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| author | bors <bors@rust-lang.org> | 2021-09-25 11:01:13 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2021-09-25 11:01:13 +0000 |
| commit | e9f29a851917a706c01b6f51331894df1d15770b (patch) | |
| tree | ad20f5095b566e7ac8f95f4befb6e6a019eec304 /compiler/rustc_mir_dataflow/src | |
| parent | 218a96cae06ed1a47549a81c09c3655fbcae1363 (diff) | |
| parent | ab64580977ca6dabc07f5944898435708bfbb0c8 (diff) | |
| download | rust-e9f29a851917a706c01b6f51331894df1d15770b.tar.gz rust-e9f29a851917a706c01b6f51331894df1d15770b.zip | |
Auto merge of #89030 - nbdd0121:box2, r=jonas-schievink
Introduce `Rvalue::ShallowInitBox` Polished version of #88700. Implements MCP rust-lang/compiler-team#460, and should allow #43596 to go forward. In short, creating an empty box is split from a nullary-op `NullOp::Box` into two steps, first a call to `exchange_malloc`, then a `Rvalue::ShallowInitBox` which transmutes `*mut u8` to a shallow-initialized `Box<T>`. This allows the `exchange_malloc` call to unwind. Details can be found in the MCP. `NullOp::Box` is not yet removed, purely to make reverting easier in case anything goes wrong as the result of this PR. If revert is needed a reversion of "Use Rvalue::ShallowInitBox for box expression" commit followed by a test bless should be sufficient. Experiments in #88700 showed a very slight compile-time perf regression due to (supposedly) slightly more time spent in LLVM. We could omit unwind edge generation (in non-`oom=panic` case) in box expression MIR construction to restore perf; but I don't think it's necessary since runtime perf isn't affected and perf difference is rather small.
Diffstat (limited to 'compiler/rustc_mir_dataflow/src')
| -rw-r--r-- | compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_mir_dataflow/src/move_paths/builder.rs | 1 |
2 files changed, 2 insertions, 0 deletions
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs index 81d84f80ad4..158ba1b9425 100644 --- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs +++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs @@ -169,6 +169,7 @@ where } mir::Rvalue::Cast(..) + | mir::Rvalue::ShallowInitBox(..) | mir::Rvalue::Use(..) | mir::Rvalue::ThreadLocalRef(..) | mir::Rvalue::Repeat(..) diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs index 407ba739463..e404b49ecb9 100644 --- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs +++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs @@ -327,6 +327,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> { Rvalue::Use(ref operand) | Rvalue::Repeat(ref operand, _) | Rvalue::Cast(_, ref operand, _) + | Rvalue::ShallowInitBox(ref operand, _) | Rvalue::UnaryOp(_, ref operand) => self.gather_operand(operand), Rvalue::BinaryOp(ref _binop, box (ref lhs, ref rhs)) | Rvalue::CheckedBinaryOp(ref _binop, box (ref lhs, ref rhs)) => { |