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Add support for nested components (#4285) * Add support for nested components This commit is an implementation of a number of features of the component model including: * Defining nested components * Outer aliases to components and modules * Instantiating nested components The implementation here is intended to be a foundational pillar of Wasmtime's component model support since recursion and nested components are the bread-and-butter of the component model. At a high level the intention for the component model implementation in Wasmtime has long been that the recursive nature of components is "erased" at compile time to something that's more optimized and efficient to process. This commit ended up exemplifying this quite well where the vast majority of the internal changes here are in the "compilation" phase of a component rather than the runtime instantiation phase. The support in the `wasmtime` crate, the runtime instantiation support, only had minor updates here while the internals of translation have seen heavy updates. The `translate` module was greatly refactored here in this commit. Previously it would, as a component is parsed, create a final `Component` to hand off to trampoline compilation and get persisted at runtime. Instead now it's a thin layer over `wasmparser` which simply records a list of `LocalInitializer` entries for how to instantiate the component and its index spaces are built. This internal representation of the instantiation of a component is pretty close to the binary format intentionally. Instead of performing dataflow legwork the `translate` phase of a component is now responsible for two primary tasks: 1. All components and modules are discovered within a component. They're assigned `Static{Component,Module}Index` depending on where they're found and a `{Module,}Translation` is prepared for each one. This "flattens" the recursive structure of the binary into an indexed list processable later. 2. The lexical scope of components is managed here to implement outer module and component aliases. This is a significant design implementation because when closing over an outer component or module that item may actually be imported or something like the result of a previous instantiation. This means that the capture of modules and components is both a lexical concern as well as a runtime concern. The handling of the "runtime" bits are handled in the next phase of compilation. The next and currently final phase of compilation is a new pass where much of the historical code in `translate.rs` has been moved to (but heavily refactored). The goal of compilation is to produce one "flat" list of initializers for a component (as happens prior to this PR) and to achieve this an "inliner" phase runs which runs through the instantiation process at compile time to produce a list of initializers. This `inline` module is the main addition as part of this PR and is now the workhorse for dataflow analysis and tracking what's actually referring to what. During the `inline` phase the local initializers recorded in the `translate` phase are processed, in sequence, to instantiate a component. Definitions of items are tracked to correspond to their root definition which allows seeing across instantiation argument boundaries and such. Handling "upvars" for component outer aliases is handled in the `inline` phase as well by creating state for a component whenever a component is defined as was recorded during the `translate` phase. Finally this phase is chiefly responsible for doing all string-based name resolution at compile time that it can. This means that at runtime no string maps will need to be consulted for item exports and such. The final result of inlining is a list of "global initializers" which is a flat list processed during instantiation time. These are almost identical to the initializers that were processed prior to this PR. There are certainly still more gaps of the component model to implement but this should be a major leg up in terms of functionality that Wasmtime implements. This commit, however leaves behind a "hole" which is not intended to be filled in at this time, namely importing and exporting components at the "root" level from and to the host. This is tracked and explained in more detail as part of #4283. cc #4185 as this completes a number of items there * Tweak code to work on stable without warning * Review comments
