06359f7453
Be explicit about source positions for `Return`s in the BytecodeGenerator, and only do self-healing explicitly in the `ReturnStatement` translation, where an end position of `kNoSourcePosition` is turned into the return position of the function literal. This allows us to reason more easily about which `Return`s actually receive a meaningful source position, and in particular it allows us to construct the internal `Return`s for `yield` and `yield*` with no source position attached to them. Previously they'd get the source position for the implicit (final) return attached to it, which confused the debugger and led to breakpoints being set in the completely wrong spot. Considering the simplified example ``` function* foo(){ var a = 1; } ``` this would previously generate the following bytecode ``` 0 : SwitchOnGeneratorState r0, [0], [1] { 0: @20 } 4 : Mov <closure>, r2 7 : Mov <this>, r3 13 E> 10 : InvokeIntrinsic [_CreateJSGeneratorObject], r2-r3 14 : Star0 13 E> 15 : SuspendGenerator r0, r0-r1, [0] 20 : ResumeGenerator r0, r0-r1 24 : Star2 25 : InvokeIntrinsic [_GeneratorGetResumeMode], r0-r0 29 : SwitchOnSmiNoFeedback [1], [2], [0] { 0: @39, 1: @36 } 33 : Ldar r2 13 E> 35 : Throw 36 : Ldar r2 30 S> 38 : Return <=========================== internal Return 27 S> 39 : LdaSmi [1] 41 : Star1 42 : LdaUndefined 30 S> 43 : Return ``` where everything between offset 4 and 42 corresponds to the implicit yield at the beginning of every generator function, in particular the code between 20 and 42 corresponds to that initial yields resumption logic. Notice how the internal Return at offset 38 gets assigned the source position of the function literal (the same as the implicit return at the end). This confuses the debugger quite a bit when trying to set a breakpoint on the closing brace, since it's going in bytecode order and will thus discover the `Return` at offset 38 first (matching the source position 30 it's currently looking for) and setting the breakpoint there. This `Return` bytecode however is only executed when the generator is resumed via `GeneratorPrototype.return()`, and it'll not hit when the developer uses the generator normally, which is not the desired behavior and extremely confusing (especially since stepping on the other hand works as expected). With this patch, we no longer slap a source position (and in particular not the function literal's return position) onto these internal `Return`s as you can see from the generated bytecode below: ``` 0 : SwitchOnGeneratorState r0, [0], [1] { 0: @20 } 4 : Mov <closure>, r2 7 : Mov <this>, r3 13 E> 10 : InvokeIntrinsic [_CreateJSGeneratorObject], r2-r3 14 : Star0 13 E> 15 : SuspendGenerator r0, r0-r1, [0] 20 : ResumeGenerator r0, r0-r1 24 : Star2 25 : InvokeIntrinsic [_GeneratorGetResumeMode], r0-r0 29 : SwitchOnSmiNoFeedback [1], [2], [0] { 0: @39, 1: @36 } 33 : Ldar r2 13 E> 35 : Throw 36 : Ldar r2 38 : Return 27 S> 39 : LdaSmi [1] 41 : Star1 42 : LdaUndefined 30 S> 43 : Return ``` This also allows us to remove the break position finding hack that was kept in BreakIterator::BreakIndexFromPosition() for generators and modules. Fixed: chromium:901819 Change-Id: If19a6b26e2622d49b6b5e54bf7a162747543f970 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2727820 Reviewed-by: Yang Guo <yangguo@chromium.org> Reviewed-by: Leszek Swirski <leszeks@chromium.org> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Cr-Commit-Position: refs/heads/master@{#73119}
320 lines
11 KiB
Plaintext
320 lines
11 KiB
Plaintext
#
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# Autogenerated by generate-bytecode-expectations.
