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Simplify MIR generation for logical ops

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This commit is contained in:
Shotaro Yamada 2018-12-17 15:57:38 +09:00
parent 1897657ef0
commit e38e954a0d
1 changed files with 24 additions and 31 deletions
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55
src/librustc_mir/build/expr/into.rs
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@ -126,18 +126,17 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
ExprKind::LogicalOp { op, lhs, rhs } => {
// And:
//
// [block: If(lhs)] -true-> [else_block: If(rhs)] -true-> [true_block]
// | | (false)
// +----------false-----------+------------------> [false_block]
// [block: If(lhs)] -true-> [else_block: dest = (rhs)]
// | (false)
// [shortcurcuit_block: dest = false]
//
// Or:
//
// [block: If(lhs)] -false-> [else_block: If(rhs)] -true-> [true_block]
// | (true) | (false)
// [true_block] [false_block]
// [block: If(lhs)] -false-> [else_block: dest = (rhs)]
// | (true)
// [shortcurcuit_block: dest = true]
let (true_block, false_block, mut else_block, join_block) = (
this.cfg.start_new_block(),
let (shortcircuit_block, mut else_block, join_block) = (
this.cfg.start_new_block(),
this.cfg.start_new_block(),
this.cfg.start_new_block(),
@ -145,47 +144,41 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
let lhs = unpack!(block = this.as_local_operand(block, lhs));
let blocks = match op {
LogicalOp::And => (else_block, false_block),
LogicalOp::Or => (true_block, else_block),
LogicalOp::And => (else_block, shortcircuit_block),
LogicalOp::Or => (shortcircuit_block, else_block),
};
let term = TerminatorKind::if_(this.hir.tcx(), lhs, blocks.0, blocks.1);
this.cfg.terminate(block, source_info, term);
let rhs = unpack!(else_block = this.as_local_operand(else_block, rhs));
let term = TerminatorKind::if_(this.hir.tcx(), rhs, true_block, false_block);
this.cfg.terminate(else_block, source_info, term);
this.cfg.push_assign_constant(
true_block,
shortcircuit_block,
source_info,
destination,
Constant {
span: expr_span,
ty: this.hir.bool_ty(),
user_ty: None,
literal: this.hir.true_literal(),
literal: match op {
LogicalOp::And => this.hir.false_literal(),
LogicalOp::Or => this.hir.true_literal(),
},
},
);
this.cfg.push_assign_constant(
false_block,
source_info,
destination,
Constant {
span: expr_span,
ty: this.hir.bool_ty(),
user_ty: None,
literal: this.hir.false_literal(),
},
);
this.cfg.terminate(
true_block,
shortcircuit_block,
source_info,
TerminatorKind::Goto { target: join_block },
);
let rhs = unpack!(else_block = this.as_local_operand(else_block, rhs));
this.cfg.push_assign(
else_block,
source_info,
destination,
Rvalue::Use(rhs),
);
this.cfg.terminate(
false_block,
else_block,
source_info,
TerminatorKind::Goto { target: join_block },
);