diff options
8 files changed, 322 insertions, 3 deletions
diff --git a/compiler/rustc_middle/src/mir/terminator.rs b/compiler/rustc_middle/src/mir/terminator.rs index 4034a3a06e9..4249914346c 100644 --- a/compiler/rustc_middle/src/mir/terminator.rs +++ b/compiler/rustc_middle/src/mir/terminator.rs @@ -444,6 +444,14 @@ impl<'tcx> Terminator<'tcx> { self.kind.successors() } + /// Return `Some` if all successors are identical. + #[inline] + pub fn identical_successor(&self) -> Option<BasicBlock> { + let mut successors = self.successors(); + let first_succ = successors.next()?; + if successors.all(|succ| first_succ == succ) { Some(first_succ) } else { None } + } + #[inline] pub fn successors_mut<'a>(&'a mut self, f: impl FnMut(&'a mut BasicBlock)) { self.kind.successors_mut(f) diff --git a/compiler/rustc_mir_transform/src/simplify.rs b/compiler/rustc_mir_transform/src/simplify.rs index 9f7bb3b0379..edea5cb2c72 100644 --- a/compiler/rustc_mir_transform/src/simplify.rs +++ b/compiler/rustc_mir_transform/src/simplify.rs @@ -144,7 +144,7 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { // statements itself to avoid moving the (relatively) large statements twice. // We do not push the statements directly into the target block (`bb`) as that is slower // due to additional reallocations - let mut merged_blocks = Vec::new(); + let mut merged_blocks: Vec<BasicBlock> = Vec::new(); let mut outer_changed = false; loop { let mut changed = false; @@ -159,8 +159,9 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { let mut terminator = self.basic_blocks[bb].terminator.take().expect("invalid terminator state"); - terminator - .successors_mut(|successor| self.collapse_goto_chain(successor, &mut changed)); + terminator.successors_mut(|successor| { + self.collapse_goto_chain(successor, &mut changed); + }); let mut inner_changed = true; merged_blocks.clear(); @@ -177,10 +178,18 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { if statements_to_merge > 0 { let mut statements = std::mem::take(&mut self.basic_blocks[bb].statements); statements.reserve(statements_to_merge); + let mut parent_bb_last_debuginfos = + std::mem::take(&mut self.basic_blocks[bb].after_last_stmt_debuginfos); for &from in &merged_blocks { + if let Some(stmt) = self.basic_blocks[from].statements.first_mut() { + stmt.debuginfos.prepend(&mut parent_bb_last_debuginfos); + } statements.append(&mut self.basic_blocks[from].statements); + parent_bb_last_debuginfos = + std::mem::take(&mut self.basic_blocks[from].after_last_stmt_debuginfos); } self.basic_blocks[bb].statements = statements; + self.basic_blocks[bb].after_last_stmt_debuginfos = parent_bb_last_debuginfos; } self.basic_blocks[bb].terminator = Some(terminator); @@ -220,10 +229,14 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { // goto chains. We should probably benchmark different sizes. let mut terminators: SmallVec<[_; 1]> = Default::default(); let mut current = *start; + // If each successor has only one predecessor, it's a trivial goto chain. + // We can move all debuginfos to the last basic block. + let mut trivial_goto_chain = true; while let Some(terminator) = self.take_terminator_if_simple_goto(current) { let Terminator { kind: TerminatorKind::Goto { target }, .. } = terminator else { unreachable!