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Store template source in OperationDescriptorData #2491
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Release notes: None Instead of storing some obscure function in OperationDescriptorData, this makes it store the template source. This brings us closer to the generator tree being an abstract intermediate format, and simplifies the code.
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Summary: Release notes: None This resolves #1944. The functionality that Prepack provides can be seen as being done by two separate engines: 1) There's the "front-end", which does symbolic execution / abstract interpretation, computing "effects" / "generator trees" for the global code and optimized functions. 2) There's the "back-end", which takes this intermediate representation, computes what's reachable, and then turns it into a new executable program by performing transformations such as breaking cycles. Before, Prepack developers had very few tools available to understand what goes on between the front-end and back-end. Usually, they just look at the final output, imagine what the intermediate representation might have been, or maybe use to debugger to poke around memory locations, or to invoke helper functions to inspect live state that way, hoping the debugger doesn't crash along the way. This PR (and other associated PRs such as #2490, #2491) try to improve that state by turning the intermediate representation into a first-class data structure that is printable into a human-readable textual form. This will help... - in understanding what's going on - enabling different back-ends by ensuring that there's a first-class intermediate representation - enabling future transformations on a well-defined intermediate data structure, ideally breaking up what the current serializer implementation does - new ways of testing, e.g. via snapshots of the intermediate representation, or (once there is a parser) feeding hand-written IR into the back-end For example, for this program... ```js let x = __abstract("number", "(x)"); if (x > 42) { let t = Date.now(); let u = 2 + 3 console.log(t + u); } else { global.result = x; } ``` ... the IR would currently look like this: ``` (entry point): "main(#0)" * value#0 = ">"(@"(x)", 42) if value#0 then: "evaluateNodeForEffects(#4)" path conditions value#0 _$0 := ABSTRACT_FROM_TEMPLATE<template source @"global.Date.now()">[isPure] * value#1 = "+"(5, _$0) CONSOLE_LOG("log", value#1) else: "evaluateNodeForEffects(#11)" * value#2 = "!"(value#0) path conditions value#2 GLOBAL_ASSIGNMENT(@"(x)", "result") ``` Notes: - Indentation reflects structure of the generator tree - Each line encodes some information. Some of the information is atemporal, e.g. - `* value#N = f(args)` // atemporal abstract value - Some of the information is temporal, e.g. - `_$N := op-type<op-data>(args)[metadata]` // generator entry that defines a temporal value - `op-data` contains various essential data - `args` tends to be a projection of `data` capturing all values that must be visited, but it's not consistent - `metadata` is information that helps the visitor compute minimal reachability, but it's not semantically relevant. - `op-type<op-data>(args)[metadata]` // generator entry that does not define a temporal value - `if ... then ... else`. ```js (function() { let obj = {}; obj.p = obj; global.result = obj; })(); ``` => ``` (entry point): "main(#0)" * object#14 = ObjectValue(properties [p], $Prototype @"Object.prototype") * object#14.p = PropertyBinding(descriptor PropertyDescriptor(writable, enumerable, configurable, value object#14)) GLOBAL_ASSIGNMENT(object#14, "result") ``` Things get slightly ugly with functions. ```js function f() { } ``` => ``` (entry point): "main(#0)" * declEnv#1 = DeclarativeEnvironmentRecord() * globEnv#2 = GlobalEnvironmentRecord($DeclarativeRecord declEnv#1, $ObjectRecord declEnv#1, $VarNames [f], $GlobalThisValue global) * lexEnv#0 = LexicalEnvironment(destroyed, environment record globEnv#2) * func#13 = ECMAScriptSourceFunctionValue($ConstructorKind base, $ThisMode global, $FunctionKind normal, $FormalParameters 0, $Environment lexEnv#0, properties [arguments, length, caller, prototype, name], $Prototype @"Function.prototype") * func#13.arguments = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * func#13.length = PropertyBinding(descriptor PropertyDescriptor(configurable, value 0)) * func#13.caller = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * object#14 = ObjectValue(properties [constructor], $Prototype @"Object.prototype") * object#14.constructor = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value func#13)) * func#13.prototype = PropertyBinding(descriptor PropertyDescriptor(writable, value object#14)) * func#13.name = PropertyBinding(descriptor PropertyDescriptor(configurable, value "f")) GLOBAL_ASSIGNMENT(func#13, "f") ``` Things get really ugly with optimized functions, but that's what it is right now: ```js function f() { return 2 + 5; } __optimize(f); ``` => ``` (entry point): "main(#0)" * declEnv#1 = DeclarativeEnvironmentRecord() * globEnv#2 = GlobalEnvironmentRecord($DeclarativeRecord declEnv#1, $ObjectRecord declEnv#1, $VarNames [f], $GlobalThisValue global) * lexEnv#0 = LexicalEnvironment(destroyed, environment record globEnv#2) * func#13 = ECMAScriptSourceFunctionValue($ConstructorKind base, $ThisMode global, $FunctionKind normal, $FormalParameters 0, $Environment lexEnv#0, properties [arguments, length, caller, prototype, name], $Prototype @"Function.prototype") * func#13.arguments = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * func#13.length = PropertyBinding(descriptor PropertyDescriptor(configurable, value 0)) * func#13.caller = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * object#15 = ObjectValue(properties [constructor], $Prototype @"Object.prototype") * object#15.constructor = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value func#13)) * func#13.prototype = PropertyBinding(descriptor PropertyDescriptor(writable, value object#15)) * func#13.name = PropertyBinding(descriptor PropertyDescriptor(configurable, value "f")) GLOBAL_ASSIGNMENT(func#13, "f") === optimized function func#13 (entry point): "AdditionalFunctionEffects(#12)" RETURN(7) * object#16 = ArgumentsExotic(properties [length, callee], symbols [@"Symbol.iterator"], $Prototype @"Object.prototype") * object#16.length = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value 0)) * declEnv#1 = DeclarativeEnvironmentRecord() * globEnv#2 = GlobalEnvironmentRecord($DeclarativeRecord declEnv#1, $ObjectRecord