Upgrade to LLVM's master branch (LLVM 7)

src/librustc/dep_graph/dep_node.rs

@@ -665,8 +665,6 @@ define_dep_nodes!( <'tcx>
 
     [] InstanceDefSizeEstimate { instance_def: InstanceDef<'tcx> },
 
-    [] WasmCustomSections(CrateNum),
-
     [input] Features,
 
     [] ProgramClausesFor(DefId),

src/librustc/hir/check_attr.rs

@@ -57,7 +57,7 @@ struct CheckAttrVisitor<'a, 'tcx: 'a> {
 impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
     /// Check any attribute.
     fn check_attributes(&self, item: &hir::Item, target: Target) {
-        if target == Target::Fn {
+        if target == Target::Fn || target == Target::Const {
             self.tcx.codegen_fn_attrs(self.tcx.hir.local_def_id(item.id));
         } else if let Some(a) = item.attrs.iter().find(|a| a.check_name("target_feature")) {
             self.tcx.sess.struct_span_err(a.span, "attribute should be applied to a function")
@@ -85,11 +85,6 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
                 if target != Target::Const {
                     self.tcx.sess.span_err(attr.span, "only allowed on consts");
                 }
-
-                if attr.value_str().is_none() {
-                    self.tcx.sess.span_err(attr.span, "must be of the form \
-                        #[wasm_custom_section = \"foo\"]");
-                }
             }
         }
 

src/librustc/hir/mod.rs

@@ -2259,6 +2259,7 @@ pub struct CodegenFnAttrs {
     pub export_name: Option<Symbol>,
     pub target_features: Vec<Symbol>,
     pub linkage: Option<Linkage>,
+    pub wasm_custom_section: Option<Symbol>,
 }
 
 bitflags! {
@@ -2283,6 +2284,7 @@ impl CodegenFnAttrs {
             export_name: None,
             target_features: vec![],
             linkage: None,
+            wasm_custom_section: None,
         }
     }
 

src/librustc/ich/impls_hir.rs

@@ -1120,6 +1120,7 @@ impl_stable_hash_for!(struct hir::CodegenFnAttrs {
     export_name,
     target_features,
     linkage,
+    wasm_custom_section,
 });
 
 impl<'hir> HashStable<StableHashingContext<'hir>> for hir::CodegenFnAttrFlags

src/librustc/mir/mono.rs

@@ -24,6 +24,7 @@ pub enum MonoItem<'tcx> {
     Fn(Instance<'tcx>),
     Static(DefId),
     GlobalAsm(NodeId),
+    CustomSection(DefId),
 }
 
 impl<'tcx> MonoItem<'tcx> {
@@ -36,7 +37,9 @@ impl<'tcx> MonoItem<'tcx> {
             },
             // Conservatively estimate the size of a static declaration
             // or assembly to be 1.
-            MonoItem::Static(_) | MonoItem::GlobalAsm(_) => 1,
+            MonoItem::Static(_) |
+            MonoItem::GlobalAsm(_) |
+            MonoItem::CustomSection(_) => 1,
         }
     }
 }
@@ -51,7 +54,8 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> {
             MonoItem::Fn(ref instance) => {
                 instance.hash_stable(hcx, hasher);
             }
-            MonoItem::Static(def_id) => {
+            MonoItem::Static(def_id) |
+            MonoItem::CustomSection(def_id) => {
                 def_id.hash_stable(hcx, hasher);
             }
             MonoItem::GlobalAsm(node_id) => {

src/librustc/ty/query/config.rs

@@ -776,12 +776,6 @@ impl<'tcx> QueryDescription<'tcx> for queries::instance_def_size_estimate<'tcx>
     }
 }
 
-impl<'tcx> QueryDescription<'tcx> for queries::wasm_custom_sections<'tcx> {
-    fn describe(_tcx: TyCtxt, _: CrateNum) -> String {
-        format!("custom wasm sections for a crate")
-    }
-}
-
 impl<'tcx> QueryDescription<'tcx> for queries::generics_of<'tcx> {
     #[inline]
     fn cache_on_disk(def_id: Self::Key) -> bool {

src/librustc/ty/query/mod.rs

@@ -546,7 +546,6 @@ define_queries! { <'tcx>
         ty::ParamEnv<'tcx>
     ) -> Clauses<'tcx>,
 
