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/* -*- Mode: c++; c-basic-offset: 4; tab-width: 40; indent-tabs-mode: nil -*- */
/* vim: set ts=40 sw=4 et tw=99: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Mozilla SpiderMonkey bytecode analysis
*
* The Initial Developer of the Original Code is
* Mozilla Foundation
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/* Definitions for javascript analysis. */
#ifndef jsanalyze_h___
#define jsanalyze_h___
#include "jsarena.h"
#include "jscompartment.h"
#include "jscntxt.h"
#include "jsinfer.h"
#include "jsscript.h"
struct JSScript;
/* Forward declaration of downstream register allocations computed for join points. */
namespace js { namespace mjit { struct RegisterAllocation; } }
namespace js {
namespace analyze {
/*
* There are three analyses we can perform on a JSScript, outlined below.
* The results of all three are stored in ScriptAnalysis, but the analyses
* themselves can be performed separately. Along with type inference results,
* per-script analysis results are tied to the per-compartment analysis pool
* and are freed on every garbage collection.
*
* - Basic bytecode analysis. For each bytecode, determine the stack depth at
* that point and control flow information needed for compilation. Also does
* a defined-variables analysis to look for local variables which have uses
* before definitions.
*
* - Lifetime analysis. Makes a backwards pass over the script to approximate
* the regions where each variable is live, avoiding a full fixpointing
* live-variables pass. This is based on the algorithm described in:
*
* "Quality and Speed in Linear-scan Register Allocation"
* Traub et. al.
* PLDI, 1998
*
* - SSA analysis of the script's variables and stack values. For each stack
* value popped and non-escaping local variable or argument read, determines
* which push(es) or write(s) produced that value.
*
* Intermediate type inference results are additionally stored here. The above
* analyses are independent from type inference.
*/
class SSAValue;
struct SSAUseChain;
struct LoopAnalysis;
struct SlotValue;
/* Information about a bytecode instruction. */
class Bytecode
{
friend class ScriptAnalysis;
public:
Bytecode() { PodZero(this); }
/* --------- Bytecode analysis --------- */
/* Whether there are any incoming jumps to this instruction. */
bool jumpTarget : 1;
/* There is a backwards jump to this instruction. */
bool loopHead : 1;
/* Whether there is fallthrough to this instruction from a non-branching instruction. */
bool fallthrough : 1;
/* Whether this instruction is the fall through point of a conditional jump. */
bool jumpFallthrough : 1;
/* Whether this instruction can be branched to from a switch statement. Implies jumpTarget. */
bool switchTarget : 1;
/*
* Whether this instruction must always execute, unless the script throws
* an exception which it does not later catch.
*/
bool unconditional : 1;
/* Whether this instruction has been analyzed to get its output defines and stack. */
bool analyzed : 1;
/* Whether this is a catch/finally entry point. */
bool exceptionEntry : 1;
/* Whether this is in a try block. */
bool inTryBlock : 1;
/* Method JIT safe point. */
bool safePoint : 1;
/*
* Side effects of this bytecode were not determined by type inference.
* Either a property set with unknown lvalue, or call with unknown callee.
*/
bool monitoredTypes : 1;
/* Call whose result should be monitored. */
bool monitoredTypesReturn : 1;
/* Stack depth before this opcode. */
uint32 stackDepth;
private:
/*
* The set of locals defined at this point. This does not include locals which
* were unconditionally defined at an earlier point in the script.
*/
uint32 defineCount;
uint32 *defineArray;
union {
/* If this is a JOF_TYPESET opcode, index into the observed types for the op. */
types::TypeSet *observedTypes;
/* If this is a loop head (TRACE or NOTRACE), information about the loop. */
LoopAnalysis *loop;
};
/* --------- Lifetime analysis --------- */
/* Any allocation computed downstream for this bytecode. */
mjit::RegisterAllocation *allocation;
/* --------- SSA analysis --------- */
/* Generated location of each value popped by this bytecode. */
SSAValue *poppedValues;
/* Points where values pushed or written by this bytecode are popped. */
SSAUseChain **pushedUses;
union {
/*
* If this is a join point (implies jumpTarget), any slots at this
* point which can have a different values than at the immediate
* predecessor in the bytecode. Array is terminated by an entry with
* a zero slot.
*/
SlotValue *newValues;
/*
* Vector used during SSA analysis to store values in need of merging
* at this point. If this has incoming forward jumps and we have not
* yet reached this point, stores values for entries on the stack and
* for variables which have changed since the branch. If this is a loop
* head and we haven't reached the back edge yet, stores loop phi nodes
* for variables and entries live at the head of the loop.
