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Improved instance & module data pointers location

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This commit is contained in:
Syrus Akbary
2018-11-14 11:05:57 -08:00
parent 278dff0fa6
commit 6bfd7d9081
2 changed files with 16 additions and 10 deletions
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8
src/webassembly/instance.rs
View File

@ -78,7 +78,11 @@ fn get_function_addr(
/// An Instance of a WebAssembly module
#[derive(Debug)]
#[repr(C)]
pub struct Instance {
// C-like pointers to data (heaps, globals, tables)
pub data_pointers: DataPointers,
/// WebAssembly table data
// pub tables: Arc<Vec<RwLock<Vec<usize>>>>,
pub tables: Arc<Vec<Vec<usize>>>,
@ -101,9 +105,6 @@ pub struct Instance {
// Region start memory location
// code_base: *const (),
// C-like pointers to data (heaps, globals, tables)
pub data_pointers: DataPointers,
// Default memory bound
// TODO: Support for only one LinearMemory for now.
pub default_memory_bound: i32,
@ -112,6 +113,7 @@ pub struct Instance {
/// Contains pointers to data (heaps, globals, tables) needed
/// by Cranelift.
#[derive(Debug)]
#[repr(C)]
pub struct DataPointers {
// Pointer to tables
pub tables: UncheckedSlice<BoundedSlice<usize>>,

18
src/webassembly/module.rs
View File

@ -332,12 +332,12 @@ impl<'environment> FuncEnvironmentTrait for FuncEnvironment<'environment> {
let vmctx = func.create_global_value(ir::GlobalValueData::VMContext);
let ptr_size = self.ptr_size();
// Given a vmctx, we want to retrieve vmctx.tables
// Create a table whose base address is stored at `vmctx+88`.
// 88 is the offset of the vmctx.tables pointer respect to vmctx pointer
// Given a instance, we want to retrieve instance.tables
// Create a table whose base address is stored at `instance+0`.
// 0 is the offset of the vmctx.tables pointer respect to vmctx pointer
let base = func.create_global_value(ir::GlobalValueData::Load {
base: vmctx,
offset: Offset32::new(88),
offset: Offset32::new(0),
global_type: self.pointer_type(),
});
@ -369,12 +369,12 @@ impl<'environment> FuncEnvironmentTrait for FuncEnvironment<'environment> {
}
fn make_heap(&mut self, func: &mut ir::Function, index: MemoryIndex) -> ir::Heap {
// Create a static heap whose base address is stored at `vmctx+96`.
// Create a static heap whose base address is stored at `instance+8`.
let vmctx = func.create_global_value(ir::GlobalValueData::VMContext);
let heap_base_addr = func.create_global_value(ir::GlobalValueData::Load {
base: vmctx,
offset: Offset32::new(96),
offset: Offset32::new(8),
global_type: self.pointer_type(),
});
@ -454,7 +454,7 @@ impl<'environment> FuncEnvironmentTrait for FuncEnvironment<'environment> {
let globals_base_addr = func.create_global_value(ir::GlobalValueData::Load {
base: vmctx,
offset: Offset32::new(104),
offset: Offset32::new(16),
global_type: self.pointer_type(),
});
@ -506,6 +506,7 @@ impl<'environment> FuncEnvironmentTrait for FuncEnvironment<'environment> {
.special_param(ir::ArgumentPurpose::VMContext)
.expect("Missing vmctx parameter");
// The `callee` value is an index into a table of function pointers.
// Apparently, that table is stored at absolute address 0 in this dummy environment.
// TODO: Generate bounds checking code.
@ -556,6 +557,9 @@ impl<'environment> FuncEnvironmentTrait for FuncEnvironment<'environment> {
.special_param(ir::ArgumentPurpose::VMContext)
.expect("Missing vmctx parameter");
// println!("POINTER BYTES {}", self.pointer_bytes());
// println!("POINTER SIZE {}", self.ptr_size());
// Build a value list for the call instruction containing the call_args and the vmctx
// parameter.
let mut args = ir::ValueList::default();