We don't need `NonNull::as_ptr` debuginfo

Stop pessimizing the use of local variables in core by skipping debug info for MIR temporaries in tiny (single-BB) functions.

For functions as simple as this -- `Pin::new`, etc -- nobody every actually wants debuginfo for them in the first place.  They're more like intrinsics than real functions, and stepping over them is good.

2 files changed, 26 insertions, 4 deletions

diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index cb6d539cdf9..936c2ca87d6 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -472,6 +472,13 @@ impl ToString for DebugInfoCompression {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Hash)]
+pub enum MirStripDebugInfo {
+    None,
+    LocalsInTinyFunctions,
+    AllLocals,
+}
+
 /// Split debug-information is enabled by `-C split-debuginfo`, this enum is only used if split
 /// debug-information is enabled (in either `Packed` or `Unpacked` modes), and the platform
 /// uses DWARF for debug-information.
@@ -2900,10 +2907,10 @@ pub(crate) mod dep_tracking {
         BranchProtection, CFGuard, CFProtection, CollapseMacroDebuginfo, CoverageOptions,
         CrateType, DebugInfo, DebugInfoCompression, ErrorOutputType, FmtDebug, FunctionReturn,
         InliningThreshold, InstrumentCoverage, InstrumentXRay, LinkerPluginLto, LocationDetail,
-        LtoCli, NextSolverConfig, OomStrategy, OptLevel, OutFileName, OutputType, OutputTypes,
-        PatchableFunctionEntry, Polonius, RemapPathScopeComponents, ResolveDocLinks,
-        SourceFileHashAlgorithm, SplitDwarfKind, SwitchWithOptPath, SymbolManglingVersion,
-        WasiExecModel,
+        LtoCli, MirStripDebugInfo, NextSolverConfig, OomStrategy, OptLevel, OutFileName,
+        OutputType, OutputTypes, PatchableFunctionEntry, Polonius, RemapPathScopeComponents,
+        ResolveDocLinks, SourceFileHashAlgorithm, SplitDwarfKind, SwitchWithOptPath,
+        SymbolManglingVersion, WasiExecModel,
     };
     use crate::lint;
     use crate::utils::NativeLib;
@@ -2971,6 +2978,7 @@ pub(crate) mod dep_tracking {
         LtoCli,
         DebugInfo,
         DebugInfoCompression,
+        MirStripDebugInfo,
         CollapseMacroDebuginfo,
         UnstableFeatures,
         NativeLib,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 9e95e278325..124f0a2525f 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -391,6 +391,8 @@ mod desc {
     pub(crate) const parse_cfprotection: &str = "`none`|`no`|`n` (default), `branch`, `return`, or `full`|`yes`|`y` (equivalent to `branch` and `return`)";
     pub(crate) const parse_debuginfo: &str = "either an integer (0, 1, 2), `none`, `line-directives-only`, `line-tables-only`, `limited`, or `full`";
     pub(crate) const parse_debuginfo_compression: &str = "one of `none`, `zlib`, or `zstd`";
+    pub(crate) const parse_mir_strip_debuginfo: &str =
+        "one of `none`, `locals-in-tiny-functions`, or `all-locals`";
     pub(crate) const parse_collapse_macro_debuginfo: &str = "one of `no`, `external`, or `yes`";
     pub(crate) const parse_strip: &str = "either `none`, `debuginfo`, or `symbols`";
     pub(crate) const parse_linker_flavor: &str = ::rustc_target::spec::LinkerFlavorCli::one_of();
@@ -925,6 +927,16 @@ pub mod parse {
         true
     }
 
+    pub(crate) fn parse_mir_strip_debuginfo(slot: &mut MirStripDebugInfo, v: Option<&str>) -> bool {
+        match v {
+            Some("none") => *slot = MirStripDebugInfo::None,
+            Some("locals-in-tiny-functions") => *slot = MirStripDebugInfo::LocalsInTinyFunctions,
+            Some("all-locals") => *slot = MirStripDebugInfo::AllLocals,
+            _ => return false,
+        };
+        true
+    }
+
     pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavorCli>, v: Option<&str>) -> bool {
         match v.and_then(LinkerFlavorCli::from_str) {
             Some(lf) => *slot = Some(lf),
@@ -1893,6 +1905,8 @@ options! {
     #[rustc_lint_opt_deny_field_access("use `Session::mir_opt_level` instead of this field")]
     mir_opt_level: Option<usize> = (None, parse_opt_number, [TRACKED],
         "MIR optimization level (0-4; default: 1 in non optimized builds and 2 in optimized builds)"),
+    mir_strip_debuginfo: MirStripDebugInfo = (MirStripDebugInfo::None, parse_mir_strip_debuginfo, [TRACKED],
+        "Whether to remove some of the MIR debug info from methods.  Default: None"),
     move_size_limit: Option<usize> = (None, parse_opt_number, [TRACKED],
         "the size at which the `large_assignments` lint starts to be emitted"),
     mutable_noalias: bool = (true, parse_bool, [TRACKED],