Rollup merge of #117650 - saethlin:inline-me-please, r=davidtwco

Add -Zcross-crate-inline-threshold=yes

``@thomcc`` says this would be useful for

>  seeing if it makes a difference in some code if i do it when building the sysroot, since -Zbuild-std + lto helps more than it seems like it should

And I've changed the possible values as a reference to ``@Manishearth`` saying

> LLVM's inlining heuristic is "yes".

2 files changed, 41 insertions, 5 deletions

diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 930fb693eb6..f745bc390ca 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -3161,10 +3161,10 @@ impl PpMode {
 pub(crate) mod dep_tracking {
     use super::{
         BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, DebugInfoCompression,
-        ErrorOutputType, InstrumentCoverage, InstrumentXRay, LinkerPluginLto, LocationDetail,
-        LtoCli, OomStrategy, OptLevel, OutFileName, OutputType, OutputTypes, Polonius,
-        RemapPathScopeComponents, ResolveDocLinks, SourceFileHashAlgorithm, SplitDwarfKind,
-        SwitchWithOptPath, SymbolManglingVersion, TraitSolver, TrimmedDefPaths,
+        ErrorOutputType, InliningThreshold, InstrumentCoverage, InstrumentXRay, LinkerPluginLto,
+        LocationDetail, LtoCli, OomStrategy, OptLevel, OutFileName, OutputType, OutputTypes,
+        Polonius, RemapPathScopeComponents, ResolveDocLinks, SourceFileHashAlgorithm,
+        SplitDwarfKind, SwitchWithOptPath, SymbolManglingVersion, TraitSolver, TrimmedDefPaths,
     };
     use crate::lint;
     use crate::options::WasiExecModel;
@@ -3270,6 +3270,7 @@ pub(crate) mod dep_tracking {
         LanguageIdentifier,
         TraitSolver,
         Polonius,
+        InliningThreshold,
     );
 
     impl<T1, T2> DepTrackingHash for (T1, T2)
@@ -3435,3 +3436,16 @@ impl Polonius {
         matches!(self, Polonius::Next)
     }
 }
+
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum InliningThreshold {
+    Always,
+    Sometimes(usize),
+    Never,
+}
+
+impl Default for InliningThreshold {
+    fn default() -> Self {
+        Self::Sometimes(100)
+    }
+}
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 7510a41485a..964a26e94fe 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -428,6 +428,8 @@ mod desc {
         "one of supported execution strategies (`same-thread`, or `cross-thread`)";
     pub const parse_dump_solver_proof_tree: &str = "one of: `always`, `on-request`, `on-error`";
     pub const parse_remap_path_scope: &str = "comma separated list of scopes: `macro`, `diagnostics`, `unsplit-debuginfo`, `split-debuginfo`, `split-debuginfo-path`, `object`, `all`";
+    pub const parse_inlining_threshold: &str =
+        "either a boolean (`yes`, `no`, `on`, `off`, etc), or a non-negative number";
 }
 
 mod parse {
@@ -1310,6 +1312,26 @@ mod parse {
         };
         true
     }
+
+    pub(crate) fn parse_inlining_threshold(slot: &mut InliningThreshold, v: Option<&str>) -> bool {
+        match v {
+            Some("always" | "yes") => {
+                *slot = InliningThreshold::Always;
+            }
+            Some("never") => {
+                *slot = InliningThreshold::Never;
+            }
+            Some(v) => {
+                if let Ok(threshold) = v.parse() {
+                    *slot = InliningThreshold::Sometimes(threshold);
+                } else {
+                    return false;
+                }
+            }
+            None => return false,
+        }
+        true
+    }
 }
 
 options! {
@@ -1479,7 +1501,7 @@ options! {
         "combine CGUs into a single one"),
     crate_attr: Vec<String> = (Vec::new(), parse_string_push, [TRACKED],
         "inject the given attribute in the crate"),
-    cross_crate_inline_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
+    cross_crate_inline_threshold: InliningThreshold = (InliningThreshold::Sometimes(100), parse_inlining_threshold, [TRACKED],
         "threshold to allow cross crate inlining of functions"),
     debug_info_for_profiling: bool = (false, parse_bool, [TRACKED],
         "emit discriminators and other data necessary for AutoFDO"),