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Hide instruction storage details (#129) 

* Hide Instructions implementation behind an iterator

* Hide instruction encoding behind isa::Instructions::push()

* Consistently use u32 for program counter storage

* Refer to instructions by position rather than index
This commit is contained in:
Will Glynn 2018-10-10 12:02:27 -05:00 committed by Sergey Pepyakin
parent 9170303aad
commit 7509477a61
4 changed files with 153 additions and 84 deletions
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80
src/isa.rs
View File

@ -93,6 +93,22 @@ pub struct Target {
pub drop_keep: DropKeep,
}
/// A relocation entry that specifies.
#[derive(Debug)]
pub enum Reloc {
/// Patch the destination of the branch instruction (br, br_eqz, br_nez)
/// at the specified pc.
Br {
pc: u32,
},
/// Patch the specified destination index inside of br_table instruction at
/// the specified pc.
BrTable {
pc: u32,
idx: usize,
},
}
#[derive(Debug, Clone, PartialEq)]
pub enum Instruction {
/// Push a local variable or an argument from the specified depth.
@ -299,5 +315,67 @@ pub enum Instruction {
#[derive(Debug, Clone)]
pub struct Instructions {
pub code: Vec<Instruction>,
vec: Vec<Instruction>,
}
impl Instructions {
pub fn with_capacity(capacity: usize) -> Self {
Instructions {
vec: Vec::with_capacity(capacity),
}
}
pub fn current_pc(&self) -> u32 {
self.vec.len() as u32
}
pub fn push(&mut self, instruction: Instruction) {
self.vec.push(instruction);
}
pub fn patch_relocation(&mut self, reloc: Reloc, dst_pc: u32) {
match reloc {
Reloc::Br { pc } => match self.vec[pc as usize] {
Instruction::Br(ref mut target)
| Instruction::BrIfEqz(ref mut target)
| Instruction::BrIfNez(ref mut target) => target.dst_pc = dst_pc,
_ => panic!("branch relocation points to a non-branch instruction"),
},
Reloc::BrTable { pc, idx } => match self.vec[pc as usize] {
Instruction::BrTable(ref mut targets) => targets[idx].dst_pc = dst_pc,
_ => panic!("brtable relocation points to not brtable instruction"),
}
}
}
pub fn iterate_from(&self, position: u32) -> InstructionIter {
InstructionIter{
instructions: &self.vec,
position,
}
}
}
pub struct InstructionIter<'a> {
instructions: &'a [Instruction],
position: u32,
}
impl<'a> InstructionIter<'a> {
#[inline]
pub fn position(&self) -> u32 {
self.position
}
}
impl<'a> Iterator for InstructionIter<'a> {
type Item = &'a Instruction;
#[inline]
fn next(&mut self) -> Option<<Self as Iterator>::Item> {
self.instructions.get(self.position as usize).map(|instruction| {
self.position += 1;
instruction
})
}
}

20
src/runner.rs
View File

@ -175,7 +175,7 @@ impl Interpreter {
let function_return =
self.do_run_function(
&mut function_context,
&function_body.code.code,
&function_body.code,
).map_err(Trap::new)?;
match function_return {
@ -229,18 +229,24 @@ impl Interpreter {
}
}
fn do_run_function(&mut self, function_context: &mut FunctionContext, instructions: &[isa::Instruction]) -> Result<RunResult, TrapKind> {
fn do_run_function(&mut self, function_context: &mut FunctionContext, instructions: &isa::Instructions)
-> Result<RunResult, TrapKind>
{
let mut iter = instructions.iterate_from(function_context.position);
loop {
let instruction = &instructions[function_context.position];
let instruction = iter.next().expect("instruction");
match self.run_instruction(function_context, instruction)? {
InstructionOutcome::RunNextInstruction => function_context.position += 1,
InstructionOutcome::RunNextInstruction => {
function_context.position = iter.position();
},
InstructionOutcome::Branch(target) => {
function_context.position = target.dst_pc as usize;
function_context.position = target.dst_pc;
iter = instructions.iterate_from(function_context.position);
self.value_stack.drop_keep(target.drop_keep);
},
InstructionOutcome::ExecuteCall(func_ref) => {
function_context.position += 1;
function_context.position = iter.position();
return Ok(RunResult::NestedCall(func_ref));
},
InstructionOutcome::Return(drop_keep) => {
@ -1077,7 +1083,7 @@ struct FunctionContext {
pub module: ModuleRef,
pub memory: Option<MemoryRef>,
/// Current instruction position.
pub position: usize,
pub position: u32,
}
impl FunctionContext {

