Rollup of 7 pull requests

compiler/rustc_codegen_llvm/src/back/archive.rs

@@ -8,10 +8,11 @@ use std::path::{Path, PathBuf};
 use std::ptr;
 use std::str;
 
+use crate::common;
 use crate::llvm::archive_ro::{ArchiveRO, Child};
 use crate::llvm::{self, ArchiveKind, LLVMMachineType, LLVMRustCOFFShortExport};
 use rustc_codegen_ssa::back::archive::{ArchiveBuilder, ArchiveBuilderBuilder};
-use rustc_session::cstore::{DllCallingConvention, DllImport};
+use rustc_session::cstore::DllImport;
 use rustc_session::Session;
 
 /// Helper for adding many files to an archive.
@@ -111,21 +112,18 @@ impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
         };
 
         let target = &sess.target;
-        let mingw_gnu_toolchain = target.vendor == "pc"
-            && target.os == "windows"
-            && target.env == "gnu"
-            && target.abi.is_empty();
+        let mingw_gnu_toolchain = common::is_mingw_gnu_toolchain(target);
 
         let import_name_and_ordinal_vector: Vec<(String, Option<u16>)> = dll_imports
             .iter()
             .map(|import: &DllImport| {
                 if sess.target.arch == "x86" {
                     (
-                        LlvmArchiveBuilder::i686_decorated_name(import, mingw_gnu_toolchain),
-                        import.ordinal,
+                        common::i686_decorated_name(import, mingw_gnu_toolchain, false),
+                        import.ordinal(),
                     )
                 } else {
-                    (import.name.to_string(), import.ordinal)
+                    (import.name.to_string(), import.ordinal())
                 }
             })
             .collect();
@@ -159,6 +157,9 @@ impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
                 }
             };
 
+            // --no-leading-underscore: For the `import_name_type` feature to work, we need to be
+            // able to control the *exact* spelling of each of the symbols that are being imported:
+            // hence we don't want `dlltool` adding leading underscores automatically.
             let dlltool = find_binutils_dlltool(sess);
             let result = std::process::Command::new(dlltool)
                 .args([
@@ -168,6 +169,7 @@ impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
                     lib_name,
                     "-l",
                     output_path.to_str().unwrap(),
+                    "--no-leading-underscore",
                 ])
                 .output();
 
@@ -322,22 +324,6 @@ impl<'a> LlvmArchiveBuilder<'a> {
             ret
         }
     }
-
-    fn i686_decorated_name(import: &DllImport, mingw: bool) -> String {
-        let name = import.name;
-        let prefix = if mingw { "" } else { "_" };
-
-        match import.calling_convention {
-            DllCallingConvention::C => format!("{}{}", prefix, name),
-            DllCallingConvention::Stdcall(arg_list_size) => {
-                format!("{}{}@{}", prefix, name, arg_list_size)
-            }
-            DllCallingConvention::Fastcall(arg_list_size) => format!("@{}@{}", name, arg_list_size),
-            DllCallingConvention::Vectorcall(arg_list_size) => {
-                format!("{}@@{}", name, arg_list_size)
-            }
-        }
-    }
 }
 
 fn string_to_io_error(s: String) -> io::Error {

compiler/rustc_codegen_llvm/src/callee.rs

@@ -6,6 +6,7 @@
 
 use crate::abi::FnAbiLlvmExt;
 use crate::attributes;
+use crate::common;
 use crate::context::CodegenCx;
 use crate::llvm;
 use crate::value::Value;
@@ -79,13 +80,18 @@ pub fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) ->
             llfn
         }
     } else {
-        let llfn = cx.declare_fn(sym, fn_abi);
+        let instance_def_id = instance.def_id();
+        let llfn = if tcx.sess.target.arch == "x86" &&
+            let Some(dllimport) = common::get_dllimport(tcx, instance_def_id, sym)
+        {
+            cx.declare_fn(&common::i686_decorated_name(&dllimport, common::is_mingw_gnu_toolchain(&tcx.sess.target), true), fn_abi)
+        } else {
+            cx.declare_fn(sym, fn_abi)
+        };
         debug!("get_fn: not casting pointer!");
 
         attributes::from_fn_attrs(cx, llfn, instance);
 
