summaryrefslogtreecommitdiffstats
path: root/js/src/jit/BaselineFrame.h
blob: c54569627f5a84ac984bc1b091bf2b9418cc2dca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jit_BaselineFrame_h
#define jit_BaselineFrame_h

#include "jit/JitFrames.h"
#include "vm/Stack.h"

namespace js {
namespace jit {

struct BaselineDebugModeOSRInfo;

// The stack looks like this, fp is the frame pointer:
//
// fp+y   arguments
// fp+x   JitFrameLayout (frame header)
// fp  => saved frame pointer
// fp-x   BaselineFrame
//        locals
//        stack values

class BaselineFrame
{
  public:
    enum Flags : uint32_t {
        // The frame has a valid return value. See also InterpreterFrame::HAS_RVAL.
        HAS_RVAL         = 1 << 0,

        // An initial environment has been pushed on the environment chain for
        // function frames that need a CallObject or eval frames that need a
        // VarEnvironmentObject.
        HAS_INITIAL_ENV  = 1 << 2,

        // Frame has an arguments object, argsObj_.
        HAS_ARGS_OBJ     = 1 << 4,

        // See InterpreterFrame::PREV_UP_TO_DATE.
        PREV_UP_TO_DATE  = 1 << 5,

        // Frame has execution observed by a Debugger.
        //
        // See comment above 'isDebuggee' in jscompartment.h for explanation of
        // invariants of debuggee compartments, scripts, and frames.
        DEBUGGEE         = 1 << 6,

        // (1 << 7 and 1 << 8 are unused)

        // Frame has over-recursed on an early check.
        OVER_RECURSED    = 1 << 9,

        // Frame has a BaselineRecompileInfo stashed in the scratch value
        // slot. See PatchBaselineFramesForDebugMode.
        HAS_DEBUG_MODE_OSR_INFO = 1 << 10,

        // This flag is intended for use whenever the frame is settled on a
        // native code address without a corresponding ICEntry. In this case,
        // the frame contains an explicit bytecode offset for frame iterators.
        //
        // There can also be an override pc if the frame has had its
        // environment chain unwound to a pc during exception handling that is
        // different from its current pc.
        //
        // This flag should never be set when we're executing JIT code.
        HAS_OVERRIDE_PC = 1 << 11,

        // If set, we're handling an exception for this frame. This is set for
        // debug mode OSR sanity checking when it handles corner cases which
        // only arise during exception handling.
        HANDLING_EXCEPTION = 1 << 12,

        // If set, this frame has been on the stack when
        // |js::SavedStacks::saveCurrentStack| was called, and so there is a
        // |js::SavedFrame| object cached for this frame.
        HAS_CACHED_SAVED_FRAME = 1 << 13
    };

  protected: // Silence Clang warning about unused private fields.
    // We need to split the Value into 2 fields of 32 bits, otherwise the C++
    // compiler may add some padding between the fields.

    union {
        struct {
            uint32_t loScratchValue_;
            uint32_t hiScratchValue_;
        };
        BaselineDebugModeOSRInfo* debugModeOSRInfo_;
    };
    uint32_t loReturnValue_;              // If HAS_RVAL, the frame's return value.
    uint32_t hiReturnValue_;
    uint32_t frameSize_;
    JSObject* envChain_;                  // Environment chain (always initialized).
    ArgumentsObject* argsObj_;            // If HAS_ARGS_OBJ, the arguments object.
    uint32_t overrideOffset_;             // If HAS_OVERRIDE_PC, the bytecode offset.
    uint32_t flags_;

  public:
    // Distance between the frame pointer and the frame header (return address).
    // This is the old frame pointer saved in the prologue.
    static const uint32_t FramePointerOffset = sizeof(void*);