2 years ago
;; simple nested component
(component
(component)
)
;; simple nested component with a nested module
(component
(component
(core module)
)
)
;; simple instantiation of a nested component
(component
(component $c)
(instance (instantiate $c))
(instance (instantiate $c
(with "x" (component $c))
))
)
;; instantiate a module during a nested component, and also instantiate it
;; as an export of the nested component
(component
(component $c
(core module $m)
(core instance (instantiate $m))
(export "m" (core module $m))
)
(instance $i (instantiate $c))
(core instance $i (instantiate (module $i "m")))
)
;; instantiate an inner exported module with two different modules and
;; verify imports match
(component
(component $c
(core module $m
(import "" "g" (global $g i32))
(import "" "f" (func $f (result i32)))
(func $start
call $f
global.get $g
i32.ne
if unreachable end)
(start $start)
)
(core module $m2
(global (export "g") i32 i32.const 1)
(func (export "f") (result i32) i32.const 1)
)
(core instance $i2 (instantiate $m2))
(core instance (instantiate $m (with "" (instance $i2))))
(export "m" (core module $m))
)
(instance $i (instantiate $c))
(core module $m2
(global (export "g") i32 i32.const 5)
(func (export "f") (result i32) i32.const 5)
)
(core instance $i2 (instantiate $m2))
(core instance (instantiate (module $i "m") (with "" (instance $i2))))
)
;; instantiate an inner component with a module import
(component
(component $c
(import "m" (core module $m
(export "g" (global i32))
))
(core instance $i (instantiate $m))
(core module $verify
(import "" "g" (global $g i32))
(func $start
global.get $g
i32.const 2
i32.ne
if unreachable end
)
(start $start)
)
(core instance (instantiate $verify (with "" (instance $i))))
)
(core module $m
(global (export "g") i32 (i32.const 2))
)
(instance (instantiate $c (with "m" (core module $m))))
)
;; instantiate an inner component with a module import that itself has imports
(component
(component $c
(import "m" (core module $m
(import "" "g" (global i32))
))
(core module $m2
(global (export "g") i32 i32.const 2100)
)
(core instance $m2 (instantiate $m2))
(core instance (instantiate $m (with "" (instance $m2))))
)
(core module $verify
(import "" "g" (global $g i32))
(func $start
global.get $g
i32.const 2100
i32.ne
if unreachable end
)
(start $start)
)
(instance (instantiate $c (with "m" (core module $verify))))
)
;; instantiate an inner component with an export from the outer component
(component $c
(core module (export "m")
(import "" "g1" (global $g1 i32))
(import "" "g2" (global $g2 i32))
(func $start
global.get $g1
i32.const 10000
i32.ne
if unreachable end
global.get $g2
i32.const 20000
i32.ne
if unreachable end
)
(start $start)
)
)
(component
(import "c" (instance $i
(export "m" (core module
(import "" "g2" (global i32))
(import "" "g1" (global i32))
))
))
(component $c
(import "m" (core module $verify
(import "" "g2" (global i32))
(import "" "g1" (global i32))
))
(core module $m
(global (export "g1") i32 i32.const 10000)
(global (export "g2") i32 i32.const 20000)
)
(core instance $m (instantiate $m))
(core instance (instantiate $verify (with "" (instance $m))))
)
(instance (instantiate $c (with "m" (core module $i "m"))))
)
;; instantiate a reexported module
(component
(core module $m
(global (export "g") i32 i32.const 7)
)
(component $c
(import "i" (instance $i
(export "m" (core module
(import "" "" (func))
(export "g" (global i32))
))
))
(export "m" (core module $i "m"))
)
(instance $c (instantiate $c (with "i" (instance (export "m" (core module $m))))))
(core module $dummy
(func (export ""))
)
(core instance $dummy (instantiate $dummy))
(core instance $m (instantiate (module $c "m") (with "" (instance $dummy))))
(core module $verify
(import "" "g" (global i32))
(func $start
global.get 0
i32.const 7
i32.ne
if unreachable end
)
(start $start)
)
(core instance (instantiate $verify (with "" (instance $m))))
)
;; module must be found through a few layers of imports
(component $c
(core module (export "m")
(global (export "g") i32 i32.const 101)
)
)
(component
(import "c" (instance $i
(export "m" (core module
(export "g" (global i32))
))
))
(component $c1
(import "c" (instance $i
(export "m" (core module
(export "g" (global i32))
))
))
(core module $verify
(import "" "g" (global i32))
(func $start
global.get 0
i32.const 101
i32.ne
if unreachable end
)
(start $start)