*/
Vector<SlotValue> *pendingValues;
};
/* --------- Type inference --------- */
/* Types for all values pushed by this bytecode. */
types::TypeSet *pushedTypes;
/* Any type barriers in place at this bytecode. */
types::TypeBarrier *typeBarriers;
/* --------- Helpers --------- */
bool mergeDefines(JSContext *cx, ScriptAnalysis *script, bool initial,
uint32 newDepth, uint32 *newArray, uint32 newCount);
/* Whether a local variable is in the define set at this bytecode. */
bool isDefined(uint32 slot)
{
JS_ASSERT(analyzed);
for (unsigned i = 0; i < defineCount; i++) {
if (defineArray[i] == slot)
return true;
}
return false;
}
};
static inline unsigned
GetBytecodeLength(jsbytecode *pc)
{
JSOp op = (JSOp)*pc;
JS_ASSERT(op < JSOP_LIMIT);
JS_ASSERT(op != JSOP_TRAP);
if (js_CodeSpec[op].length != -1)
return js_CodeSpec[op].length;
return js_GetVariableBytecodeLength(pc);
}
static inline unsigned
GetDefCount(JSScript *script, unsigned offset)
{
JS_ASSERT(offset < script->length);
jsbytecode *pc = script->code + offset;
JS_ASSERT(JSOp(*pc) != JSOP_TRAP);
if (js_CodeSpec[*pc].ndefs == -1)
return js_GetEnterBlockStackDefs(NULL, script, pc);
/*
* Add an extra pushed value for OR/AND opcodes, so that they are included
* in the pushed array of stack values for type inference.
*/
switch (JSOp(*pc)) {
case JSOP_OR:
case JSOP_ORX:
case JSOP_AND:
case JSOP_ANDX:
return 1;
case JSOP_FILTER:
return 2;
case JSOP_PICK:
/*
* Pick pops and pushes how deep it looks in the stack + 1
* items. i.e. if the stack were |a b[2] c[1] d[0]|, pick 2
* would pop b, c, and d to rearrange the stack to |a c[0]
* d[1] b[2]|.
*/
return (pc[1] + 1);
default:
return js_CodeSpec[*pc].ndefs;
}
}
static inline unsigned
GetUseCount(JSScript *script, unsigned offset)
{
JS_ASSERT(offset < script->length);
jsbytecode *pc = script->code + offset;
JS_ASSERT(JSOp(*pc) != JSOP_TRAP);
if (JSOp(*pc) == JSOP_PICK)
return (pc[1] + 1);
if (js_CodeSpec[*pc].nuses == -1)
return js_GetVariableStackUses(JSOp(*pc), pc);
return js_CodeSpec[*pc].nuses;
}
/*
* For opcodes which assign to a local variable or argument, track an extra def
* during SSA analysis for the value's use chain and assigned type.
*/
static inline bool
ExtendedDef(jsbytecode *pc)
{
JS_ASSERT(JSOp(*pc) != JSOP_TRAP);
switch ((JSOp)*pc) {
case JSOP_SETARG:
case JSOP_INCARG:
case JSOP_DECARG:
case JSOP_ARGINC:
case JSOP_ARGDEC:
case JSOP_SETLOCAL:
case JSOP_SETLOCALPOP:
case JSOP_DEFLOCALFUN:
case JSOP_DEFLOCALFUN_FC:
case JSOP_INCLOCAL:
case JSOP_DECLOCAL:
case JSOP_LOCALINC:
case JSOP_LOCALDEC:
return true;
default:
return false;
}
}
/*
* For opcodes which access local variables or arguments, we track an extra
* use during SSA analysis for the value of the variable before/after the op.
*/
static inline bool
ExtendedUse(jsbytecode *pc)
{
if (ExtendedDef(pc))
return true;
switch ((JSOp)*pc) {
case JSOP_GETARG:
case JSOP_CALLARG:
case JSOP_GETLOCAL:
case JSOP_CALLLOCAL:
return true;
default:
return false;
}
}
static inline ptrdiff_t
GetJumpOffset(jsbytecode *pc, jsbytecode *pc2)
{
JS_ASSERT(JSOp(*pc) != JSOP_TRAP);
uint32 type = JOF_OPTYPE(*pc);
if (JOF_TYPE_IS_EXTENDED_JUMP(type))
return GET_JUMPX_OFFSET(pc2);
return GET_JUMP_OFFSET(pc2);
}
static inline JSOp
ReverseCompareOp(JSOp op)
{
switch (op) {
case JSOP_GT:
return JSOP_LT;
case JSOP_GE:
return JSOP_LE;
case JSOP_LT:
return JSOP_GT;
case JSOP_LE:
return JSOP_GE;
default:
JS_NOT_REACHED("unrecognized op");
return op;
}
}
/* Untrap a single PC, and retrap it at scope exit. */
struct UntrapOpcode
{
jsbytecode *pc;
bool trap;
UntrapOpcode(JSContext *cx, JSScript *script, jsbytecode *pc)
: pc(pc), trap(JSOp(*pc) == JSOP_TRAP)
{
if (trap)
*pc = JS_GetTrapOpcode(cx, script, pc);
}
void retrap()
{
if (trap) {
*pc = JSOP_TRAP;
trap = false;
}
}
~UntrapOpcode()
{
retrap();
}
};
static inline unsigned
FollowBranch(JSContext *cx, JSScript *script, unsigned offset)
{
/*
* Get the target offset of a branch. For GOTO opcodes implementing
* 'continue' statements, short circuit any artificial backwards jump
* inserted by the emitter.
