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Rollup merge of #78191 - tmiasko:temp-match-branch-simplification, r=oli-obk 

Introduce a temporary for discriminant value in MatchBranchSimplification

The optimization introduces additional uses of the discriminant operand, but
does not ensure that it is still valid to evaluate it or that it still
evaluates to the same value.

Evaluate it once at original position, and store the result in a new temporary.

Follow up on #78151. The optimization remains disabled by default.

Closes #78239.
This commit is contained in:
Jonas Schievink 2020-10-24 22:39:55 +02:00 committed by GitHub
parent e3808edeee a4dc92b483
commit 597b4c5bb4
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
9 changed files with 311 additions and 50 deletions
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30
compiler/rustc_mir/src/transform/match_branches.rs
View File

@ -38,19 +38,16 @@ pub struct MatchBranchSimplification;
impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
// FIXME: This optimization can result in unsoundness, because it introduces
// additional uses of a place holding the discriminant value without ensuring that
// it is valid to do so.
if !tcx.sess.opts.debugging_opts.unsound_mir_opts {
if tcx.sess.opts.debugging_opts.mir_opt_level <= 1 {
return;
}
let param_env = tcx.param_env(body.source.def_id());
let bbs = body.basic_blocks_mut();
let (bbs, local_decls) = body.basic_blocks_and_local_decls_mut();
'outer: for bb_idx in bbs.indices() {
let (discr, val, switch_ty, first, second) = match bbs[bb_idx].terminator().kind {
TerminatorKind::SwitchInt {
discr: Operand::Copy(ref place) | Operand::Move(ref place),
discr: ref discr @ (Operand::Copy(_) | Operand::Move(_)),
switch_ty,
ref targets,
..
@ -59,7 +56,7 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
if target == targets.otherwise() {
continue;
}
(place, value, switch_ty, target, targets.otherwise())
(discr, value, switch_ty, target, targets.otherwise())
}
// Only optimize switch int statements
_ => continue,
@ -99,6 +96,10 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
// Take ownership of items now that we know we can optimize.
let discr = discr.clone();
// Introduce a temporary for the discriminant value.
let source_info = bbs[bb_idx].terminator().source_info;
let discr_local = local_decls.push(LocalDecl::new(switch_ty, source_info.span));
// We already checked that first and second are different blocks,
// and bb_idx has a different terminator from both of them.
let (from, first, second) = bbs.pick3_mut(bb_idx, first, second);
@ -127,7 +128,11 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
rustc_span::DUMMY_SP,
);
let op = if f_b { BinOp::Eq } else { BinOp::Ne };
let rhs = Rvalue::BinaryOp(op, Operand::Copy(discr.clone()), const_cmp);
let rhs = Rvalue::BinaryOp(
op,
Operand::Copy(Place::from(discr_local)),
const_cmp,
);
Statement {
source_info: f.source_info,
kind: StatementKind::Assign(box (*lhs, rhs)),
@ -138,7 +143,16 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
_ => unreachable!(),
}
});
from.statements
.push(Statement { source_info, kind: StatementKind::StorageLive(discr_local) });
from.statements.push(Statement {
source_info,
kind: StatementKind::Assign(box (Place::from(discr_local), Rvalue::Use(discr))),
});
from.statements.extend(new_stmts);
from.statements
.push(Statement { source_info, kind: StatementKind::StorageDead(discr_local) });
from.terminator_mut().kind = first.terminator().kind.clone();
}
}

8
src/test/mir-opt/matches_reduce_branches.bar.MatchBranchSimplification.32bit.diff
View File

@ -10,6 +10,7 @@
let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:9: 35:10
let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:12: 35:13
let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:15: 35:16
+ let mut _11: i32; // in scope 0 at $DIR/matches_reduce_branches.rs:19:9: 19:10
scope 1 {
debug a => _2; // in scope 1 at $DIR/matches_reduce_branches.rs:13:9: 13:10
let _3: bool; // in scope 1 at $DIR/matches_reduce_branches.rs:14:9: 14:10
@ -33,10 +34,13 @@
StorageLive(_5); // scope 3 at $DIR/matches_reduce_branches.rs:16:9: 16:10
StorageLive(_6); // scope 4 at $DIR/matches_reduce_branches.rs:18:5: 33:6
- switchInt(_1) -> [7_i32: bb2, otherwise: bb1]; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _2 = Ne(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
+ _3 = Eq(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
+ StorageLive(_11); // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _11 = _1; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _2 = Ne(_11, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
+ _3 = Eq(_11, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
+ _4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:22
+ _5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:23:13: 23:21
+ StorageDead(_11); // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
}

