Ship LLVM-C.dll on Windows

src/bootstrap/dist.rs

@@ -18,7 +18,7 @@ use build_helper::{output, t};
 
 use crate::{Compiler, Mode, LLVM_TOOLS};
 use crate::channel;
-use crate::util::{is_dylib, exe};
+use crate::util::{is_dylib, exe, libdir};
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::compile;
 use crate::tool::{self, Tool};
@@ -2047,8 +2047,8 @@ pub fn maybe_install_llvm_dylib(builder: &Builder<'_>,
                                 sysroot: &Path) {
     let src_libdir = builder
         .llvm_out(target)
-        .join("lib");
-    let dst_libdir = sysroot.join("lib/rustlib").join(&*target).join("lib");
+        .join(libdir(&target));
+    let dst_libdir = sysroot.join("lib").join("rustlib").join(&*target).join("lib");
     t!(fs::create_dir_all(&dst_libdir));
 
     if target.contains("apple-darwin") {
@@ -2059,6 +2059,17 @@ pub fn maybe_install_llvm_dylib(builder: &Builder<'_>,
         return
     }
 
+    // Install the LLVM-C library for Windows as LLVM does not support
+    // creating a C++ shared library there.
+    // This is done because rust-ptx-linker requires LLVM.
+    if target.contains("pc-windows") {
+        let llvm_dylib_path = src_libdir.join("LLVM-C.dll");
+        if llvm_dylib_path.exists() {
+            builder.install(&llvm_dylib_path, &dst_libdir, 0o644);
+        }
+        return
+    }
+
     // Usually libLLVM.so is a symlink to something like libLLVM-6.0.so.
     // Since tools link to the latter rather than the former, we have to
     // follow the symlink to find out what to distribute.

src/bootstrap/native.rs

@@ -181,6 +181,10 @@ impl Step for Llvm {
             cfg.define("LLVM_LINK_LLVM_DYLIB", "ON");
         }
 
+        if target.contains("pc-windows") {
+            cfg.define("LLVM_BUILD_LLVM_C_DYLIB", "ON");
+        }
+
         // For distribution we want the LLVM tools to be *statically* linked to libstdc++
         if builder.config.llvm_tools_enabled || want_lldb {
             if !target.contains("windows") {