*/
jsbytecode *pc = script->code + offset;
unsigned targetOffset = offset + GetJumpOffset(pc, pc);
if (targetOffset < offset) {
jsbytecode *target = script->code + targetOffset;
UntrapOpcode untrap(cx, script, target);
JSOp nop = JSOp(*target);
if (nop == JSOP_GOTO || nop == JSOP_GOTOX)
return targetOffset + GetJumpOffset(target, target);
}
return targetOffset;
}
/* Common representation of slots throughout analyses and the compiler. */
static inline uint32 CalleeSlot() {
return 0;
}
static inline uint32 ThisSlot() {
return 1;
}
static inline uint32 ArgSlot(uint32 arg) {
return 2 + arg;
}
static inline uint32 LocalSlot(JSScript *script, uint32 local) {
return 2 + (script->hasFunction ? script->function()->nargs : 0) + local;
}
static inline uint32 TotalSlots(JSScript *script) {
return LocalSlot(script, 0) + script->nfixed;
}
static inline uint32 StackSlot(JSScript *script, uint32 index) {
return TotalSlots(script) + index;
}
static inline uint32 GetBytecodeSlot(JSScript *script, jsbytecode *pc)
{
switch (JSOp(*pc)) {
case JSOP_GETARG:
case JSOP_CALLARG:
case JSOP_SETARG:
case JSOP_INCARG:
case JSOP_DECARG:
case JSOP_ARGINC:
case JSOP_ARGDEC:
return ArgSlot(GET_SLOTNO(pc));
case JSOP_GETLOCAL:
case JSOP_CALLLOCAL:
case JSOP_SETLOCAL:
case JSOP_SETLOCALPOP:
case JSOP_DEFLOCALFUN:
case JSOP_DEFLOCALFUN_FC:
case JSOP_INCLOCAL:
case JSOP_DECLOCAL:
case JSOP_LOCALINC:
case JSOP_LOCALDEC:
return LocalSlot(script, GET_SLOTNO(pc));
case JSOP_THIS:
return ThisSlot();
default:
JS_NOT_REACHED("Bad slot opcode");
return 0;
}
}
static inline int32
GetBytecodeInteger(jsbytecode *pc)
{
switch (JSOp(*pc)) {
case JSOP_ZERO: return 0;
case JSOP_ONE: return 1;
case JSOP_UINT16: return GET_UINT16(pc);
case JSOP_UINT24: return GET_UINT24(pc);
case JSOP_INT8: return GET_INT8(pc);
case JSOP_INT32: return GET_INT32(pc);
default:
JS_NOT_REACHED("Bad op");
return 0;
}
}
/*
* Information about the lifetime of a local or argument. These form a linked
* list describing successive intervals in the program where the variable's
* value may be live. At points in the script not in one of these segments
* (points in a 'lifetime hole'), the variable is dead and registers containing
* its type/payload can be discarded without needing to be synced.
*/
struct Lifetime
{
/*
* Start and end offsets of this lifetime. The variable is live at the
* beginning of every bytecode in this (inclusive) range.
*/
uint32 start;
uint32 end;
/*
* In a loop body, endpoint to extend this lifetime with if the variable is
* live in the next iteration.
*/
uint32 savedEnd;
/*
* This is an artificial segment extending the lifetime of this variable
* when it is live at the head of the loop. It will not be used until the
* next iteration.
*/
bool loopTail;
/*
* The start of this lifetime is a bytecode writing the variable. Each
* write to a variable is associated with a lifetime.
*/
bool write;
/* Next lifetime. The variable is dead from this->end to next->start. */
Lifetime *next;
Lifetime(uint32 offset, uint32 savedEnd, Lifetime *next)
: start(offset), end(offset), savedEnd(savedEnd),
loopTail(false), write(false), next(next)
{}
};
/* Basic information for a loop. */
struct LoopAnalysis
{
/* Any loop this one is nested in. */
LoopAnalysis *parent;
/* Offset of the head of the loop. */
uint32 head;
/*
* Offset of the unique jump going to the head of the loop. The code
* between the head and the backedge forms the loop body.
*/
uint32 backedge;
/* Target offset of the initial jump or fallthrough into the loop. */
uint32 entry;
/*
* Start of the last basic block in the loop, excluding the initial jump to
* entry. All code between lastBlock and the backedge runs in every
* iteration, and if entry >= lastBlock all code between entry and the
* backedge runs when the loop is initially entered.
*/
uint32 lastBlock;
/*
* This loop contains safe points in its body which the interpreter might
* join at directly.