    MOZ_MUST_USE bool initForOsr(InterpreterFrame* fp, uint32_t numStackValues);

    uint32_t frameSize() const {
        return frameSize_;
    }
    void setFrameSize(uint32_t frameSize) {
        frameSize_ = frameSize;
    }
    inline uint32_t* addressOfFrameSize() {
        return &frameSize_;
    }
    JSObject* environmentChain() const {
        return envChain_;
    }
    void setEnvironmentChain(JSObject* envChain) {
        envChain_ = envChain;
    }
    inline JSObject** addressOfEnvironmentChain() {
        return &envChain_;
    }

    inline Value* addressOfScratchValue() {
        return reinterpret_cast<Value*>(&loScratchValue_);
    }

    template <typename SpecificEnvironment>
    inline void pushOnEnvironmentChain(SpecificEnvironment& env);
    template <typename SpecificEnvironment>
    inline void popOffEnvironmentChain();
    inline void replaceInnermostEnvironment(EnvironmentObject& env);

    CalleeToken calleeToken() const {
        uint8_t* pointer = (uint8_t*)this + Size() + offsetOfCalleeToken();
        return *(CalleeToken*)pointer;
    }
    void replaceCalleeToken(CalleeToken token) {
        uint8_t* pointer = (uint8_t*)this + Size() + offsetOfCalleeToken();
        *(CalleeToken*)pointer = token;
    }
    bool isConstructing() const {
        return CalleeTokenIsConstructing(calleeToken());
    }
    JSScript* script() const {
        return ScriptFromCalleeToken(calleeToken());
    }
    JSFunction* callee() const {
        return CalleeTokenToFunction(calleeToken());
    }
    Value calleev() const {
        return ObjectValue(*callee());
    }
    size_t numValueSlots() const {
        size_t size = frameSize();

        MOZ_ASSERT(size >= BaselineFrame::FramePointerOffset + BaselineFrame::Size());
        size -= BaselineFrame::FramePointerOffset + BaselineFrame::Size();

        MOZ_ASSERT((size % sizeof(Value)) == 0);
        return size / sizeof(Value);
    }
    Value* valueSlot(size_t slot) const {
        MOZ_ASSERT(slot < numValueSlots());
        return (Value*)this - (slot + 1);
    }

    Value& unaliasedFormal(unsigned i, MaybeCheckAliasing checkAliasing = CHECK_ALIASING) const {
        MOZ_ASSERT(i < numFormalArgs());
        MOZ_ASSERT_IF(checkAliasing, !script()->argsObjAliasesFormals() &&
                                     !script()->formalIsAliased(i));
        return argv()[i];
    }

    Value& unaliasedActual(unsigned i, MaybeCheckAliasing checkAliasing = CHECK_ALIASING) const {
        MOZ_ASSERT(i < numActualArgs());
        MOZ_ASSERT_IF(checkAliasing, !script()->argsObjAliasesFormals());
        MOZ_ASSERT_IF(checkAliasing && i < numFormalArgs(), !script()->formalIsAliased(i));
        return argv()[i];
    }

    Value& unaliasedLocal(uint32_t i) const {
        MOZ_ASSERT(i < script()->nfixed());
        return *valueSlot(i);
    }

    unsigned numActualArgs() const {
        return *(size_t*)(reinterpret_cast<const uint8_t*>(this) +
                             BaselineFrame::Size() +
                             offsetOfNumActualArgs());
    }
    unsigned numFormalArgs() const {
        return script()->functionNonDelazifying()->nargs();
    }
    Value& thisArgument() const {
        MOZ_ASSERT(isFunctionFrame());
        return *(Value*)(reinterpret_cast<const uint8_t*>(this) +
                         BaselineFrame::Size() +
                         offsetOfThis());
    }
    Value* argv() const {
        return (Value*)(reinterpret_cast<const uint8_t*>(this) +
                         BaselineFrame::Size() +
                         offsetOfArg(0));
    }

  private:
    Value* evalNewTargetAddress() const {
        MOZ_ASSERT(isEvalFrame());
        MOZ_ASSERT(script()->isDirectEvalInFunction());
        return (Value*)(reinterpret_cast<const uint8_t*>(this) +
                        BaselineFrame::Size() +
                        offsetOfEvalNewTarget());
    }

