7 files changed, 36 insertions, 20 deletions
diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index e723187ff1f..017513721b7 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -551,6 +551,8 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'_>>) ->
                 format!("{{{}}}", reg.name())
             }
         }
+        // The constraints can be retrieved from
+        // https://llvm.org/docs/LangRef.html#supported-constraint-code-list
         InlineAsmRegOrRegClass::RegClass(reg) => match reg {
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg) => "w",
@@ -624,6 +626,8 @@ fn modifier_to_llvm(
     reg: InlineAsmRegClass,
     modifier: Option<char>,
 ) -> Option<char> {
+    // The modifiers can be retrieved from
+    // https://llvm.org/docs/LangRef.html#asm-template-argument-modifiers
     match reg {
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => modifier,
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg)
diff --git a/compiler/rustc_codegen_llvm/src/back/archive.rs b/compiler/rustc_codegen_llvm/src/back/archive.rs
index 20a063f80fd..082665bba38 100644
--- a/compiler/rustc_codegen_llvm/src/back/archive.rs
+++ b/compiler/rustc_codegen_llvm/src/back/archive.rs
@@ -165,10 +165,12 @@ impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
         lib_name: &str,
         dll_imports: &[DllImport],
         tmpdir: &Path,
+        is_direct_dependency: bool,
     ) -> PathBuf {
+        let name_suffix = if is_direct_dependency { "_imports" } else { "_imports_indirect" };
         let output_path = {
             let mut output_path: PathBuf = tmpdir.to_path_buf();
-            output_path.push(format!("{}_imports", lib_name));
+            output_path.push(format!("{}{}", lib_name, name_suffix));
             output_path.with_extension("lib")
         };
 
@@ -195,7 +197,8 @@ impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
             // that loaded but crashed with an AV upon calling one of the imported
             // functions.  Therefore, use binutils to create the import library instead,
             // by writing a .DEF file to the temp dir and calling binutils's dlltool.
-            let def_file_path = tmpdir.join(format!("{}_imports", lib_name)).with_extension("def");
+            let def_file_path =
+                tmpdir.join(format!("{}{}", lib_name, name_suffix)).with_extension("def");
 
             let def_file_content = format!(
                 "EXPORTS\n{}",
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 2049422b79a..a49cc7f8d66 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -32,8 +32,8 @@ pub const THIN_LTO_KEYS_INCR_COMP_FILE_NAME: &str = "thin-lto-past-keys.bin";
 
 pub fn crate_type_allows_lto(crate_type: CrateType) -> bool {
     match crate_type {
-        CrateType::Executable | CrateType::Staticlib | CrateType::Cdylib => true,
-        CrateType::Dylib | CrateType::Rlib | CrateType::ProcMacro => false,
+        CrateType::Executable | CrateType::Dylib | CrateType::Staticlib | CrateType::Cdylib => true,
+        CrateType::Rlib | CrateType::ProcMacro => false,
     }
 }
 
@@ -73,17 +73,6 @@ fn prepare_lto(
     // with either fat or thin LTO
     let mut upstream_modules = Vec::new();
     if cgcx.lto != Lto::ThinLocal {
-        if cgcx.opts.cg.prefer_dynamic {
-            diag_handler
-                .struct_err("cannot prefer dynamic linking when performing LTO")
-                .note(
-                    "only 'staticlib', 'bin', and 'cdylib' outputs are \
-                               supported with LTO",
-                )
-                .emit();
-            return Err(FatalError);
-        }
-
         // Make sure we actually can run LTO
         for crate_type in cgcx.crate_types.iter() {
             if !crate_type_allows_lto(*crate_type) {
@@ -92,9 +81,25 @@ fn prepare_lto(
                                             static library outputs",
                 );
                 return Err(e);
+            } else if *crate_type == CrateType::Dylib {
+                if !cgcx.opts.unstable_opts.dylib_lto {
+                    return Err(diag_handler
+                        .fatal("lto cannot be used for `dylib` crate type without `-Zdylib-lto`"));
+                }
             }
         }
 
+        if cgcx.opts.cg.prefer_dynamic && !cgcx.opts.unstable_opts.dylib_lto {
+            diag_handler
+                .struct_err("cannot prefer dynamic linking when performing LTO")
+                .note(
+                    "only 'staticlib', 'bin', and 'cdylib' outputs are \
+                               supported with LTO",
+                )
+                .emit();
+            return Err(FatalError);
+        }
+
         for &(cnum, ref path) in cgcx.each_linked_rlib_for_lto.iter() {
             let exported_symbols =
                 cgcx.exported_symbols.as_ref().expect("needs exported symbols for LTO");
@@ -573,7 +578,7 @@ pub(crate) fn run_pass_manager(
     module: &mut ModuleCodegen<ModuleLlvm>,
     thin: bool,
 ) -> Result<(), FatalError> {
-    let _timer = cgcx.prof.extra_verbose_generic_activity("LLVM_lto_optimize", &*module.name);
+    let _timer = cgcx.prof.verbose_generic_activity_with_arg("LLVM_lto_optimize", &*module.name);
     let config = cgcx.config(module.kind);
 
     // Now we have one massive module inside of llmod. Time to run the
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index db526746fa7..11053a8f6c4 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -537,7 +537,7 @@ pub(crate) fn link(
     mut modules: Vec<ModuleCodegen<ModuleLlvm>>,
 ) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
     use super::lto::{Linker, ModuleBuffer};
-    // Sort the modules by name to ensure to ensure deterministic behavior.
+    // Sort the modules by name to ensure deterministic behavior.
     modules.sort_by(|a, b| a.name.cmp(&b.name));
     let (first, elements) =
         modules.split_first().expect("Bug! modules must contain at least one module.");
diff --git a/compiler/rustc_codegen_llvm/src/callee.rs b/compiler/rustc_codegen_llvm/src/callee.rs
index b83c1e8f08f..6f0d1b7ce84 100644
--- a/compiler/rustc_codegen_llvm/src/callee.rs
+++ b/compiler/rustc_codegen_llvm/src/callee.rs
@@ -179,7 +179,8 @@ pub fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) ->
             // MinGW: For backward compatibility we rely on the linker to decide whether it
             // should use dllimport for functions.
             if cx.use_dll_storage_attrs
-                && tcx.is_dllimport_foreign_item(instance_def_id)
+                && let Some(library) = tcx.native_library(instance_def_id)
+                && library.kind.is_dllimport()
                 && !matches!(tcx.sess.target.env.as_ref(), "gnu" | "uclibc")
             {
                 llvm::LLVMSetDLLStorageClass(llfn, llvm::DLLStorageClass::DllImport);
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index ee2fc65e37b..dd3c43ba5ca 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -332,7 +332,10 @@ impl<'ll> CodegenCx<'ll, '_> {
             }
         }
 
-        if self.use_dll_storage_attrs && self.tcx.is_dllimport_foreign_item(def_id) {
+        if self.use_dll_storage_attrs
+            && let Some(library) = self.tcx.native_library(def_id)
+            && library.kind.is_dllimport()
+        {
             // For foreign (native) libs we know the exact storage type to use.
             unsafe {
                 llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
index 0d1df6fb1ac..433f043209e 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs
@@ -129,7 +129,7 @@ impl CoverageMapGenerator {
             // LLVM Coverage Mapping Format version 6 (zero-based encoded as 5)
             // requires setting the first filename to the compilation directory.
             // Since rustc generates coverage maps with relative paths, the
-            // compilation directory can be combined with the the relative paths
+            // compilation directory can be combined with the relative paths
             // to get absolute paths, if needed.
             let working_dir = tcx
                 .sess