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#
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---
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wrap: no
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test function name: f
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---
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snippet: "
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function* f() { }
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f();
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"
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frame size: 3
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parameter count: 1
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bytecode array length: 41
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bytecodes: [
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B(SwitchOnGeneratorState), R(0), U8(0), U8(1),
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B(Mov), R(closure), R(1),
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B(Mov), R(this), R(2),
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/* 11 E> */ B(InvokeIntrinsic), U8(Runtime::k_CreateJSGeneratorObject), R(1), U8(2),
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B(Star0),
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/* 11 E> */ B(SuspendGenerator), R(0), R(0), U8(1), U8(0),
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B(ResumeGenerator), R(0), R(0), U8(1),
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B(Star1),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(1), U8(2), I8(0),
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B(Ldar), R(1),
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/* 11 E> */ B(Throw),
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B(Ldar), R(1),
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B(Return),
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B(LdaUndefined),
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/* 16 S> */ B(Return),
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]
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constant pool: [
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Smi [20],
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Smi [10],
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Smi [7],
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]
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handlers: [
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]
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---
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snippet: "
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function* f() { yield 42 }
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f();
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"
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frame size: 3
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parameter count: 1
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bytecode array length: 74
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bytecodes: [
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B(SwitchOnGeneratorState), R(0), U8(0), U8(2),
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B(Mov), R(closure), R(1),
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B(Mov), R(this), R(2),
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/* 11 E> */ B(InvokeIntrinsic), U8(Runtime::k_CreateJSGeneratorObject), R(1), U8(2),
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B(Star0),
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/* 11 E> */ B(SuspendGenerator), R(0), R(0), U8(1), U8(0),
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B(ResumeGenerator), R(0), R(0), U8(1),
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B(Star1),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(2), U8(2), I8(0),
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B(Ldar), R(1),
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/* 11 E> */ B(Throw),
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B(Ldar), R(1),
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B(Return),
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/* 16 S> */ B(LdaSmi), I8(42),
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B(Star1),
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B(LdaFalse),
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B(Star2),
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B(InvokeIntrinsic), U8(Runtime::k_CreateIterResultObject), R(1), U8(2),
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/* 16 E> */ B(SuspendGenerator), R(0), R(0), U8(1), U8(1),
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B(ResumeGenerator), R(0), R(0), U8(1),
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B(Star1),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(4), U8(2), I8(0),
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B(Ldar), R(1),
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/* 16 E> */ B(Throw),
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B(Ldar), R(1),
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B(Return),
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B(LdaUndefined),
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/* 25 S> */ B(Return),
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]
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constant pool: [
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Smi [20],
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Smi [53],
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Smi [10],
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Smi [7],
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Smi [10],
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Smi [7],
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]
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handlers: [
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]
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---
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snippet: "
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function* f() { for (let x of [42]) yield x }
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f();
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"
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frame size: 14
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parameter count: 1
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bytecode array length: 210
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bytecodes: [
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B(SwitchOnGeneratorState), R(0), U8(0), U8(2),
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B(Mov), R(closure), R(4),
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B(Mov), R(this), R(5),
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/* 11 E> */ B(InvokeIntrinsic), U8(Runtime::k_CreateJSGeneratorObject), R(4), U8(2),
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B(Star0),
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/* 11 E> */ B(SuspendGenerator), R(0), R(0), U8(4), U8(0),
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B(ResumeGenerator), R(0), R(0), U8(4),
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B(Star4),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(2), U8(2), I8(0),
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B(Ldar), R(4),
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/* 11 E> */ B(Throw),
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B(Ldar), R(4),
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B(Return),
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/* 30 S> */ B(CreateArrayLiteral), U8(4), U8(0), U8(37),
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B(Star6),
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B(GetIterator), R(6), U8(1), U8(3),
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B(JumpIfJSReceiver), U8(7),
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B(CallRuntime), U16(Runtime::kThrowSymbolIteratorInvalid), R(0), U8(0),
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B(Star5),
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B(LdaNamedProperty), R(5), U8(5), U8(5),
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B(Star4),
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B(LdaFalse),
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B(Star6),
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B(Mov), R(context), R(9),
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B(LdaTrue),
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B(Star6),
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/* 25 S> */ B(CallProperty0), R(4), R(5), U8(7),
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B(Star10),
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B(JumpIfJSReceiver), U8(7),
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B(CallRuntime), U16(Runtime::kThrowIteratorResultNotAnObject), R(10), U8(1),
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B(LdaNamedProperty), R(10), U8(6), U8(9),
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B(JumpIfToBooleanTrue), U8(58),
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B(LdaNamedProperty), R(10), U8(7), U8(11),
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B(Star10),
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B(LdaFalse),
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B(Star6),
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B(Mov), R(10), R(1),
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/* 25 S> */ B(Mov), R(1), R(3),
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/* 36 S> */ B(LdaFalse),
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B(Star12),
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B(Mov), R(3), R(11),
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B(InvokeIntrinsic), U8(Runtime::k_CreateIterResultObject), R(11), U8(2),
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/* 36 E> */ B(SuspendGenerator), R(0), R(0), U8(11), U8(1),
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B(ResumeGenerator), R(0), R(0), U8(11),
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B(Star11),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(8), U8(2), I8(0),
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B(Ldar), R(11),
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/* 36 E> */ B(Throw),
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B(LdaSmi), I8(1),
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B(Star7),
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B(Mov), R(11), R(8),
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B(Jump), U8(16),
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B(Ldar), R(11),
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/* 16 E> */ B(JumpLoop), U8(73), I8(0),
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B(LdaSmi), I8(-1),
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B(Star8),
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B(Star7),
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B(Jump), U8(5),
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B(Star8),
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B(LdaZero),
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B(Star7),
