Merge pull request #18566 from lnicola/sync-from-rust

minor: Sync from downstream

1 files changed, 20 insertions, 150 deletions

diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 2e4c503f3ce..02fd289b6ef 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -13,17 +13,16 @@ use rustc_hir::intravisit::{Visitor, walk_expr};
 use rustc_middle::hir::map::Map;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::mir::coverage::{
-    CoverageKind, DecisionInfo, FunctionCoverageInfo, Mapping, MappingKind, SourceRegion,
+    CoverageKind, DecisionInfo, FunctionCoverageInfo, Mapping, MappingKind,
 };
 use rustc_middle::mir::{
     self, BasicBlock, BasicBlockData, SourceInfo, Statement, StatementKind, Terminator,
     TerminatorKind,
 };
 use rustc_middle::ty::TyCtxt;
+use rustc_span::Span;
 use rustc_span::def_id::LocalDefId;
-use rustc_span::source_map::SourceMap;
-use rustc_span::{BytePos, Pos, RelativeBytePos, Span, Symbol};
-use tracing::{debug, debug_span, instrument, trace};
+use tracing::{debug, debug_span, trace};
 
 use crate::coverage::counters::{CounterIncrementSite, CoverageCounters};
 use crate::coverage::graph::CoverageGraph;
@@ -97,7 +96,7 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
     let coverage_counters =
         CoverageCounters::make_bcb_counters(&basic_coverage_blocks, &bcbs_with_counter_mappings);
 
-    let mappings = create_mappings(tcx, &hir_info, &extracted_mappings, &coverage_counters);
+    let mappings = create_mappings(&extracted_mappings, &coverage_counters);
     if mappings.is_empty() {
         // No spans could be converted into valid mappings, so skip this function.
         debug!("no spans could be converted into valid mappings; skipping");
@@ -122,6 +121,7 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
 
     mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
         function_source_hash: hir_info.function_source_hash,
+        body_span: hir_info.body_span,
         num_counters: coverage_counters.num_counters(),
         mcdc_bitmap_bits: extracted_mappings.mcdc_bitmap_bits,
         expressions: coverage_counters.into_expressions(),
@@ -135,26 +135,12 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
 ///
 /// Precondition: All BCBs corresponding to those spans have been given
 /// coverage counters.
-fn create_mappings<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    hir_info: &ExtractedHirInfo,
+fn create_mappings(
     extracted_mappings: &ExtractedMappings,
     coverage_counters: &CoverageCounters,
 ) -> Vec<Mapping> {
-    let source_map = tcx.sess.source_map();
-    let body_span = hir_info.body_span;
-
-    let source_file = source_map.lookup_source_file(body_span.lo());
-
-    use rustc_session::RemapFileNameExt;
-    use rustc_session::config::RemapPathScopeComponents;
-    let file_name = Symbol::intern(
-        &source_file.name.for_scope(tcx.sess, RemapPathScopeComponents::MACRO).to_string_lossy(),
-    );
-
     let term_for_bcb =
         |bcb| coverage_counters.term_for_bcb(bcb).expect("all BCBs with spans were given counters");
-    let region_for_span = |span: Span| make_source_region(source_map, file_name, span, body_span);
 
     // Fully destructure the mappings struct to make sure we don't miss any kinds.
     let ExtractedMappings {
@@ -167,22 +153,20 @@ fn create_mappings<'tcx>(
     } = extracted_mappings;
     let mut mappings = Vec::new();
 
-    mappings.extend(code_mappings.iter().filter_map(
+    mappings.extend(code_mappings.iter().map(
         // Ordinary code mappings are the simplest kind.
         |&mappings::CodeMapping { span, bcb }| {
-            let source_region = region_for_span(span)?;
             let kind = MappingKind::Code(term_for_bcb(bcb));
-            Some(Mapping { kind, source_region })
+            Mapping { kind, span }
         },
     ));
 
-    mappings.extend(branch_pairs.iter().filter_map(
+    mappings.extend(branch_pairs.iter().map(
         |&mappings::BranchPair { span, true_bcb, false_bcb }| {
             let true_term = term_for_bcb(true_bcb);
             let false_term = term_for_bcb(false_bcb);
             let kind = MappingKind::Branch { true_term, false_term };
-            let source_region = region_for_span(span)?;
-            Some(Mapping { kind, source_region })
+            Mapping { kind, span }
         },
     ));
 
