From d1d7fb1ae53a02f5073a7cf0ab1497aaa9617ebe Mon Sep 17 00:00:00 2001 From: Rich Kadel Date: Sun, 18 Apr 2021 11:51:42 -0700 Subject: [PATCH] Only generate dummy assign when instrumenting coverage And make the LocalDecl internal, to avoid needing to declare storage. (For multiple `continue` stateuemtns, it must also be mutable.) --- compiler/rustc_mir_build/src/build/scope.rs | 25 +++++++++++-------- ....main.SimplifyCfg-promote-consts.after.mir | 4 --- 2 files changed, 15 insertions(+), 14 deletions(-) diff --git a/compiler/rustc_mir_build/src/build/scope.rs b/compiler/rustc_mir_build/src/build/scope.rs index 2727e70f278..41fc925c049 100644 --- a/compiler/rustc_mir_build/src/build/scope.rs +++ b/compiler/rustc_mir_build/src/build/scope.rs @@ -618,16 +618,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { } } else { assert!(value.is_none(), "`return` and `break` should have a destination"); - // `continue` statements generate no MIR statement with the `continue` statement's Span, - // and the `InstrumentCoverage` statement will have no way to generate a coverage - // code region for the `continue` statement, unless we add a dummy `Assign` here: - let mut local_decl = LocalDecl::new(self.tcx.mk_unit(), span); - local_decl = local_decl.immutable(); - let temp = self.local_decls.push(local_decl); - let temp_place = Place::from(temp); - self.cfg.push(block, Statement { source_info, kind: StatementKind::StorageLive(temp) }); - self.cfg.push_assign_unit(block, source_info, temp_place, self.tcx); - self.cfg.push(block, Statement { source_info, kind: StatementKind::StorageDead(temp) }); + if self.tcx.sess.instrument_coverage() { + // Unlike `break` and `return`, which push an `Assign` statement to MIR, from which + // a Coverage code region can be generated, `continue` needs no `Assign`; but + // without one, the `InstrumentCoverage` MIR pass cannot generate a code region for + // `continue`. Coverage will be missing unless we add a dummy `Assign` to MIR. + self.add_dummy_assignment(&span, block, source_info); + } } let region_scope = self.scopes.breakable_scopes[break_index].region_scope; @@ -653,6 +650,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { self.cfg.start_new_block().unit() } + // Add a dummy `Assign` statement to the CFG, with the span for the source code's `continue` + // statement. + fn add_dummy_assignment(&mut self, span: &Span, block: BasicBlock, source_info: SourceInfo) { + let local_decl = LocalDecl::new(self.tcx.mk_unit(), *span).internal(); + let temp_place = Place::from(self.local_decls.push(local_decl)); + self.cfg.push_assign_unit(block, source_info, temp_place, self.tcx); + } + crate fn exit_top_scope( &mut self, mut block: BasicBlock, diff --git a/src/test/mir-opt/loop_test.main.SimplifyCfg-promote-consts.after.mir b/src/test/mir-opt/loop_test.main.SimplifyCfg-promote-consts.after.mir index f6120447017..99c7ac8d5b7 100644 --- a/src/test/mir-opt/loop_test.main.SimplifyCfg-promote-consts.after.mir +++ b/src/test/mir-opt/loop_test.main.SimplifyCfg-promote-consts.after.mir @@ -8,7 +8,6 @@ fn main() -> () { let mut _4: !; // in scope 0 at $DIR/loop_test.rs:13:5: 16:6 let mut _5: (); // in scope 0 at $DIR/loop_test.rs:6:1: 17:2 let _6: i32; // in scope 0 at $DIR/loop_test.rs:14:13: 14:14 - let _7: (); // in scope 0 at $DIR/loop_test.rs:15:9: 15:17 scope 1 { debug x => _6; // in scope 1 at $DIR/loop_test.rs:14:13: 14:14 } @@ -43,9 +42,6 @@ fn main() -> () { StorageLive(_6); // scope 0 at $DIR/loop_test.rs:14:13: 14:14 _6 = const 1_i32; // scope 0 at $DIR/loop_test.rs:14:17: 14:18 FakeRead(ForLet(None), _6); // scope 0 at $DIR/loop_test.rs:14:13: 14:14 - StorageLive(_7); // scope 1 at $DIR/loop_test.rs:15:9: 15:17 - _7 = const (); // scope 1 at $DIR/loop_test.rs:15:9: 15:17 - StorageDead(_7); // scope 1 at $DIR/loop_test.rs:15:9: 15:17 StorageDead(_6); // scope 0 at $DIR/loop_test.rs:16:5: 16:6 goto -> bb3; // scope 0 at $DIR/loop_test.rs:1:1: 1:1 }