(); }; + trivial_goto_chain &= self.pred_count[target] == 1; terminators.push((current, terminator)); current = target; } @@ -235,6 +248,17 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { else { unreachable!(); }; + if trivial_goto_chain { + let mut pred_debuginfos = + std::mem::take(&mut self.basic_blocks[current].after_last_stmt_debuginfos); + let debuginfos = if let Some(stmt) = self.basic_blocks[last].statements.first_mut() + { + &mut stmt.debuginfos + } else { + &mut self.basic_blocks[last].after_last_stmt_debuginfos + }; + debuginfos.prepend(&mut pred_debuginfos); + } *changed |= *target != last; *target = last; debug!("collapsing goto chain from {:?} to {:?}", current, target); diff --git a/tests/mir-opt/debuginfo/simplifycfg.drop_debuginfo.SimplifyCfg-final.diff b/tests/mir-opt/debuginfo/simplifycfg.drop_debuginfo.SimplifyCfg-final.diff index d4a73351ee4..7a1ac92f6dd 100644 --- a/tests/mir-opt/debuginfo/simplifycfg.drop_debuginfo.SimplifyCfg-final.diff +++ b/tests/mir-opt/debuginfo/simplifycfg.drop_debuginfo.SimplifyCfg-final.diff @@ -14,11 +14,13 @@ - - bb1: { - // DBG: _3 = &((*_1).0: i32); +- nop; - goto -> bb2; - } - - bb2: { // DBG: _4 = &((*_1).1: i64); +- nop; _0 = copy ((*_1).2: i32); return; } diff --git a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_1.SimplifyCfg-final.diff b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_1.SimplifyCfg-final.diff index 1c12358ad89..fa4d3aebf83 100644 --- a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_1.SimplifyCfg-final.diff +++ b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_1.SimplifyCfg-final.diff @@ -17,13 +17,16 @@ - bb1: { (*_2) = const true; // DBG: _3 = &((*_1).0: i32); +- nop; - goto -> bb2; - } - - bb2: { // DBG: _4 = &((*_1).1: i64); +- nop; _0 = copy ((*_1).2: i32); // DBG: _5 = &((*_1).2: i32); +- nop; return; } } diff --git a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_2.SimplifyCfg-final.diff b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_2.SimplifyCfg-final.diff index de8e5612c87..b01c91f196b 100644 --- a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_2.SimplifyCfg-final.diff +++ b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_2.SimplifyCfg-final.diff @@ -16,13 +16,16 @@ - - bb1: { // DBG: _2 = &((*_1).0: i32); +- nop; - goto -> bb2; - } - - bb2: { // DBG: _3 = &((*_1).1: i64); +- nop; _0 = copy ((*_1).2: i32); // DBG: _4 = &((*_1).2: i32); +- nop; return; } } diff --git a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_3.SimplifyCfg-final.diff b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_3.SimplifyCfg-final.diff new file mode 100644 index 00000000000..caa90d79a1c --- /dev/null +++ b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_3.SimplifyCfg-final.diff @@ -0,0 +1,40 @@ +- // MIR for `preserve_debuginfo_3` before SimplifyCfg-final ++ // MIR for `preserve_debuginfo_3` after SimplifyCfg-final + + fn preserve_debuginfo_3(_1: &Foo, _2: bool) -> i32 { + debug foo_a => _3; + debug foo_b => _4; + debug foo_c => _5; + let mut _0: i32; + let mut _3: &i32; + let mut _4: &i64; + let mut _5: &i32; + + bb0: { +- switchInt(copy _2) -> [1: bb1, otherwise: bb2]; ++ switchInt(copy _2) -> [1: bb2, otherwise: bb1]; + } + + bb1: { +- // DBG: _3 = &((*_1).0: i32); +- nop; +- goto -> bb3; +- } +- +- bb2: { + // DBG: _4 = &((*_1).1: i64); +- nop; + _0 = copy ((*_1).2: i32); + return; + } + +- bb3: { ++ bb2: { ++ // DBG: _3 = &((*_1).0: i32); + // DBG: _5 = &((*_1).2: i32); +- nop; + _0 = copy ((*_1).0: i32); + return; + } + } + diff --git a/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_identical_succs.SimplifyCfg-final.diff b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_identical_succs.SimplifyCfg-final.diff new file mode 100644 index 00000000000..d8c36990a5f --- /dev/null +++ b/tests/mir-opt/debuginfo/simplifycfg.preserve_debuginfo_identical_succs.SimplifyCfg-final.diff @@ -0,0 +1,32 @@ +- // MIR for `preserve_debuginfo_identical_succs` before SimplifyCfg-final ++ // MIR for `preserve_debuginfo_identical_succs` after SimplifyCfg-final + + fn preserve_debuginfo_identical_succs(_1: &Foo, _2: bool) -> i32 { + debug foo_a => _3; + debug foo_b => _4; + debug foo_c => _5; + let mut _0: i32; + let mut _3: &i32; + let mut _4: &i64; + let mut _5: &i32; + + bb0: { +- switchInt(copy _2) -> [1: bb1, otherwise: bb1]; +- } +- +- bb1: { + // DBG: _3 = &((*_1).0: i32); +- nop; +- goto -> bb2; +- } +- +- bb2: { + // DBG: _4 = &((*_1).1: i64); +- nop; + _0 = copy ((*_1).2: i32); + // DBG: _5 = &((*_1).2: i32); +- nop; + return; + } + } + diff --git a/tests/mir-opt/debuginfo/simplifycfg.rs b/tests/mir-opt/debuginfo/simplifycfg.rs new file mode 100644 index 00000000000..2bd510fd3b9 --- /dev/null +++ b/tests/mir-opt/debuginfo/simplifycfg.rs @@ -0,0 +1,207 @@ +//@ test-mir-pass: SimplifyCfg-final +//@ compile-flags: -Zmir-enable-passes=+DeadStoreElimination-initial + +#![feature(core_intrinsics, custom_mir)] +#![crate_type = "lib"] + +use std::intrinsics::mir::*; + +pub struct Foo { + a: i32, + b: i64, + c: i32, +} + +// EMIT_MIR simplifycfg.drop_debuginfo.SimplifyCfg-final.diff +#[custom_mir(dialect = "runtime", phase = "post-cleanup")] +pub fn drop_debuginfo(foo: &Foo, c: bool) -> i32 { + // CHECK-LABEL: fn drop_debuginfo + // CHECK: debug foo_b => [[foo_b:_[0-9]+]]; + // CHECK: bb0: { + // CHECK-NEXT: DBG: [[foo_b]] = &((*_1).1: i64) + // CHECK-NEXT: _0 = copy ((*_1).2: i32); + // CHECK-NEXT: return; + mir! { + let _foo_a: &i32; + let _foo_b: &i64; + debug foo_a => _foo_a; + debug foo_b => _foo_b; + { + match c { + true => tmp, + _ => ret, + } + } + tmp = { + // Because we don't know if `c` is always true, we must drop this debuginfo. + _foo_a = &(*foo).a; + Goto(ret) + } + ret = { + _foo_b = &(*foo).b; + RET = (*foo).c; + Return() + } + } +} + +// EMIT_MIR simplifycfg.preserve_debuginfo_1.SimplifyCfg-final.diff +#[custom_mir(dialect = "runtime", phase = "post-cleanup")] +pub fn preserve_debuginfo_1(foo: &Foo, v: &mut bool) -> i32 { + // CHECK-LABEL: fn preserve_debuginfo_1 + // CHECK: debug foo_a => [[foo_a:_[0-9]+]]; + // CHECK: debug foo_b => [[foo_b:_[0-9]+]]; + // CHECK: debug foo_c => [[foo_c:_[0-9]+]]; + // CHECK: bb0: { + // CHECK-NEXT: (*_2) = const true; + // CHECK-NEXT: DBG: [[foo_a]] = &((*_1).0: i32) + // CHECK-NEXT: DBG: [[foo_b]] = &((*_1).1: i64) + // CHECK-NEXT: _0 = copy ((*_1).2: i32); + // CHECK-NEXT: DBG: [[foo_c]] = &((*_1).2: i32) + // CHECK-NEXT: return; + mir! { + let _foo_a: &i32; + let _foo_b: &i64; + let _foo_c: &i32; + debug foo_a => _foo_a; + debug