@@ -190,7 +174,7 @@ fn create_mappings<'tcx>(
         |bcb| coverage_counters.term_for_bcb(bcb).expect("all BCBs with spans were given counters");
 
     // MCDC branch mappings are appended with their decisions in case decisions were ignored.
-    mappings.extend(mcdc_degraded_branches.iter().filter_map(
+    mappings.extend(mcdc_degraded_branches.iter().map(
         |&mappings::MCDCBranch {
              span,
              true_bcb,
@@ -199,10 +183,9 @@ fn create_mappings<'tcx>(
              true_index: _,
              false_index: _,
          }| {
-            let source_region = region_for_span(span)?;
             let true_term = term_for_bcb(true_bcb);
             let false_term = term_for_bcb(false_bcb);
-            Some(Mapping { kind: MappingKind::Branch { true_term, false_term }, source_region })
+            Mapping { kind: MappingKind::Branch { true_term, false_term }, span }
         },
     ));
 
@@ -210,7 +193,7 @@ fn create_mappings<'tcx>(
         let num_conditions = branches.len() as u16;
         let conditions = branches
             .into_iter()
-            .filter_map(
+            .map(
                 |&mappings::MCDCBranch {
                      span,
                      true_bcb,
@@ -219,31 +202,29 @@ fn create_mappings<'tcx>(
                      true_index: _,
                      false_index: _,
                  }| {
-                    let source_region = region_for_span(span)?;
                     let true_term = term_for_bcb(true_bcb);
                     let false_term = term_for_bcb(false_bcb);
-                    Some(Mapping {
+                    Mapping {
                         kind: MappingKind::MCDCBranch {
                             true_term,
                             false_term,
                             mcdc_params: condition_info,
                         },
-                        source_region,
-                    })
+                        span,
+                    }
                 },
             )
             .collect::<Vec<_>>();
 
-        if conditions.len() == num_conditions as usize
-            && let Some(source_region) = region_for_span(decision.span)
-        {
+        if conditions.len() == num_conditions as usize {
             // LLVM requires end index for counter mapping regions.
             let kind = MappingKind::MCDCDecision(DecisionInfo {
                 bitmap_idx: (decision.bitmap_idx + decision.num_test_vectors) as u32,
                 num_conditions,
             });
             mappings.extend(
-                std::iter::once(Mapping { kind, source_region }).chain(conditions.into_iter()),
+                std::iter::once(Mapping { kind, span: decision.span })
+                    .chain(conditions.into_iter()),
             );
         } else {
             mappings.extend(conditions.into_iter().map(|mapping| {
@@ -252,10 +233,7 @@ fn create_mappings<'tcx>(
                 else {
                     unreachable!("all mappings here are MCDCBranch as shown above");
                 };
-                Mapping {
-                    kind: MappingKind::Branch { true_term, false_term },
-                    source_region: mapping.source_region,
-                }
+                Mapping { kind: MappingKind::Branch { true_term, false_term }, span: mapping.span }
             }))
         }
     }
@@ -398,114 +376,6 @@ fn inject_statement(mir_body: &mut mir::Body<'_>, counter_kind: CoverageKind, bb
     data.statements.insert(0, statement);
 }
 