55
src/validation/func.rs
View File

@ -1406,9 +1406,7 @@ impl<'a> FunctionValidationContext<'a> {
}
fn into_code(self) -> isa::Instructions {
isa::Instructions {
code: self.sink.into_inner(),
}
self.sink.into_inner()
}
}
@ -1628,22 +1626,6 @@ struct Target {
drop_keep: isa::DropKeep,
}
/// A relocation entry that specifies.
#[derive(Debug)]
enum Reloc {
/// Patch the destination of the branch instruction (br, br_eqz, br_nez)
/// at the specified pc.
Br {
pc: u32,
},
/// Patch the specified destination index inside of br_table instruction at
/// the specified pc.
BrTable {
pc: u32,
idx: usize,
},
}
/// Identifier of a label.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
struct LabelId(usize);
@ -1655,23 +1637,23 @@ enum Label {
}
struct Sink {
ins: Vec<isa::Instruction>,
labels: Vec<(Label, Vec<Reloc>)>,
ins: isa::Instructions,
labels: Vec<(Label, Vec<isa::Reloc>)>,
}
impl Sink {
fn with_instruction_capacity(capacity: usize) -> Sink {
Sink {
ins: Vec::with_capacity(capacity),
ins: isa::Instructions::with_capacity(capacity),
labels: Vec::new(),
}
}
fn cur_pc(&self) -> u32 {
self.ins.len() as u32
self.ins.current_pc()
}
fn pc_or_placeholder<F: FnOnce() -> Reloc>(&mut self, label: LabelId, reloc_creator: F) -> u32 {
fn pc_or_placeholder<F: FnOnce() -> isa::Reloc>(&mut self, label: LabelId, reloc_creator: F) -> u32 {
match self.labels[label.0] {
(Label::Resolved(dst_pc), _) => dst_pc,
(Label::NotResolved, ref mut unresolved) => {
@ -1692,7 +1674,7 @@ impl Sink {
drop_keep,
} = target;
let pc = self.cur_pc();
let dst_pc = self.pc_or_placeholder(label, || Reloc::Br { pc });
let dst_pc = self.pc_or_placeholder(label, || isa::Reloc::Br { pc });
self.ins.push(isa::Instruction::Br(isa::Target {
dst_pc,
drop_keep: drop_keep.into(),
@ -1705,7 +1687,7 @@ impl Sink {
drop_keep,
} = target;
let pc = self.cur_pc();
let dst_pc = self.pc_or_placeholder(label, || Reloc::Br { pc });
let dst_pc = self.pc_or_placeholder(label, || isa::Reloc::Br { pc });
self.ins.push(isa::Instruction::BrIfEqz(isa::Target {
dst_pc,
drop_keep: drop_keep.into(),
@ -1718,7 +1700,7 @@ impl Sink {
drop_keep,
} = target;
let pc = self.cur_pc();
let dst_pc = self.pc_or_placeholder(label, || Reloc::Br { pc });
let dst_pc = self.pc_or_placeholder(label, || isa::Reloc::Br { pc });
self.ins.push(isa::Instruction::BrIfNez(isa::Target {
dst_pc,
drop_keep: drop_keep.into(),
@ -1731,7 +1713,7 @@ impl Sink {
let pc = self.cur_pc();
let mut isa_targets = Vec::new();
for (idx, &Target { label, drop_keep }) in targets.iter().chain(iter::once(&default)).enumerate() {
let dst_pc = self.pc_or_placeholder(label, || Reloc::BrTable { pc, idx });
let dst_pc = self.pc_or_placeholder(label, || isa::Reloc::BrTable { pc, idx });
isa_targets.push(
isa::Target {
dst_pc,
@ -1768,26 +1750,15 @@ impl Sink {
// particular label.
let unresolved_rels = mem::replace(&mut self.labels[label.0].1, Vec::new());
for reloc in unresolved_rels {
match reloc {
Reloc::Br { pc } => match self.ins[pc as usize] {
isa::Instruction::Br(ref mut target)
| isa::Instruction::BrIfEqz(ref mut target)
| isa::Instruction::BrIfNez(ref mut target) => target.dst_pc = dst_pc,
_ => panic!("branch relocation points to a non-branch instruction"),
},
Reloc::BrTable { pc, idx } => match self.ins[pc as usize] {
isa::Instruction::BrTable(ref mut targets) => targets[idx].dst_pc = dst_pc,
_ => panic!("brtable relocation points to not brtable instruction"),
}
}
self.ins.patch_relocation(reloc, dst_pc);
}
// Mark this label as resolved.
self.labels[label.0] = (Label::Resolved(dst_pc), Vec::new());
}
/// Consume this Sink and returns isa::Instruction.
fn into_inner(self) -> Vec<isa::Instruction> {
/// Consume this Sink and returns isa::Instructions.
fn into_inner(self) -> isa::Instructions {
// At this moment all labels should be resolved.
assert!({
self.labels.iter().all(|(state, unresolved)|

