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Simplify naming and add end block
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@HalidOdat
HalidOdat committed Dec 9, 2023
1 parent bc23182 commit 106accd
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Showing 2 changed files with 40 additions and 33 deletions.
23 changes: 8 additions & 15 deletions core/engine/src/optimizer/control_flow_graph/basic_block.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ bitflags! {
/// TODO: doc
#[derive(Default, Clone)]
pub struct BasicBlock {
pub(crate) predecessors: Vec<BasicBlockKey>,
pub(crate) previous: Vec<BasicBlockKey>,
pub(crate) instructions: Vec<Instruction>,
pub(crate) terminator: Terminator,
pub(crate) handler: Option<BasicBlockKey>,
Expand Down Expand Up @@ -54,23 +54,15 @@ impl BasicBlock {
self.flags.contains(BasicBlockFlags::REACHABLE)
}

pub(crate) fn successors(&self) -> Vec<BasicBlockKey> {
match self.terminator {
Terminator::None => vec![],
Terminator::JumpUnconditional { target, .. } => {
vec![target]
}
Terminator::JumpConditional { no, yes, .. }
| Terminator::TemplateLookup { no, yes, .. } => {
vec![no, yes]
}
Terminator::Return => Vec::new(),
}
pub(crate) fn next(&self) -> Vec<BasicBlockKey> {
let mut result = Vec::new();
self.next_into(&mut result);
result
}

pub(crate) fn next(&self, nexts: &mut Vec<BasicBlockKey>) {
pub(crate) fn next_into(&self, nexts: &mut Vec<BasicBlockKey>) {
match self.terminator {
Terminator::None | Terminator::Return => {}
Terminator::None => {}
Terminator::JumpUnconditional { target, .. } => {
nexts.push(target);
}
Expand All @@ -79,6 +71,7 @@ impl BasicBlock {
nexts.push(no);
nexts.push(yes);
}
Terminator::Return { end } => nexts.push(end),
}
}
}
50 changes: 32 additions & 18 deletions core/engine/src/optimizer/control_flow_graph/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ pub(crate) enum Terminator {
},

/// TODO: doc
Return,
Return { end: BasicBlockKey },
}

impl Terminator {
Expand Down Expand Up @@ -89,6 +89,7 @@ impl Terminator {
/// TODO: doc
pub struct ControlFlowGraph {
basic_block_start: BasicBlockKey,
basic_block_end: BasicBlockKey,
basic_blocks: SlotMap<BasicBlockKey, BasicBlock>,
}

Expand Down Expand Up @@ -122,19 +123,26 @@ impl Debug for ControlFlowGraph {
if basic_block.reachable() { "" } else { "not " }
)?;

if !basic_block.predecessors.is_empty() {
write!(f, " -- predecessors ")?;
for predecessor in &basic_block.predecessors {
if key == self.basic_block_start {
write!(f, " -- start")?;
}
if key == self.basic_block_end {
write!(f, " -- end")?;
}

if !basic_block.previous.is_empty() {
write!(f, " -- previous ")?;
for predecessor in &basic_block.previous {
let index = index_from_basic_block(*predecessor);
write!(f, "B{index}, ")?;
}
}

let successors = basic_block.successors();
if !successors.is_empty() {
write!(f, " -- successors ")?;
for successor in &successors {
let index = index_from_basic_block(*successor);
let next = basic_block.next();
if !next.is_empty() {
write!(f, " -- next ")?;
for bb in &next {
let index = index_from_basic_block(*bb);
write!(f, "B{index}, ")?;
}
}
Expand Down Expand Up @@ -171,8 +179,9 @@ impl Debug for ControlFlowGraph {
let target = index_from_basic_block(*yes);
write!(f, "TemplateLookup B{target}")?;
}
Terminator::Return => {
write!(f, "Return")?;
Terminator::Return { end } => {
let target = index_from_basic_block(*end);
write!(f, "Return B{target}")?;
}
}
writeln!(f)?;
Expand Down Expand Up @@ -271,6 +280,8 @@ impl ControlFlowGraph {
basic_block_keys[index]
};

let basic_block_end = basic_block_keys[leaders.len() - 1];

let mut iter = InstructionIterator::new(bytecode);
for (i, leader) in leaders
.iter()
Expand All @@ -296,12 +307,14 @@ impl ControlFlowGraph {
while let Some((_, _, instruction)) = iter.next() {
match instruction {
Instruction::Return => {
terminator = Terminator::Return;
terminator = Terminator::Return {
end: basic_block_end,
};
}
Instruction::Jump { address } | Instruction::Default { address } => {
let target = basic_block_from_bytecode_position(address);

basic_blocks[target].predecessors.push(key);
basic_blocks[target].previous.push(key);

terminator = Terminator::JumpUnconditional {
opcode: instruction.opcode(),
Expand All @@ -315,8 +328,8 @@ impl ControlFlowGraph {
let yes = basic_block_from_bytecode_position(address);
let no = basic_block_keys[i + 1];

basic_blocks[yes].predecessors.push(key);
basic_blocks[no].predecessors.push(key);
basic_blocks[yes].previous.push(key);
basic_blocks[no].previous.push(key);

terminator = Terminator::TemplateLookup { no, yes, site };
}
Expand All @@ -325,8 +338,8 @@ impl ControlFlowGraph {
let yes = basic_block_from_bytecode_position(address);
let no = basic_block_keys[i + 1];

basic_blocks[yes].predecessors.push(key);
basic_blocks[no].predecessors.push(key);
basic_blocks[yes].previous.push(key);
basic_blocks[no].previous.push(key);

terminator = Terminator::JumpConditional {
opcode: instruction.opcode(),
Expand All @@ -351,6 +364,7 @@ impl ControlFlowGraph {

Self {
basic_block_start: basic_block_keys[0],
basic_block_end,
basic_blocks,
}
}
Expand Down Expand Up @@ -520,7 +534,7 @@ impl GraphEliminateUnreachableBasicBlocks {
// "reachable basic blocks should not be eliminated"
// );

// basic_block.predecessors.clear();
// basic_block.previous.clear();
// basic_block.terminator = Terminator::None;

// changed |= true;
Expand Down

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