cranelift-wasm: Create ModuleTranslationState and polish API a little (#1111)
* cranelift-wasm: replace `WasmTypesMap` with `ModuleTranslationState`
The `ModuleTranslationState` contains information decoded from the Wasm module
that must be referenced during each Wasm function's translation.
This is only for data that is maintained by `cranelift-wasm` itself, as opposed
to being maintained by the embedder. Data that is maintained by the embedder is
represented with `ModuleEnvironment`.
A `ModuleTranslationState` is returned by `translate_module`, and can then be
used when translating functions from that module.
* cranelift-wasm: rename `TranslationState` to `FuncTranslationState`
To disambiguate a bit with the new `ModuleTranslationState`.
* cranelift-wasm: Reorganize the internal `state` module into submodules
One module for the `ModuleTranslationState` and another for the
`FuncTranslationState`.
* cranelift-wasm: replace `FuncTranslator` with methods on `ModuleTranslationState`
`FuncTranslator` was two methods that always took ownership of `self`, so it
didn't really make sense as an object as opposed to two different functions, or
in this case methods on the object that actually persists for a longer time.
I think this improves ergonomics nicely.
Before:
```rust
let module_translation = translate_module(...)?;
for body in func_bodies {
let mut translator = FuncTranslator::new();
translator.translate(body, ...)?;
}
```
After:
```rust
let module_translation = translate_module(...)?;
for body in func_bodies {
module_translation.translate_func(body, ...)?;
}
```
Note that this commit does not remove `FuncTranslator`. It still exists, but is
just a wrapper over the `ModuleTranslationState` methods, and it is marked
deprecated, so that downstream users get a heads up. This should make the
transition easier.
* Revert "cranelift-wasm: replace `FuncTranslator` with methods on `ModuleTranslationState`"
This reverts commit 075f9ae933bcaae39348b61287c8f78a4009340d.
This commit is contained in:
Nick Fitzgerald
488
cranelift/wasm/src/state/func_state.rs
Normal file
488
cranelift/wasm/src/state/func_state.rs
Normal file
@@ -0,0 +1,488 @@
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//! WebAssembly module and function translation state.
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//!
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//! The `ModuleTranslationState` struct defined in this module is used to keep track of data about
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//! the whole WebAssembly module, such as the decoded type signatures.
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//!
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//! The `FuncTranslationState` struct defined in this module is used to keep track of the WebAssembly
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//! value and control stacks during the translation of a single function.
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use crate::environ::{FuncEnvironment, GlobalVariable, WasmResult};
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use crate::translation_utils::{FuncIndex, GlobalIndex, MemoryIndex, SignatureIndex, TableIndex};
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use crate::{HashMap, Occupied, Vacant};
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use cranelift_codegen::ir::{self, Ebb, Inst, Value};
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use std::vec::Vec;
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/// Information about the presence of an associated `else` for an `if`, or the
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/// lack thereof.
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#[derive(Debug)]
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pub enum ElseData {
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/// The `if` does not already have an `else` block.
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NoElse {
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/// If we discover that we need an `else` block, this is the jump
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/// instruction that needs to be fixed up to point to the new `else`
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/// block rather than the destination block after the `if...end`.
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branch_inst: Inst,
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},
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/// We have already allocated an `else` block.
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WithElse {
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/// This is the `else` block.
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else_block: Ebb,
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},
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}
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/// A control stack frame can be an `if`, a `block` or a `loop`, each one having the following
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/// fields:
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///
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/// - `destination`: reference to the `Ebb` that will hold the code after the control block;
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/// - `num_return_values`: number of values returned by the control block;
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/// - `original_stack_size`: size of the value stack at the beginning of the control block.
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///
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/// Moreover, the `if` frame has the `branch_inst` field that points to the `brz` instruction
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/// separating the `true` and `false` branch. The `loop` frame has a `header` field that references
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/// the `Ebb` that contains the beginning of the body of the loop.
