Remove ConstGoto and SeparateConstSwitch.

1 files changed, 0 insertions, 128 deletions

diff --git a/compiler/rustc_mir_transform/src/const_goto.rs b/compiler/rustc_mir_transform/src/const_goto.rs
deleted file mode 100644
index cb5b66b314d..00000000000
--- a/compiler/rustc_mir_transform/src/const_goto.rs
+++ /dev/null
@@ -1,128 +0,0 @@
-//! This pass optimizes the following sequence
-//! ```rust,ignore (example)
-//! bb2: {
-//!     _2 = const true;
-//!     goto -> bb3;
-//! }
-//!
-//! bb3: {
-//!     switchInt(_2) -> [false: bb4, otherwise: bb5];
-//! }
-//! ```
-//! into
-//! ```rust,ignore (example)
-//! bb2: {
-//!     _2 = const true;
-//!     goto -> bb5;
-//! }
-//! ```
-
-use rustc_middle::mir::*;
-use rustc_middle::ty::TyCtxt;
-use rustc_middle::{mir::visit::Visitor, ty::ParamEnv};
-
-use super::simplify::{simplify_cfg, simplify_locals};
-
-pub struct ConstGoto;
-
-impl<'tcx> MirPass<'tcx> for ConstGoto {
-    fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        // This pass participates in some as-of-yet untested unsoundness found
-        // in https://github.com/rust-lang/rust/issues/112460
-        sess.mir_opt_level() >= 2 && sess.opts.unstable_opts.unsound_mir_opts
-    }
-
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        trace!("Running ConstGoto on {:?}", body.source);
-        let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
-        let mut opt_finder =
-            ConstGotoOptimizationFinder { tcx, body, optimizations: vec![], param_env };
-        opt_finder.visit_body(body);
-        let should_simplify = !opt_finder.optimizations.is_empty();
-        for opt in opt_finder.optimizations {
-            let block = &mut body.basic_blocks_mut()[opt.bb_with_goto];
-            block.statements.extend(opt.stmts_move_up);
-            let terminator = block.terminator_mut();
-            let new_goto = TerminatorKind::Goto { target: opt.target_to_use_in_goto };
-            debug!("SUCCESS: replacing `{:?}` with `{:?}`", terminator.kind, new_goto);
-            terminator.kind = new_goto;
-        }
-
-        // if we applied optimizations, we potentially have some cfg to cleanup to
-        // make it easier for further passes
-        if should_simplify {
-            simplify_cfg(body);
-            simplify_locals(body, tcx);
-        }
-    }
-}
-
-impl<'tcx> Visitor<'tcx> for ConstGotoOptimizationFinder<'_, 'tcx> {
-    fn visit_basic_block_data(&mut self, block: BasicBlock, data: &BasicBlockData<'tcx>) {
-        if data.is_cleanup {
-            // Because of the restrictions around control flow in cleanup blocks, we don't perform
-            // this optimization at all in such blocks.
-            return;
-        }
-        self.super_basic_block_data(block, data);
-    }
-
-    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
-        let _: Option<_> = try {
-            let target = terminator.kind.as_goto()?;
-            // We only apply this optimization if the last statement is a const assignment
-            let last_statement = self.body.basic_blocks[location.block].statements.last()?;
-
-            if let (place, Rvalue::Use(Operand::Constant(_const))) =
-                last_statement.kind.as_assign()?
-            {
-                // We found a constant being assigned to `place`.
-                // Now check that the target of this Goto switches on this place.
-                let target_bb = &self.body.basic_blocks[target];
-
-                // The `StorageDead(..)` statement does not affect the functionality of mir.
-                // We can move this part of the statement up to the predecessor.
-                let mut stmts_move_up = Vec::new();
-                for stmt in &target_bb.statements {
-                    if let StatementKind::StorageDead(..) = stmt.kind {
-                        stmts_move_up.push(stmt.clone())
-                    } else {
-                        None?;
-                    }
-                }
-
-                let target_bb_terminator = target_bb.terminator();
-                let (discr, targets) = target_bb_terminator.kind.as_switch()?;
-                if discr.place() == Some(*place) {
-                    let switch_ty = place.ty(self.body.local_decls(), self.tcx).ty;
-                    debug_assert_eq!(switch_ty, _const.ty());
-                    // We now know that the Switch matches on the const place, and it is statementless
-                    // Now find which value in the Switch matches the const value.
-                    let const_value = _const.const_.try_eval_bits(self.tcx, self.param_env)?;
-                    let target_to_use_in_goto = targets.target_for_value(const_value);
-                    self.optimizations.push(OptimizationToApply {
-                        bb_with_goto: location.block,
-                        target_to_use_in_goto,
-                        stmts_move_up,
-                    });
-                }
-            }
-            Some(())
-        };
-
-        self.super_terminator(terminator, location);
-    }
-}
-
-struct OptimizationToApply<'tcx> {
-    bb_with_goto: BasicBlock,
-    target_to_use_in_goto: BasicBlock,
-    stmts_move_up: Vec<Statement<'tcx>>,
-}
-
-pub struct ConstGotoOptimizationFinder<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    body: &'a Body<'tcx>,
-    param_env: ParamEnv<'tcx>,
-    optimizations: Vec<OptimizationToApply<'tcx>>,
-}