Rollup of 8 pull requests

compiler/rustc_ast_lowering/src/expr.rs

@@ -1499,46 +1499,64 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // previous iteration.
                 required_features.clear();
 
-                // Validate register classes against currently enabled target
-                // features. We check that at least one type is available for
-                // the current target.
                 let reg_class = reg.reg_class();
                 if reg_class == asm::InlineAsmRegClass::Err {
                     continue;
                 }
-                for &(_, feature) in reg_class.supported_types(asm_arch.unwrap()) {
-                    if let Some(feature) = feature {
-                        if self.sess.target_features.contains(&Symbol::intern(feature)) {
+
+                // We ignore target feature requirements for clobbers: if the
+                // feature is disabled then the compiler doesn't care what we
+                // do with the registers.
+                //
+                // Note that this is only possible for explicit register
+                // operands, which cannot be used in the asm string.
+                let is_clobber = matches!(
+                    op,
+                    hir::InlineAsmOperand::Out {
+                        reg: asm::InlineAsmRegOrRegClass::Reg(_),
+                        late: _,
+                        expr: None
+                    }
+                );
+
+                if !is_clobber {
+                    // Validate register classes against currently enabled target
+                    // features. We check that at least one type is available for
+                    // the current target.
+                    for &(_, feature) in reg_class.supported_types(asm_arch.unwrap()) {
+                        if let Some(feature) = feature {
+                            if self.sess.target_features.contains(&Symbol::intern(feature)) {
+                                required_features.clear();
+                                break;
+                            } else {
+                                required_features.push(feature);
+                            }
+                        } else {
                             required_features.clear();
                             break;
-                        } else {
-                            required_features.push(feature);
                         }
-                    } else {
-                        required_features.clear();
-                        break;
                     }
-                }
-                // We are sorting primitive strs here and can use unstable sort here
-                required_features.sort_unstable();
-                required_features.dedup();
-                match &required_features[..] {
-                    [] => {}
-                    [feature] => {
-                        let msg = format!(
-                            "register class `{}` requires the `{}` target feature",
-                            reg_class.name(),
-                            feature
-                        );
-                        sess.struct_span_err(op_sp, &msg).emit();
-                    }
-                    features => {
-                        let msg = format!(
-                            "register class `{}` requires at least one target feature: {}",
-                            reg_class.name(),
-                            features.join(", ")
-                        );
-                        sess.struct_span_err(op_sp, &msg).emit();
+                    // We are sorting primitive strs here and can use unstable sort here
+                    required_features.sort_unstable();
+                    required_features.dedup();
+                    match &required_features[..] {
+                        [] => {}
+                        [feature] => {
+                            let msg = format!(
+                                "register class `{}` requires the `{}` target feature",
+                                reg_class.name(),
+                                feature
+                            );
+                            sess.struct_span_err(op_sp, &msg).emit();
+                        }
+                        features => {
+                            let msg = format!(
+                                "register class `{}` requires at least one target feature: {}",
+                                reg_class.name(),
+                                features.join(", ")
+                            );
+                            sess.struct_span_err(op_sp, &msg).emit();
+                        }
                     }
                 }
 

compiler/rustc_codegen_llvm/src/asm.rs

@@ -14,7 +14,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir as hir;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::{bug, span_bug};
-use rustc_span::{Pos, Span};
+use rustc_span::{Pos, Span, Symbol};
 use rustc_target::abi::*;
 use rustc_target::asm::*;
 
@@ -125,15 +125,39 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
 
         // Collect the types of output operands
         let mut constraints = vec![];
+        let mut clobbers = vec![];
         let mut output_types = vec![];
         let mut op_idx = FxHashMap::default();
         for (idx, op) in operands.iter().enumerate() {
             match *op {
                 InlineAsmOperandRef::Out { reg, late, place } => {
+                    let is_target_supported = |reg_class: InlineAsmRegClass| {
+                        for &(_, feature) in reg_class.supported_types(asm_arch) {
+                            if let Some(feature) = feature {
+                                if self.tcx.sess.target_features.contains(&Symbol::intern(feature))
+                                {
+                                    return true;
+                                }
+                            } else {
+                                // Register class is unconditionally supported
+                                return true;
+                            }
+                        }
+                        false
+                    };
+
                     let mut layout = None;
                     let ty = if let Some(ref place) = place {
                         layout = Some(&place.layout);
                         llvm_fixup_output_type(self.cx, reg.reg_class(), &place.layout)
+                    } else if !is_target_supported(reg.reg_class()) {
+                        // We turn discarded outputs into clobber constraints
+                        // if the target feature needed by the register class is
+                        // disabled. This is necessary otherwise LLVM will try
+                        // to actually allocate a register for the dummy output.
+                        assert!(matches!(reg, InlineAsmRegOrRegClass::Reg(_)));
+                        clobbers.push(format!("~{}", reg_to_llvm(reg, None)));
+                        continue;
                     } else {
                         // If the output is discarded, we don't really care what
                         // type is used. We're just using this to tell LLVM to
@@ -244,6 +268,7 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             }
         }
 