*/
bool hasSafePoints;
/* This loop has calls or inner loops. */
bool hasCallsLoops;
};
/* Current lifetime information for a variable. */
struct LifetimeVariable
{
/* If the variable is currently live, the lifetime segment. */
Lifetime *lifetime;
/* If the variable is currently dead, the next live segment. */
Lifetime *saved;
/* Jump preceding the basic block which killed this variable. */
uint32 savedEnd : 31;
/* If the variable needs to be kept alive until lifetime->start. */
bool ensured : 1;
/* Whether this variable is live at offset. */
Lifetime * live(uint32 offset) const {
if (lifetime && lifetime->end >= offset)
return lifetime;
Lifetime *segment = lifetime ? lifetime : saved;
while (segment && segment->start <= offset) {
if (segment->end >= offset)
return segment;
segment = segment->next;
}
return NULL;
}
/*
* Get the offset of the first write to the variable in an inclusive range,
* -1 if the variable is not written in the range.
*/
uint32 firstWrite(uint32 start, uint32 end) const {
Lifetime *segment = lifetime ? lifetime : saved;
while (segment && segment->start <= end) {
if (segment->start >= start && segment->write)
return segment->start;
segment = segment->next;
}
return uint32(-1);
}
uint32 firstWrite(LoopAnalysis *loop) const {
return firstWrite(loop->head, loop->backedge);
}
/* Return true if the variable cannot decrease during the body of a loop. */
bool nonDecreasing(JSScript *script, LoopAnalysis *loop) const {
Lifetime *segment = lifetime ? lifetime : saved;
while (segment && segment->start <= loop->backedge) {
if (segment->start >= loop->head && segment->write) {
switch (JSOp(script->code[segment->start])) {
case JSOP_INCLOCAL:
case JSOP_LOCALINC:
case JSOP_INCARG:
case JSOP_ARGINC:
break;
default:
return false;
}
}
segment = segment->next;
}
return true;
}
/*
* If the variable is only written once in the body of a loop, offset of
* that write. -1 otherwise.
*/
uint32 onlyWrite(LoopAnalysis *loop) const {
uint32 offset = uint32(-1);
Lifetime *segment = lifetime ? lifetime : saved;
while (segment && segment->start <= loop->backedge) {
if (segment->start >= loop->head && segment->write) {
if (offset != uint32(-1))
return uint32(-1);
offset = segment->start;
}
segment = segment->next;
}
return offset;
}
#ifdef DEBUG
void print() const;
#endif
};
struct SSAPhiNode;
/*
* Representation of values on stack or in slots at each point in the script.
* Values are independent from the bytecode position, and mean the same thing
* everywhere in the script. SSA values are immutable, except for contents of
* the values and types in an SSAPhiNode.
*/
class SSAValue
{
friend class ScriptAnalysis;
public:
enum Kind {
EMPTY = 0, /* Invalid entry. */
PUSHED = 1, /* Value pushed by some bytecode. */
VAR = 2, /* Initial or written value to some argument or local. */
PHI = 3 /* Selector for one of several values. */
};
Kind kind() const {
JS_ASSERT(u.pushed.kind == u.var.kind && u.pushed.kind == u.phi.kind);
/* Use a bitmask because MSVC wants to use -1 for PHI nodes. */
return (Kind) (u.pushed.kind & 0x3);
}
bool equals(const SSAValue &o) const {
return !memcmp(this, &o, sizeof(SSAValue));
}
/* Accessors for values pushed by a bytecode within this script. */
uint32 pushedOffset() const {
JS_ASSERT(kind() == PUSHED);
return u.pushed.offset;
}
uint32 pushedIndex() const {
JS_ASSERT(kind() == PUSHED);
return u.pushed.index;
}
/* Accessors for initial and written values of arguments and (undefined) locals. */
bool varInitial() const {
JS_ASSERT(kind() == VAR);
return u.var.initial;
}
uint32 varSlot() const {
JS_ASSERT(kind() == VAR);
return u.var.slot;
}
uint32 varOffset() const {
JS_ASSERT(!varInitial());
return u.var.offset;
}
/* Accessors for phi nodes. */
uint32 phiSlot() const;
uint32 phiLength() const;
const SSAValue &phiValue(uint32 i) const;
types::TypeSet *phiTypes() const;
/* Offset at which this phi node was created. */
uint32 phiOffset() const {
JS_ASSERT(kind() == PHI);
return u.phi.offset;
}
SSAPhiNode *phiNode() const {
JS_ASSERT(kind() == PHI);
return u.phi.node;
}
/* Other accessors. */
#ifdef DEBUG
void print() const;
#endif
void clear() {
PodZero(this);
JS_ASSERT(kind() == EMPTY);
}
void initPushed(uint32 offset, uint32 index) {
clear();
u.pushed.kind = PUSHED;
u.pushed.offset = offset;
u.pushed.index = index;
}
static SSAValue PushedValue(uint32 offset, uint32 index) {
SSAValue v;
v.initPushed(offset, index);
return v;
}
void initInitial(uint32 slot) {
clear();
u.var.kind = VAR;
u.var.initial = true;
u.var.slot = slot;
}
void initWritten(uint32 slot, uint32 offset) {
clear();
u.var.kind = VAR;
u.var.initial = false;
u.var.slot = slot;
u.var.offset = offset;
}
static SSAValue WrittenVar(uint32 slot, uint32 offset) {
SSAValue v;
v.initWritten(slot, offset);
return v;
}
void initPhi(uint32 offset, SSAPhiNode *node) {
clear();
u.phi.kind = PHI;
u.phi.offset = offset;
u.phi.node = node;
}
static SSAValue PhiValue(uint32 offset, SSAPhiNode *node) {
SSAValue v;
v.initPhi(offset, node);
return v;
}
private:
union {
struct {
Kind kind : 2;
uint32 offset : 30;
uint32 index;
} pushed;
struct {
Kind kind : 2;
bool initial : 1;
uint32 slot : 29;
uint32 offset;
} var;
struct {
Kind kind : 2;
uint32 offset : 30;
SSAPhiNode *node;
} phi;
} u;
};
/*
* Mutable component of a phi node, with the possible values of the phi
* and the possible types of the node as determined by type inference.
