Rollup merge of #85196 - richkadel:reverts-cover-unreachable-statements, r=tmandry

Revert "Auto merge of #84797 - richkadel:cover-unreachable-statements…

This reverts commit e5f83d2, reversing
changes made to ac888e8.

See #84797 (comment)

r? `@tmandry`

Author: JohnTitor

compiler/rustc_mir/src/transform/const_goto.rs

@@ -47,7 +47,7 @@ impl<'tcx> MirPass<'tcx> for ConstGoto {
         // if we applied optimizations, we potentially have some cfg to cleanup to
         // make it easier for further passes
         if should_simplify {
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
             simplify_locals(body, tcx);
         }
     }

compiler/rustc_mir/src/transform/deduplicate_blocks.rs

@@ -26,7 +26,7 @@ impl<'tcx> MirPass<'tcx> for DeduplicateBlocks {
         if has_opts_to_apply {
             let mut opt_applier = OptApplier { tcx, duplicates };
             opt_applier.visit_body(body);
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
         }
     }
 }

compiler/rustc_mir/src/transform/early_otherwise_branch.rs

@@ -164,7 +164,7 @@ impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
         // Since this optimization adds new basic blocks and invalidates others,
         // clean up the cfg to make it nicer for other passes
         if should_cleanup {
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
         }
     }
 }

compiler/rustc_mir/src/transform/generator.rs

@@ -964,7 +964,7 @@ fn create_generator_drop_shim<'tcx>(
 
     // Make sure we remove dead blocks to remove
     // unrelated code from the resume part of the function
-    simplify::remove_dead_blocks(tcx, &mut body);
+    simplify::remove_dead_blocks(&mut body);
 
     dump_mir(tcx, None, "generator_drop", &0, &body, |_, _| Ok(()));
 
@@ -1137,7 +1137,7 @@ fn create_generator_resume_function<'tcx>(
 
     // Make sure we remove dead blocks to remove
     // unrelated code from the drop part of the function
-    simplify::remove_dead_blocks(tcx, body);
+    simplify::remove_dead_blocks(body);
 
     dump_mir(tcx, None, "generator_resume", &0, body, |_, _| Ok(()));
 }

compiler/rustc_mir/src/transform/inline.rs

@@ -57,7 +57,7 @@ impl<'tcx> MirPass<'tcx> for Inline {
         if inline(tcx, body) {
             debug!("running simplify cfg on {:?}", body.source);
             CfgSimplifier::new(body).simplify();
-            remove_dead_blocks(tcx, body);
+            remove_dead_blocks(body);
         }
     }
 }

compiler/rustc_mir/src/transform/match_branches.rs

@@ -167,7 +167,7 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
         }
 
         if should_cleanup {
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
         }
     }
 }

compiler/rustc_mir/src/transform/multiple_return_terminators.rs

@@ -38,6 +38,6 @@ impl<'tcx> MirPass<'tcx> for MultipleReturnTerminators {
             }
         }
 
-        simplify::remove_dead_blocks(tcx, body)
+        simplify::remove_dead_blocks(body)
     }
 }

compiler/rustc_mir/src/transform/remove_unneeded_drops.rs

@@ -36,7 +36,7 @@ impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops {
         // if we applied optimizations, we potentially have some cfg to cleanup to
         // make it easier for further passes
         if should_simplify {
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
         }
     }
 }

compiler/rustc_mir/src/transform/simplify.rs

@@ -29,7 +29,6 @@
 
 use crate::transform::MirPass;
 use rustc_index::vec::{Idx, IndexVec};
-use rustc_middle::mir::coverage::*;
 use rustc_middle::mir::visit::{MutVisitor, MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
 use rustc_middle::ty::TyCtxt;
@@ -47,9 +46,9 @@ impl SimplifyCfg {
     }
 }
 
-pub fn simplify_cfg(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) {
+pub fn simplify_cfg(body: &mut Body<'_>) {
     CfgSimplifier::new(body).simplify();
-    remove_dead_blocks(tcx, body);
+    remove_dead_blocks(body);
 
     // FIXME: Should probably be moved into some kind of pass manager
     body.basic_blocks_mut().raw.shrink_to_fit();
@@ -60,9 +59,9 @@ impl<'tcx> MirPass<'tcx> for SimplifyCfg {
         Cow::Borrowed(&self.label)
     }
 
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+    fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!("SimplifyCfg({:?}) - simplifying {:?}", self.label, body.source);
-        simplify_cfg(tcx, body);
+        simplify_cfg(body);
     }
 }
 
@@ -287,7 +286,7 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
     }
 }
 
-pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) {
+pub fn remove_dead_blocks(body: &mut Body<'_>) {
     let reachable = traversal::reachable_as_bitset(body);
     let num_blocks = body.basic_blocks().len();
     if num_blocks == reachable.count() {
@@ -307,11 +306,6 @@ pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) {
         }
         used_blocks += 1;
     }
-
-    if tcx.sess.instrument_coverage() {
-        save_unreachable_coverage(basic_blocks, used_blocks);
-    }
-
     basic_blocks.raw.truncate(used_blocks);
 
     for block in basic_blocks {
@@ -321,32 +315,6 @@ pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) {
     }
 }
 
-fn save_unreachable_coverage(
-    basic_blocks: &mut IndexVec<BasicBlock, BasicBlockData<'_>>,
-    first_dead_block: usize,
-) {
-    // retain coverage info for dead blocks, so coverage reports will still
-    // report `0` executions for the uncovered code regions.
-    let mut dropped_coverage = Vec::new();
-    for dead_block in first_dead_block..basic_blocks.len() {
-        for statement in basic_blocks[BasicBlock::new(dead_block)].statements.iter() {
-            if let StatementKind::Coverage(coverage) = &statement.kind {
-                if let Some(code_region) = &coverage.code_region {
-                    dropped_coverage.push((statement.source_info, code_region.clone()));
-                }
-            }
-        }
-    }
-    for (source_info, code_region) in dropped_coverage {
-        basic_blocks[START_BLOCK].statements.push(Statement {
-            source_info,
-            kind: StatementKind::Coverage(box Coverage {
-                kind: CoverageKind::Unreachable,
-                code_region: Some(code_region),
-            }),
-        })
-    }
-}
 pub struct SimplifyLocals;
 
 impl<'tcx> MirPass<'tcx> for SimplifyLocals {

compiler/rustc_mir/src/transform/simplify_try.rs

@@ -558,7 +558,7 @@ impl<'tcx> MirPass<'tcx> for SimplifyBranchSame {
 
         if did_remove_blocks {
             // We have dead blocks now, so remove those.
-            simplify::remove_dead_blocks(tcx, body);
+            simplify::remove_dead_blocks(body);
         }
     }
 }