)
(core instance $m (instantiate (module $i "m")))
(core instance (instantiate $verify (with "" (instance $m))))
)
(instance (instantiate $c1 (with "c" (instance $i))))
)
;; instantiate outer alias to self
(component $C
(core module $m)
(alias outer $C $m (core module $other_m))
(core instance (instantiate $other_m))
)
(component $C
(component $m)
(alias outer $C $m (component $other_m))
(instance (instantiate $other_m))
)
;; closing over an outer alias which is actually an argument to some
;; instantiation
(component
(component $c
(import "c" (core module $c
(export "a" (global i32))
))
(component (export "c")
(export "m" (core module $c))
)
)
(core module $m1 (global (export "a") i32 i32.const 1))
(core module $m2 (global (export "a") i32 i32.const 2))
(instance $c1 (instantiate $c (with "c" (core module $m1))))
(instance $c2 (instantiate $c (with "c" (core module $m2))))
(instance $m1_container (instantiate (component $c1 "c")))
(instance $m2_container (instantiate (component $c2 "c")))
(core instance $core1 (instantiate (module $m1_container "m")))
(core instance $core2 (instantiate (module $m2_container "m")))
(core module $verify
(import "core1" "a" (global $a i32))
(import "core2" "a" (global $b i32))
(func $start
global.get $a
i32.const 1
i32.ne
if unreachable end
global.get $b
i32.const 2
i32.ne
if unreachable end
)
(start $start)
)
(core instance (instantiate $verify
(with "core1" (instance $core1))
(with "core2" (instance $core2))
))
)
;; simple importing of a component
(component
(component $C)
(component $other
(import "x" (component $c))
(instance (instantiate $c))
)
(instance (instantiate $other (with "x" (component $C))))
)
;; deep nesting
(component $C
(core module $m
(global (export "g") i32 (i32.const 1))
)
(component $c
(core module (export "m")
(global (export "g") i32 (i32.const 2))
)
)
(component $c1
(component $c2 (export "")
(component $c3 (export "")
(alias outer $C $m (core module $my_module))
(alias outer $C $c (component $my_component))
(export "m" (core module $my_module))
(export "c" (component $my_component))
)
)
)
(instance $i1 (instantiate $c1))
(instance $i2 (instantiate (component $i1 "")))
(instance $i3 (instantiate (component $i2 "")))
(core instance $m1 (instantiate (module $i3 "m")))
(instance $c (instantiate (component $i3 "c")))
(core instance $m2 (instantiate (module $c "m")))
(core module $verify
(import "m1" "g" (global $m1 i32))
(import "m2" "g" (global $m2 i32))
(func $start
global.get $m1
i32.const 1
i32.ne
if unreachable end
global.get $m2
i32.const 2
i32.ne
if unreachable end
)
(start $start)
)
(core instance (instantiate $verify (with "m1" (instance $m1)) (with "m2" (instance $m2))))
)
;; Try threading through component instantiation arguments as various forms of
;; instances.
(component
(component $c
(core module $m (export "m"))
(component $c (export "c")
(core module (export "m"))
)
(instance $i (instantiate $c))
(instance $i2
(export "m" (core module $m))
(export "c" (component $c))
(export "i" (instance $i))
)
(export "i" (instance $i))
(export "i2" (instance $i2))
)
(instance $i (instantiate $c))
(component $another
(import "host" (instance
(export "m" (core module))
(export "c" (component))
(export "i" (instance))
))
)
(instance (instantiate $another (with "host" (instance $i))))
(instance (instantiate $another (with "host" (instance $i "i2"))))
(instance $reexport
(export "c" (component $i "c"))
(export "m" (core module $i "m"))
(export "i" (instance $i "i"))
)
(instance (instantiate $another (with "host" (instance $reexport))))
)
;; thread host functions around
(component
(import "host-return-two" (func $import (result u32)))
;; thread the host function through an instance
(component $c
(import "" (func $f (result u32)))
(export "f" (func $f))
)
(instance $c (instantiate $c (with "" (func $import))))
(alias export $c "f" (func $import2))
;; thread the host function into a nested component
(component $c2
(import "host" (instance $i (export "return-two" (func (result u32)))))
(core module $m
(import "host" "return-two" (func $host (result i32)))
(func $start
call $host
i32.const 2
i32.ne
if unreachable end
)
(start $start)
)
(core func $return_two
(canon lower (func $i "return-two"))
)
(core instance (instantiate $m
(with "host" (instance
(export "return-two" (func $return_two))
))
))
)
(instance (instantiate $c2
(with "host" (instance
(export "return-two" (func $import2))
))
))
)