* When phi nodes are copied around, any updates to the original will
* be seen by all copies made.
*/
struct SSAPhiNode
{
types::TypeSet types;
uint32 slot;
uint32 length;
SSAValue *options;
SSAUseChain *uses;
SSAPhiNode() { PodZero(this); }
};
inline uint32
SSAValue::phiSlot() const
{
return u.phi.node->slot;
}
inline uint32
SSAValue::phiLength() const
{
JS_ASSERT(kind() == PHI);
return u.phi.node->length;
}
inline const SSAValue &
SSAValue::phiValue(uint32 i) const
{
JS_ASSERT(kind() == PHI && i < phiLength());
return u.phi.node->options[i];
}
inline types::TypeSet *
SSAValue::phiTypes() const
{
JS_ASSERT(kind() == PHI);
return &u.phi.node->types;
}
struct SSAUseChain
{
bool popped : 1;
uint32 offset : 31;
union {
uint32 which;
SSAPhiNode *phi;
} u;
SSAUseChain *next;
SSAUseChain() { PodZero(this); }
};
struct SlotValue
{
uint32 slot;
SSAValue value;
SlotValue(uint32 slot, const SSAValue &value) : slot(slot), value(value) {}
};
/* Analysis information about a script. */
class ScriptAnalysis
{
friend class Bytecode;
JSScript *script;
Bytecode **codeArray;
uint32 numSlots;
bool outOfMemory;
bool hadFailure;
JSPackedBool *escapedSlots;
/* Which analyses have been performed. */
bool ranBytecode_;
bool ranSSA_;
bool ranLifetimes_;
bool ranInference_;
/* --------- Bytecode analysis --------- */
bool usesRval;
bool usesScope;
bool usesThis;
bool hasCalls;
bool canTrackVars;
bool isInlineable;
uint32 numReturnSites_;
bool modifiesArguments_;
bool localsAliasStack_;
/* Offsets at which each local becomes unconditionally defined, or a value below. */
uint32 *definedLocals;
static const uint32 LOCAL_USE_BEFORE_DEF = uint32(-1);
static const uint32 LOCAL_CONDITIONALLY_DEFINED = uint32(-2);
/* --------- Lifetime analysis --------- */
LifetimeVariable *lifetimes;
public:
ScriptAnalysis(JSScript *script) { PodZero(this); this->script = script; }
bool ranBytecode() { return ranBytecode_; }
bool ranSSA() { return ranSSA_; }
bool ranLifetimes() { return ranLifetimes_; }
bool ranInference() { return ranInference_; }
void analyzeBytecode(JSContext *cx);
void analyzeSSA(JSContext *cx);
void analyzeLifetimes(JSContext *cx);
void analyzeTypes(JSContext *cx);
/* Analyze the effect of invoking 'new' on script. */
void analyzeTypesNew(JSContext *cx);
bool OOM() { return outOfMemory; }
bool failed() { return hadFailure; }
bool inlineable(uint32 argc) { return isInlineable && argc == script->function()->nargs; }
/* Whether there are POPV/SETRVAL bytecodes which can write to the frame's rval. */
bool usesReturnValue() const { return usesRval; }
/* Whether there are NAME bytecodes which can access the frame's scope chain. */
bool usesScopeChain() const { return usesScope; }
bool usesThisValue() const { return usesThis; }
bool hasFunctionCalls() const { return hasCalls; }
uint32 numReturnSites() const { return numReturnSites_; }
/*
* True if all named formal arguments are not modified. If the arguments
* object cannot escape, the arguments are never modified within the script.