8
src/test/mir-opt/matches_reduce_branches.bar.MatchBranchSimplification.64bit.diff
View File

@ -10,6 +10,7 @@
let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:9: 35:10
let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:12: 35:13
let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:15: 35:16
+ let mut _11: i32; // in scope 0 at $DIR/matches_reduce_branches.rs:19:9: 19:10
scope 1 {
debug a => _2; // in scope 1 at $DIR/matches_reduce_branches.rs:13:9: 13:10
let _3: bool; // in scope 1 at $DIR/matches_reduce_branches.rs:14:9: 14:10
@ -33,10 +34,13 @@
StorageLive(_5); // scope 3 at $DIR/matches_reduce_branches.rs:16:9: 16:10
StorageLive(_6); // scope 4 at $DIR/matches_reduce_branches.rs:18:5: 33:6
- switchInt(_1) -> [7_i32: bb2, otherwise: bb1]; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _2 = Ne(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
+ _3 = Eq(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
+ StorageLive(_11); // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _11 = _1; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ _2 = Ne(_11, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
+ _3 = Eq(_11, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
+ _4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:22
+ _5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:23:13: 23:21
+ StorageDead(_11); // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
+ goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
}

6
src/test/mir-opt/matches_reduce_branches.foo.MatchBranchSimplification.32bit.diff
View File

@ -6,12 +6,16 @@
let mut _0: (); // return place in scope 0 at $DIR/matches_reduce_branches.rs:6:25: 6:25
let mut _2: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
let mut _3: isize; // in scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ let mut _4: isize; // in scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
bb0: {
StorageLive(_2); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
_3 = discriminant(_1); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
- switchInt(move _3) -> [0_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _2 = Eq(_3, const 0_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+ StorageLive(_4); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _4 = move _3; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _2 = Eq(_4, const 0_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+ StorageDead(_4); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
}

6
src/test/mir-opt/matches_reduce_branches.foo.MatchBranchSimplification.64bit.diff
View File

@ -6,12 +6,16 @@
let mut _0: (); // return place in scope 0 at $DIR/matches_reduce_branches.rs:6:25: 6:25
let mut _2: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
let mut _3: isize; // in scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ let mut _4: isize; // in scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
bb0: {
StorageLive(_2); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
_3 = discriminant(_1); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
- switchInt(move _3) -> [0_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _2 = Eq(_3, const 0_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+ StorageLive(_4); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _4 = move _3; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ _2 = Eq(_4, const 0_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+ StorageDead(_4); // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
+ goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:7:22: 7:26
}

116
src/test/mir-opt/matches_reduce_branches.match_nested_if.MatchBranchSimplification.32bit.diff Normal file
View File

@ -0,0 +1,116 @@
- // MIR for `match_nested_if` before MatchBranchSimplification
+ // MIR for `match_nested_if` after MatchBranchSimplification
fn match_nested_if() -> bool {
let mut _0: bool; // return place in scope 0 at $DIR/matches_reduce_branches.rs:38:25: 38:29
let _1: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:39:9: 39:12
let mut _2: (); // in scope 0 at $DIR/matches_reduce_branches.rs:39:21: 39:23
let mut _3: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
let mut _4: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
let mut _5: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
let mut _6: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
+ let mut _7: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
scope 1 {
debug val => _1; // in scope 1 at $DIR/matches_reduce_branches.rs:39:9: 39:12
}
bb0: {
StorageLive(_1); // scope 0 at $DIR/matches_reduce_branches.rs:39:9: 39:12
StorageLive(_2); // scope 0 at $DIR/matches_reduce_branches.rs:39:21: 39:23
StorageLive(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
StorageLive(_4); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
StorageLive(_5); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
StorageLive(_6); // scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
_6 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
- switchInt(_6) -> [false: bb2, otherwise: bb1]; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ StorageLive(_7); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ _7 = _6; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ _5 = Ne(_7, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:42: 40:47
+ StorageDead(_7); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb1: {
_5 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:30: 40:34
goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb2: {
_5 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:42: 40:47
goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb3: {
StorageDead(_6); // scope 0 at $DIR/matches_reduce_branches.rs:40:47: 40:48
- switchInt(_5) -> [false: bb4, otherwise: bb5]; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ StorageLive(_8); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ _8 = _5; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ _4 = Ne(_8, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:62: 40:67
+ StorageDead(_8); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb4: {
_4 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:62: 40:67
goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb5: {
_4 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:50: 40:54
goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb6: {
StorageDead(_5); // scope 0 at $DIR/matches_reduce_branches.rs:40:67: 40:68
- switchInt(_4) -> [false: bb7, otherwise: bb8]; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageLive(_9); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _9 = _4; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _3 = Ne(_9, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:82: 40:87
+ StorageDead(_9); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb7: {
_3 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:82: 40:87
goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb8: {
_3 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:70: 40:74
goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb9: {
StorageDead(_4); // scope 0 at $DIR/matches_reduce_branches.rs:40:87: 40:88
- switchInt(move _3) -> [false: bb11, otherwise: bb10]; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageLive(_10); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _10 = move _3; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
+ _1 = Ne(_10, const false); // scope 0 at $DIR/matches_reduce_branches.rs:41:14: 41:19
+ StorageDead(_10); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb10: {
StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
_1 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:92: 40:96
goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:39:15: 42:6
}
bb11: {
StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
_1 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:41:14: 41:19
goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:39:15: 42:6
}
bb12: {
StorageDead(_2); // scope 0 at $DIR/matches_reduce_branches.rs:42:6: 42:7
_0 = _1; // scope 1 at $DIR/matches_reduce_branches.rs:43:5: 43:8
StorageDead(_1); // scope 0 at $DIR/matches_reduce_branches.rs:44:1: 44:2
return; // scope 0 at $DIR/matches_reduce_branches.rs:44:2: 44:2
}
}