82
src/validation/tests.rs
View File

@ -310,15 +310,29 @@ fn validate(wat: &str) -> ValidatedModule {
validated_module
}
fn compile(wat: &str) -> Vec<isa::Instruction> {
fn compile(wat: &str) -> (Vec<isa::Instruction>, Vec<u32>) {
let validated_module = validate(wat);
let code = &validated_module.code_map[0];
code.code.clone()
let mut instructions = Vec::new();
let mut pcs = Vec::new();
let mut iter = code.iterate_from(0);
loop {
let pc = iter.position();
if let Some(instruction) = iter.next() {
instructions.push(instruction.clone());
pcs.push(pc);
} else {
break
}
}
(instructions, pcs)
}
#[test]
fn implicit_return_no_value() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call")
)
@ -337,7 +351,7 @@ fn implicit_return_no_value() {
#[test]
fn implicit_return_with_value() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (result i32)
i32.const 0
@ -358,7 +372,7 @@ fn implicit_return_with_value() {
#[test]
fn implicit_return_param() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (param i32)
)
@ -377,7 +391,7 @@ fn implicit_return_param() {
#[test]
fn get_local() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (param i32) (result i32)
get_local 0
@ -398,7 +412,7 @@ fn get_local() {
#[test]
fn explicit_return() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (param i32) (result i32)
get_local 0
@ -424,7 +438,7 @@ fn explicit_return() {
#[test]
fn add_params() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (param i32) (param i32) (result i32)
get_local 0
@ -454,7 +468,7 @@ fn add_params() {
#[test]
fn drop_locals() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call") (param i32)
(local i32)
@ -478,7 +492,7 @@ fn drop_locals() {
#[test]
fn if_without_else() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call") (param i32) (result i32)
i32.const 1
@ -495,7 +509,7 @@ fn if_without_else() {
vec![
isa::Instruction::I32Const(1),
isa::Instruction::BrIfEqz(isa::Target {
dst_pc: 4,
dst_pc: pcs[4],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -517,7 +531,7 @@ fn if_without_else() {
#[test]
fn if_else() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
(local i32)
@ -537,7 +551,7 @@ fn if_else() {
vec![
isa::Instruction::I32Const(1),
isa::Instruction::BrIfEqz(isa::Target {
dst_pc: 5,
dst_pc: pcs[5],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -546,7 +560,7 @@ fn if_else() {
isa::Instruction::I32Const(2),
isa::Instruction::SetLocal(1),
isa::Instruction::Br(isa::Target {
dst_pc: 7,
dst_pc: pcs[7],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -564,7 +578,7 @@ fn if_else() {
#[test]
fn if_else_returns_result() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
i32.const 1
@ -582,7 +596,7 @@ fn if_else_returns_result() {
vec![
isa::Instruction::I32Const(1),
isa::Instruction::BrIfEqz(isa::Target {
dst_pc: 4,
dst_pc: pcs[4],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -590,7 +604,7 @@ fn if_else_returns_result() {
}),
isa::Instruction::I32Const(2),
isa::Instruction::Br(isa::Target {
dst_pc: 5,
dst_pc: pcs[5],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -608,7 +622,7 @@ fn if_else_returns_result() {