*/
bool modifiesArguments() { return modifiesArguments_; }
/*
* True if there are any LOCAL opcodes aliasing values on the stack (above
* script->nfixed).
*/
bool localsAliasStack() { return localsAliasStack_; }
/* Accessors for bytecode information. */
Bytecode& getCode(uint32 offset) {
JS_ASSERT(script->compartment->activeAnalysis);
JS_ASSERT(offset < script->length);
JS_ASSERT(codeArray[offset]);
return *codeArray[offset];
}
Bytecode& getCode(const jsbytecode *pc) { return getCode(pc - script->code); }
Bytecode* maybeCode(uint32 offset) {
JS_ASSERT(script->compartment->activeAnalysis);
JS_ASSERT(offset < script->length);
return codeArray[offset];
}
Bytecode* maybeCode(const jsbytecode *pc) { return maybeCode(pc - script->code); }
bool jumpTarget(uint32 offset) {
JS_ASSERT(offset < script->length);
return codeArray[offset] && codeArray[offset]->jumpTarget;
}
bool jumpTarget(const jsbytecode *pc) { return jumpTarget(pc - script->code); }
bool popGuaranteed(jsbytecode *pc) {
jsbytecode *next = pc + GetBytecodeLength(pc);
return JSOp(*next) == JSOP_POP && !jumpTarget(next);
}
bool incrementInitialValueObserved(jsbytecode *pc) {
const JSCodeSpec *cs = &js_CodeSpec[*pc];
return (cs->format & JOF_POST) && !popGuaranteed(pc);
}
types::TypeSet *bytecodeTypes(const jsbytecode *pc) {
JS_ASSERT(JSOp(*pc) == JSOP_TRAP || (js_CodeSpec[*pc].format & JOF_TYPESET));
return getCode(pc).observedTypes;
}
const SSAValue &poppedValue(uint32 offset, uint32 which) {
JS_ASSERT(offset < script->length);
JS_ASSERT_IF(script->code[offset] != JSOP_TRAP,
which < GetUseCount(script, offset) +
(ExtendedUse(script->code + offset) ? 1 : 0));
return getCode(offset).poppedValues[which];
}
const SSAValue &poppedValue(const jsbytecode *pc, uint32 which) {
return poppedValue(pc - script->code, which);
}
const SlotValue *newValues(uint32 offset) {
JS_ASSERT(offset < script->length);
return getCode(offset).newValues;
}
const SlotValue *newValues(const jsbytecode *pc) { return newValues(pc - script->code); }
types::TypeSet *pushedTypes(uint32 offset, uint32 which = 0) {
JS_ASSERT(offset < script->length);
JS_ASSERT_IF(script->code[offset] != JSOP_TRAP,
which < GetDefCount(script, offset) +
(ExtendedDef(script->code + offset) ? 1 : 0));
types::TypeSet *array = getCode(offset).pushedTypes;
JS_ASSERT(array);
return array + which;
}
types::TypeSet *pushedTypes(const jsbytecode *pc, uint32 which) {
return pushedTypes(pc - script->code, which);
}
bool hasPushedTypes(const jsbytecode *pc) { return getCode(pc).pushedTypes != NULL; }
types::TypeBarrier *typeBarriers(uint32 offset) {
if (getCode(offset).typeBarriers)
pruneTypeBarriers(offset);
return getCode(offset).typeBarriers;
}
types::TypeBarrier *typeBarriers(const jsbytecode *pc) {
return typeBarriers(pc - script->code);
}
void addTypeBarrier(JSContext *cx, const jsbytecode *pc,
types::TypeSet *target, types::Type type);
void addSingletonTypeBarrier(JSContext *cx, const jsbytecode *pc,
types::TypeSet *target, JSObject *singleton, jsid singletonId);
/* Remove obsolete type barriers at the given offset. */
void pruneTypeBarriers(uint32 offset);
/*
* Remove still-active type barriers at the given offset. If 'all' is set,
* then all barriers are removed, otherwise only those deemed excessive
* are removed.
*/
void breakTypeBarriers(JSContext *cx, uint32 offset, bool all);
/* Break all type barriers used in computing v. */
void breakTypeBarriersSSA(JSContext *cx, const SSAValue &v);
inline void addPushedType(JSContext *cx, uint32 offset, uint32 which, types::Type type);
types::TypeSet *getValueTypes(const SSAValue &v) {
switch (v.kind()) {
case SSAValue::PUSHED:
return pushedTypes(v.pushedOffset(), v.pushedIndex());
case SSAValue::VAR:
JS_ASSERT(!slotEscapes(v.varSlot()));
if (v.varInitial()) {
return types::TypeScript::SlotTypes(script, v.varSlot());
} else {
/*
* Results of intermediate assignments have the same type as
* the first type pushed by the assignment op. Note that this
* may not be the exact same value as was pushed, due to
* post-inc/dec ops.
