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remove unreachable cases

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This commit is contained in:
Folkert 2021-11-22 21:38:07 +01:00
parent f2f4f3bd72
commit 44fdf8df18
1 changed files with 14 additions and 54 deletions
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68
compiler/gen_wasm/src/storage.rs
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@ -269,63 +269,24 @@ impl<'a> Storage<'a> {
}
}
/// Return a value with the C calling convention. The difference with passing an argument is in
/// the StackMemory case, where we pass a pointer to write the result into.
fn return_symbol_ccc(&mut self, code_builder: &mut CodeBuilder, sym: Symbol) {
/// stack memory values are returned by pointer. e.g. a roc function
///
/// add : I128, I128 -> I128
///
/// is given the wasm type
///
/// add : (i32, i64, i64, i64, i64) -> nil
///
/// The returned value is written to the address passed as the first argument
fn load_return_address_ccc(&mut self, code_builder: &mut CodeBuilder, sym: Symbol) {
let storage = self.get(&sym).to_owned();
match storage {
StoredValue::VirtualMachineStack {
vm_state,
value_type,
size,
} => {
let next_local_id = self.get_next_local_id();
let maybe_next_vm_state = code_builder.load_symbol(sym, vm_state, next_local_id);
match maybe_next_vm_state {
// The act of loading the value changed the VM state, so update it
Some(next_vm_state) => {
self.symbol_storage_map.insert(
sym,
StoredValue::VirtualMachineStack {
vm_state: next_vm_state,
value_type,
size,
},
);
}
None => {
// Loading the value required creating a new local, because
// it was not in a convenient position in the VM stack.
self.local_types.push(value_type);
self.symbol_storage_map.insert(
sym,
StoredValue::Local {
local_id: next_local_id,
value_type,
size,
},
);
}
}
StoredValue::VirtualMachineStack { .. } | StoredValue::Local { .. } => {
unreachable!("these storage types are not returned by writing to a pointer")
}
StoredValue::Local { local_id, .. } => {
code_builder.get_local(local_id);
code_builder.set_top_symbol(sym);
}
StoredValue::StackMemory { location, .. } => {
let (local_id, offset) = location.local_and_offset(self.stack_frame_pointer);
// stack memory values are returned by pointer. e.g. a roc function
//
// add : I128, I128 -> I128
//
// is given the wasm type
//
// add : (i32, i64, i64, i64, i64) -> nil
//
// The returned value is written to the address passed as the first argument
code_builder.get_local(local_id);
if offset != 0 {
code_builder.i32_const(offset as i32);
@ -368,9 +329,8 @@ impl<'a> Storage<'a> {
if return_layout.is_stack_memory() {
// Load the address where the return value should be written
// Apparently for return values we still use a pointer to stack memory
self.return_symbol_ccc(code_builder, return_symbol);
};
self.load_return_address_ccc(code_builder, return_symbol);
}
for sym in symbols {
if let StoredValue::StackMemory {