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Eliminate ret_field and ret intermediates in array clone shim

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This commit is contained in:
Manish Goregaokar 2018-01-30 17:30:15 +05:30
parent f97629160f
commit dfd244d952
1 changed files with 10 additions and 24 deletions
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34
src/librustc_mir/shim.rs
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@ -505,11 +505,11 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
fn array_shim(&mut self, ty: Ty<'tcx>, len: u64) {
let tcx = self.tcx;
let span = self.span;
let rcvr = Place::Local(Local::new(1+0)).deref();
let src = Place::Local(Local::new(1+0)).deref();
let dest = Place::Local(RETURN_PLACE);
let beg = self.local_decls.push(temp_decl(Mutability::Mut, tcx.types.usize, span));
let end = self.make_place(Mutability::Not, tcx.types.usize);
let ret = self.make_place(Mutability::Mut, tcx.mk_array(ty, len));
// BB #0
// `let mut beg = 0;`
@ -539,25 +539,17 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
self.loop_header(Place::Local(beg), end, BasicBlock::new(2), BasicBlock::new(4), false);
// BB #2
// `let cloned = Clone::clone(rcvr[beg])`;
// `dest[i] = Clone::clone(src[beg])`;
// Goto #3 if ok, #5 if unwinding happens.
let rcvr_field = rcvr.clone().index(beg);
let cloned = self.make_place(Mutability::Not, ty);
self.make_clone_call(cloned.clone(), rcvr_field, ty, BasicBlock::new(3),
let dest_field = dest.clone().index(beg);
let src_field = src.clone().index(beg);
self.make_clone_call(dest_field, src_field, ty, BasicBlock::new(3),
BasicBlock::new(5));
// BB #3
// `ret[beg] = cloned;`
// `beg = beg + 1;`
// `goto #1`;
let ret_field = ret.clone().index(beg);
let statements = vec![
self.make_statement(
StatementKind::Assign(
ret_field,
Rvalue::Use(Operand::Move(cloned))
)
),
self.make_statement(
StatementKind::Assign(
Place::Local(beg),
@ -572,14 +564,8 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
self.block(statements, TerminatorKind::Goto { target: BasicBlock::new(1) }, false);
// BB #4
// `return ret;`
let ret_statement = self.make_statement(
StatementKind::Assign(
Place::Local(RETURN_PLACE),
Rvalue::Use(Operand::Move(ret.clone())),
)
);
self.block(vec![ret_statement], TerminatorKind::Return, false);
// `return dest;`
self.block(vec![], TerminatorKind::Return, false);
// BB #5 (cleanup)
// `let end = beg;`
@ -604,9 +590,9 @@ impl<'a, 'tcx> CloneShimBuilder<'a, 'tcx> {
BasicBlock::new(7), BasicBlock::new(9), true);
// BB #7 (cleanup)
// `drop(ret[beg])`;
// `drop(dest[beg])`;
self.block(vec![], TerminatorKind::Drop {
location: ret.index(beg),
location: dest.index(beg),
target: BasicBlock::new(8),
unwind: None,
}, true);