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Avoid calling Vec::split_off, avoiding more heap allocations.

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This commit is contained in:
Dan Gohman
2017-09-05 09:15:29 -07:00
parent 9ea40ad44a
commit ef3ea72422
2 changed files with 54 additions and 35 deletions
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84
lib/wasm/src/code_translator.rs
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@@ -153,8 +153,8 @@ pub fn translate_function_body(
// explicitely in Cretonne IL.
if !builder.is_filled() && (!builder.is_unreachable() || !builder.is_pristine()) {
let cut_index = state.stack.len() - sig.return_types.len();
let return_vals = state.stack.split_off(cut_index);
builder.ins().return_(&return_vals);
builder.ins().return_(&state.stack[cut_index..]);
state.stack.truncate(cut_index);
}
// Because the function has an implicit block as body, we need to explicitely close it.
let frame = state.control_stack.pop().unwrap();
@@ -167,8 +167,8 @@ pub fn translate_function_body(
builder.ebb_args(frame.following_code()),
);
let cut_index = state.stack.len() - sig.return_types.len();
let return_vals = state.stack.split_off(cut_index);
builder.ins().return_(&return_vals);
builder.ins().return_(&state.stack[cut_index..]);
state.stack.truncate(cut_index);
}
}
Ok((func, func_imports))
@@ -288,8 +288,8 @@ fn translate_operator(
_ => panic!("should not happen"),
};
let cut_index = state.stack.len() - return_values.len();
let jump_args = state.stack.split_off(cut_index);
builder.ins().jump(destination, &jump_args);
builder.ins().jump(destination, &state.stack[cut_index..]);
state.stack.truncate(cut_index);
// We change the target of the branch instruction
let else_ebb = builder.create_ebb();
builder.change_jump_destination(branch_inst, else_ebb);
@@ -300,8 +300,11 @@ fn translate_operator(
let frame = state.control_stack.pop().unwrap();
if !builder.is_unreachable() || !builder.is_pristine() {
let cut_index = state.stack.len() - frame.return_values().len();
let jump_args = state.stack.split_off(cut_index);
builder.ins().jump(frame.following_code(), &jump_args);
builder.ins().jump(
frame.following_code(),
&state.stack[cut_index..],
);
state.stack.truncate(cut_index);
}
builder.switch_to_block(frame.following_code(), frame.return_values());
builder.seal_block(frame.following_code());
@@ -339,13 +342,17 @@ fn translate_operator(
Operator::Br { relative_depth } => {
let i = state.control_stack.len() - 1 - (relative_depth as usize);
let frame = &mut state.control_stack[i];
let jump_args = if frame.is_loop() {
Vec::new()
} else {
let cut_index = state.stack.len() - frame.return_values().len();
state.stack.split_off(cut_index)
};
builder.ins().jump(frame.br_destination(), &jump_args);
let cut_index = state.stack.len() -
if frame.is_loop() {
0
} else {
frame.return_values().len()
};
builder.ins().jump(
frame.br_destination(),
&state.stack[cut_index..],
);
state.stack.truncate(cut_index);
// We signal that all the code that follows until the next End is unreachable
frame.set_reachable();
state.real_unreachable_stack_depth = 1 + relative_depth as usize;
@@ -354,17 +361,20 @@ fn translate_operator(
let val = state.pop1();
let i = state.control_stack.len() - 1 - (relative_depth as usize);
let frame = &mut state.control_stack[i];
let jump_args = if frame.is_loop() {
Vec::new()
} else {
let cut_index = state.stack.len() - frame.return_values().len();
state.stack.split_off(cut_index)
};
builder.ins().brnz(val, frame.br_destination(), &jump_args);
let cut_index = state.stack.len() -
if frame.is_loop() {
0
} else {
frame.return_values().len()
};
builder.ins().brnz(
val,
frame.br_destination(),
&state.stack[cut_index..],
);
// The values returned by the branch are still available for the reachable
// code that comes after it
frame.set_reachable();
state.stack.extend(jump_args);
}
Operator::BrTable { ref table } => {
let (depths, default) = table.read_table();
@@ -406,7 +416,6 @@ fn translate_operator(
// We then proceed to split the edges going out of the br_table
let val = state.pop1();
let cut_index = state.stack.len() - jump_args_count;
let jump_args = state.stack.split_off(cut_index);
let jt = builder.create_jump_table();
let dest_ebbs: HashMap<usize, Ebb> =
depths.iter().enumerate().fold(HashMap::new(), |mut acc,
@@ -425,25 +434,25 @@ fn translate_operator(
let default_ebb = state.control_stack[state.control_stack.len() - 1 -
(default as usize)]
.br_destination();
builder.ins().jump(default_ebb, &jump_args);
state.stack.extend_from_slice(&jump_args);
builder.ins().jump(default_ebb, &state.stack[cut_index..]);
for (depth, dest_ebb) in dest_ebbs {
builder.switch_to_block(dest_ebb, &[]);
builder.seal_block(dest_ebb);
let i = state.control_stack.len() - 1 - depth;
let frame = &mut state.control_stack[i];
let real_dest_ebb = frame.br_destination();
builder.ins().jump(real_dest_ebb, &jump_args);
builder.ins().jump(real_dest_ebb, &state.stack[cut_index..]);
frame.set_reachable();
}
state.stack.truncate(cut_index);
state.real_unreachable_stack_depth = 1 + min_depth as usize;
}
}
Operator::Return => {
let return_count = sig.return_types.len();
let cut_index = state.stack.len() - return_count;
let return_args = state.stack.split_off(cut_index);
builder.ins().return_(&return_args);
builder.ins().return_(&state.stack[cut_index..]);
state.stack.truncate(cut_index);
state.real_unreachable_stack_depth = 1;
}
/************************************ Calls ****************************************
@@ -454,7 +463,6 @@ fn translate_operator(
Operator::Call { function_index } => {
let args_num = args_count(function_index as usize, functions, signatures);
let cut_index = state.stack.len() - args_num;
let call_args = state.stack.split_off(cut_index);
let internal_function_index = find_function_import(
function_index as usize,
builder,
@@ -463,7 +471,11 @@ fn translate_operator(
exports,
signatures,
);
let call_inst = builder.ins().call(internal_function_index, &call_args);
let call_inst = builder.ins().call(
internal_function_index,
&state.stack[cut_index..],
);
state.stack.truncate(cut_index);
let ret_values = builder.inst_results(call_inst);
for val in ret_values {
state.push1(*val);
@@ -480,9 +492,13 @@ fn translate_operator(
let args_num = builder.signature(sigref).unwrap().argument_types.len();
let index_val = state.pop1();
let cut_index = state.stack.len() - args_num;
let call_args = state.stack.split_off(cut_index);
let ret_values =
runtime.translate_call_indirect(builder, sigref, index_val, &call_args);
let ret_values = runtime.translate_call_indirect(
builder,
sigref,
index_val,
&state.stack[cut_index..],
);
state.stack.truncate(cut_index);
for val in ret_values {
state.push1(*val);
}