foo_b => _foo_b; + debug foo_c => _foo_c; + { + Goto(tmp) + } + tmp = { + *v = true; + _foo_a = &(*foo).a; + Goto(ret) + } + ret = { + _foo_b = &(*foo).b; + RET = (*foo).c; + _foo_c = &(*foo).c; + Return() + } + } +} + +// EMIT_MIR simplifycfg.preserve_debuginfo_2.SimplifyCfg-final.diff +#[custom_mir(dialect = "runtime", phase = "post-cleanup")] +pub fn preserve_debuginfo_2(foo: &Foo) -> i32 { + // CHECK-LABEL: fn preserve_debuginfo_2 + // CHECK: debug foo_a => [[foo_a:_[0-9]+]]; + // CHECK: debug foo_b => [[foo_b:_[0-9]+]]; + // CHECK: debug foo_c => [[foo_c:_[0-9]+]]; + // CHECK: bb0: { + // CHECK-NEXT: DBG: [[foo_a]] = &((*_1).0: i32) + // CHECK-NEXT: DBG: [[foo_b]] = &((*_1).1: i64) + // CHECK-NEXT: _0 = copy ((*_1).2: i32); + // CHECK-NEXT: DBG: [[foo_c]] = &((*_1).2: i32) + // CHECK-NEXT: return; + mir! { + let _foo_a: &i32; + let _foo_b: &i64; + let _foo_c: &i32; + debug foo_a => _foo_a; + debug foo_b => _foo_b; + debug foo_c => _foo_c; + { + Goto(tmp) + } + tmp = { + _foo_a = &(*foo).a; + Goto(ret) + } + ret = { + _foo_b = &(*foo).b; + RET = (*foo).c; + _foo_c = &(*foo).c; + Return() + } + } +} + +// EMIT_MIR simplifycfg.preserve_debuginfo_3.SimplifyCfg-final.diff +#[custom_mir(dialect = "runtime", phase = "post-cleanup")] +pub fn preserve_debuginfo_3(foo: &Foo, c: bool) -> i32 { + // CHECK-LABEL: fn preserve_debuginfo_3 + // CHECK: debug foo_a => [[foo_a:_[0-9]+]]; + // CHECK: debug foo_b => [[foo_b:_[0-9]+]]; + // CHECK: debug foo_c => [[foo_c:_[0-9]+]]; + // CHECK: bb0: { + // CHECK-NEXT: switchInt(copy _2) -> [1: bb2, otherwise: bb1]; + // CHECK: bb1: { + // CHECK-NEXT: DBG: [[foo_b]] = &((*_1).1: i64) + // CHECK-NEXT: _0 = copy ((*_1).2: i32); + // CHECK-NEXT: return; + // CHECK: bb2: { + // CHECK-NEXT: DBG: [[foo_a]] = &((*_1).0: i32) + // CHECK-NEXT: DBG: [[foo_c]] = &((*_1).2: i32) + // CHECK-NEXT: _0 = copy ((*_1).0: i32); + // CHECK-NEXT: return; + mir! { + let _foo_a: &i32; + let _foo_b: &i64; + let _foo_c: &i32; + debug foo_a => _foo_a; + debug foo_b => _foo_b; + debug foo_c => _foo_c; + { + match c { + true => tmp, + _ => ret, + } + } + tmp = { + _foo_a = &(*foo).a; + Goto(ret_1) + } + ret = { + _foo_b = &(*foo).b; + RET = (*foo).c; + Return() + } + ret_1 = { + _foo_c = &(*foo).c; + RET = (*foo).a; + Return() + } + } +} + +// EMIT_MIR simplifycfg.preserve_debuginfo_identical_succs.SimplifyCfg-final.diff +#[custom_mir(dialect = "runtime", phase = "post-cleanup")] +pub fn preserve_debuginfo_identical_succs(foo: &Foo, c: bool) -> i32 { + // CHECK-LABEL: fn preserve_debuginfo_identical_succs + // CHECK: debug foo_a => [[foo_a:_[0-9]+]]; + // CHECK: debug foo_b => [[foo_b:_[0-9]+]]; + // CHECK: debug foo_c => [[foo_c:_[0-9]+]]; + // CHECK: bb0: { + // CHECK-NEXT: DBG: [[foo_a]] = &((*_1).0: i32) + // CHECK-NEXT: DBG: [[foo_b]] = &((*_1).1: i64) + // CHECK-NEXT: _0 = copy ((*_1).2: i32); + // CHECK-NEXT: DBG: [[foo_c]] = &((*_1).2: i32) + // CHECK-NEXT: return; + mir! { + let _foo_a: &i32; + let _foo_b: &i64; + let _foo_c: &i32; + debug foo_a => _foo_a; + debug foo_b => _foo_b; + debug foo_c => _foo_c; + { + match c { + true => tmp, + _ => tmp, + } + } + tmp = { + _foo_a = &(*foo).a; + Goto(ret) + } + ret = { + _foo_b = &(*foo).b; + RET = (*foo).c; + _foo_c = &(*foo).c; + Return() + } + } +} |