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#[derive(Debug)]
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pub enum ControlStackFrame {
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If {
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destination: Ebb,
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else_data: ElseData,
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num_param_values: usize,
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num_return_values: usize,
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original_stack_size: usize,
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exit_is_branched_to: bool,
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reachable_from_top: bool,
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blocktype: wasmparser::TypeOrFuncType,
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},
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Block {
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destination: Ebb,
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num_param_values: usize,
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num_return_values: usize,
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original_stack_size: usize,
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exit_is_branched_to: bool,
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},
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Loop {
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destination: Ebb,
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header: Ebb,
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num_param_values: usize,
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num_return_values: usize,
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original_stack_size: usize,
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},
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}
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/// Helper methods for the control stack objects.
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impl ControlStackFrame {
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pub fn num_return_values(&self) -> usize {
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match *self {
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ControlStackFrame::If {
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num_return_values, ..
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}
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| ControlStackFrame::Block {
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num_return_values, ..
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}
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| ControlStackFrame::Loop {
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num_return_values, ..
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} => num_return_values,
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}
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}
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pub fn num_param_values(&self) -> usize {
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match *self {
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ControlStackFrame::If {
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num_param_values, ..
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}
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| ControlStackFrame::Block {
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num_param_values, ..
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}
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| ControlStackFrame::Loop {
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num_param_values, ..
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} => num_param_values,
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}
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}
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pub fn following_code(&self) -> Ebb {
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match *self {
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ControlStackFrame::If { destination, .. }
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| ControlStackFrame::Block { destination, .. }
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| ControlStackFrame::Loop { destination, .. } => destination,
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}
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}
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pub fn br_destination(&self) -> Ebb {
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match *self {
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ControlStackFrame::If { destination, .. }
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| ControlStackFrame::Block { destination, .. } => destination,
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ControlStackFrame::Loop { header, .. } => header,
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}
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}
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pub fn original_stack_size(&self) -> usize {
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match *self {
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ControlStackFrame::If {
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original_stack_size,
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..
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}
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| ControlStackFrame::Block {
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original_stack_size,
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..
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}
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| ControlStackFrame::Loop {
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original_stack_size,
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..
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} => original_stack_size,
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}
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}
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pub fn is_loop(&self) -> bool {
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match *self {
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ControlStackFrame::If { .. } | ControlStackFrame::Block { .. } => false,
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ControlStackFrame::Loop { .. } => true,
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}
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}
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pub fn exit_is_branched_to(&self) -> bool {
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match *self {
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ControlStackFrame::If {
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exit_is_branched_to,
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..
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}
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| ControlStackFrame::Block {
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exit_is_branched_to,
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..
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} => exit_is_branched_to,
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ControlStackFrame::Loop { .. } => false,
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}
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}
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pub fn set_branched_to_exit(&mut self) {
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match *self {
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ControlStackFrame::If {
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ref mut exit_is_branched_to,
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..
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}
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| ControlStackFrame::Block {
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ref mut exit_is_branched_to,
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..
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} => *exit_is_branched_to = true,
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ControlStackFrame::Loop { .. } => {}
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}
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}
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}
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/// Contains information passed along during a function's translation and that records:
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///
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/// - The current value and control stacks.
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/// - The depth of the two unreachable control blocks stacks, that are manipulated when translating
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/// unreachable code;
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pub struct FuncTranslationState {
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/// A stack of values corresponding to the active values in the input wasm function at this
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/// point.
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pub(crate) stack: Vec<Value>,
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/// A stack of active control flow operations at this point in the input wasm function.
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pub(crate) control_stack: Vec<ControlStackFrame>,
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/// Is the current translation state still reachable? This is false when translating operators
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/// like End, Return, or Unreachable.
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pub(crate) reachable: bool,
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// Map of global variables that have already been created by `FuncEnvironment::make_global`.
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globals: HashMap<GlobalIndex, GlobalVariable>,
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// Map of heaps that have been created by `FuncEnvironment::make_heap`.