116
src/test/mir-opt/matches_reduce_branches.match_nested_if.MatchBranchSimplification.64bit.diff Normal file
View File

@ -0,0 +1,116 @@
- // MIR for `match_nested_if` before MatchBranchSimplification
+ // MIR for `match_nested_if` after MatchBranchSimplification
fn match_nested_if() -> bool {
let mut _0: bool; // return place in scope 0 at $DIR/matches_reduce_branches.rs:38:25: 38:29
let _1: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:39:9: 39:12
let mut _2: (); // in scope 0 at $DIR/matches_reduce_branches.rs:39:21: 39:23
let mut _3: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
let mut _4: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
let mut _5: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
let mut _6: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
+ let mut _7: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
scope 1 {
debug val => _1; // in scope 1 at $DIR/matches_reduce_branches.rs:39:9: 39:12
}
bb0: {
StorageLive(_1); // scope 0 at $DIR/matches_reduce_branches.rs:39:9: 39:12
StorageLive(_2); // scope 0 at $DIR/matches_reduce_branches.rs:39:21: 39:23
StorageLive(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
StorageLive(_4); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
StorageLive(_5); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
StorageLive(_6); // scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
_6 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:24: 40:28
- switchInt(_6) -> [false: bb2, otherwise: bb1]; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ StorageLive(_7); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ _7 = _6; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ _5 = Ne(_7, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:42: 40:47
+ StorageDead(_7); // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
+ goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb1: {
_5 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:30: 40:34
goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb2: {
_5 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:42: 40:47
goto -> bb3; // scope 0 at $DIR/matches_reduce_branches.rs:40:21: 40:48
}
bb3: {
StorageDead(_6); // scope 0 at $DIR/matches_reduce_branches.rs:40:47: 40:48
- switchInt(_5) -> [false: bb4, otherwise: bb5]; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ StorageLive(_8); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ _8 = _5; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ _4 = Ne(_8, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:62: 40:67
+ StorageDead(_8); // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
+ goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb4: {
_4 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:62: 40:67
goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb5: {
_4 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:50: 40:54
goto -> bb6; // scope 0 at $DIR/matches_reduce_branches.rs:40:18: 40:68
}
bb6: {
StorageDead(_5); // scope 0 at $DIR/matches_reduce_branches.rs:40:67: 40:68
- switchInt(_4) -> [false: bb7, otherwise: bb8]; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageLive(_9); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _9 = _4; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _3 = Ne(_9, const false); // scope 0 at $DIR/matches_reduce_branches.rs:40:82: 40:87
+ StorageDead(_9); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb7: {
_3 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:40:82: 40:87
goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb8: {
_3 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:70: 40:74
goto -> bb9; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb9: {
StorageDead(_4); // scope 0 at $DIR/matches_reduce_branches.rs:40:87: 40:88
- switchInt(move _3) -> [false: bb11, otherwise: bb10]; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageLive(_10); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ _10 = move _3; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
+ _1 = Ne(_10, const false); // scope 0 at $DIR/matches_reduce_branches.rs:41:14: 41:19
+ StorageDead(_10); // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
+ goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:40:15: 40:88
}
bb10: {
StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
_1 = const true; // scope 0 at $DIR/matches_reduce_branches.rs:40:92: 40:96
goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:39:15: 42:6
}
bb11: {
StorageDead(_3); // scope 0 at $DIR/matches_reduce_branches.rs:40:95: 40:96
_1 = const false; // scope 0 at $DIR/matches_reduce_branches.rs:41:14: 41:19
goto -> bb12; // scope 0 at $DIR/matches_reduce_branches.rs:39:15: 42:6
}
bb12: {
StorageDead(_2); // scope 0 at $DIR/matches_reduce_branches.rs:42:6: 42:7
_0 = _1; // scope 1 at $DIR/matches_reduce_branches.rs:43:5: 43:8
StorageDead(_1); // scope 0 at $DIR/matches_reduce_branches.rs:44:1: 44:2
return; // scope 0 at $DIR/matches_reduce_branches.rs:44:2: 44:2
}
}