declEnv#1, $VarNames [f], $GlobalThisValue global) * lexEnv#0 = LexicalEnvironment(destroyed, environment record globEnv#2) * func#13 = ECMAScriptSourceFunctionValue($ConstructorKind base, $ThisMode global, $FunctionKind normal, $FormalParameters 0, $Environment lexEnv#0, properties [arguments, length, caller, prototype, name], $Prototype @"Function.prototype") * func#13.arguments = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * func#13.length = PropertyBinding(descriptor PropertyDescriptor(configurable, value 0)) * func#13.caller = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value undefined)) * object#15 = ObjectValue(properties [constructor], $Prototype @"Object.prototype") * object#15.constructor = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value func#13)) * func#13.prototype = PropertyBinding(descriptor PropertyDescriptor(writable, value object#15)) * func#13.name = PropertyBinding(descriptor PropertyDescriptor(configurable, value "f")) * object#16.callee = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value func#13)) * object#16.@"Symbol.iterator" = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value @"Array.prototype.values")) * object#16.$Prototype = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value @"Object.prototype")) * object#16.$Extensible = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value true)) * object#16._isPartial = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#16._isLeaked = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#16._isSimple = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#16._simplicityIsTransitive = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#16._isFinal = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#17 = ObjectValue($Prototype null) * object#17.$Prototype = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value null)) * object#17.$Extensible = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value true)) * object#17._isPartial = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#17._isLeaked = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#17._isSimple = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#17._simplicityIsTransitive = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#17._isFinal = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18 = ObjectValue(properties [next], $Prototype @"([][Symbol.iterator]().__proto__.__proto__)") * func#19 = NativeFunctionValue(properties [length, name], $Prototype @"Function.prototype") * func#19.length = PropertyBinding(descriptor PropertyDescriptor(configurable, value 0)) * func#19.name = PropertyBinding(descriptor PropertyDescriptor(configurable, value "next")) * object#18.next = PropertyBinding(descriptor PropertyDescriptor(writable, configurable, value func#19)) * object#18.$Prototype = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value @"([][Symbol.iterator]().__proto__.__proto__)")) * object#18.$Extensible = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value true)) * object#18._isPartial = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18._isLeaked = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18._isSimple = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18._simplicityIsTransitive = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18._isFinal = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * object#18.$IteratedList = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(some array)) * func#19.$Prototype = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value @"Function.prototype")) * func#19.$Extensible = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value true)) * func#19._isPartial = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * func#19._isLeaked = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * func#19._isSimple = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * func#19._simplicityIsTransitive = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) * func#19._isFinal = PropertyBinding(internal slot, descriptor InternalSlotDescriptor(value false)) modified property bindings: [object#16.$Prototype, object#16.$Extensible, object#16._isPartial, object#16._isLeaked, object#16._isSimple, object#16._simplicityIsTransitive, object#16._isFinal, object#17.$Prototype, object#17.$Extensible, object#17._isPartial, object#17._isLeaked, object#17._isSimple, object#17._simplicityIsTransitive, object#17._isFinal, object#16.length, object#16.@"Symbol.iterator", object#16.callee, object#18.$Prototype, object#18.$Extensible, object#18._isPartial, object#18._isLeaked, object#18._isSimple, object#18._simplicityIsTransitive, object#18._isFinal, object#18.$IteratedList, func#19.$Prototype, func#19.$Extensible, func#19._isPartial, func#19._isLeaked, func#19._isSimple, func#19._simplicityIsTransitive, func#19._isFinal, func#19.length, func#19.name, object#18.next] created objects: [object#16, object#17, object#18, func#19] result: SimpleNormalCompletion(value 7) ``` There are still a good number of things left to do. In particular: - further simplify printing to make it more readable (and writable) - further extend printed format to make it round-trippable - some details of the current IR is really just an artefact of 2 years of hacking. It is in need of some additional rounds of refactorings and simplifications. - Particularly problematic / overly complicated are invariants INVARIANT, FULL_INVARIANT_ABSTRACT, FOR_IN, REACT_SSR_TEMPLATE_LITERAL - In `TemporalOperationEntry`, there's some duplication going on with `args` and `data`. Consider eliminating `args` and deriving this information when needed from `data`. - `OperationDescriptorData` could use some structure, or a (sub)type hierarchy. - There are already dedicated generator entry classes for some operations, and then there is `TemporalOperationEntry` with its `data` dumping ground for everything else. This is all a bit arbitrary and should be unified. - ...there's much more cruft. In a way, this PR just provides yet another way of dumping values and generators. Some of the other existing ways should be consolidated or killed. Added option --ir to test-runner to activate (and test) IR dumping. Pull Request resolved: #2493 Differential Revision: D9560883 Pulled By: NTillmann fbshipit-source-id: 70920c8e1b4139c69329d8f5ab6e6267a35f058b
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Release notes: None
Instead of storing some obscure function in OperationDescriptorData, this makes it store the template source.
This brings us closer to the generator tree being an abstract intermediate format, and simplifies the code.