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Reworked stack computation

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This commit is contained in:
Dmitry Sinyavin
2022-08-04 21:47:32 +02:00
parent 5b2f75a066
commit 659d3bf12c
4 changed files with 111 additions and 75 deletions
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src/stack_limiter/mod.rs
+2 -31
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@@ -173,7 +173,7 @@ fn compute_stack_costs(module: &elements::Module) -> Result<Vec<u32>, &'static s
/// Stack cost of the given *defined* function is the sum of it's locals count (that is,
/// number of arguments plus number of local variables) and the maximal stack
/// height.
fn compute_stack_cost(func_idx: u32, module: &elements::Module) -> Result<u32, &'static str> {
pub fn compute_stack_cost(func_idx: u32, module: &elements::Module) -> Result<u32, &'static str> {
// To calculate the cost of a function we need to convert index from
// function index space to defined function spaces.
let func_imports = module.import_count(elements::ImportCountType::Function) as u32;
@@ -181,36 +181,7 @@ fn compute_stack_cost(func_idx: u32, module: &elements::Module) -> Result<u32, &
.checked_sub(func_imports)
.ok_or("This should be a index of a defined function")?;
let func_section = module.function_section().ok_or("No function section")?;
let code_section = module.code_section().ok_or("No code section")?;
let type_section = module.type_section().ok_or("No type section")?;
let func_sig_idx = func_section
.entries()
.get(func_idx as usize)
.ok_or("Function is not found in func section")?
.type_ref();
let Type::Function(func_signature) = type_section
.types()
.get(func_sig_idx as usize)
.ok_or("Function is not found in func section")?;
let body = &code_section
.bodies()
.get(defined_func_idx as usize)
.ok_or("Function body is out of bounds")?;
let mut locals_count: u32 = 0;
for local_group in body.locals() {
locals_count =
locals_count.checked_add(local_group.count()).ok_or("Overflow in local count")?;
}
locals_count = locals_count.checked_add(func_signature.params().len() as u32).ok_or("Overflow in parameter count")?;
let max_stack_height = max_height::compute(defined_func_idx, module)?;
locals_count
.checked_add(max_stack_height)
.ok_or("Overflow in adding locals_count and max_stack_height")
max_height::compute(defined_func_idx, module)
}
fn instrument_functions(