diff --git a/compiler/rustc_mir_transform/src/deduplicate_blocks.rs b/compiler/rustc_mir_transform/src/deduplicate_blocks.rs deleted file mode 100644 index 63257df66fb9b..0000000000000 --- a/compiler/rustc_mir_transform/src/deduplicate_blocks.rs +++ /dev/null @@ -1,195 +0,0 @@ -//! This pass finds basic blocks that are completely equal, -//! and replaces all uses with just one of them. - -use std::collections::hash_map::Entry; -use std::hash::{Hash, Hasher}; -use std::iter; - -use rustc_data_structures::fx::FxHashMap; -use rustc_middle::mir::visit::MutVisitor; -use rustc_middle::mir::*; -use rustc_middle::ty::TyCtxt; -use tracing::debug; - -use super::simplify::simplify_cfg; - -pub(super) struct DeduplicateBlocks; - -impl<'tcx> crate::MirPass<'tcx> for DeduplicateBlocks { - fn is_enabled(&self, sess: &rustc_session::Session) -> bool { - sess.mir_opt_level() >= 4 - } - - fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { - debug!("Running DeduplicateBlocks on `{:?}`", body.source); - let duplicates = find_duplicates(body); - let has_opts_to_apply = !duplicates.is_empty(); - - if has_opts_to_apply { - let mut opt_applier = OptApplier { tcx, duplicates }; - opt_applier.visit_body(body); - simplify_cfg(body); - } - } - - fn is_required(&self) -> bool { - false - } -} - -struct OptApplier<'tcx> { - tcx: TyCtxt<'tcx>, - duplicates: FxHashMap, -} - -impl<'tcx> MutVisitor<'tcx> for OptApplier<'tcx> { - fn tcx(&self) -> TyCtxt<'tcx> { - self.tcx - } - - fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, location: Location) { - for target in terminator.successors_mut() { - if let Some(replacement) = self.duplicates.get(target) { - debug!("SUCCESS: Replacing: `{:?}` with `{:?}`", target, replacement); - *target = *replacement; - } - } - - self.super_terminator(terminator, location); - } -} - -fn find_duplicates(body: &Body<'_>) -> FxHashMap { - let mut duplicates = FxHashMap::default(); - - let bbs_to_go_through = - body.basic_blocks.iter_enumerated().filter(|(_, bbd)| !bbd.is_cleanup).count(); - - let mut same_hashes = - FxHashMap::with_capacity_and_hasher(bbs_to_go_through, Default::default()); - - // Go through the basic blocks backwards. This means that in case of duplicates, - // we can use the basic block with the highest index as the replacement for all lower ones. - // For example, if bb1, bb2 and bb3 are duplicates, we will first insert bb3 in same_hashes. - // Then we will see that bb2 is a duplicate of bb3, - // and insert bb2 with the replacement bb3 in the duplicates list. - // When we see bb1, we see that it is a duplicate of bb3, and therefore insert it in the - // duplicates list with replacement bb3. - // When the duplicates are removed, we will end up with only bb3. - for (bb, bbd) in body.basic_blocks.iter_enumerated().rev().filter(|(_, bbd)| !bbd.is_cleanup) { - // Basic blocks can get really big, so to avoid checking for duplicates in basic blocks - // that are unlikely to have duplicates, we stop early. The early bail number has been - // found experimentally by eprintln while compiling the crates in the rustc-perf suite. - if bbd.statements.len() > 10 { - continue; - } - - let to_hash = BasicBlockHashable { basic_block_data: bbd }; - let entry = same_hashes.entry(to_hash); - match entry { - Entry::Occupied(occupied) => { - // The basic block was already in the hashmap, which means we have a duplicate - let value = *occupied.get(); - debug!("Inserting {:?} -> {:?}", bb, value); - duplicates.try_insert(bb, value).expect("key was already inserted"); - } - Entry::Vacant(vacant) => { - vacant.insert(bb); - } - } - } - - duplicates -} - -struct BasicBlockHashable<'a, 'tcx> { - basic_block_data: &'a BasicBlockData<'tcx>, -} - -impl Hash for BasicBlockHashable<'_, '_> { - fn hash(&self, state: &mut H) { - hash_statements(state, self.basic_block_data.statements.iter()); - // Note that since we only hash the kind, we lose span information if we deduplicate the - // blocks. - self.basic_block_data.terminator().kind.hash(state); - } -} - -impl Eq for BasicBlockHashable<'_, '_> {} - -impl PartialEq for