, JOF_BYTE) \
\
/*
@ -799,7 +901,16 @@
macro(JSOP_UNUSED104, 104, "unused104", NULL, 1, 0, 0, JOF_BYTE) \
macro(JSOP_UNUSED105, 105, "unused105", NULL, 1, 0, 0, JOF_BYTE) \
\
/* The argument is the offset to the next statement and is used by IonMonkey. */ \
/*
* This opcode precedes every labeled statement. It's a no-op.
*
* 'offset' is the offset to the next instruction after this statement,
* the one 'break LABEL;' would jump to. IonMonkey uses this.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: =>
*/ \
macro(JSOP_LABEL, 106,"label", NULL, 5, 0, 0, JOF_JUMP) \
\
macro(JSOP_UNUSED107, 107,"unused107", NULL, 1, 0, 0, JOF_BYTE) \
@ -822,7 +933,15 @@
*/ \
macro(JSOP_FUNCALL, 108,"funcall", NULL, 3, -1, 1, JOF_UINT16|JOF_INVOKE|JOF_TYPESET) \
\
/* This opcode is the target of the backwards jump for some loop. */ \
/*
* Another no-op.
*
* This opcode is the target of the backwards jump for some loop.
* Category: Statements
* Type: Jumps
* Operands:
* Stack: =>
*/ \
macro(JSOP_LOOPHEAD, 109,"loophead", NULL, 1, 0, 0, JOF_BYTE) \
\
/* ECMA-compliant assignment ops. */ \
@ -847,6 +966,14 @@
macro(JSOP_SETNAME, 111,"setname", NULL, 5, 2, 1, JOF_ATOM|JOF_NAME|JOF_SET|JOF_DETECTING) \
\
/* Exception handling ops. */ \
/*
* Pops the top of stack value as 'v', sets pending exception as 'v', then
* raises error.
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: v =>
*/ \
macro(JSOP_THROW, 112,js_throw_str, NULL, 1, 1, 0, JOF_BYTE) \
\
/*
@ -880,11 +1007,41 @@
*/ \
macro(JSOP_DEBUGGER, 115,"debugger", NULL, 1, 0, 0, JOF_BYTE) \
\
/* gosub/retsub for finally handling */ \
/*
* Pushes 'false' and next bytecode's PC onto the stack, and jumps to
* a 32-bit offset from the current bytecode.
*
* This opcode is used for entering 'finally' block.
* Category: Statements
* Type: Exception Handling
* Operands: int32_t offset
* Stack: => false, (next bytecode's PC)
*/ \
macro(JSOP_GOSUB, 116,"gosub", NULL, 5, 0, 0, JOF_JUMP) \
/*
* Pops the top two values on the stack as 'rval' and 'lval', converts
* 'lval' into a boolean, raises error if the result is 'true',
* jumps to a 32-bit absolute PC: 'rval' if 'false'.
*
* This opcode is used for returning from 'finally' block.
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: lval, rval =>
*/ \
macro(JSOP_RETSUB, 117,"retsub", NULL, 1, 2, 0, JOF_BYTE) \
\
/* More exception handling ops. */ \
/*
* Pushes the current pending exception onto the stack and clears the
* pending exception. This is only emitted at the beginning of code for a
* catch-block, so it is known that an exception is pending. It is used to
* implement catch-blocks and 'yield*'.
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: => exception
*/ \
macro(JSOP_EXCEPTION, 118,"exception", NULL, 1, 0, 1, JOF_BYTE) \
\
/*
@ -896,12 +1053,58 @@
macro(JSOP_LINENO, 119,"lineno", NULL, 3, 0, 0, JOF_UINT16) \
\
/*
* ECMA-compliant switch statement ops.
* CONDSWITCH is a decompilable NOP; CASE is ===, POP, jump if true, re-push
* lval if false; and DEFAULT is POP lval and GOTO.
* This no-op appears after the bytecode for EXPR in 'switch (EXPR) {...}'
* if the switch cannot be optimized using JSOP_TABLESWITCH.
* For a non-optimized switch statement like this:
*
* switch (EXPR) {
* case V0:
* C0;
* ...