-        let instance_def_id = instance.def_id();
-
         // Apply an appropriate linkage/visibility value to our item that we
         // just declared.
         //

compiler/rustc_codegen_llvm/src/common.rs

@@ -10,12 +10,17 @@ use crate::value::Value;
 use rustc_ast::Mutability;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::*;
+use rustc_hir::def_id::DefId;
 use rustc_middle::bug;
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
+use rustc_middle::ty::TyCtxt;
+use rustc_session::cstore::{DllCallingConvention, DllImport, PeImportNameType};
 use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size};
+use rustc_target::spec::Target;
 
 use libc::{c_char, c_uint};
+use std::fmt::Write;
 use tracing::debug;
 
 /*
@@ -357,3 +362,74 @@ fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
 fn try_as_const_integral(v: &Value) -> Option<&ConstantInt> {
     unsafe { llvm::LLVMIsAConstantInt(v) }
 }
+
+pub(crate) fn get_dllimport<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    id: DefId,
+    name: &str,
+) -> Option<&'tcx DllImport> {
+    tcx.native_library(id)
+        .map(|lib| lib.dll_imports.iter().find(|di| di.name.as_str() == name))
+        .flatten()
+}
+
+pub(crate) fn is_mingw_gnu_toolchain(target: &Target) -> bool {
+    target.vendor == "pc" && target.os == "windows" && target.env == "gnu" && target.abi.is_empty()
+}
+
+pub(crate) fn i686_decorated_name(
+    dll_import: &DllImport,
+    mingw: bool,
+    disable_name_mangling: bool,
+) -> String {
+    let name = dll_import.name.as_str();
+
+    let (add_prefix, add_suffix) = match dll_import.import_name_type {
+        Some(PeImportNameType::NoPrefix) => (false, true),
+        Some(PeImportNameType::Undecorated) => (false, false),
+        _ => (true, true),
+    };
+
+    // Worst case: +1 for disable name mangling, +1 for prefix, +4 for suffix (@@__).
+    let mut decorated_name = String::with_capacity(name.len() + 6);
+
+    if disable_name_mangling {
+        // LLVM uses a binary 1 ('\x01') prefix to a name to indicate that mangling needs to be disabled.
+        decorated_name.push('\x01');
+    }
+
+    let prefix = if add_prefix && dll_import.is_fn {
+        match dll_import.calling_convention {
+            DllCallingConvention::C | DllCallingConvention::Vectorcall(_) => None,
+            DllCallingConvention::Stdcall(_) => (!mingw
+                || dll_import.import_name_type == Some(PeImportNameType::Decorated))
+            .then_some('_'),
+            DllCallingConvention::Fastcall(_) => Some('@'),
+        }
+    } else if !dll_import.is_fn && !mingw {
+        // For static variables, prefix with '_' on MSVC.
+        Some('_')
+    } else {
+        None
+    };
+    if let Some(prefix) = prefix {
+        decorated_name.push(prefix);
+    }
+
+    decorated_name.push_str(name);
+
+    if add_suffix && dll_import.is_fn {
+        match dll_import.calling_convention {
+            DllCallingConvention::C => {}
+            DllCallingConvention::Stdcall(arg_list_size)
+            | DllCallingConvention::Fastcall(arg_list_size) => {
+                write!(&mut decorated_name, "@{}", arg_list_size).unwrap();
+            }
+            DllCallingConvention::Vectorcall(arg_list_size) => {
+                write!(&mut decorated_name, "@@{}", arg_list_size).unwrap();
+            }
+        }
+    }
+
+    decorated_name
+}

