Auto merge of #55835 - alexcrichton:llvm-upgrade, r=nikomatsakis

Upgrade LLVM to trunk, still version 8

This commit upgrades the LLVM/LLD/compiler-rt submodules used to the current trunk versions in upstream. Some activity has happened on the wasm SIMD side of things as well as LLD which we'd like to pick up!

.travis.yml

@@ -30,7 +30,7 @@ matrix:
 
     - env: >
         RUST_CHECK_TARGET=dist
-        RUST_CONFIGURE_ARGS="--enable-extended --enable-profiler --enable-lldb --set rust.jemalloc"
+        RUST_CONFIGURE_ARGS="--enable-extended --enable-profiler --set rust.jemalloc"
         SRC=.
         DEPLOY_ALT=1
         RUSTC_RETRY_LINKER_ON_SEGFAULT=1
@@ -87,7 +87,7 @@ matrix:
     # OSX 10.7 and `xcode7` is the latest Xcode able to compile LLVM for 10.7.
     - env: >
         RUST_CHECK_TARGET=dist
-        RUST_CONFIGURE_ARGS="--build=i686-apple-darwin --enable-full-tools --enable-profiler --enable-lldb --set rust.jemalloc"
+        RUST_CONFIGURE_ARGS="--build=i686-apple-darwin --enable-full-tools --enable-profiler --set rust.jemalloc"
         SRC=.
         DEPLOY=1
         RUSTC_RETRY_LINKER_ON_SEGFAULT=1
@@ -102,7 +102,7 @@ matrix:
 
     - env: >
         RUST_CHECK_TARGET=dist
-        RUST_CONFIGURE_ARGS="--target=aarch64-apple-ios,armv7-apple-ios,armv7s-apple-ios,i386-apple-ios,x86_64-apple-ios --enable-full-tools --enable-sanitizers --enable-profiler --enable-lldb --set rust.jemalloc"
+        RUST_CONFIGURE_ARGS="--target=aarch64-apple-ios,armv7-apple-ios,armv7s-apple-ios,i386-apple-ios,x86_64-apple-ios --enable-full-tools --enable-sanitizers --enable-profiler --set rust.jemalloc"
         SRC=.
         DEPLOY=1
         RUSTC_RETRY_LINKER_ON_SEGFAULT=1

src/librustc_codegen_ssa/back/linker.rs

@@ -1037,6 +1037,17 @@ impl<'a> Linker for WasmLd<'a> {
         // indicative of bugs, let's prevent them.
         self.cmd.arg("--fatal-warnings");
 
+        // The symbol visibility story is a bit in flux right now with LLD.
+        // It's... not entirely clear to me what's going on, but this looks to
+        // make everything work when `export_symbols` isn't otherwise called for
+        // things like executables.
+        self.cmd.arg("--export-dynamic");
+
+        // LLD only implements C++-like demangling, which doesn't match our own
+        // mangling scheme. Tell LLD to not demangle anything and leave it up to
+        // us to demangle these symbols later.
+        self.cmd.arg("--no-demangle");
+
         ::std::mem::replace(&mut self.cmd, Command::new(""))
     }
 

src/rustllvm/PassWrapper.cpp

@@ -922,7 +922,11 @@ LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules,
                               GlobalValue::LinkageTypes NewLinkage) {
     ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
   };
+#if LLVM_VERSION_GE(8, 0)
+  thinLTOResolvePrevailingInIndex(Ret->Index, isPrevailing, recordNewLinkage);
+#else
   thinLTOResolveWeakForLinkerInIndex(Ret->Index, isPrevailing, recordNewLinkage);
+#endif
 
   // Here we calculate an `ExportedGUIDs` set for use in the `isExported`
   // callback below. This callback below will dictate the linkage for all
@@ -977,7 +981,11 @@ extern "C" bool
 LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
   Module &Mod = *unwrap(M);
   const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
+#if LLVM_VERSION_GE(8, 0)
+  thinLTOResolvePrevailingInModule(Mod, DefinedGlobals);
+#else
   thinLTOResolveWeakForLinkerModule(Mod, DefinedGlobals);
+#endif
   return true;
 }
 

src/rustllvm/RustWrapper.cpp

@@ -708,7 +708,11 @@ extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateStaticVariable(
   llvm::DIGlobalVariableExpression *VarExpr = Builder->createGlobalVariableExpression(
       unwrapDI<DIDescriptor>(Context), Name, LinkageName,
       unwrapDI<DIFile>(File), LineNo, unwrapDI<DIType>(Ty), IsLocalToUnit,
-      InitExpr, unwrapDIPtr<MDNode>(Decl), AlignInBits);
+      InitExpr, unwrapDIPtr<MDNode>(Decl),
+#if LLVM_VERSION_GE(8, 0)
+      /* templateParams */ nullptr,
+#endif
+      AlignInBits);
 
   InitVal->setMetadata("dbg", VarExpr);