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Improve efficiency of resetting stack pointer

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This commit is contained in:
Jef
2019-03-27 12:57:49 +01:00
parent 652e2fdeec
commit 79f26328d4
3 changed files with 25 additions and 69 deletions
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10
README.md
View File

@@ -142,15 +142,13 @@ fib:
push rax
push rax
mov rsi, rcx
call fib
add eax, dword ptr [rsp + 8]
mov rcx, qword ptr [rsp + 0x10]
call 0
add eax, [rsp + 8]
mov rcx, [rsp + 0x10]
add ecx, 0xfffffffe
cmp ecx, 1
mov rsi, rcx
pop rcx
pop rcx
pop rcx
lea rsp, [rsp + 0x18]
ja .Lloop
.Lreturn:
ret

56
src/backend.rs
View File

@@ -2262,7 +2262,10 @@ impl<'this, M: ModuleContext> Context<'this, M> {
self.free_value(selector);
}
fn set_stack_depth_preserve_flags(&mut self, depth: StackDepth) {
fn set_stack_depth(&mut self, depth: StackDepth) {
if self.block_state.depth.0 != depth.0 {
let diff = depth.0 as i32 - self.block_state.depth.0 as i32;
if diff.abs() == 1 {
if self.block_state.depth.0 < depth.0 {
for _ in 0..depth.0 - self.block_state.depth.0 {
dynasm!(self.asm
@@ -2278,24 +2281,15 @@ impl<'this, M: ModuleContext> Context<'this, M> {
}
self.block_state.regs.release(trash);
}
self.block_state.depth = depth;
}
fn set_stack_depth(&mut self, depth: StackDepth) {
if self.block_state.depth.0 != depth.0 {
let diff = depth.0 as i32 - self.block_state.depth.0 as i32;
if diff.abs() == 1 {
self.set_stack_depth_preserve_flags(depth);
} else {
dynasm!(self.asm
; add rsp, (self.block_state.depth.0 as i32 - depth.0 as i32) * WORD_SIZE as i32
; lea rsp, [rsp + (self.block_state.depth.0 as i32 - depth.0 as i32) * WORD_SIZE as i32]
);
}
self.block_state.depth = depth;
}
}
}
fn do_pass_block_args(&mut self, cc: &BlockCallingConvention) {
let args = &cc.arguments;
@@ -2325,43 +2319,6 @@ impl<'this, M: ModuleContext> Context<'this, M> {
self.set_stack_depth(cc.stack_depth);
}
pub fn pass_block_args_preserve_flags(&mut self, cc: &BlockCallingConvention) {
self.do_pass_block_args(cc);
self.set_stack_depth_preserve_flags(cc.stack_depth);
}
pub fn serialize_block_args_preserve_flags(
&mut self,
cc: &BlockCallingConvention,
other_to_drop: Option<RangeInclusive<u32>>,
) -> BlockCallingConvention {
self.do_pass_block_args(cc);
let mut out_args = cc.arguments.clone();
out_args.reverse();
if let Some(to_drop) = other_to_drop {
for _ in to_drop {
let val = self.pop();
// TODO: We can use stack slots for values already on the stack but we
// don't refcount stack slots right now
let loc = CCLoc::Reg(self.into_temp_reg(None, val));
out_args.push(loc);
}
}
out_args.reverse();
self.set_stack_depth_preserve_flags(cc.stack_depth);
BlockCallingConvention {
stack_depth: cc.stack_depth,
arguments: out_args,
}
}
pub fn serialize_block_args(
&mut self,
cc: &BlockCallingConvention,
@@ -5054,3 +5011,4 @@ impl IntoLabel for (LabelValue, LabelValue) {
Box::new(const_values(self.0, self.1))
}
}

2
src/function_body.rs
View File

@@ -314,7 +314,7 @@ where
((Some(Left(ref cc)), to_drop), ref mut other @ (None, _))
| (ref mut other @ (None, _), (Some(Left(ref cc)), to_drop)) => {
let mut cc =
ctx.serialize_block_args_preserve_flags(cc, to_drop.clone());
ctx.serialize_block_args(cc, to_drop.clone());
if let Some(to_drop) = other.1 {
drop_elements(&mut cc.arguments, to_drop.clone());
}