-    [] fn wasm_custom_sections: WasmCustomSections(CrateNum) -> Lrc<Vec<DefId>>,
     [] fn wasm_import_module_map: WasmImportModuleMap(CrateNum)
         -> Lrc<FxHashMap<DefId, String>>,
 }

src/librustc/ty/query/plumbing.rs

@@ -1208,7 +1208,6 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
         DepKind::Features => { force!(features_query, LOCAL_CRATE); }
 
         DepKind::ProgramClausesFor => { force!(program_clauses_for, def_id!()); }
-        DepKind::WasmCustomSections => { force!(wasm_custom_sections, krate!()); }
         DepKind::WasmImportModuleMap => { force!(wasm_import_module_map, krate!()); }
         DepKind::ForeignModules => { force!(foreign_modules, krate!()); }
 

src/librustc_codegen_llvm/attributes.rs

@@ -11,9 +11,8 @@
 
 use std::ffi::{CStr, CString};
 
-use rustc::hir::{self, CodegenFnAttrFlags};
+use rustc::hir::CodegenFnAttrFlags;
 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
-use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::session::Session;
 use rustc::session::config::Sanitizer;
 use rustc::ty::TyCtxt;
@@ -222,37 +221,9 @@ pub fn provide(providers: &mut Providers) {
         }
     };
 
-    providers.wasm_custom_sections = |tcx, cnum| {
-        assert_eq!(cnum, LOCAL_CRATE);
-        let mut finder = WasmSectionFinder { tcx, list: Vec::new() };
-        tcx.hir.krate().visit_all_item_likes(&mut finder);
-        Lrc::new(finder.list)
-    };
-
     provide_extern(providers);
 }
 
-struct WasmSectionFinder<'a, 'tcx: 'a> {
-    tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    list: Vec<DefId>,
-}
-
-impl<'a, 'tcx: 'a> ItemLikeVisitor<'tcx> for WasmSectionFinder<'a, 'tcx> {
-    fn visit_item(&mut self, i: &'tcx hir::Item) {
-        match i.node {
-            hir::ItemConst(..) => {}
-            _ => return,
-        }
-        if i.attrs.iter().any(|i| i.check_name("wasm_custom_section")) {
-            self.list.push(self.tcx.hir.local_def_id(i.id));
-        }
-    }
-
-    fn visit_trait_item(&mut self, _: &'tcx hir::TraitItem) {}
-
-    fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem) {}
-}
-
 pub fn provide_extern(providers: &mut Providers) {
     providers.wasm_import_module_map = |tcx, cnum| {
         let mut ret = FxHashMap();

src/librustc_codegen_llvm/back/link.rs

@@ -29,7 +29,7 @@ use rustc::util::common::time;
 use rustc::util::fs::fix_windows_verbatim_for_gcc;
 use rustc::hir::def_id::CrateNum;
 use tempfile::{Builder as TempFileBuilder, TempDir};
-use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor, TargetTriple};
+use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor};
 use rustc_data_structures::fx::FxHashSet;
 use context::get_reloc_model;
 use llvm;
@@ -837,10 +837,8 @@ fn link_natively(sess: &Session,
         }
     }
 
-    if sess.opts.target_triple == TargetTriple::from_triple("wasm32-unknown-unknown") {
+    if sess.opts.target_triple.triple() == "wasm32-unknown-unknown" {
         wasm::rewrite_imports(&out_filename, &codegen_results.crate_info.wasm_imports);
-        wasm::add_custom_sections(&out_filename,
-                                  &codegen_results.crate_info.wasm_custom_sections);
     }
 }
 

src/librustc_codegen_llvm/back/linker.rs

@@ -86,6 +86,7 @@ impl LinkerInfo {
             LinkerFlavor::Lld(LldFlavor::Wasm) => {
                 Box::new(WasmLd {
                     cmd,
+                    sess,
                 }) as Box<Linker>
             }
         }
@@ -919,11 +920,12 @@ fn exported_symbols(tcx: TyCtxt, crate_type: CrateType) -> Vec<String> {
     symbols
 }
 
-pub struct WasmLd {
+pub struct WasmLd<'a> {
     cmd: Command,
+    sess: &'a Session,
 }
 
