Auto merge of #137176 - matthiaskrgr:rollup-eht05gr, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #136959 (Simplify switch sources)
 - #137020 (Pass vendored sources from bootstrap to generate-copyright)
 - #137073 (boostrap: skip no_std targets in Std doc step)
 - #137165 (Use `tell` for `<File as Seek>::stream_position`)
 - #137166 (Update default loongarch code model in docs)
 - #137168 (correct comment)
 - #137169 (CI: rfl: move job forward to Linux v6.14-rc3)
 - #137170 (Allow configuring jemalloc per target)
 - #137173 (Subtree update of `rust-analyzer`)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_middle/src/mir/basic_blocks.rs

@@ -20,7 +20,22 @@ pub struct BasicBlocks<'tcx> {
 // Typically 95%+ of basic blocks have 4 or fewer predecessors.
 type Predecessors = IndexVec<BasicBlock, SmallVec<[BasicBlock; 4]>>;
 
-type SwitchSources = FxHashMap<(BasicBlock, BasicBlock), SmallVec<[Option<u128>; 1]>>;
+/// Each `(target, switch)` entry in the map contains a list of switch values
+/// that lead to a `target` block from a `switch` block.
+///
+/// Note: this type is currently never instantiated, because it's only used for
+/// `BasicBlocks::switch_sources`, which is only called by backwards analyses
+/// that do `SwitchInt` handling, and we don't have any of those, not even in
+/// tests. See #95120 and #94576.
+type SwitchSources = FxHashMap<(BasicBlock, BasicBlock), SmallVec<[SwitchTargetValue; 1]>>;
+
+#[derive(Debug, Clone, Copy)]
+pub enum SwitchTargetValue {
+    // A normal switch value.
+    Normal(u128),
+    // The final "otherwise" fallback value.
+    Otherwise,
+}
 
 #[derive(Clone, Default, Debug)]
 struct Cache {
@@ -70,8 +85,8 @@ impl<'tcx> BasicBlocks<'tcx> {
         })
     }
 
-    /// `switch_sources()[&(target, switch)]` returns a list of switch
-    /// values that lead to a `target` block from a `switch` block.
+    /// Returns info about switch values that lead from one block to another
+    /// block. See `SwitchSources`.
     #[inline]
     pub fn switch_sources(&self) -> &SwitchSources {
         self.cache.switch_sources.get_or_init(|| {
@@ -82,9 +97,15 @@ impl<'tcx> BasicBlocks<'tcx> {
                 }) = &data.terminator
                 {
                     for (value, target) in targets.iter() {
-                        switch_sources.entry((target, bb)).or_default().push(Some(value));
+                        switch_sources
+                            .entry((target, bb))
+                            .or_default()
+                            .push(SwitchTargetValue::Normal(value));
                     }
-                    switch_sources.entry((targets.otherwise(), bb)).or_default().push(None);
+                    switch_sources
+                        .entry((targets.otherwise(), bb))
+                        .or_default()
+                        .push(SwitchTargetValue::Otherwise);
                 }
             }
             switch_sources

compiler/rustc_middle/src/mir/mod.rs

@@ -7,7 +7,7 @@ use std::fmt::{self, Debug, Formatter};
 use std::ops::{Index, IndexMut};
 use std::{iter, mem};
 
-pub use basic_blocks::BasicBlocks;
+pub use basic_blocks::{BasicBlocks, SwitchTargetValue};
 use either::Either;
 use polonius_engine::Atom;
 use rustc_abi::{FieldIdx, VariantIdx};