*/
return pushedTypes(v.varOffset(), 0);
}
case SSAValue::PHI:
return &v.phiNode()->types;
default:
/* Cannot compute types for empty SSA values. */
JS_NOT_REACHED("Bad SSA value");
return NULL;
}
}
types::TypeSet *poppedTypes(uint32 offset, uint32 which) {
return getValueTypes(poppedValue(offset, which));
}
types::TypeSet *poppedTypes(const jsbytecode *pc, uint32 which) {
return getValueTypes(poppedValue(pc, which));
}
bool trackUseChain(const SSAValue &v) {
JS_ASSERT_IF(v.kind() == SSAValue::VAR, trackSlot(v.varSlot()));
return v.kind() != SSAValue::EMPTY &&
(v.kind() != SSAValue::VAR || !v.varInitial());
}
/*
* Get the use chain for an SSA value. May be invalid for some opcodes in
* scripts where localsAliasStack(). You have been warned!
*/
SSAUseChain *& useChain(const SSAValue &v) {
JS_ASSERT(trackUseChain(v));
if (v.kind() == SSAValue::PUSHED)
return getCode(v.pushedOffset()).pushedUses[v.pushedIndex()];
if (v.kind() == SSAValue::VAR)
return getCode(v.varOffset()).pushedUses[GetDefCount(script, v.varOffset())];
return v.phiNode()->uses;
}
mjit::RegisterAllocation *&getAllocation(uint32 offset) {
JS_ASSERT(offset < script->length);
return getCode(offset).allocation;
}
mjit::RegisterAllocation *&getAllocation(const jsbytecode *pc) {
return getAllocation(pc - script->code);
}
LoopAnalysis *getLoop(uint32 offset) {
JS_ASSERT(offset < script->length);
JS_ASSERT(getCode(offset).loop);
return getCode(offset).loop;
}
LoopAnalysis *getLoop(const jsbytecode *pc) { return getLoop(pc - script->code); }
/* For a JSOP_CALL* op, get the pc of the corresponding JSOP_CALL/NEW/etc. */
jsbytecode *getCallPC(jsbytecode *pc)
{
JS_ASSERT(js_CodeSpec[*pc].format & JOF_CALLOP);
SSAUseChain *uses = useChain(SSAValue::PushedValue(pc - script->code, 1));
JS_ASSERT(uses && !uses->next && uses->popped);
return script->code + uses->offset;
}
/* Accessors for local variable information. */
bool localHasUseBeforeDef(uint32 local) {
JS_ASSERT(!failed());
return slotEscapes(LocalSlot(script, local)) ||
definedLocals[local] == LOCAL_USE_BEFORE_DEF;
}
/* These return true for variables that may have a use before def. */
bool localDefined(uint32 local, uint32 offset) {
return localHasUseBeforeDef(local) || (definedLocals[local] <= offset) ||
getCode(offset).isDefined(local);
}
bool localDefined(uint32 local, jsbytecode *pc) {
return localDefined(local, pc - script->code);
}
/*
* Escaping slots include all slots that can be accessed in ways other than
* through the corresponding LOCAL/ARG opcode. This includes all closed
* slots in the script, all slots in scripts which use eval or are in debug
* mode, and slots which are aliased by NAME or similar opcodes in the
* containing script (which does not imply the variable is closed).
*/
bool slotEscapes(uint32 slot) {
JS_ASSERT(script->compartment->activeAnalysis);
if (slot >= numSlots)
return true;
return escapedSlots[slot];
}
/*
* Whether we distinguish different writes of this variable while doing
* SSA analysis. Escaping locals can be written in other scripts, and the
* presence of NAME opcodes, switch or try blocks keeps us from tracking
* variable values at each point.
