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Remove the last_inst_return field.

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It's not necessary to explicitly track whether the last instruction is a
return; if the builder for the last block isn't filled by the time we reach
the end, it needs a return to fill it.
This commit is contained in:
Dan Gohman
2017-08-29 04:40:48 -07:00
parent ea1d053831
commit 4afa5df3b6
1 changed files with 1 additions and 9 deletions
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10
lib/wasm/src/code_translator.rs
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@@ -126,11 +126,9 @@ impl ControlStackFrame {
/// Contains information passed along during the translation and that records: /// Contains information passed along during the translation and that records:
/// ///
/// - if the last instruction added was a `return`;
/// - the depth of the two unreachable control blocks stacks, that are manipulated when translating /// - the depth of the two unreachable control blocks stacks, that are manipulated when translating
/// unreachable code; /// unreachable code;
struct TranslationState { struct TranslationState {
last_inst_return: bool,
phantom_unreachable_stack_depth: usize, phantom_unreachable_stack_depth: usize,
real_unreachable_stack_depth: usize, real_unreachable_stack_depth: usize,
} }
@@ -216,7 +214,6 @@ pub fn translate_function_body(parser: &mut Parser,
} }
} }
let mut state = TranslationState { let mut state = TranslationState {
last_inst_return: false,
phantom_unreachable_stack_depth: 0, phantom_unreachable_stack_depth: 0,
real_unreachable_stack_depth: 0, real_unreachable_stack_depth: 0,
}; };
@@ -265,8 +262,7 @@ pub fn translate_function_body(parser: &mut Parser,
} }
// In WebAssembly, the final return instruction is implicit so we need to build it // In WebAssembly, the final return instruction is implicit so we need to build it
// explicitely in Cretonne IL. // explicitely in Cretonne IL.
if !state.last_inst_return && !builder.is_filled() && if !builder.is_filled() && (!builder.is_unreachable() || !builder.is_pristine()) {
(!builder.is_unreachable() || !builder.is_pristine()) {
let cut_index = stack.len() - sig.return_types.len(); let cut_index = stack.len() - sig.return_types.len();
let return_vals = stack.split_off(cut_index); let return_vals = stack.split_off(cut_index);
builder.ins().return_(return_vals.as_slice()); builder.ins().return_(return_vals.as_slice());
@@ -300,7 +296,6 @@ fn translate_operator(op: &Operator,
signatures: &Vec<Signature>, signatures: &Vec<Signature>,
exports: &Option<HashMap<FunctionIndex, String>>, exports: &Option<HashMap<FunctionIndex, String>>,
func_imports: &mut FunctionImports) { func_imports: &mut FunctionImports) {
state.last_inst_return = false;
// This big match treats all Wasm code operators. // This big match treats all Wasm code operators.
match *op { match *op {
/********************************** Locals **************************************** /********************************** Locals ****************************************
@@ -600,7 +595,6 @@ fn translate_operator(op: &Operator,
let cut_index = stack.len() - return_count; let cut_index = stack.len() - return_count;
let return_args = stack.split_off(cut_index); let return_args = stack.split_off(cut_index);
builder.ins().return_(return_args.as_slice()); builder.ins().return_(return_args.as_slice());
state.last_inst_return = true;
state.real_unreachable_stack_depth = 1; state.real_unreachable_stack_depth = 1;
} }
/************************************ Calls **************************************** /************************************ Calls ****************************************
@@ -1265,7 +1259,6 @@ fn translate_unreachable_operator(op: &Operator,
stack.extend_from_slice(builder.ebb_args(frame.following_code())); stack.extend_from_slice(builder.ebb_args(frame.following_code()));
} }
state.real_unreachable_stack_depth -= 1; state.real_unreachable_stack_depth -= 1;
state.last_inst_return = false;
} }
} }
Operator::Else => { Operator::Else => {
@@ -1292,7 +1285,6 @@ fn translate_unreachable_operator(op: &Operator,
// by unreachable code that hasn't been translated // by unreachable code that hasn't been translated
stack.truncate(original_stack_size); stack.truncate(original_stack_size);
state.real_unreachable_stack_depth = 0; state.real_unreachable_stack_depth = 0;
state.last_inst_return = false;
} }
} }
_ => { _ => {