Add a smoketest for combining PGO with xLTO.

src/test/run-make-fulldeps/cross-lang-lto-pgo-smoketest/Makefile

@@ -0,0 +1,87 @@
+# needs-matching-clang
+
+# This test makes sure that cross-language inlining can be used in conjunction
+# with profile-guided optimization. The test only tests that the whole workflow
+# can be executed without anything crashing. It does not test whether PGO or
+# xLTO have any specific effect on the generated code.
+
+-include ../tools.mk
+
+COMMON_FLAGS=-Copt-level=3 -Ccodegen-units=1
+
+# LLVM doesn't support instrumenting binaries that use SEH:
+# https://bugs.llvm.org/show_bug.cgi?id=41279
+#
+# Things work fine with -Cpanic=abort though.
+ifdef IS_MSVC
+COMMON_FLAGS+= -Cpanic=abort
+endif
+
+all: cpp-executable rust-executable
+
+cpp-executable:
+	$(RUSTC) -Clinker-plugin-lto=on \
+	         -Zpgo-gen="$(TMPDIR)"/cpp-profdata \
+	         -o "$(TMPDIR)"/librustlib-xlto.a \
+	         $(COMMON_FLAGS) \
+	         ./rustlib.rs
+	$(CLANG) -flto=thin \
+	         -fprofile-generate="$(TMPDIR)"/cpp-profdata \
+	         -fuse-ld=lld \
+	         -L "$(TMPDIR)" \
+	         -lrustlib-xlto \
+	         -o "$(TMPDIR)"/cmain \
+	         -O3 \
+	         ./cmain.c
+	$(TMPDIR)/cmain
+	# Postprocess the profiling data so it can be used by the compiler
+	"$(LLVM_BIN_DIR)"/llvm-profdata merge \
+		-o "$(TMPDIR)"/cpp-profdata/merged.profdata \
+		"$(TMPDIR)"/cpp-profdata/default_*.profraw
+	$(RUSTC) -Clinker-plugin-lto=on \
+	         -Zpgo-use="$(TMPDIR)"/cpp-profdata/merged.profdata \
+	         -o "$(TMPDIR)"/librustlib-xlto.a \
+	         $(COMMON_FLAGS) \
+	         ./rustlib.rs
+	$(CLANG) -flto=thin \
+	         -fprofile-use="$(TMPDIR)"/cpp-profdata/merged.profdata \
+	         -fuse-ld=lld \
+	         -L "$(TMPDIR)" \
+	         -lrustlib-xlto \
+	         -o "$(TMPDIR)"/cmain \
+	         -O3 \
+	         ./cmain.c
+
+rust-executable:
+	exit
+	$(CLANG) ./clib.c -fprofile-generate="$(TMPDIR)"/rs-profdata -flto=thin -c -o $(TMPDIR)/clib.o -O3
+	(cd $(TMPDIR); $(AR) crus ./libxyz.a ./clib.o)
+	$(RUSTC) -Clinker-plugin-lto=on \
+	         -Zpgo-gen="$(TMPDIR)"/rs-profdata \
+	         -L$(TMPDIR) \
+	         $(COMMON_FLAGS) \
+	         -Clinker=$(CLANG) \
+	         -Clink-arg=-fuse-ld=lld \
+	         -o $(TMPDIR)/rsmain \
+	         ./main.rs
+	$(TMPDIR)/rsmain
+	# Postprocess the profiling data so it can be used by the compiler
+	"$(LLVM_BIN_DIR)"/llvm-profdata merge \
+		-o "$(TMPDIR)"/rs-profdata/merged.profdata \
+		"$(TMPDIR)"/rs-profdata/default_*.profraw
+	$(CLANG) ./clib.c \
+	         -fprofile-use="$(TMPDIR)"/rs-profdata/merged.profdata \
+	         -flto=thin \
+	         -c \
+	         -o $(TMPDIR)/clib.o \
+	         -O3
+	rm "$(TMPDIR)"/libxyz.a
+	(cd $(TMPDIR); $(AR) crus ./libxyz.a ./clib.o)
+	$(RUSTC) -Clinker-plugin-lto=on \
+	         -Zpgo-use="$(TMPDIR)"/rs-profdata/merged.profdata \
+	         -L$(TMPDIR) \
+	         $(COMMON_FLAGS) \
+	         -Clinker=$(CLANG) \
+	         -Clink-arg=-fuse-ld=lld \
+	         -o $(TMPDIR)/rsmain \
+	         ./main.rs

src/test/run-make-fulldeps/cross-lang-lto-pgo-smoketest/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-pgo-smoketest/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()) * 0;
+}

src/test/run-make-fulldeps/cross-lang-lto-pgo-smoketest/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-pgo-smoketest/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
+}