#[test]
fn if_else_branch_from_true_branch() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
i32.const 1
@ -630,7 +644,7 @@ fn if_else_branch_from_true_branch() {
vec![
isa::Instruction::I32Const(1),
isa::Instruction::BrIfEqz(isa::Target {
dst_pc: 8,
dst_pc: pcs[8],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -639,7 +653,7 @@ fn if_else_branch_from_true_branch() {
isa::Instruction::I32Const(1),
isa::Instruction::I32Const(1),
isa::Instruction::BrIfNez(isa::Target {
dst_pc: 9,
dst_pc: pcs[9],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::Single,
@ -648,7 +662,7 @@ fn if_else_branch_from_true_branch() {
isa::Instruction::Drop,
isa::Instruction::I32Const(2),
isa::Instruction::Br(isa::Target {
dst_pc: 9,
dst_pc: pcs[9],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -666,7 +680,7 @@ fn if_else_branch_from_true_branch() {
#[test]
fn if_else_branch_from_false_branch() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
i32.const 1
@ -688,7 +702,7 @@ fn if_else_branch_from_false_branch() {
vec![
isa::Instruction::I32Const(1),
isa::Instruction::BrIfEqz(isa::Target {
dst_pc: 4,
dst_pc: pcs[4],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -696,7 +710,7 @@ fn if_else_branch_from_false_branch() {
}),
isa::Instruction::I32Const(1),
isa::Instruction::Br(isa::Target {
dst_pc: 9,
dst_pc: pcs[9],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -705,7 +719,7 @@ fn if_else_branch_from_false_branch() {
isa::Instruction::I32Const(2),
isa::Instruction::I32Const(1),
isa::Instruction::BrIfNez(isa::Target {
dst_pc: 9,
dst_pc: pcs[9],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::Single,
@ -724,7 +738,7 @@ fn if_else_branch_from_false_branch() {
#[test]
fn loop_() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call")
loop (result i32)
@ -759,7 +773,7 @@ fn loop_() {
#[test]
fn loop_empty() {
let code = compile(r#"
let (code, _) = compile(r#"
(module
(func (export "call")
loop
@ -780,7 +794,7 @@ fn loop_empty() {
#[test]
fn brtable() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
block $1
@ -806,7 +820,7 @@ fn brtable() {
},
},
isa::Target {
dst_pc: 2,
dst_pc: pcs[2],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,
@ -824,7 +838,7 @@ fn brtable() {
#[test]
fn brtable_returns_result() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call")
block $1 (result i32)
@ -847,14 +861,14 @@ fn brtable_returns_result() {
isa::Instruction::BrTable(
vec![
isa::Target {
dst_pc: 3,
dst_pc: pcs[3],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::Single,
},
},
isa::Target {
dst_pc: 4,
dst_pc: pcs[4],
drop_keep: isa::DropKeep {
keep: isa::Keep::Single,
drop: 0,
@ -874,7 +888,7 @@ fn brtable_returns_result() {
#[test]
fn wabt_example() {
let code = compile(r#"
let (code, pcs) = compile(r#"
(module
(func (export "call") (param i32) (result i32)
block $exit
@ -893,7 +907,7 @@ fn wabt_example() {
vec![
isa::Instruction::GetLocal(1),
isa::Instruction::BrIfNez(isa::Target {
dst_pc: 4,
dst_pc: pcs[4],
drop_keep: isa::DropKeep {
drop: 0,
keep: isa::Keep::None,