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heaps: HashMap<MemoryIndex, ir::Heap>,
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// Map of tables that have been created by `FuncEnvironment::make_table`.
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tables: HashMap<TableIndex, ir::Table>,
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// Map of indirect call signatures that have been created by
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// `FuncEnvironment::make_indirect_sig()`.
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// Stores both the signature reference and the number of WebAssembly arguments
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signatures: HashMap<SignatureIndex, (ir::SigRef, usize)>,
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// Imported and local functions that have been created by
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// `FuncEnvironment::make_direct_func()`.
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// Stores both the function reference and the number of WebAssembly arguments
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functions: HashMap<FuncIndex, (ir::FuncRef, usize)>,
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}
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// Public methods that are exposed to non-`cranelift_wasm` API consumers.
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impl FuncTranslationState {
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/// True if the current translation state expresses reachable code, false if it is unreachable.
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#[inline]
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pub fn reachable(&self) -> bool {
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self.reachable
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}
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}
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impl FuncTranslationState {
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/// Construct a new, empty, `FuncTranslationState`
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pub(crate) fn new() -> Self {
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Self {
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stack: Vec::new(),
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control_stack: Vec::new(),
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reachable: true,
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globals: HashMap::new(),
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heaps: HashMap::new(),
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tables: HashMap::new(),
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signatures: HashMap::new(),
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functions: HashMap::new(),
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}
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}
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fn clear(&mut self) {
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debug_assert!(self.stack.is_empty());
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debug_assert!(self.control_stack.is_empty());
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self.reachable = true;
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self.globals.clear();
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self.heaps.clear();
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self.tables.clear();
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self.signatures.clear();
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self.functions.clear();
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}
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/// Initialize the state for compiling a function with the given signature.
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///
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/// This resets the state to containing only a single block representing the whole function.
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/// The exit block is the last block in the function which will contain the return instruction.
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pub(crate) fn initialize(&mut self, sig: &ir::Signature, exit_block: Ebb) {
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self.clear();
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self.push_block(
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exit_block,
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0,
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sig.returns
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.iter()
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.filter(|arg| arg.purpose == ir::ArgumentPurpose::Normal)
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.count(),
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);
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}
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/// Push a value.
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pub(crate) fn push1(&mut self, val: Value) {
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self.stack.push(val);
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}
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/// Push multiple values.
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pub(crate) fn pushn(&mut self, vals: &[Value]) {
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self.stack.extend_from_slice(vals);
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}
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/// Pop one value.
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pub(crate) fn pop1(&mut self) -> Value {
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self.stack
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.pop()
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.expect("attempted to pop a value from an empty stack")
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}
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/// Peek at the top of the stack without popping it.
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pub(crate) fn peek1(&self) -> Value {
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*self
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.stack
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.last()
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.expect("attempted to peek at a value on an empty stack")
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}
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/// Pop two values. Return them in the order they were pushed.
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pub(crate) fn pop2(&mut self) -> (Value, Value) {
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let v2 = self.stack.pop().unwrap();
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let v1 = self.stack.pop().unwrap();
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(v1, v2)
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}
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/// Pop three values. Return them in the order they were pushed.
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pub(crate) fn pop3(&mut self) -> (Value, Value, Value) {
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let v3 = self.stack.pop().unwrap();
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let v2 = self.stack.pop().unwrap();
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let v1 = self.stack.pop().unwrap();
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(v1, v2, v3)
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}
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/// Pop the top `n` values on the stack.
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///
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/// The popped values are not returned. Use `peekn` to look at them before popping.
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pub(crate) fn popn(&mut self, n: usize) {
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debug_assert!(
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n <= self.stack.len(),
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"popn({}) but stack only has {} values",
|
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n,
|
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self.stack.len()
|
||||
);
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let new_len = self.stack.len() - n;
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self.stack.truncate(new_len);
|
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}
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|
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/// Peek at the top `n` values on the stack in the order they were pushed.
