Merging upstream version 1.75.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 130 insertions, 0 deletions

diff --git a/compiler/rustc_mir_transform/src/cross_crate_inline.rs b/compiler/rustc_mir_transform/src/cross_crate_inline.rs
new file mode 100644
index 000000000..261d9dd44
--- /dev/null
+++ b/compiler/rustc_mir_transform/src/cross_crate_inline.rs
@@ -0,0 +1,130 @@
+use crate::inline;
+use crate::pass_manager as pm;
+use rustc_attr::InlineAttr;
+use rustc_hir::def::DefKind;
+use rustc_hir::def_id::LocalDefId;
+use rustc_middle::mir::visit::Visitor;
+use rustc_middle::mir::*;
+use rustc_middle::query::Providers;
+use rustc_middle::ty::TyCtxt;
+use rustc_session::config::InliningThreshold;
+use rustc_session::config::OptLevel;
+
+pub fn provide(providers: &mut Providers) {
+    providers.cross_crate_inlinable = cross_crate_inlinable;
+}
+
+fn cross_crate_inlinable(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
+    let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
+    // If this has an extern indicator, then this function is globally shared and thus will not
+    // generate cgu-internal copies which would make it cross-crate inlinable.
+    if codegen_fn_attrs.contains_extern_indicator() {
+        return false;
+    }
+
+    // Obey source annotations first; this is important because it means we can use
+    // #[inline(never)] to force code generation.
+    match codegen_fn_attrs.inline {
+        InlineAttr::Never => return false,
+        InlineAttr::Hint | InlineAttr::Always => return true,
+        _ => {}
+    }
+
+    // This just reproduces the logic from Instance::requires_inline.
+    match tcx.def_kind(def_id) {
+        DefKind::Ctor(..) | DefKind::Closure => return true,
+        DefKind::Fn | DefKind::AssocFn => {}
+        _ => return false,
+    }
+
+    // Don't do any inference when incremental compilation is enabled; the additional inlining that
+    // inference permits also creates more work for small edits.
+    if tcx.sess.opts.incremental.is_some() {
+        return false;
+    }
+
+    // Don't do any inference if codegen optimizations are disabled and also MIR inlining is not
+    // enabled. This ensures that we do inference even if someone only passes -Zinline-mir,
+    // which is less confusing than having to also enable -Copt-level=1.
+    if matches!(tcx.sess.opts.optimize, OptLevel::No) && !pm::should_run_pass(tcx, &inline::Inline)
+    {
+        return false;
+    }
+
+    if !tcx.is_mir_available(def_id) {
+        return false;
+    }
+
+    let threshold = match tcx.sess.opts.unstable_opts.cross_crate_inline_threshold {
+        InliningThreshold::Always => return true,
+        InliningThreshold::Sometimes(threshold) => threshold,
+        InliningThreshold::Never => return false,
+    };
+
+    let mir = tcx.optimized_mir(def_id);
+    let mut checker =
+        CostChecker { tcx, callee_body: mir, calls: 0, statements: 0, landing_pads: 0, resumes: 0 };
+    checker.visit_body(mir);
+    checker.calls == 0
+        && checker.resumes == 0
+        && checker.landing_pads == 0
+        && checker.statements <= threshold
+}
+
+struct CostChecker<'b, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    callee_body: &'b Body<'tcx>,
+    calls: usize,
+    statements: usize,
+    landing_pads: usize,
+    resumes: usize,
+}
+
+impl<'tcx> Visitor<'tcx> for CostChecker<'_, 'tcx> {
+    fn visit_statement(&mut self, statement: &Statement<'tcx>, _: Location) {
+        // Don't count StorageLive/StorageDead in the inlining cost.
+        match statement.kind {
+            StatementKind::StorageLive(_)
+            | StatementKind::StorageDead(_)
+            | StatementKind::Deinit(_)
+            | StatementKind::Nop => {}
+            _ => self.statements += 1,
+        }
+    }
+
+    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, _: Location) {
+        let tcx = self.tcx;
+        match terminator.kind {
+            TerminatorKind::Drop { ref place, unwind, .. } => {
+                let ty = place.ty(self.callee_body, tcx).ty;
+                if !ty.is_trivially_pure_clone_copy() {
+                    self.calls += 1;
+                    if let UnwindAction::Cleanup(_) = unwind {
+                        self.landing_pads += 1;
+                    }
+                }
+            }
+            TerminatorKind::Call { unwind, .. } => {
+                self.calls += 1;
+                if let UnwindAction::Cleanup(_) = unwind {
+                    self.landing_pads += 1;
+                }
+            }
+            TerminatorKind::Assert { unwind, .. } => {
+                self.calls += 1;
+                if let UnwindAction::Cleanup(_) = unwind {
+                    self.landing_pads += 1;
+                }
+            }
+            TerminatorKind::UnwindResume => self.resumes += 1,
+            TerminatorKind::InlineAsm { unwind, .. } => {
+                self.statements += 1;
+                if let UnwindAction::Cleanup(_) = unwind {
+                    self.landing_pads += 1;
+                }
+            }
+            TerminatorKind::Return => {}
+            _ => self.statements += 1,
+        }
+    }
+}