Add an end-to-end run-make test for cross-lang LTO.

src/test/run-make-fulldeps/cross-lang-lto-clang/Makefile

@@ -0,0 +1,25 @@
+# needs-matching-clang
+
+# This test makes sure that cross-language inlining actually works by checking
+# the generated machine code.
+
+-include ../tools.mk
+
+all: cpp-executable rust-executable
+
+cpp-executable:
+	$(RUSTC) -Zcross-lang-lto=on -o $(TMPDIR)/librustlib-xlto.a -Copt-level=2 -Ccodegen-units=1 ./rustlib.rs
+	clang -flto=thin -fuse-ld=lld -L $(TMPDIR) -lrustlib-xlto -o $(TMPDIR)/cmain ./cmain.c -O3
+	# Make sure we don't find a call instruction to the function we expect to
+	# always be inlined.
+	llvm-objdump -d $(TMPDIR)/cmain | $(CGREP) -v -e "call.*rust_always_inlined"
+	# As a sanity check, make sure we do find a call instruction to a
+	# non-inlined function
+	llvm-objdump -d $(TMPDIR)/cmain | $(CGREP) -e "call.*rust_never_inlined"
+
+rust-executable:
+	clang ./clib.c -flto=thin -c -o $(TMPDIR)/clib.o -O2
+	(cd $(TMPDIR); $(AR) crus ./libxyz.a ./clib.o)
+	$(RUSTC) -Zcross-lang-lto=on -L$(TMPDIR) -Copt-level=2 -Clinker=clang -Clink-arg=-fuse-ld=lld ./main.rs -o $(TMPDIR)/rsmain
+	llvm-objdump -d $(TMPDIR)/rsmain | $(CGREP) -e "call.*c_never_inlined"
+	llvm-objdump -d $(TMPDIR)/rsmain | $(CGREP) -v -e "call.*c_always_inlined"

src/test/run-make-fulldeps/cross-lang-lto-clang/clib.c

@@ -0,0 +1,9 @@
+#include <stdint.h>
+
+uint32_t c_always_inlined() {
+    return 1234;
+}
+
+__attribute__((noinline)) uint32_t c_never_inlined() {
+    return 12345;
+}

src/test/run-make-fulldeps/cross-lang-lto-clang/cmain.c

@@ -0,0 +1,12 @@
+#include <stdint.h>
+
+// A trivial function defined in Rust, returning a constant value. This should
+// always be inlined.
+uint32_t rust_always_inlined();
+
+
+uint32_t rust_never_inlined();
+
+int main(int argc, char** argv) {
+    return rust_never_inlined() + rust_always_inlined();
+}

src/test/run-make-fulldeps/cross-lang-lto-clang/main.rs

@@ -0,0 +1,11 @@
+#[link(name = "xyz")]
+extern "C" {
+    fn c_always_inlined() -> u32;
+    fn c_never_inlined() -> u32;
+}
+
+fn main() {
+    unsafe {
+        println!("blub: {}", c_always_inlined() + c_never_inlined());
+    }
+}

src/test/run-make-fulldeps/cross-lang-lto-clang/rustlib.rs

@@ -0,0 +1,12 @@
+#![crate_type="staticlib"]
+
+#[no_mangle]
+pub extern "C" fn rust_always_inlined() -> u32 {
+    42
+}
+
+#[no_mangle]
+#[inline(never)]
+pub extern "C" fn rust_never_inlined() -> u32 {
+    421
+}