BasicBlockHashable<'_, '_> { - fn eq(&self, other: &Self) -> bool { - self.basic_block_data.statements.len() == other.basic_block_data.statements.len() - && &self.basic_block_data.terminator().kind == &other.basic_block_data.terminator().kind - && iter::zip(&self.basic_block_data.statements, &other.basic_block_data.statements) - .all(|(x, y)| statement_eq(&x.kind, &y.kind)) - } -} - -fn hash_statements<'a, 'tcx, H: Hasher>( - hasher: &mut H, - iter: impl Iterator>, -) where - 'tcx: 'a, -{ - for stmt in iter { - statement_hash(hasher, &stmt.kind); - } -} - -fn statement_hash(hasher: &mut H, stmt: &StatementKind<'_>) { - match stmt { - StatementKind::Assign(box (place, rvalue)) => { - place.hash(hasher); - rvalue_hash(hasher, rvalue) - } - x => x.hash(hasher), - }; -} - -fn rvalue_hash(hasher: &mut H, rvalue: &Rvalue<'_>) { - match rvalue { - Rvalue::Use(op) => operand_hash(hasher, op), - x => x.hash(hasher), - }; -} - -fn operand_hash(hasher: &mut H, operand: &Operand<'_>) { - match operand { - Operand::Constant(box ConstOperand { user_ty: _, const_, span: _ }) => const_.hash(hasher), - x => x.hash(hasher), - }; -} - -fn statement_eq<'tcx>(lhs: &StatementKind<'tcx>, rhs: &StatementKind<'tcx>) -> bool { - let res = match (lhs, rhs) { - ( - StatementKind::Assign(box (place, rvalue)), - StatementKind::Assign(box (place2, rvalue2)), - ) => place == place2 && rvalue_eq(rvalue, rvalue2), - (x, y) => x == y, - }; - debug!("statement_eq lhs: `{:?}` rhs: `{:?}` result: {:?}", lhs, rhs, res); - res -} - -fn rvalue_eq<'tcx>(lhs: &Rvalue<'tcx>, rhs: &Rvalue<'tcx>) -> bool { - let res = match (lhs, rhs) { - (Rvalue::Use(op1), Rvalue::Use(op2)) => operand_eq(op1, op2), - (x, y) => x == y, - }; - debug!("rvalue_eq lhs: `{:?}` rhs: `{:?}` result: {:?}", lhs, rhs, res); - res -} - -fn operand_eq<'tcx>(lhs: &Operand<'tcx>, rhs: &Operand<'tcx>) -> bool { - let res = match (lhs, rhs) { - ( - Operand::Constant(box ConstOperand { user_ty: _, const_, span: _ }), - Operand::Constant(box ConstOperand { user_ty: _, const_: const2, span: _ }), - ) => const_ == const2, - (x, y) => x == y, - }; - debug!("operand_eq lhs: `{:?}` rhs: `{:?}` result: {:?}", lhs, rhs, res); - res -} diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index b572f6ca0b36a..397d21a857f00 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -135,7 +135,6 @@ declare_passes! { Initial, Final }; - mod deduplicate_blocks : DeduplicateBlocks; mod deref_separator : Derefer; mod dest_prop : DestinationPropagation; pub mod dump_mir : Marker; @@ -700,7 +699,6 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { &nrvo::RenameReturnPlace, &simplify::SimplifyLocals::Final, &multiple_return_terminators::MultipleReturnTerminators, - &deduplicate_blocks::DeduplicateBlocks, &large_enums::EnumSizeOpt { discrepancy: 128 }, // Some cleanup necessary at least for LLVM and potentially other codegen backends. &add_call_guards::CriticalCallEdges, diff --git a/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-abort.diff b/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-abort.diff deleted file mode 100644 index 60742ef0e9a90..0000000000000 --- a/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-abort.diff +++ /dev/null @@ -1,100 +0,0 @@ -- // MIR for `is_line_doc_comment_2` before DeduplicateBlocks -+ // MIR for `is_line_doc_comment_2` after DeduplicateBlocks - - fn is_line_doc_comment_2(_1: &str) -> bool { - debug s => _1; - let mut _0: bool; - let mut _2: &[u8]; - let mut _3: &str; - let mut _4: usize; - let mut _5: usize; - let mut _6: bool; - let mut _7: usize; - let mut _8: usize; - let mut _9: bool; - - bb0: { - StorageLive(_2); - StorageLive(_3); - _3 = &(*_1); - _2 = core::str::::as_bytes(move _3) -> [return: bb1, unwind unreachable]; - } - - bb1: { - StorageDead(_3); - _4 = Len((*_2)); - _5 = const 4_usize; - _6 = Ge(move _4, move _5); - switchInt(move _6) -> [0: bb2, otherwise: bb3]; - } - - bb2: { - _7 = Len((*_2)); - _8 = const 3_usize; - _9 = Ge(move _7, move _8); -- switchInt(move _9) -> [0: bb7, otherwise: bb8]; -+ switchInt(move _9) -> [0: bb11, otherwise: bb7]; - } - - bb3: { - switchInt(copy (*_2)[0 of 4]) -> [47: bb4, otherwise: bb2]; - } - - bb4: { - switchInt(copy (*_2)[1 of 4]) -> [47: bb5, otherwise: bb2]; - } - - bb5: { - switchInt(copy (*_2)[2 of 4]) -> [47: bb6, otherwise: bb2]; - } - - bb6: { -- switchInt(copy (*_2)[3 of 4]) -> [47: bb13, otherwise: bb2]; -+ switchInt(copy (*_2)[3 of 4]) -> [47: bb11, otherwise: bb2]; - } - - bb7: { -- _0 = const false; -- goto -> bb14; -+ switchInt(copy (*_2)[0 of 3]) -> [47: bb8, otherwise: bb11]; - } - - bb8: { -- switchInt(copy (*_2)[0 of 3]) -> [47: bb9, otherwise: bb7]; -+ switchInt(copy (*_2)[1 of 3]) -> [47: bb9, otherwise: bb11]; - } - - bb9: { -- switchInt(copy (*_2)[1 of 3]) -> [47: bb10, otherwise: bb7]; -+ switchInt(copy (*_2)[2 of 3]) -> [47: bb10, 33: bb10, otherwise: bb11]; - } - - bb10: { -- switchInt(copy (*_2)[2 of 3]) -> [47: bb12, 33: bb11, otherwise: bb7]; -- } -- -- bb11: { - _0 = const true; -- goto -> bb14; -+ goto -> bb12; - } - -- bb12: { -- _0 = const true; -- goto -> bb14; -- } -- -- bb13: { -+ bb11: { - _0 = const false; -- goto -> bb14; -+ goto -> bb12; - } - -- bb14: { -+ bb12: { - StorageDead(_2); - return; - } - } - diff --git a/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-unwind.diff b/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-unwind.diff deleted file mode 100644 index 7337a32f525f9..0000000000000 --- a/tests/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.panic-unwind.diff +++ /dev/null @@ -1,100 +0,0 @@ -- // MIR for `is_line_doc_comment_2` before DeduplicateBlocks -+ // MIR for `is_line_doc_comment_2` after DeduplicateBlocks - - fn is_line_doc_comment_2(_1: &str) -> bool { - debug s => _1; - let mut _0: bool; - let mut _2: &[u8]; - let mut _3: &str; - let mut _4: usize; - let mut _5: usize; - let mut _6: bool; - let mut _7: usize; - let mut _8: usize; - let mut _9: bool; - - bb0: { - StorageLive(_2); - StorageLive(_3); - _3 = &(*_1); - _2 = core::str::::as_bytes(move _3) -> [return: bb1, unwind continue]; - } - - bb1: { - StorageDead(_3); - _4 = Len((*_2)); - _5 = const 4_usize; - _6 = Ge(move _4, move _5); - switchInt(move _6) -> [0: bb2, otherwise: bb3]; - } - - bb2: { - _7 = Len((*_2)); - _8 = const 3_usize; - _9 = Ge(move _7, move _8); -- switchInt(move _9) -> [0: bb7, otherwise: bb8]; -+ switchInt(move _9) -> [0: bb11, otherwise: bb7]; - } - - bb3: { - switchInt(copy (*_2)[0 of 4]) -> [47: bb4, otherwise: bb2]; - } - - bb4: { - switchInt(copy (*_2)[1 of 4]) -> [47: bb5, otherwise: bb2]; - } - - bb5: { - switchInt(copy (*_2)[2 of 4]) -> [47: bb6, otherwise: bb2]; - } - - bb6: { -- switchInt(copy (*_2)[3 of 4]) -> [47: bb13, otherwise: bb2]; -+ switchInt(copy (*_2)[3 of 4]) -> [47: bb11, otherwise: bb2]; - } - - bb7: { -- _0 = const false; -- goto -> bb14; -+ switchInt(copy (*_2)[0 of 3]) -> [47: bb8, otherwise: bb11]; - } - - bb8: { -- switchInt(copy (*_2)[0 of 3]) -> [47: bb9, otherwise: bb7]; -+ switchInt(copy (*_2)[1 of 3]) -> [47: bb9, otherwise: bb11]; - } - - bb9: { -- switchInt(copy (*_2)[1 of 3]) -> [47: bb10, otherwise: bb7]; -+ switchInt(copy (*_2)[2 of 3]) -> [47: bb10, 33: bb10, otherwise: bb11]; - } - - bb10: { -- switchInt(copy (*_2)[2 of 3]) -> [47: bb12, 33: bb11, otherwise: bb7]; -- } -- -- bb11: { - _0 = const true; -- goto -> bb14; -+ goto -> bb12; - } - -- bb12: { -- _0 = const true; -- goto -> bb14; -- } -- -- bb13: { -+ bb11: { - _0 = const false; -- goto -> bb14; -+ goto -> bb12; - } - -- bb14: { -+ bb12: { - StorageDead(_2); - return; - } - } - diff --git a/tests/mir-opt/deduplicate_blocks.rs b/tests/mir-opt/deduplicate_blocks.rs deleted file mode 100644 index 3a164cb09a094..0000000000000 --- a/tests/mir-opt/deduplicate_blocks.rs +++ /dev/null @@ -1,17 +0,0 @@ -// skip-filecheck -// EMIT_MIR_FOR_EACH_PANIC_STRATEGY -//@ test-mir-pass: DeduplicateBlocks - -// EMIT_MIR deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff -pub const fn is_line_doc_comment_2(s: &str) -> bool { - match s.as_bytes() { - [b'/', b'/', b'/', b'/', ..] => false, - [b'/', b'/', b'/', ..] => true, - [b'/', b'/', b'!', ..] => true, - _ => false, - } -} - -fn main() { - is_line_doc_comment_2("asd"); -}