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Add const folding, fix returning values from blocks

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This commit is contained in:
Jef
2018-12-14 16:20:28 +01:00
parent 17ecd049a1
commit b832832c76
3 changed files with 200 additions and 126 deletions
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258
src/backend.rs
View File

@@ -118,6 +118,8 @@ enum ValueLocation {
/// first local, and so will have to be adjusted with `adjusted_offset`
/// before reading (as RSP may have been changed by `push`/`pop`).
Stack(i32),
/// Value is a literal (TODO: Support more than just `i32`)
Immediate(i32),
}
// TODO: This assumes only system-v calling convention.
@@ -207,13 +209,22 @@ impl TranslatedCodeSection {
enum Value {
Local(u32),
Temp(GPR),
Immediate(i32),
}
impl Value {
fn immediate(&self) -> Option<i32> {
match *self {
Value::Immediate(i) => Some(i),
_ => None,
}
}
fn location(&self, locals: &Locals) -> ValueLocation {
match *self {
Value::Local(loc) => local_location(locals, loc),
Value::Temp(reg) => ValueLocation::Reg(reg),
Value::Immediate(reg) => ValueLocation::Immediate(reg),
}
}
}
@@ -222,6 +233,7 @@ impl Value {
enum StackValue {
Local(u32),
Temp(GPR),
Immediate(i32),
Pop,
}
@@ -229,6 +241,7 @@ impl StackValue {
fn location(&self, locals: &Locals) -> Option<ValueLocation> {
match *self {
StackValue::Local(loc) => Some(local_location(locals, loc)),
StackValue::Immediate(i) => Some(ValueLocation::Immediate(i)),
StackValue::Temp(reg) => Some(ValueLocation::Reg(reg)),
StackValue::Pop => None,
}
@@ -244,7 +257,7 @@ struct Locals {
#[derive(Default, Clone)]
pub struct BlockState {
stack: Stack,
depth: StackDepth,
pub depth: StackDepth,
regs: Registers,
}
@@ -309,6 +322,37 @@ pub fn current_block_state(ctx: &Context) -> BlockState {
ctx.block_state.clone()
}
pub fn return_from_block(ctx: &mut Context, new_depth: StackDepth) {
let diff = ((ctx.block_state.depth.0 - new_depth.0) * WORD_SIZE) as i32;
if let Some(loc) = ctx.block_state.stack.last().unwrap().location(&ctx.locals) {
match loc {
ValueLocation::Reg(r) => {
dynasm!(ctx.asm
; push Rq(r)
);
}
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; push QWORD [rsp + offset]
);
}
ValueLocation::Immediate(imm) => {
dynasm!(ctx.asm
; push imm
);
}
}
}
// If `location` is `None` then we don't need to do anything.
}
pub fn push_block_return_value(ctx: &mut Context) {
ctx.block_state.depth.reserve(1);
ctx.block_state.stack.push(StackValue::Pop);
}
pub fn restore_block_state(ctx: &mut Context, block_state: BlockState) {
ctx.block_state = block_state;
}
@@ -320,6 +364,7 @@ pub fn push_return_value(ctx: &mut Context) {
fn push_i32(ctx: &mut Context, value: Value) {
let stack_loc = match value {
Value::Local(loc) => StackValue::Local(loc),
Value::Immediate(i) => StackValue::Immediate(i),
Value::Temp(gpr) => {
if ctx.block_state.regs.free_scratch() >= 1 {
StackValue::Temp(gpr)
@@ -340,6 +385,7 @@ fn push_i32(ctx: &mut Context, value: Value) {
fn pop_i32(ctx: &mut Context) -> Value {
match ctx.block_state.stack.pop().expect("Stack is empty") {
StackValue::Local(loc) => Value::Local(loc),
StackValue::Immediate(i) => Value::Immediate(i),
StackValue::Temp(reg) => Value::Temp(reg),
StackValue::Pop => {
ctx.block_state.depth.free(1);
@@ -362,7 +408,7 @@ fn pop_i32_into(ctx: &mut Context, dst: ValueLocation) {
fn free_val(ctx: &mut Context, val: Value) {
match val {
Value::Temp(reg) => ctx.block_state.regs.release_scratch_gpr(reg),
Value::Local(_) => {}
Value::Local(_) | Value::Immediate(_) => {}
}
}
@@ -377,6 +423,13 @@ fn into_reg(ctx: &mut Context, val: Value) -> GPR {
);
scratch
}
ValueLocation::Immediate(i) => {
let scratch = ctx.block_state.regs.take_scratch_gpr();
dynasm!(ctx.asm
; mov Rq(scratch), i
);
scratch
}
ValueLocation::Reg(reg) => reg,
}
}
@@ -400,7 +453,19 @@ fn into_temp_reg(ctx: &mut Context, val: Value) -> GPR {
; mov Rq(scratch), Rq(reg)
);
}
ValueLocation::Immediate(_) => {
panic!("We shouldn't be storing immediates in locals for now")
}
}
scratch
}
Value::Immediate(i) => {
let scratch = ctx.block_state.regs.take_scratch_gpr();
dynasm!(ctx.asm
; mov Rq(scratch), i
);
scratch
}
@@ -408,34 +473,68 @@ fn into_temp_reg(ctx: &mut Context, val: Value) -> GPR {
}
}
// TODO: For the commutative instructions we can do operands in either
// order, so we can choose the operand order that creates the
// least unnecessary temps.
pub fn i32_add(ctx: &mut Context) {
macro_rules! commutative_binop {
($name:ident, $instr:ident, $const_fallback:expr) => {
pub fn $name(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