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pub(crate) fn peekn(&self, n: usize) -> &[Value] {
|
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debug_assert!(
|
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n <= self.stack.len(),
|
||||
"peekn({}) but stack only has {} values",
|
||||
n,
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||||
self.stack.len()
|
||||
);
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&self.stack[self.stack.len() - n..]
|
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}
|
||||
|
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/// Push a block on the control stack.
|
||||
pub(crate) fn push_block(
|
||||
&mut self,
|
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following_code: Ebb,
|
||||
num_param_types: usize,
|
||||
num_result_types: usize,
|
||||
) {
|
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debug_assert!(num_param_types <= self.stack.len());
|
||||
self.control_stack.push(ControlStackFrame::Block {
|
||||
destination: following_code,
|
||||
original_stack_size: self.stack.len() - num_param_types,
|
||||
num_param_values: num_param_types,
|
||||
num_return_values: num_result_types,
|
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exit_is_branched_to: false,
|
||||
});
|
||||
}
|
||||
|
||||
/// Push a loop on the control stack.
|
||||
pub(crate) fn push_loop(
|
||||
&mut self,
|
||||
header: Ebb,
|
||||
following_code: Ebb,
|
||||
num_param_types: usize,
|
||||
num_result_types: usize,
|
||||
) {
|
||||
debug_assert!(num_param_types <= self.stack.len());
|
||||
self.control_stack.push(ControlStackFrame::Loop {
|
||||
header,
|
||||
destination: following_code,
|
||||
original_stack_size: self.stack.len() - num_param_types,
|
||||
num_param_values: num_param_types,
|
||||
num_return_values: num_result_types,
|
||||
});
|
||||
}
|
||||
|
||||
/// Push an if on the control stack.
|
||||
pub(crate) fn push_if(
|
||||
&mut self,
|
||||
destination: Ebb,
|
||||
else_data: ElseData,
|
||||
num_param_types: usize,
|
||||
num_result_types: usize,
|
||||
blocktype: wasmparser::TypeOrFuncType,
|
||||
) {
|
||||
debug_assert!(num_param_types <= self.stack.len());
|
||||
|
||||
// Push a second copy of our `if`'s parameters on the stack. This lets
|
||||
// us avoid saving them on the side in the `ControlStackFrame` for our
|
||||
// `else` block (if it exists), which would require a second heap
|
||||
// allocation. See also the comment in `translate_operator` for
|
||||
// `Operator::Else`.
|
||||
self.stack.reserve(num_param_types);
|
||||
for i in (self.stack.len() - num_param_types)..self.stack.len() {
|
||||
let val = self.stack[i];
|
||||
self.stack.push(val);
|
||||
}
|
||||
|
||||
let has_else = match else_data {
|
||||
ElseData::NoElse { .. } => false,
|
||||
ElseData::WithElse { .. } => true,
|
||||
};
|
||||
|
||||
self.control_stack.push(ControlStackFrame::If {
|
||||
destination,
|
||||
else_data,
|
||||
original_stack_size: self.stack.len() - num_param_types,
|
||||
num_param_values: num_param_types,
|
||||
num_return_values: num_result_types,
|
||||
exit_is_branched_to: false,
|
||||
reachable_from_top: self.reachable && !has_else,
|
||||
blocktype,
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
/// Methods for handling entity references.
|
||||
impl FuncTranslationState {
|
||||
/// Get the `GlobalVariable` reference that should be used to access the global variable
|
||||
/// `index`. Create the reference if necessary.
|
||||
/// Also return the WebAssembly type of the global.