compiler/rustc_codegen_llvm/src/consts.rs

@@ -1,5 +1,5 @@
 use crate::base;
-use crate::common::CodegenCx;
+use crate::common::{self, CodegenCx};
 use crate::debuginfo;
 use crate::llvm::{self, True};
 use crate::llvm_util;
@@ -160,7 +160,7 @@ fn check_and_apply_linkage<'ll, 'tcx>(
     attrs: &CodegenFnAttrs,
     ty: Ty<'tcx>,
     sym: &str,
-    span_def_id: DefId,
+    def_id: DefId,
 ) -> &'ll Value {
     let llty = cx.layout_of(ty).llvm_type(cx);
     if let Some(linkage) = attrs.linkage {
@@ -175,7 +175,7 @@ fn check_and_apply_linkage<'ll, 'tcx>(
             cx.layout_of(mt.ty).llvm_type(cx)
         } else {
             cx.sess().span_fatal(
-                cx.tcx.def_span(span_def_id),
+                cx.tcx.def_span(def_id),
                 "must have type `*const T` or `*mut T` due to `#[linkage]` attribute",
             )
         };
@@ -194,14 +194,18 @@ fn check_and_apply_linkage<'ll, 'tcx>(
             real_name.push_str(sym);
             let g2 = cx.define_global(&real_name, llty).unwrap_or_else(|| {
                 cx.sess().span_fatal(
-                    cx.tcx.def_span(span_def_id),
+                    cx.tcx.def_span(def_id),
                     &format!("symbol `{}` is already defined", &sym),
                 )
             });
             llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
             llvm::LLVMSetInitializer(g2, g1);
             g2
         }
+    } else if cx.tcx.sess.target.arch == "x86" &&
+        let Some(dllimport) = common::get_dllimport(cx.tcx, def_id, sym)
+    {
+        cx.declare_global(&common::i686_decorated_name(&dllimport, common::is_mingw_gnu_toolchain(&cx.tcx.sess.target), true), llty)
     } else {
         // Generate an external declaration.
         // FIXME(nagisa): investigate whether it can be changed into define_global

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -1892,7 +1892,7 @@ impl<B: ExtraBackendMethods> OngoingCodegen<B> {
             }
         });
 
-        sess.cgu_reuse_tracker.check_expected_reuse(sess.diagnostic());
+        sess.cgu_reuse_tracker.check_expected_reuse(sess);
 
         sess.abort_if_errors();
 

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -13,8 +13,7 @@ use rustc_ast as ast;
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_hir::lang_items::LangItem;
 use rustc_index::vec::Idx;
-use rustc_middle::mir::AssertKind;
-use rustc_middle::mir::{self, SwitchTargets};
+use rustc_middle::mir::{self, AssertKind, SwitchTargets};
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
 use rustc_middle::ty::{self, Instance, Ty, TypeVisitable};

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -35,21 +35,7 @@ impl<'mir, 'tcx> InterpCx<'mir, 'tcx, CompileTimeInterpreter<'mir, 'tcx>> {
         // All `#[rustc_do_not_const_check]` functions should be hooked here.
         let def_id = instance.def_id();
 
-        if Some(def_id) == self.tcx.lang_items().const_eval_select() {
-            // redirect to const_eval_select_ct
-            if let Some(const_eval_select) = self.tcx.lang_items().const_eval_select_ct() {
-                return Ok(Some(
-                    ty::Instance::resolve(
-                        *self.tcx,
-                        ty::ParamEnv::reveal_all(),
-                        const_eval_select,
-                        instance.substs,
-                    )
-                    .unwrap()
-                    .unwrap(),
-                ));
-            }
-        } else if Some(def_id) == self.tcx.lang_items().panic_display()
+        if Some(def_id) == self.tcx.lang_items().panic_display()
             || Some(def_id) == self.tcx.lang_items().begin_panic_fn()
         {
             // &str or &&str

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -8,6 +8,7 @@ use std::convert::TryFrom;
 use std::fmt::Write;
 use std::num::NonZeroUsize;
 