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B(LdaTheHole),
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B(SetPendingMessage),
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B(Star9),
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B(Ldar), R(6),
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B(JumpIfToBooleanTrue), U8(35),
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B(Mov), R(context), R(11),
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B(LdaNamedProperty), R(5), U8(10), U8(13),
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B(JumpIfUndefinedOrNull), U8(26),
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B(Star12),
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B(CallProperty0), R(12), R(5), U8(15),
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B(JumpIfJSReceiver), U8(19),
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B(Star13),
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B(CallRuntime), U16(Runtime::kThrowIteratorResultNotAnObject), R(13), U8(1),
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B(Jump), U8(11),
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B(Star11),
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B(LdaZero),
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B(TestReferenceEqual), R(7),
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B(JumpIfTrue), U8(5),
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B(Ldar), R(11),
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B(ReThrow),
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B(Ldar), R(9),
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B(SetPendingMessage),
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B(Ldar), R(7),
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B(SwitchOnSmiNoFeedback), U8(11), U8(2), I8(0),
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B(Jump), U8(8),
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B(Ldar), R(8),
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B(ReThrow),
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B(Ldar), R(8),
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B(Return),
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B(LdaUndefined),
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/* 44 S> */ B(Return),
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]
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constant pool: [
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Smi [20],
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Smi [113],
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Smi [10],
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Smi [7],
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ARRAY_BOILERPLATE_DESCRIPTION_TYPE,
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["next"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["done"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["value"],
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Smi [15],
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Smi [7],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["return"],
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Smi [6],
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Smi [9],
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]
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handlers: [
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[66, 142, 148],
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[161, 180, 182],
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]
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---
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snippet: "
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function* g() { yield 42 }
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function* f() { yield* g() }
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f();
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"
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frame size: 7
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parameter count: 1
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bytecode array length: 188
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bytecodes: [
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B(SwitchOnGeneratorState), R(0), U8(0), U8(2),
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B(Mov), R(closure), R(1),
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B(Mov), R(this), R(2),
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/* 38 E> */ B(InvokeIntrinsic), U8(Runtime::k_CreateJSGeneratorObject), R(1), U8(2),
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B(Star0),
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/* 38 E> */ B(SuspendGenerator), R(0), R(0), U8(1), U8(0),
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B(ResumeGenerator), R(0), R(0), U8(1),
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B(Star1),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(SwitchOnSmiNoFeedback), U8(2), U8(2), I8(0),
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B(Ldar), R(1),
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/* 38 E> */ B(Throw),
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B(Ldar), R(1),
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B(Return),
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/* 43 S> */ B(LdaGlobal), U8(4), U8(0),
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B(Star5),
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/* 50 E> */ B(CallUndefinedReceiver0), R(5), U8(2),
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B(Star6),
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B(GetIterator), R(6), U8(4), U8(6),
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B(JumpIfJSReceiver), U8(7),
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B(CallRuntime), U16(Runtime::kThrowSymbolIteratorInvalid), R(0), U8(0),
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B(Star3),
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B(LdaNamedProperty), R(3), U8(5), U8(8),
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B(Star5),
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B(LdaUndefined),
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B(Star4),
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B(LdaZero),
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B(Star2),
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B(Ldar), R(2),
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B(SwitchOnSmiNoFeedback), U8(6), U8(2), I8(1),
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B(CallProperty1), R(5), R(3), R(4), U8(10),
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B(Jump), U8(59),
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B(LdaNamedProperty), R(3), U8(8), U8(12),
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B(JumpIfUndefinedOrNull), U8(10),
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B(Star6),
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B(CallProperty1), R(6), R(3), R(4), U8(14),
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B(Jump), U8(45),
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B(Ldar), R(4),
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B(Return),
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B(LdaNamedProperty), R(3), U8(9), U8(16),
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B(JumpIfUndefinedOrNull), U8(10),
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B(Star6),
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B(CallProperty1), R(6), R(3), R(4), U8(18),
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B(Jump), U8(28),
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B(LdaNamedProperty), R(3), U8(8), U8(20),
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B(JumpIfUndefinedOrNull), U8(17),
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B(Star6),
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B(CallProperty0), R(6), R(3), U8(22),
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B(Jump), U8(2),
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B(JumpIfJSReceiver), U8(8),
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B(Star6),
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B(CallRuntime), U16(Runtime::kThrowIteratorResultNotAnObject), R(6), U8(1),
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B(CallRuntime), U16(Runtime::kThrowThrowMethodMissing), R(0), U8(0),
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B(Star1),
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B(JumpIfJSReceiver), U8(7),
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B(CallRuntime), U16(Runtime::kThrowIteratorResultNotAnObject), R(1), U8(1),
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B(LdaNamedProperty), R(1), U8(10), U8(24),
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B(JumpIfToBooleanTrue), U8(22),
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B(Ldar), R(1),
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/* 43 E> */ B(SuspendGenerator), R(0), R(0), U8(6), U8(1),
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B(ResumeGenerator), R(0), R(0), U8(6),
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B(Star4),
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B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(0), U8(1),
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B(Star2),
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B(JumpLoop), U8(101), I8(0),
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B(LdaNamedProperty), R(1), U8(11), U8(26),
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B(Star3),
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B(LdaSmi), I8(1),
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B(TestReferenceEqual), R(2),
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B(JumpIfFalse), U8(5),
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B(Ldar), R(3),
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B(Return),
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B(LdaUndefined),
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/* 54 S> */ B(Return),
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]
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constant pool: [
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Smi [20],
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Smi [159],
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Smi [10],
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Smi [7],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["g"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["next"],
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Smi [11],
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Smi [28],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["return"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["throw"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["done"],
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ONE_BYTE_INTERNALIZED_STRING_TYPE ["value"],
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]
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handlers: [
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]
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