let op1 = pop_i32(ctx);
if let Some(i1) = op1.immediate() {
if let Some(i0) = op0.immediate() {
ctx.block_state.stack.push(StackValue::Immediate($const_fallback(i1, i0)));
return;
}
}
let (op1, op0) = match op1 {
Value::Temp(reg) => (reg, op0),
_ => (into_temp_reg(ctx, op0), op1),
};
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
; add Rd(op1), Rd(reg)
; $instr Rd(op1), Rd(reg)
);
}
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; add Rd(op1), [rsp + offset]
; $instr Rd(op1), [rsp + offset]
);
}
ValueLocation::Immediate(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; $instr Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
}
}
commutative_binop!(i32_add, add, |a, b| a + b);
commutative_binop!(i32_and, and, |a, b| a & b);
commutative_binop!(i32_or, or, |a, b| a | b);
commutative_binop!(i32_xor, xor, |a, b| a ^ b);
commutative_binop!(i32_mul, imul, |a, b| a * b);
pub fn i32_sub(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
let op1 = pop_i32(ctx);
if let Some(i1) = op1.immediate() {
if let Some(i0) = op0.immediate() {
ctx.block_state.stack.push(StackValue::Immediate(i1 - i0));
return;
}
}
let op1 = into_temp_reg(ctx, op1);
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
@@ -448,91 +547,14 @@ pub fn i32_sub(ctx: &mut Context) {
; sub Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
pub fn i32_and(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
; and Rd(op1), Rd(reg)
);
}
ValueLocation::Stack(offset) => {
ValueLocation::Immediate(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; and Rd(op1), [rsp + offset]
; sub Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
pub fn i32_or(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
; or Rd(op1), Rd(reg)
);
}
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; or Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
pub fn i32_xor(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
; xor Rd(op1), Rd(reg)
);
}
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; xor Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
pub fn i32_mul(ctx: &mut Context) {
let op0 = pop_i32(ctx);
let tmp = pop_i32(ctx);
let op1 = into_temp_reg(ctx, tmp);
match op0.location(&ctx.locals) {
ValueLocation::Reg(reg) => {
dynasm!(ctx.asm
; imul Rd(op1), Rd(reg)
);
}
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; imul Rd(op1), [rsp + offset]
);
}
}
ctx.block_state.stack.push(StackValue::Temp(op1));
free_val(ctx, op0);
}
@@ -551,19 +573,40 @@ pub fn set_local_i32(ctx: &mut Context, local_idx: u32) {
free_val(ctx, val);
}
// TODO: Don't store literals at all, roll them into `Value`
pub fn literal_i32(ctx: &mut Context, imm: i32) {
let gpr = ctx.block_state.regs.take_scratch_gpr();
dynasm!(ctx.asm
; mov Rd(gpr), imm
);
push_i32(ctx, Value::Temp(gpr));
push_i32(ctx, Value::Immediate(imm));
}
pub fn relop_eq_i32(ctx: &mut Context) {
let right = pop_i32(ctx);
let left = pop_i32(ctx);
let result = ctx.block_state.regs.take_scratch_gpr();
if let Some(i) = left.immediate() {
match right.location(&ctx.locals) {
ValueLocation::Stack(offset) => {
let offset = adjusted_offset(ctx, offset);
dynasm!(ctx.asm
; xor Rq(result), Rq(result)
; cmp DWORD [rsp + offset], i
; sete Rb(result)
);
}
ValueLocation::Reg(rreg) => {
dynasm!(ctx.asm
; xor Rq(result), Rq(result)
; cmp Rd(rreg), i
; sete Rb(result)
);
}
ValueLocation::Immediate(right) => {
let is_equal = if i == right { 1i8 } else { 0 };
dynasm!(ctx.asm
; mov Rb(result), is_equal
);
}
}
} else {
let lreg = into_reg(ctx, left);
match right.location(&ctx.locals) {
ValueLocation::Stack(offset) => {
@@ -581,7 +624,16 @@ pub fn relop_eq_i32(ctx: &mut Context) {
; sete Rb(result)
);
}
ValueLocation::Immediate(i) => {
dynasm!(ctx.asm
; xor Rq(result), Rq(result)
; cmp Rd(lreg), i
; sete Rb(result)
);
}
}
}
push_i32(ctx, Value::Temp(result));
free_val(ctx, left);
free_val(ctx, right);
@@ -630,6 +682,12 @@ fn copy_value(ctx: &mut Context, src: ValueLocation, dst: ValueLocation) {
; mov [rsp + out_offset], Rq(in_reg)
);
}
(ValueLocation::Immediate(i), ValueLocation::Stack(out_offset)) => {
let out_offset = adjusted_offset(ctx, out_offset);
dynasm!(ctx.asm
; mov DWORD [rsp + out_offset], i
);
}
(ValueLocation::Stack(in_offset), ValueLocation::Reg(out_reg)) => {
let in_offset = adjusted_offset(ctx, in_offset);
dynasm!(ctx.asm
@@ -643,6 +701,12 @@ fn copy_value(ctx: &mut Context, src: ValueLocation, dst: ValueLocation) {
);
}
}
(ValueLocation::Immediate(i), ValueLocation::Reg(out_reg)) => {
dynasm!(ctx.asm
; mov Rq(out_reg), i
);
}
(_, ValueLocation::Immediate(_)) => panic!("Tried to copy to an immediate value!"),
}
}