+        constraints.append(&mut clobbers);
         if !options.contains(InlineAsmOptions::PRESERVES_FLAGS) {
             match asm_arch {
                 InlineAsmArch::AArch64 | InlineAsmArch::Arm => {

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -317,7 +317,7 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
     // Note that currently the `wasm-import-module` doesn't do anything, but
     // eventually LLVM 7 should read this and ferry the appropriate import
     // module to the output file.
-    if cx.tcx.sess.target.arch == "wasm32" {
+    if cx.tcx.sess.target.is_like_wasm {
         if let Some(module) = wasm_import_module(cx.tcx, instance.def_id()) {
             llvm::AddFunctionAttrStringValue(
                 llfn,

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -170,10 +170,7 @@ pub fn target_machine_factory(
     // On the wasm target once the `atomics` feature is enabled that means that
     // we're no longer single-threaded, or otherwise we don't want LLVM to
     // lower atomic operations to single-threaded operations.
-    if singlethread
-        && sess.target.llvm_target.contains("wasm32")
-        && sess.target_features.contains(&sym::atomics)
-    {
+    if singlethread && sess.target.is_like_wasm && sess.target_features.contains(&sym::atomics) {
         singlethread = false;
     }
 

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -1083,9 +1083,9 @@ pub fn compile_unit_metadata(
             );
         }
 
-        // Insert `llvm.ident` metadata on the wasm32 targets since that will
+        // Insert `llvm.ident` metadata on the wasm targets since that will
         // get hooked up to the "producer" sections `processed-by` information.
-        if tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
+        if tcx.sess.target.is_like_wasm {
             let name_metadata = llvm::LLVMMDStringInContext(
                 debug_context.llcontext,
                 rustc_producer.as_ptr().cast(),

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1411,15 +1411,10 @@ fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_ty
     }
 }
 
-/// Add arbitrary "user defined" args defined from command line and by `#[link_args]` attributes.
+/// Add arbitrary "user defined" args defined from command line.
 /// FIXME: Determine where exactly these args need to be inserted.
-fn add_user_defined_link_args(
-    cmd: &mut dyn Linker,
-    sess: &Session,
-    codegen_results: &CodegenResults,
-) {
+fn add_user_defined_link_args(cmd: &mut dyn Linker, sess: &Session) {
     cmd.args(&sess.opts.cg.link_args);
-    cmd.args(&*codegen_results.crate_info.link_args);
 }
 
 /// Add arbitrary "late link" args defined by the target spec.
@@ -1761,7 +1756,7 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
     add_rpath_args(cmd, sess, codegen_results, out_filename);
 
     // OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
-    add_user_defined_link_args(cmd, sess, codegen_results);
+    add_user_defined_link_args(cmd, sess);
 
     // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
     cmd.finalize();

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -186,7 +186,7 @@ impl<'a> GccLinker<'a> {
         // * On OSX they have their own linker, not binutils'
         // * For WebAssembly the only functional linker is LLD, which doesn't
         //   support hint flags
-        !self.sess.target.is_like_osx && self.sess.target.arch != "wasm32"
+        !self.sess.target.is_like_osx && !self.sess.target.is_like_wasm
     }
 
     // Some platforms take hints about whether a library is static or dynamic.

compiler/rustc_codegen_ssa/src/base.rs

@@ -754,7 +754,6 @@ impl CrateInfo {
             is_no_builtins: Default::default(),
             native_libraries: Default::default(),
             used_libraries: tcx.native_libraries(LOCAL_CRATE).iter().map(Into::into).collect(),
-            link_args: tcx.link_args(LOCAL_CRATE),
             crate_name: Default::default(),
             used_crates_dynamic: cstore::used_crates(tcx, LinkagePreference::RequireDynamic),
             used_crates_static: cstore::used_crates(tcx, LinkagePreference::RequireStatic),

compiler/rustc_codegen_ssa/src/lib.rs

@@ -139,7 +139,6 @@ pub struct CrateInfo {
     pub native_libraries: FxHashMap<CrateNum, Vec<NativeLib>>,
     pub crate_name: FxHashMap<CrateNum, String>,
     pub used_libraries: Vec<NativeLib>,
-    pub link_args: Lrc<Vec<String>>,
     pub used_crate_source: FxHashMap<CrateNum, Lrc<CrateSource>>,
     pub used_crates_static: Vec<(CrateNum, LibSource)>,
     pub used_crates_dynamic: Vec<(CrateNum, LibSource)>,

