Auto merge of #57514 - michaelwoerister:xlto-tests, r=alexcrichton

compiletest: Support opt-in Clang-based run-make tests and use them for testing xLTO.

Some cross-language run-make tests need a Clang compiler that matches the LLVM version of `rustc`. Since such a compiler usually isn't available these tests (marked with the `needs-matching-clang`
directive) are ignored by default.

For some CI jobs we do need these tests to run unconditionally though. In order to support this a `--force-clang-based-tests` flag is added to compiletest. If this flag is specified, `compiletest` will fail if it can't detect an appropriate version of Clang.

@rust-lang/infra The PR doesn't yet enable the tests yet. Do you have any recommendation for which jobs to enable them?

cc #57438

r? @alexcrichton

5 files changed, 69 insertions, 0 deletions

diff --git a/src/test/run-make-fulldeps/cross-lang-lto-clang/Makefile b/src/test/run-make-fulldeps/cross-lang-lto-clang/Makefile
new file mode 100644
index 00000000000..cf687070bc2
--- /dev/null
+++ b/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"
diff --git a/src/test/run-make-fulldeps/cross-lang-lto-clang/clib.c b/src/test/run-make-fulldeps/cross-lang-lto-clang/clib.c
new file mode 100644
index 00000000000..90f33f24dc4
--- /dev/null
+++ b/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;
+}
diff --git a/src/test/run-make-fulldeps/cross-lang-lto-clang/cmain.c b/src/test/run-make-fulldeps/cross-lang-lto-clang/cmain.c
new file mode 100644
index 00000000000..e62a40117ce
--- /dev/null
+++ b/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();
+}
diff --git a/src/test/run-make-fulldeps/cross-lang-lto-clang/main.rs b/src/test/run-make-fulldeps/cross-lang-lto-clang/main.rs
new file mode 100644
index 00000000000..8129dcb85d9
--- /dev/null
+++ b/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());
+    }
+}
diff --git a/src/test/run-make-fulldeps/cross-lang-lto-clang/rustlib.rs b/src/test/run-make-fulldeps/cross-lang-lto-clang/rustlib.rs
new file mode 100644
index 00000000000..8a74d74a420
--- /dev/null
+++ b/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
+}