-/// Convert the Span into its file name, start line and column, and end line and column.
-///
-/// Line numbers and column numbers are 1-based. Unlike most column numbers emitted by
-/// the compiler, these column numbers are denoted in **bytes**, because that's what
-/// LLVM's `llvm-cov` tool expects to see in coverage maps.
-///
-/// Returns `None` if the conversion failed for some reason. This shouldn't happen,
-/// but it's hard to rule out entirely (especially in the presence of complex macros
-/// or other expansions), and if it does happen then skipping a span or function is
-/// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
-#[instrument(level = "debug", skip(source_map))]
-fn make_source_region(
-    source_map: &SourceMap,
-    file_name: Symbol,
-    span: Span,
-    body_span: Span,
-) -> Option<SourceRegion> {
-    let lo = span.lo();
-    let hi = span.hi();
-
-    let file = source_map.lookup_source_file(lo);
-    if !file.contains(hi) {
-        debug!(?span, ?file, ?lo, ?hi, "span crosses multiple files; skipping");
-        return None;
-    }
-
-    // Column numbers need to be in bytes, so we can't use the more convenient
-    // `SourceMap` methods for looking up file coordinates.
-    let rpos_and_line_and_byte_column = |pos: BytePos| -> Option<(RelativeBytePos, usize, usize)> {
-        let rpos = file.relative_position(pos);
-        let line_index = file.lookup_line(rpos)?;
-        let line_start = file.lines()[line_index];
-        // Line numbers and column numbers are 1-based, so add 1 to each.
-        Some((rpos, line_index + 1, (rpos - line_start).to_usize() + 1))
-    };
-
-    let (lo_rpos, mut start_line, mut start_col) = rpos_and_line_and_byte_column(lo)?;
-    let (hi_rpos, mut end_line, mut end_col) = rpos_and_line_and_byte_column(hi)?;
-
-    // If the span is empty, try to expand it horizontally by one character's
-    // worth of bytes, so that it is more visible in `llvm-cov` reports.
-    // We do this after resolving line/column numbers, so that empty spans at the
-    // end of a line get an extra column instead of wrapping to the next line.
-    if span.is_empty()
-        && body_span.contains(span)
-        && let Some(src) = &file.src
-    {
-        // Prefer to expand the end position, if it won't go outside the body span.
-        if hi < body_span.hi() {
-            let hi_rpos = hi_rpos.to_usize();
-            let nudge_bytes = src.ceil_char_boundary(hi_rpos + 1) - hi_rpos;
-            end_col += nudge_bytes;
-        } else if lo > body_span.lo() {
-            let lo_rpos = lo_rpos.to_usize();
-            let nudge_bytes = lo_rpos - src.floor_char_boundary(lo_rpos - 1);
-            // Subtract the nudge, but don't go below column 1.
-            start_col = start_col.saturating_sub(nudge_bytes).max(1);
-        }
-        // If neither nudge could be applied, stick with the empty span coordinates.
-    }
-
-    // Apply an offset so that code in doctests has correct line numbers.
-    // FIXME(#79417): Currently we have no way to offset doctest _columns_.
-    start_line = source_map.doctest_offset_line(&file.name, start_line);
-    end_line = source_map.doctest_offset_line(&file.name, end_line);
-
-    check_source_region(SourceRegion {
-        file_name,
-        start_line: start_line as u32,
-        start_col: start_col as u32,
-        end_line: end_line as u32,
-        end_col: end_col as u32,
-    })
-}
-
-/// If `llvm-cov` sees a source region that is improperly ordered (end < start),
-/// it will immediately exit with a fatal error. To prevent that from happening,
-/// discard regions that are improperly ordered, or might be interpreted in a
-/// way that makes them improperly ordered.
-fn check_source_region(source_region: SourceRegion) -> Option<SourceRegion> {
-    let SourceRegion { file_name: _, start_line, start_col, end_line, end_col } = source_region;
-
-    // Line/column coordinates are supposed to be 1-based. If we ever emit
-    // coordinates of 0, `llvm-cov` might misinterpret them.
-    let all_nonzero = [start_line, start_col, end_line, end_col].into_iter().all(|x| x != 0);
-    // Coverage mappings use the high bit of `end_col` to indicate that a
-    // region is actually a "gap" region, so make sure it's unset.
-    let end_col_has_high_bit_unset = (end_col & (1 << 31)) == 0;
-    // If a region is improperly ordered (end < start), `llvm-cov` will exit
-    // with a fatal error, which is inconvenient for users and hard to debug.
-    let is_ordered = (start_line, start_col) <= (end_line, end_col);
-
-    if all_nonzero && end_col_has_high_bit_unset && is_ordered {
-        Some(source_region)
-    } else {
-        debug!(
-            ?source_region,
-            ?all_nonzero,
-            ?end_col_has_high_bit_unset,
-            ?is_ordered,
-            "Skipping source region that would be misinterpreted or rejected by LLVM"
-        );
-        // If this happens in a debug build, ICE to make it easier to notice.
-        debug_assert!(false, "Improper source region: {source_region:?}");
-        None
-    }
-}
-
 /// Function information extracted from HIR by the coverage instrumentor.
 #[derive(Debug)]
 struct ExtractedHirInfo {