-impl Linker for WasmLd {
+impl<'a> Linker for WasmLd<'a> {
     fn link_dylib(&mut self, lib: &str) {
         self.cmd.arg("-l").arg(lib);
     }
@@ -988,9 +990,20 @@ impl Linker for WasmLd {
     }
 
     fn gc_sections(&mut self, _keep_metadata: bool) {
+        self.cmd.arg("--gc-sections");
     }
 
     fn optimize(&mut self) {
+        self.cmd.arg(match self.sess.opts.optimize {
+            OptLevel::No => "-O0",
+            OptLevel::Less => "-O1",
+            OptLevel::Default => "-O2",
+            OptLevel::Aggressive => "-O3",
+            // Currently LLD doesn't support `Os` and `Oz`, so pass through `O2`
+            // instead.
+            OptLevel::Size => "-O2",
+            OptLevel::SizeMin => "-O2"
+        });
     }
 
     fn pgo_gen(&mut self) {
@@ -1020,8 +1033,28 @@ impl Linker for WasmLd {
         // this isn't yet the bottleneck of compilation at all anyway.
         self.cmd.arg("--no-threads");
 
+        // By default LLD only gives us one page of stack (64k) which is a
+        // little small. Default to a larger stack closer to other PC platforms
+        // (1MB) and users can always inject their own link-args to override this.
         self.cmd.arg("-z").arg("stack-size=1048576");
 
+        // By default LLD's memory layout is:
+        //
+        // 1. First, a blank page
+        // 2. Next, all static data
+        // 3. Finally, the main stack (which grows down)
+        //
+        // This has the unfortunate consequence that on stack overflows you
+        // corrupt static data and can cause some exceedingly weird bugs. To
+        // help detect this a little sooner we instead request that the stack is
+        // placed before static data.
+        //
+        // This means that we'll generate slightly larger binaries as references
+        // to static data will take more bytes in the ULEB128 encoding, but
+        // stack overflow will be guaranteed to trap as it underflows instead of
+        // corrupting static data.
+        self.cmd.arg("--stack-first");
+
         // FIXME we probably shouldn't pass this but instead pass an explicit
         // whitelist of symbols we'll allow to be undefined. Unfortunately
         // though we can't handle symbols like `log10` that LLVM injects at a

src/librustc_codegen_llvm/back/wasm.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::collections::BTreeMap;
 use std::fs;
 use std::path::Path;
 use std::str;
@@ -24,45 +23,6 @@ const WASM_EXTERNAL_KIND_TABLE: u8 = 1;
 const WASM_EXTERNAL_KIND_MEMORY: u8 = 2;
 const WASM_EXTERNAL_KIND_GLOBAL: u8 = 3;
 
-/// Append all the custom sections listed in `sections` to the wasm binary
-/// specified at `path`.
-///
-/// LLVM 6 which we're using right now doesn't have the ability to create custom
-/// sections in wasm files nor does LLD have the ability to merge these sections
-/// into one larger section when linking. It's expected that this will
-/// eventually get implemented, however!
-///
-/// Until that time though this is a custom implementation in rustc to append
-/// all sections to a wasm file to the finished product that LLD produces.
-///
-/// Support for this is landing in LLVM in https://reviews.llvm.org/D43097,
-/// although after that support will need to be in LLD as well.
-pub fn add_custom_sections(path: &Path, sections: &BTreeMap<String, Vec<u8>>) {
-    if sections.len() == 0 {
-        return
-    }
-
-    let wasm = fs::read(path).expect("failed to read wasm output");
-
-    // see https://webassembly.github.io/spec/core/binary/modules.html#custom-section
-    let mut wasm = WasmEncoder { data: wasm };
-    for (section, bytes) in sections {
-        // write the `id` identifier, 0 for a custom section
-        wasm.byte(0);
-
-        // figure out how long our name descriptor will be
-        let mut name = WasmEncoder::new();
-        name.str(section);
-
-        // write the length of the payload followed by all its contents
-        wasm.u32((bytes.len() + name.data.len()) as u32);
-        wasm.data.extend_from_slice(&name.data);
-        wasm.data.extend_from_slice(bytes);
-    }
-
-    fs::write(path, &wasm.data).expect("failed to write wasm output");
-}
-
 /// Rewrite the module imports are listed from in a wasm module given the field
 /// name to module name mapping in `import_map`.
 ///
@@ -80,7 +40,7 @@ pub fn add_custom_sections(path: &Path, sections: &BTreeMap<String, Vec<u8>>) {
 ///
 /// Support for this was added to LLVM in
 /// https://github.com/llvm-mirror/llvm/commit/0f32e1365, although support still
-/// needs to be added (AFAIK at the time of this writing) to LLD
+/// needs to be added, tracked at https://bugs.llvm.org/show_bug.cgi?id=37168
 pub fn rewrite_imports(path: &Path, import_map: &FxHashMap<String, String>) {
     if import_map.len() == 0 {
         return