|
||||
pub(crate) fn get_global<FE: FuncEnvironment + ?Sized>(
|
||||
&mut self,
|
||||
func: &mut ir::Function,
|
||||
index: u32,
|
||||
environ: &mut FE,
|
||||
) -> WasmResult<GlobalVariable> {
|
||||
let index = GlobalIndex::from_u32(index);
|
||||
match self.globals.entry(index) {
|
||||
Occupied(entry) => Ok(*entry.get()),
|
||||
Vacant(entry) => Ok(*entry.insert(environ.make_global(func, index)?)),
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the `Heap` reference that should be used to access linear memory `index`.
|
||||
/// Create the reference if necessary.
|
||||
pub(crate) fn get_heap<FE: FuncEnvironment + ?Sized>(
|
||||
&mut self,
|
||||
func: &mut ir::Function,
|
||||
index: u32,
|
||||
environ: &mut FE,
|
||||
) -> WasmResult<ir::Heap> {
|
||||
let index = MemoryIndex::from_u32(index);
|
||||
match self.heaps.entry(index) {
|
||||
Occupied(entry) => Ok(*entry.get()),
|
||||
Vacant(entry) => Ok(*entry.insert(environ.make_heap(func, index)?)),
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the `Table` reference that should be used to access table `index`.
|
||||
/// Create the reference if necessary.
|
||||
pub(crate) fn get_table<FE: FuncEnvironment + ?Sized>(
|
||||
&mut self,
|
||||
func: &mut ir::Function,
|
||||
index: u32,
|
||||
environ: &mut FE,
|
||||
) -> WasmResult<ir::Table> {
|
||||
let index = TableIndex::from_u32(index);
|
||||
match self.tables.entry(index) {
|
||||
Occupied(entry) => Ok(*entry.get()),
|
||||
Vacant(entry) => Ok(*entry.insert(environ.make_table(func, index)?)),
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the `SigRef` reference that should be used to make an indirect call with signature
|
||||
/// `index`. Also return the number of WebAssembly arguments in the signature.
|
||||
///
|
||||
/// Create the signature if necessary.
|
||||
pub(crate) fn get_indirect_sig<FE: FuncEnvironment + ?Sized>(
|
||||
&mut self,
|
||||
func: &mut ir::Function,
|
||||
index: u32,
|
||||
environ: &mut FE,
|
||||
) -> WasmResult<(ir::SigRef, usize)> {
|
||||
let index = SignatureIndex::from_u32(index);
|
||||
match self.signatures.entry(index) {
|
||||
Occupied(entry) => Ok(*entry.get()),
|
||||
Vacant(entry) => {
|
||||
let sig = environ.make_indirect_sig(func, index)?;
|
||||
Ok(*entry.insert((sig, normal_args(&func.dfg.signatures[sig]))))
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Get the `FuncRef` reference that should be used to make a direct call to function
|
||||
/// `index`. Also return the number of WebAssembly arguments in the signature.
|
||||
///
|
||||
/// Create the function reference if necessary.
|
||||
pub(crate) fn get_direct_func<FE: FuncEnvironment + ?Sized>(
|
||||
&mut self,
|
||||
func: &mut ir::Function,
|
||||
index: u32,
|
||||
environ: &mut FE,
|
||||
) -> WasmResult<(ir::FuncRef, usize)> {
|
||||
let index = FuncIndex::from_u32(index);
|
||||
match self.functions.entry(index) {
|
||||
Occupied(entry) => Ok(*entry.get()),
|
||||
Vacant(entry) => {
|
||||
let fref = environ.make_direct_func(func, index)?;
|
||||
let sig = func.dfg.ext_funcs[fref].signature;
|
||||
Ok(*entry.insert((fref, normal_args(&func.dfg.signatures[sig]))))
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Count the number of normal parameters in a signature.
|
||||
/// Exclude special-purpose parameters that represent runtime stuff and not WebAssembly arguments.
|
||||
fn normal_args(sig: &ir::Signature) -> usize {
|
||||
sig.params
|
||||
.iter()
|
||||
.filter(|arg| arg.purpose == ir::ArgumentPurpose::Normal)
|
||||
.count()
|
||||
}
|
||||
Reference in New Issue
Block a user