reorder liveness to bring the more significant code up top
This commit is contained in:
Niko Matsakis
parent
899c7ad9b2
commit
cb56ff5a77
1 changed files with 107 additions and 107 deletions
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@ -47,6 +47,113 @@ use std::io::{self, Write};
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pub type LocalSet = IdxSetBuf<Local>;
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// This gives the result of the liveness analysis at the boundary of basic blocks
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pub struct LivenessResult {
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pub ins: IndexVec<BasicBlock, LocalSet>,
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pub outs: IndexVec<BasicBlock, LocalSet>,
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}
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pub fn liveness_of_locals<'tcx>(mir: &Mir<'tcx>) -> LivenessResult {
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let locals = mir.local_decls.len();
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let def_use: IndexVec<_, _> = mir.basic_blocks().iter().map(|b| {
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block(b, locals)
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}).collect();
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let mut ins: IndexVec<_, _> = mir.basic_blocks()
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.indices()
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.map(|_| LocalSet::new_empty(locals))
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.collect();
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let mut outs = ins.clone();
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let mut changed = true;
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let mut bits = LocalSet::new_empty(locals);
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while changed {
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changed = false;
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for b in mir.basic_blocks().indices().rev() {
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// outs[b] = ∪ {ins of successors}
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bits.clear();
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for &successor in mir.basic_blocks()[b].terminator().successors().into_iter() {
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bits.union(&ins[successor]);
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}
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outs[b].clone_from(&bits);
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// bits = use ∪ (bits - def)
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def_use[b].apply(&mut bits);
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// update bits on entry and flag if they have changed
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if ins[b] != bits {
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ins[b].clone_from(&bits);
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changed = true;
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}
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}
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}
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LivenessResult {
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ins,
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outs,
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}
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}
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impl LivenessResult {
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/// Walks backwards through the statements/terminator in the given
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/// basic block `block`. At each point within `block`, invokes
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/// the callback `op` with the current location and the set of
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/// variables that are live on entry to that location.
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pub fn simulate_block<'tcx, OP>(&self,
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mir: &Mir<'tcx>,
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block: BasicBlock,
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mut callback: OP)
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where OP: FnMut(Location, &LocalSet)
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{
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let data = &mir[block];
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// Get a copy of the bits on exit from the block.
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let mut bits = self.outs[block].clone();
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// Start with the maximal statement index -- i.e., right before
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// the terminator executes.
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let mut statement_index = data.statements.len();
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// Compute liveness right before terminator and invoke callback.
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let terminator_location = Location { block, statement_index };
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let terminator_defs_uses = self.defs_uses(mir, terminator_location, &data.terminator);
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terminator_defs_uses.apply(&mut bits);
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callback(terminator_location, &bits);
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// Compute liveness before each statement (in rev order) and invoke callback.
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for statement in data.statements.iter().rev() {
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statement_index -= 1;
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let statement_location = Location { block, statement_index };
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let statement_defs_uses = self.defs_uses(mir, statement_location, statement);
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statement_defs_uses.apply(&mut bits);
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callback(statement_location, &bits);
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}
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assert_eq!(bits, self.ins[block]);
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}
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fn defs_uses<'tcx, V>(&self,
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mir: &Mir<'tcx>,
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location: Location,
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thing: &V)
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-> DefsUses
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where V: MirVisitable<'tcx>,
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{
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let locals = mir.local_decls.len();
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let mut visitor = DefsUses {
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defs: LocalSet::new_empty(locals),
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uses: LocalSet::new_empty(locals),
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};
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// Visit the various parts of the basic block in reverse. If we go
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// forward, the logic in `add_def` and `add_use` would be wrong.
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thing.apply(location, &mut visitor);
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visitor
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}
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}
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#[derive(Eq, PartialEq, Clone)]
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struct DefsUses {
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defs: LocalSet,
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@ -159,113 +266,6 @@ fn block<'tcx>(b: &BasicBlockData<'tcx>, locals: usize) -> DefsUses {
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visitor
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}
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// This gives the result of the liveness analysis at the boundary of basic blocks
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pub struct LivenessResult {
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pub ins: IndexVec<BasicBlock, LocalSet>,
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pub outs: IndexVec<BasicBlock, LocalSet>,
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}
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pub fn liveness_of_locals<'tcx>(mir: &Mir<'tcx>) -> LivenessResult {
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let locals = mir.local_decls.len();
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let def_use: IndexVec<_, _> = mir.basic_blocks().iter().map(|b| {
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block(b, locals)
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}).collect();
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let mut ins: IndexVec<_, _> = mir.basic_blocks()
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.indices()
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.map(|_| LocalSet::new_empty(locals))
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.collect();
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let mut outs = ins.clone();
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let mut changed = true;
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let mut bits = LocalSet::new_empty(locals);
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while changed {
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changed = false;
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for b in mir.basic_blocks().indices().rev() {
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// outs[b] = ∪ {ins of successors}
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bits.clear();
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for &successor in mir.basic_blocks()[b].terminator().successors().into_iter() {
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bits.union(&ins[successor]);
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}
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outs[b].clone_from(&bits);
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// bits = use ∪ (bits - def)
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def_use[b].apply(&mut bits);
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// update bits on entry and flag if they have changed
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if ins[b] != bits {
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ins[b].clone_from(&bits);
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changed = true;
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}
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}
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}
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LivenessResult {
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ins,
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outs,
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}
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}
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impl LivenessResult {
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/// Walks backwards through the statements/terminator in the given
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/// basic block `block`. At each point within `block`, invokes
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/// the callback `op` with the current location and the set of
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/// variables that are live on entry to that location.
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pub fn simulate_block<'tcx, OP>(&self,
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mir: &Mir<'tcx>,
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block: BasicBlock,
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mut callback: OP)
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where OP: FnMut(Location, &LocalSet)
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{
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let data = &mir[block];
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// Get a copy of the bits on exit from the block.
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let mut bits = self.outs[block].clone();
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// Start with the maximal statement index -- i.e., right before
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// the terminator executes.
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let mut statement_index = data.statements.len();
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// Compute liveness right before terminator and invoke callback.
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let terminator_location = Location { block, statement_index };
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let terminator_defs_uses = self.defs_uses(mir, terminator_location, &data.terminator);
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terminator_defs_uses.apply(&mut bits);
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callback(terminator_location, &bits);
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// Compute liveness before each statement (in rev order) and invoke callback.
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for statement in data.statements.iter().rev() {
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statement_index -= 1;
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let statement_location = Location { block, statement_index };
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let statement_defs_uses = self.defs_uses(mir, statement_location, statement);
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statement_defs_uses.apply(&mut bits);
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callback(statement_location, &bits);
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}
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assert_eq!(bits, self.ins[block]);
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}
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fn defs_uses<'tcx, V>(&self,
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mir: &Mir<'tcx>,
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location: Location,
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thing: &V)
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-> DefsUses
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where V: MirVisitable<'tcx>,
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{
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let locals = mir.local_decls.len();
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let mut visitor = DefsUses {
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defs: LocalSet::new_empty(locals),
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uses: LocalSet::new_empty(locals),
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};
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// Visit the various parts of the basic block in reverse. If we go
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// forward, the logic in `add_def` and `add_use` would be wrong.
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thing.apply(location, &mut visitor);
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visitor
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}
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}
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trait MirVisitable<'tcx> {
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fn apply<V>(&self, location: Location, visitor: &mut V)
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where V: Visitor<'tcx>;
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