*/
bool trackSlot(uint32 slot) { return !slotEscapes(slot) && canTrackVars; }
const LifetimeVariable & liveness(uint32 slot) {
JS_ASSERT(script->compartment->activeAnalysis);
JS_ASSERT(!slotEscapes(slot));
return lifetimes[slot];
}
void printSSA(JSContext *cx);
void printTypes(JSContext *cx);
void clearAllocations();
private:
void setOOM(JSContext *cx) {
if (!outOfMemory)
js_ReportOutOfMemory(cx);
outOfMemory = true;
hadFailure = true;
}
/* Bytecode helpers */
inline bool addJump(JSContext *cx, unsigned offset,
unsigned *currentOffset, unsigned *forwardJump,
unsigned stackDepth, uint32 *defineArray, unsigned defineCount);
inline void setLocal(uint32 local, uint32 offset);
void checkAliasedName(JSContext *cx, jsbytecode *pc);
/* Lifetime helpers */
inline void addVariable(JSContext *cx, LifetimeVariable &var, unsigned offset,
LifetimeVariable **&saved, unsigned &savedCount);
inline void killVariable(JSContext *cx, LifetimeVariable &var, unsigned offset,
LifetimeVariable **&saved, unsigned &savedCount);
inline void extendVariable(JSContext *cx, LifetimeVariable &var, unsigned start, unsigned end);
inline void ensureVariable(LifetimeVariable &var, unsigned until);
/* SSA helpers */
bool makePhi(JSContext *cx, uint32 slot, uint32 offset, SSAValue *pv);
void insertPhi(JSContext *cx, SSAValue &phi, const SSAValue &v);
void mergeValue(JSContext *cx, uint32 offset, const SSAValue &v, SlotValue *pv);
void checkPendingValue(JSContext *cx, const SSAValue &v, uint32 slot,
Vector<SlotValue> *pending);
void checkBranchTarget(JSContext *cx, uint32 targetOffset, Vector<uint32> &branchTargets,
SSAValue *values, uint32 stackDepth);
void mergeBranchTarget(JSContext *cx, const SSAValue &value, uint32 slot,
const Vector<uint32> &branchTargets);
void removeBranchTarget(Vector<uint32> &branchTargets, uint32 offset);
void freezeNewValues(JSContext *cx, uint32 offset);
struct TypeInferenceState {
Vector<SSAPhiNode *> phiNodes;
bool hasGetSet;
bool hasHole;
types::TypeSet *forTypes;
TypeInferenceState(JSContext *cx)
: phiNodes(cx), hasGetSet(false), hasHole(false), forTypes(NULL)
{}
};
/* Type inference helpers */
bool analyzeTypesBytecode(JSContext *cx, unsigned offset, TypeInferenceState &state);
bool followEscapingArguments(JSContext *cx, const SSAValue &v, Vector<SSAValue> *seen);
bool followEscapingArguments(JSContext *cx, SSAUseChain *use, Vector<SSAValue> *seen);
};
/* Protect analysis structures from GC while they are being used. */
struct AutoEnterAnalysis
{
JSContext *cx;
bool oldActiveAnalysis;
bool left;
AutoEnterAnalysis(JSContext *cx)
: cx(cx), oldActiveAnalysis(cx->compartment->activeAnalysis), left(false)
{
cx->compartment->activeAnalysis = true;
}
void leave()
{
if (!left) {
left = true;
cx->compartment->activeAnalysis = oldActiveAnalysis;
}
}
~AutoEnterAnalysis()
{
leave();
}
};
/* SSA value as used by CrossScriptSSA, identifies the frame it came from. */
struct CrossSSAValue
{
unsigned frame;
SSAValue v;
CrossSSAValue(unsigned frame, const SSAValue &v) : frame(frame), v(v) {}
};
/*
* Analysis for managing SSA values from multiple call stack frames. These are
* created by the backend compiler when inlining functions, and allow for
* values to be tracked as they flow into or out of the inlined frames.
*/
class CrossScriptSSA
{
public:
static const uint32 OUTER_FRAME = uint32(-1);
static const unsigned INVALID_FRAME = uint32(-2);
struct Frame {
uint32 index;
JSScript *script;
uint32 depth; /* Distance from outer frame to this frame, in sizeof(Value) */
uint32 parent;
jsbytecode *parentpc;
Frame(uint32 index, JSScript *script, uint32 depth, uint32 parent, jsbytecode *parentpc)
: index(index), script(script), depth(depth), parent(parent), parentpc(parentpc)
{}
};
const Frame &getFrame(uint32 index) {
if (index == OUTER_FRAME)
return outerFrame;
return inlineFrames[index];
}
unsigned numFrames() { return 1 + inlineFrames.length(); }
const Frame &iterFrame(unsigned i) {
if (i == 0)
return outerFrame;
return inlineFrames[i - 1];
}
JSScript *outerScript() { return outerFrame.script; }
/* Total length of scripts preceding a frame. */
size_t frameLength(uint32 index) {
if (index == OUTER_FRAME)
return 0;
size_t res = outerFrame.script->length;
for (unsigned i = 0; i < index; i++)
res += inlineFrames[i].script->length;
return res;
}
types::TypeSet *getValueTypes(const CrossSSAValue &cv) {
return getFrame(cv.frame).script->analysis()->getValueTypes(cv.v);
}
bool addInlineFrame(JSScript *script, uint32 depth, uint32 parent, jsbytecode *parentpc)
{
uint32 index = inlineFrames.length();
return inlineFrames.append(Frame(index, script, depth, parent, parentpc));
}
CrossScriptSSA(JSContext *cx, JSScript *outer)
: cx(cx), outerFrame(OUTER_FRAME, outer, 0, INVALID_FRAME, NULL), inlineFrames(cx)
{}
CrossSSAValue foldValue(const CrossSSAValue &cv);
private:
JSContext *cx;
Frame outerFrame;
Vector<Frame> inlineFrames;
};
#ifdef DEBUG
void PrintBytecode(JSContext *cx, JSScript *script, jsbytecode *pc);
#endif
} /* namespace analyze */
} /* namespace js */
#endif // jsanalyze_h___
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