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Don't allocate context if it's unused

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This commit is contained in:
Jef
2019-01-17 14:34:34 +01:00
parent e0f032a0e5
commit d06be92a4e
3 changed files with 80 additions and 20 deletions
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60
src/backend.rs
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@@ -1036,14 +1036,55 @@ impl Context<'_> {
cmp_i64!(i64_gt_s, setg, setnge, |a, b| a > b);
cmp_i64!(i64_ge_s, setge, setng, |a, b| a >= b);
// TODO: Should we do this logic in `eq` and just have this delegate to `eq`?
// That would mean that `eqz` and `eq` with a const 0 argument don't
// result in different code.
pub fn i32_eqz(&mut self) {
self.push(Value::Immediate(0));
self.i32_eq();
let val = self.pop();
if let Value::Immediate(i) = val {
self.push(Value::Immediate(if i == 0 { 1 } else { 0 }));
return;
}
let (reg, needs_release) = self.into_reg(val);
let out = self.block_state.regs.take_scratch_gpr();
dynasm!(self.asm
; xor Rd(out), Rd(out)
; test Rd(reg), Rd(reg)
; setz Rb(out)
);
if needs_release {
self.block_state.regs.release_scratch_gpr(reg);
}
self.push(Value::Temp(out));
}
pub fn i64_eqz(&mut self) {
self.push(Value::Immediate(0));
self.i64_eq();
let val = self.pop();
if let Value::Immediate(i) = val {
self.push(Value::Immediate(if i == 0 { 1 } else { 0 }));
return;
}
let (reg, needs_release) = self.into_reg(val);
let out = self.block_state.regs.take_scratch_gpr();
dynasm!(self.asm
; xor Rd(out), Rd(out)
; test Rq(reg), Rq(reg)
; setz Rb(out)
);
if needs_release {
self.block_state.regs.release_scratch_gpr(reg);
}
self.push(Value::Temp(out));
}
/// Pops i32 predicate and branches to the specified label
@@ -2133,7 +2174,8 @@ impl Context<'_> {
pub fn start_function(&mut self, arguments: u32, locals: u32) -> FunctionEnd {
// To support `vmctx`
let arguments = arguments + 1;
let (reg_args, locals_in_gprs) = ARGS_IN_GPRS.split_at((arguments as usize).min(ARGS_IN_GPRS.len()));
let (reg_args, locals_in_gprs) =
ARGS_IN_GPRS.split_at((arguments as usize).min(ARGS_IN_GPRS.len()));
let reg_locals = &locals_in_gprs[..(locals as usize).min(locals_in_gprs.len())];
// We need space to store the register arguments if we need to call a function
@@ -2144,8 +2186,12 @@ impl Context<'_> {
let aligned_stack_slots = (stack_slots + 1) & !1;
let frame_size: i32 = aligned_stack_slots as i32 * WORD_SIZE as i32;
self.block_state.locals.register_locals =
reg_args.iter().chain(reg_locals).cloned().map(ArgLoc::Register).collect();
self.block_state.locals.register_locals = reg_args
.iter()
.chain(reg_locals)
.cloned()
.map(ArgLoc::Register)
.collect();
self.block_state.locals.num_stack_args = arguments.saturating_sub(ARGS_IN_GPRS.len() as _);
self.block_state.locals.num_local_stack_slots = stack_slots;
self.block_state.return_register = Some(RAX);