bjoernager/rust
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Simplify logical operations CFG

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This is basically same commit as e38e954a0d which was reverted later in 676953fde9
In both cases, this changes weren't benchmarked.
e38e954a0d leads to missed optimization described in [this issue](https://github.com/rust-lang/rust/issues/62993)
676953fde9 leads to missed optimization described in [this issue](https://github.com/rust-lang/rust/issues/83623)

Also it changes some src/test/run-make-fulldeps/coverage-spanview/expected_mir_dump* files automatically.
This commit is contained in:
AngelicosPhosphoros 2021-03-30 00:19:10 +03:00
parent cc4103089f
commit 4464cc2256
8 changed files with 360 additions and 325 deletions
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63
compiler/rustc_mir_build/src/build/expr/into.rs
View file

@ -111,18 +111,17 @@ impl<'a, 'tcx> Builder<'a, '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(),
@ -130,41 +129,31 @@ impl<'a, 'tcx> Builder<'a, '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.tcx, lhs, blocks.0, blocks.1);
this.cfg.terminate(block, source_info, term);
this.cfg.push_assign_constant(
shortcircuit_block,
source_info,
destination,
Constant {
span: expr_span,
user_ty: None,
literal: match op {
LogicalOp::And => ty::Const::from_bool(this.tcx, false).into(),
LogicalOp::Or => ty::Const::from_bool(this.tcx, true).into(),
},
},
);
this.cfg.goto(shortcircuit_block, source_info, join_block);
let rhs = unpack!(else_block = this.as_local_operand(else_block, rhs));
let term = TerminatorKind::if_(this.tcx, rhs, true_block, false_block);
this.cfg.terminate(else_block, source_info, term);
this.cfg.push_assign(else_block, source_info, destination, Rvalue::Use(rhs));
this.cfg.goto(else_block, source_info, join_block);
this.cfg.push_assign_constant(
true_block,
source_info,
destination,
Constant {
span: expr_span,
user_ty: None,
literal: ty::Const::from_bool(this.tcx, true).into(),
},
);
this.cfg.push_assign_constant(
false_block,
source_info,
destination,
Constant {
span: expr_span,
user_ty: None,
literal: ty::Const::from_bool(this.tcx, false).into(),
},
);
// Link up both branches:
this.cfg.goto(true_block, source_info, join_block);
this.cfg.goto(false_block, source_info, join_block);
join_block.unit()
}
ExprKind::Loop { body } => {