* default:
* D;
* }
*
* the bytecode looks like this:
*
* (EXPR)
* condswitch
* (V0)
* case ->C0
* ...
* default ->D
* (C0)
* ...
* (D)
*
* Note that code for all case-labels is emitted first, then code for
* the body of each case clause.
* Category: Statements
* Type: Switch Statement
* Operands:
* Stack: =>
*/ \
macro(JSOP_CONDSWITCH,120,"condswitch", NULL, 1, 0, 0, JOF_BYTE) \
/*
* Pops the top two values on the stack as 'rval' and 'lval', compare them
* with '===', if the result is 'true', jumps to a 32-bit offset from the
* current bytecode, re-pushes 'lval' onto the stack if 'false'.
* Category: Statements
* Type: Switch Statement
* Operands: int32_t offset
* Stack: lval, rval => lval(if lval !== rval)
*/ \
macro(JSOP_CASE, 121,"case", NULL, 5, 2, 1, JOF_JUMP) \
/*
* This appears after all cases in a JSOP_CONDSWITCH, whether there is a
* 'default:' label in the switch statement or not. Pop the switch operand
* from the stack and jump to a 32-bit offset from the current bytecode.
* offset from the current bytecode.
* Category: Statements
* Type: Switch Statement
* Operands: int32_t offset
* Stack: lval =>
*/ \
macro(JSOP_DEFAULT, 122,"default", NULL, 5, 1, 0, JOF_JUMP) \
\
/* ECMA-compliant call to eval op. */ \
@ -1000,10 +1203,24 @@
macro(JSOP_PICK, 133, "pick", NULL, 2, 0, 0, JOF_UINT8|JOF_TMPSLOT2) \
\
/*
* Exception handling no-op, for more economical byte-coding than SRC_TRYFIN
* srcnote-annotated JSOP_NOPs and to simply stack balance handling.
* This no-op appears at the top of the bytecode for a 'TryStatement'.
*
* Location information for catch/finally blocks is stored in a
* side table, 'script->trynotes()'.
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: =>
*/ \
macro(JSOP_TRY, 134,"try", NULL, 1, 0, 0, JOF_BYTE) \
/*
* This opcode has a def count of 2, but these values are already on the
* stack (they're pushed by JSOP_GOSUB).
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: => false, (next bytecode's PC)
*/ \
macro(JSOP_FINALLY, 135,"finally", NULL, 1, 0, 2, JOF_BYTE) \
\
/*
@ -1080,11 +1297,27 @@
macro(JSOP_UNUSED147, 147,"unused147", NULL, 1, 0, 0, JOF_BYTE) \
macro(JSOP_UNUSED148, 148,"unused148", NULL, 1, 0, 0, JOF_BYTE) \
\
/* Placeholders for a real jump opcode set during backpatch chain fixup. */ \
/*
* Placeholder opcode used during bytecode generation. This never
* appears in a finished script. FIXME: bug 473671.
* Category: Statements
* Type: Jumps
* Operands: int32_t offset
* Stack: =>
*/ \
macro(JSOP_BACKPATCH, 149,"backpatch", NULL, 5, 0, 0, JOF_JUMP) \
macro(JSOP_UNUSED150, 150,"unused150", NULL, 1, 0, 0, JOF_BYTE) \
\
/* Set pending exception from the stack, to trigger rethrow. */ \
/*
* Pops the top of stack value as 'v', sets pending exception as 'v',
* to trigger rethrow.
*
* This opcode is used in conditional catch clauses.
* Category: Statements
* Type: Exception Handling
* Operands:
* Stack: v =>
*/ \
macro(JSOP_THROWING, 151,"throwing", NULL, 1, 1, 0, JOF_BYTE) \
\
/*
@ -1411,6 +1644,10 @@
* loops all have the same value. The upper bit is set if Ion should be
* able to OSR at this point, which is true unless there is non-loop state
* on the stack.
* Category: Statements
* Type: Jumps
* Operands: uint8_t BITFIELD
* Stack: =>
*/ \
macro(JSOP_LOOPENTRY, 227, "loopentry", NULL, 2, 0, 0, JOF_UINT8)