  public:
    Value newTarget() const {
        if (isEvalFrame())
            return *evalNewTargetAddress();
        MOZ_ASSERT(isFunctionFrame());
        if (callee()->isArrow())
            return callee()->getExtendedSlot(FunctionExtended::ARROW_NEWTARGET_SLOT);
        if (isConstructing()) {
            return *(Value*)(reinterpret_cast<const uint8_t*>(this) +
                             BaselineFrame::Size() +
                             offsetOfArg(Max(numFormalArgs(), numActualArgs())));
        }
        return UndefinedValue();
    }

    bool hasReturnValue() const {
        return flags_ & HAS_RVAL;
    }
    MutableHandleValue returnValue() {
        if (!hasReturnValue())
            addressOfReturnValue()->setUndefined();
        return MutableHandleValue::fromMarkedLocation(addressOfReturnValue());
    }
    void setReturnValue(const Value& v) {
        returnValue().set(v);
        flags_ |= HAS_RVAL;
    }
    inline Value* addressOfReturnValue() {
        return reinterpret_cast<Value*>(&loReturnValue_);
    }

    bool hasInitialEnvironment() const {
        return flags_ & HAS_INITIAL_ENV;
    }

    inline CallObject& callObj() const;

    void setFlags(uint32_t flags) {
        flags_ = flags;
    }
    uint32_t* addressOfFlags() {
        return &flags_;
    }

    inline MOZ_MUST_USE bool pushLexicalEnvironment(JSContext* cx, Handle<LexicalScope*> scope);
    inline MOZ_MUST_USE bool freshenLexicalEnvironment(JSContext* cx);
    inline MOZ_MUST_USE bool recreateLexicalEnvironment(JSContext* cx);

    MOZ_MUST_USE bool initFunctionEnvironmentObjects(JSContext* cx);
    MOZ_MUST_USE bool pushVarEnvironment(JSContext* cx, HandleScope scope);

    void initArgsObjUnchecked(ArgumentsObject& argsobj) {
        flags_ |= HAS_ARGS_OBJ;
        argsObj_ = &argsobj;
    }
    void initArgsObj(ArgumentsObject& argsobj) {
        MOZ_ASSERT(script()->needsArgsObj());
        initArgsObjUnchecked(argsobj);
    }
    bool hasArgsObj() const {
        return flags_ & HAS_ARGS_OBJ;
    }
    ArgumentsObject& argsObj() const {
        MOZ_ASSERT(hasArgsObj());
        MOZ_ASSERT(script()->needsArgsObj());
        return *argsObj_;
    }

    bool prevUpToDate() const {
        return flags_ & PREV_UP_TO_DATE;
    }
    void setPrevUpToDate() {
        flags_ |= PREV_UP_TO_DATE;
    }
    void unsetPrevUpToDate() {
        flags_ &= ~PREV_UP_TO_DATE;
    }

    bool isDebuggee() const {
        return flags_ & DEBUGGEE;
    }
    void setIsDebuggee() {
        flags_ |= DEBUGGEE;
    }
    inline void unsetIsDebuggee();

    bool isHandlingException() const {
        return flags_ & HANDLING_EXCEPTION;
    }
    void setIsHandlingException() {
        flags_ |= HANDLING_EXCEPTION;
    }
    void unsetIsHandlingException() {
        flags_ &= ~HANDLING_EXCEPTION;
    }

    bool hasCachedSavedFrame() const {
        return flags_ & HAS_CACHED_SAVED_FRAME;
    }
    void setHasCachedSavedFrame() {
        flags_ |= HAS_CACHED_SAVED_FRAME;
    }

    bool overRecursed() const {
        return flags_ & OVER_RECURSED;
    }

    void setOverRecursed() {
        flags_ |= OVER_RECURSED;
    }

    BaselineDebugModeOSRInfo* debugModeOSRInfo() {
        MOZ_ASSERT(flags_ & HAS_DEBUG_MODE_OSR_INFO);
        return debugModeOSRInfo_;
    }

    BaselineDebugModeOSRInfo* getDebugModeOSRInfo() {
        if (flags_ & HAS_DEBUG_MODE_OSR_INFO)
            return debugModeOSRInfo();
        return nullptr;
    }

    void setDebugModeOSRInfo(BaselineDebugModeOSRInfo* info) {
        flags_ |= HAS_DEBUG_MODE_OSR_INFO;
        debugModeOSRInfo_ = info;
    }

    void deleteDebugModeOSRInfo();