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -161,7 +161,7 @@ pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Opt
         "mips" | "mips64" => MIPS_ALLOWED_FEATURES,
         "powerpc" | "powerpc64" => POWERPC_ALLOWED_FEATURES,
         "riscv32" | "riscv64" => RISCV_ALLOWED_FEATURES,
-        "wasm32" => WASM_ALLOWED_FEATURES,
+        "wasm32" | "wasm64" => WASM_ALLOWED_FEATURES,
         _ => &[],
     }
 }

compiler/rustc_feature/src/active.rs

@@ -258,9 +258,6 @@ declare_features! (
     // feature-group-start: actual feature gates
     // -------------------------------------------------------------------------
 
-    /// Allows using the `#[link_args]` attribute.
-    (active, link_args, "1.0.0", Some(29596), None),
-
     /// Allows defining identifiers beyond ASCII.
     (active, non_ascii_idents, "1.0.0", Some(55467), None),
 

compiler/rustc_feature/src/builtin_attrs.rs

@@ -279,11 +279,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
 
     // Linking:
     gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)),
-    gated!(
-        link_args, Normal, template!(NameValueStr: "args"),
-        "the `link_args` attribute is experimental and not portable across platforms, \
-        it is recommended to use `#[link(name = \"foo\")] instead",
-    ),
     gated!(
         link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib,
         experimental!(link_ordinal)

compiler/rustc_feature/src/removed.rs

@@ -128,6 +128,10 @@ declare_features! (
     /// Allows comparing raw pointers during const eval.
     (removed, const_compare_raw_pointers, "1.46.0", Some(53020), None,
      Some("cannot be allowed in const eval in any meaningful way")),
+    /// Allows using the `#[link_args]` attribute.
+    (removed, link_args, "1.53.0", Some(29596), None,
+     Some("removed in favor of using `-C link-arg=ARG` on command line, \
+           which is available from cargo build scripts with `cargo:rustc-link-arg` now")),
 
     // -------------------------------------------------------------------------
     // feature-group-end: removed features

compiler/rustc_metadata/src/lib.rs

@@ -26,7 +26,6 @@ pub use rmeta::{provide, provide_extern};
 
 mod dependency_format;
 mod foreign_modules;
-mod link_args;
 mod native_libs;
 mod rmeta;
 

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -1,6 +1,5 @@
 use crate::creader::{CStore, LoadedMacro};
 use crate::foreign_modules;
-use crate::link_args;
 use crate::native_libs;
 use crate::rmeta::{self, encoder};
 
@@ -295,10 +294,6 @@ pub fn provide(providers: &mut Providers) {
                 foreign_modules::collect(tcx).into_iter().map(|m| (m.def_id, m)).collect();
             Lrc::new(modules)
         },
-        link_args: |tcx, cnum| {
-            assert_eq!(cnum, LOCAL_CRATE);
-            Lrc::new(link_args::collect(tcx))
-        },
 
         // Returns a map from a sufficiently visible external item (i.e., an
         // external item that is visible from at least one local module) to a

compiler/rustc_middle/src/query/mod.rs

@@ -1253,11 +1253,6 @@ rustc_queries! {
         desc { |tcx| "native_library_kind({})", tcx.def_path_str(def_id) }
     }
 
-    query link_args(_: CrateNum) -> Lrc<Vec<String>> {
-        eval_always
-        desc { "looking up link arguments for a crate" }
-    }
-
     /// Does lifetime resolution, but does not descend into trait items. This
     /// should only be used for resolving lifetimes of on trait definitions,
     /// and is used to avoid cycles. Importantly, `resolve_lifetimes` still visits

compiler/rustc_session/src/config.rs

@@ -822,6 +822,9 @@ pub fn default_configuration(sess: &Session) -> CrateConfig {
         }
     }
     ret.insert((sym::target_arch, Some(Symbol::intern(arch))));
+    if sess.target.is_like_wasm {
+        ret.insert((sym::wasm, None));
+    }
     ret.insert((sym::target_endian, Some(Symbol::intern(end.as_str()))));
     ret.insert((sym::target_pointer_width, Some(Symbol::intern(&wordsz))));
     ret.insert((sym::target_env, Some(Symbol::intern(env))));

compiler/rustc_span/src/symbol.rs

@@ -1294,6 +1294,7 @@ symbols! {
         vreg,
         vreg_low16,
         warn,
+        wasm,
         wasm_import_module,
         wasm_target_feature,
         while_let,