11
src/function_body.rs
View File

@@ -147,6 +147,10 @@ pub fn translate(
block_state,
..
}) => {
if ty != Type::EmptyBlockType {
return_from_block(&mut ctx, block_state.depth);
}
// Finalize if..else block by jumping to the `end_label`.
br(&mut ctx, end_label);
@@ -174,6 +178,10 @@ pub fn translate(
Operator::End => {
let control_frame = control_frames.pop().expect("control stack is never empty");
if control_frame.ty != Type::EmptyBlockType && !control_frames.is_empty() {
return_from_block(&mut ctx, control_frame.block_state.depth);
}
if !control_frame.kind.is_loop() {
// Branches to a control frame with block type directs control flow to the header of the loop
// and we don't need to resolve it here. Branching to other control frames always lead
@@ -191,7 +199,8 @@ pub fn translate(
prepare_return_value(&mut ctx);
}
// restore_block_state(&mut ctx, control_frame.block_state);
restore_block_state(&mut ctx, control_frame.block_state);
push_block_return_value(&mut ctx);
}
Operator::I32Eq => relop_eq_i32(&mut ctx),
Operator::I32Add => i32_add(&mut ctx),

3
src/tests.rs
View File

@@ -259,7 +259,8 @@ fn function_write_args_spill_to_stack() {
assert_eq!(
{
let translated = translate_wat(code);
let out: u32 = unsafe { translated.execute_func(0, (11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)) };
let out: u32 =
unsafe { translated.execute_func(0, (11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)) };
out
},
11