10
src/test/mir-opt/matches_reduce_branches.rs
View File

@ -1,7 +1,7 @@
// compile-flags: -Zunsound-mir-opts
// EMIT_MIR_FOR_EACH_BIT_WIDTH
// EMIT_MIR matches_reduce_branches.foo.MatchBranchSimplification.diff
// EMIT_MIR matches_reduce_branches.bar.MatchBranchSimplification.diff
// EMIT_MIR matches_reduce_branches.match_nested_if.MatchBranchSimplification.diff
fn foo(bar: Option<()>) {
if matches!(bar, None) {
@ -35,9 +35,17 @@ fn bar(i: i32) -> (bool, bool, bool, bool) {
(a, b, c, d)
}
fn match_nested_if() -> bool {
let val = match () {
() if if if if true {true} else {false} {true} else {false} {true} else {false} => true,
_ => false,
};
val
}
fn main() {
let _ = foo(None);
let _ = foo(Some(()));
let _ = bar(0);
let _ = match_nested_if();
}

61
src/test/mir-opt/not_equal_false.opt.InstCombine.diff
View File

@ -8,61 +8,52 @@
let mut _3: isize; // in scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
let mut _4: bool; // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
let mut _5: isize; // in scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
let mut _6: isize; // in scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
let mut _7: isize; // in scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
let mut _8: bool; // in scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
bb0: {
StorageLive(_2); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
_3 = discriminant(_1); // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
switchInt(move _3) -> [0_isize: bb6, otherwise: bb5]; // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
StorageLive(_6); // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
_6 = move _3; // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
_2 = Eq(_6, const 0_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
StorageDead(_6); // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
goto -> bb4; // scope 0 at $DIR/not_equal_false.rs:4:17: 4:21
}
bb1: {
_0 = const true; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
goto -> bb4; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
goto -> bb3; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
}
bb2: {
_0 = const false; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
goto -> bb4; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
StorageLive(_4); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
_5 = discriminant(_1); // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
StorageLive(_7); // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
_7 = move _5; // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
_4 = Eq(_7, const 1_isize); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
StorageDead(_7); // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
goto -> bb5; // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
}
bb3: {
StorageLive(_4); // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
_5 = discriminant(_1); // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
switchInt(move _5) -> [1_isize: bb9, otherwise: bb8]; // scope 0 at $DIR/not_equal_false.rs:4:38: 4:45
}
bb4: {
StorageDead(_4); // scope 0 at $DIR/not_equal_false.rs:4:45: 4:46
StorageDead(_2); // scope 0 at $DIR/not_equal_false.rs:4:45: 4:46
return; // scope 0 at $DIR/not_equal_false.rs:5:2: 5:2
}
bb4: {
switchInt(move _2) -> [false: bb2, otherwise: bb1]; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
}
bb5: {
_2 = const false; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
goto -> bb7; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
}
bb6: {
_2 = const true; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
goto -> bb7; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
}
bb7: {
switchInt(move _2) -> [false: bb3, otherwise: bb1]; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
}
bb8: {
_4 = const false; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
goto -> bb10; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
}
bb9: {
_4 = const true; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
goto -> bb10; // scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
}
bb10: {
switchInt(move _4) -> [false: bb2, otherwise: bb1]; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
StorageLive(_8); // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
_8 = move _4; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
- _0 = Ne(_8, const false); // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
+ _0 = _8; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
StorageDead(_8); // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
goto -> bb3; // scope 0 at $DIR/not_equal_false.rs:4:5: 4:46
}
}