    // See the HAS_OVERRIDE_PC comment.
    bool hasOverridePc() const {
        return flags_ & HAS_OVERRIDE_PC;
    }

    jsbytecode* overridePc() const {
        MOZ_ASSERT(hasOverridePc());
        return script()->offsetToPC(overrideOffset_);
    }

    jsbytecode* maybeOverridePc() const {
        if (hasOverridePc())
            return overridePc();
        return nullptr;
    }

    void setOverridePc(jsbytecode* pc) {
        flags_ |= HAS_OVERRIDE_PC;
        overrideOffset_ = script()->pcToOffset(pc);
    }

    void clearOverridePc() {
        flags_ &= ~HAS_OVERRIDE_PC;
    }

    void trace(JSTracer* trc, JitFrameIterator& frame);

    bool isGlobalFrame() const {
        return script()->isGlobalCode();
    }
    bool isModuleFrame() const {
        return script()->module();
    }
    bool isEvalFrame() const {
        return script()->isForEval();
    }
    bool isStrictEvalFrame() const {
        return isEvalFrame() && script()->strict();
    }
    bool isNonStrictEvalFrame() const {
        return isEvalFrame() && !script()->strict();
    }
    bool isNonGlobalEvalFrame() const;
    bool isNonStrictDirectEvalFrame() const {
        return isNonStrictEvalFrame() && isNonGlobalEvalFrame();
    }
    bool isFunctionFrame() const {
        return CalleeTokenIsFunction(calleeToken());
    }
    bool isDebuggerEvalFrame() const {
        return false;
    }

    JitFrameLayout* framePrefix() const {
        uint8_t* fp = (uint8_t*)this + Size() + FramePointerOffset;
        return (JitFrameLayout*)fp;
    }

    // Methods below are used by the compiler.
    static size_t offsetOfCalleeToken() {
        return FramePointerOffset + js::jit::JitFrameLayout::offsetOfCalleeToken();
    }
    static size_t offsetOfThis() {
        return FramePointerOffset + js::jit::JitFrameLayout::offsetOfThis();
    }
    static size_t offsetOfEvalNewTarget() {
        return FramePointerOffset + js::jit::JitFrameLayout::offsetOfEvalNewTarget();
    }
    static size_t offsetOfArg(size_t index) {
        return FramePointerOffset + js::jit::JitFrameLayout::offsetOfActualArg(index);
    }
    static size_t offsetOfNumActualArgs() {
        return FramePointerOffset + js::jit::JitFrameLayout::offsetOfNumActualArgs();
    }
    static size_t Size() {
        return sizeof(BaselineFrame);
    }

    // The reverseOffsetOf methods below compute the offset relative to the
    // frame's base pointer. Since the stack grows down, these offsets are
    // negative.
    static int reverseOffsetOfFrameSize() {
        return -int(Size()) + offsetof(BaselineFrame, frameSize_);
    }
    static int reverseOffsetOfScratchValue() {
        return -int(Size()) + offsetof(BaselineFrame, loScratchValue_);
    }
    static int reverseOffsetOfEnvironmentChain() {
        return -int(Size()) + offsetof(BaselineFrame, envChain_);
    }
    static int reverseOffsetOfArgsObj() {
        return -int(Size()) + offsetof(BaselineFrame, argsObj_);
    }
    static int reverseOffsetOfFlags() {
        return -int(Size()) + offsetof(BaselineFrame, flags_);
    }
    static int reverseOffsetOfReturnValue() {
        return -int(Size()) + offsetof(BaselineFrame, loReturnValue_);
    }
    static int reverseOffsetOfLocal(size_t index) {
        return -int(Size()) - (index + 1) * sizeof(Value);
    }
};

// Ensure the frame is 8-byte aligned (required on ARM).
JS_STATIC_ASSERT(((sizeof(BaselineFrame) + BaselineFrame::FramePointerOffset) % 8) == 0);

} // namespace jit
} // namespace js

#endif /* jit_BaselineFrame_h */