+use rustc_ast::Mutability;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_middle::mir::interpret::InterpError;
@@ -411,34 +412,51 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
             // Proceed recursively even for ZST, no reason to skip them!
             // `!` is a ZST and we want to validate it.
             if let Ok((alloc_id, _offset, _prov)) = self.ecx.ptr_try_get_alloc_id(place.ptr) {
-                // Special handling for pointers to statics (irrespective of their type).
+                // Let's see what kind of memory this points to.
                 let alloc_kind = self.ecx.tcx.try_get_global_alloc(alloc_id);
-                if let Some(GlobalAlloc::Static(did)) = alloc_kind {
-                    assert!(!self.ecx.tcx.is_thread_local_static(did));
-                    assert!(self.ecx.tcx.is_static(did));
-                    if matches!(
-                        self.ctfe_mode,
-                        Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
-                    ) {
-                        // See const_eval::machine::MemoryExtra::can_access_statics for why
-                        // this check is so important.
-                        // This check is reachable when the const just referenced the static,
-                        // but never read it (so we never entered `before_access_global`).
-                        throw_validation_failure!(self.path,
-                            { "a {} pointing to a static variable", kind }
-                        );
+                match alloc_kind {
+                    Some(GlobalAlloc::Static(did)) => {
+                        // Special handling for pointers to statics (irrespective of their type).
+                        assert!(!self.ecx.tcx.is_thread_local_static(did));
+                        assert!(self.ecx.tcx.is_static(did));
+                        if matches!(
+                            self.ctfe_mode,
+                            Some(CtfeValidationMode::Const { allow_static_ptrs: false, .. })
+                        ) {
+                            // See const_eval::machine::MemoryExtra::can_access_statics for why
+                            // this check is so important.
+                            // This check is reachable when the const just referenced the static,
+                            // but never read it (so we never entered `before_access_global`).
+                            throw_validation_failure!(self.path,
+                                { "a {} pointing to a static variable in a constant", kind }
+                            );
+                        }
+                        // We skip recursively checking other statics. These statics must be sound by
+                        // themselves, and the only way to get broken statics here is by using
+                        // unsafe code.
+                        // The reasons we don't check other statics is twofold. For one, in all
+                        // sound cases, the static was already validated on its own, and second, we
+                        // trigger cycle errors if we try to compute the value of the other static
+                        // and that static refers back to us.
+                        // We might miss const-invalid data,
+                        // but things are still sound otherwise (in particular re: consts
+                        // referring to statics).
+                        return Ok(());
                     }
-                    // We skip checking other statics. These statics must be sound by
-                    // themselves, and the only way to get broken statics here is by using
-                    // unsafe code.
-                    // The reasons we don't check other statics is twofold. For one, in all
-                    // sound cases, the static was already validated on its own, and second, we
-                    // trigger cycle errors if we try to compute the value of the other static
-                    // and that static refers back to us.
-                    // We might miss const-invalid data,
-                    // but things are still sound otherwise (in particular re: consts
-                    // referring to statics).
-                    return Ok(());
+                    Some(GlobalAlloc::Memory(alloc)) => {
+                        if alloc.inner().mutability == Mutability::Mut
+                            && matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
+                        {
+                            // This should be unreachable, but if someone manages to copy a pointer
+                            // out of a `static`, then that pointer might point to mutable memory,
+                            // and we would catch that here.
+                            throw_validation_failure!(self.path,
+                                { "a {} pointing to mutable memory in a constant", kind }
+                            );
+                        }
+                    }
+                    // Nothing to check for these.
+                    None | Some(GlobalAlloc::Function(..) | GlobalAlloc::VTable(..)) => {}
                 }
             }
             let path = &self.path;
@@ -544,7 +562,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
             }
             ty::Ref(_, ty, mutbl) => {
                 if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { .. }))
-                    && *mutbl == hir::Mutability::Mut
+                    && *mutbl == Mutability::Mut
                 {
                     // A mutable reference inside a const? That does not seem right (except if it is
                     // a ZST).