PGO - Add a smoketest for combining PGO with cross-language LTO.

src/bootstrap/native.rs

@@ -203,8 +203,16 @@ impl Step for Llvm {
             cfg.define("LLVM_BUILD_32_BITS", "ON");
         }
 
+        let mut enabled_llvm_projects = Vec::new();
+
+        if util::forcing_clang_based_tests() {
+            enabled_llvm_projects.push("clang");
+            enabled_llvm_projects.push("compiler-rt");
+        }
+
         if want_lldb {
-            cfg.define("LLVM_ENABLE_PROJECTS", "clang;lldb");
+            enabled_llvm_projects.push("clang");
+            enabled_llvm_projects.push("lldb");
             // For the time being, disable code signing.
             cfg.define("LLDB_CODESIGN_IDENTITY", "");
             cfg.define("LLDB_NO_DEBUGSERVER", "ON");
@@ -214,6 +222,12 @@ impl Step for Llvm {
             cfg.define("LLVM_ENABLE_LIBXML2", "OFF");
         }
 
+        if enabled_llvm_projects.len() > 0 {
+            enabled_llvm_projects.sort();
+            enabled_llvm_projects.dedup();
+            cfg.define("LLVM_ENABLE_PROJECTS", enabled_llvm_projects.join(";"));
+        }
+
         if let Some(num_linkers) = builder.config.llvm_link_jobs {
             if num_linkers > 0 {
                 cfg.define("LLVM_PARALLEL_LINK_JOBS", num_linkers.to_string());

src/bootstrap/test.rs

@@ -1143,24 +1143,9 @@ impl Step for Compiletest {
             }
         }
 
-        if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
-            match &var.to_string_lossy().to_lowercase()[..] {
-                "1" | "yes" | "on" => {
-                    assert!(builder.config.lldb_enabled,
-                        "RUSTBUILD_FORCE_CLANG_BASED_TESTS needs Clang/LLDB to \
-                         be built.");
-                    let clang_exe = builder.llvm_out(target).join("bin").join("clang");
-                    cmd.arg("--run-clang-based-tests-with").arg(clang_exe);
-                }
-                "0" | "no" | "off" => {
-                    // Nothing to do.
-                }
-                other => {
-                    // Let's make sure typos don't get unnoticed
-                    panic!("Unrecognized option '{}' set in \
-                            RUSTBUILD_FORCE_CLANG_BASED_TESTS", other);
-                }
-            }
+        if util::forcing_clang_based_tests() {
+            let clang_exe = builder.llvm_out(target).join("bin").join("clang");
+            cmd.arg("--run-clang-based-tests-with").arg(clang_exe);
         }
 
         // Get paths from cmd args

src/bootstrap/util.rs

@@ -356,3 +356,19 @@ impl CiEnv {
         }
     }
 }
+
+pub fn forcing_clang_based_tests() -> bool {
+    if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
+        match &var.to_string_lossy().to_lowercase()[..] {
+            "1" | "yes" | "on" => true,
+            "0" | "no" | "off" => false,
+            other => {
+                // Let's make sure typos don't go unnoticed
+                panic!("Unrecognized option '{}' set in \
+                        RUSTBUILD_FORCE_CLANG_BASED_TESTS", other)
+            }
+        }
+    } else {
+        false
+    }
+}

src/librustc/session/config.rs

@@ -1381,7 +1381,7 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
                      "insert profiling code"),
     pgo_gen: PgoGenerate = (PgoGenerate::Disabled, parse_pgo_generate, [TRACKED],
         "Generate PGO profile data, to a given file, or to the default location if it's empty."),
-    pgo_use: String = (String::new(), parse_string, [TRACKED],
+    pgo_use: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
         "Use PGO profile data from the given profile file."),
     disable_instrumentation_preinliner: bool = (false, parse_bool, [TRACKED],
         "Disable the instrumentation pre-inliner, useful for profiling / PGO."),
@@ -2021,7 +2021,7 @@ pub fn build_session_options_and_crate_config(
         }
     }
 
-    if debugging_opts.pgo_gen.enabled() && !debugging_opts.pgo_use.is_empty() {
+    if debugging_opts.pgo_gen.enabled() && debugging_opts.pgo_use.is_some() {
         early_error(
             error_format,
             "options `-Z pgo-gen` and `-Z pgo-use` are exclusive",
@@ -3211,7 +3211,7 @@ mod tests {
         assert_ne!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
 
         opts = reference.clone();
-        opts.debugging_opts.pgo_use = String::from("abc");
+        opts.debugging_opts.pgo_use = Some(PathBuf::from("abc"));
         assert_ne!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
 
         opts = reference.clone();

src/librustc/session/mod.rs

@@ -1272,6 +1272,15 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
         sess.err("Linker plugin based LTO is not supported together with \
                   `-C prefer-dynamic` when targeting MSVC");
     }
+
+    // Make sure that any given profiling data actually exists so LLVM can't
+    // decide to silently skip PGO.
+    if let Some(ref path) = sess.opts.debugging_opts.pgo_use {
+        if !path.exists() {
+            sess.err(&format!("File `{}` passed to `-Zpgo-use` does not exist.",
+                              path.display()));
+        }
+    }
 }
 
 /// Hash value constructed out of all the `-C metadata` arguments passed to the

src/librustc_codegen_llvm/back/write.rs

@@ -721,11 +721,9 @@ pub unsafe fn with_llvm_pmb(llmod: &llvm::Module,
         }
     };
 
-    let pgo_use_path = if config.pgo_use.is_empty() {
-        None
-    } else {
-        Some(CString::new(config.pgo_use.as_bytes()).unwrap())
-    };
+    let pgo_use_path = config.pgo_use.as_ref().map(|path_buf| {
+        CString::new(path_buf.to_string_lossy().as_bytes()).unwrap()
+    });
 
     llvm::LLVMRustConfigurePassManagerBuilder(
         builder,

src/librustc_codegen_ssa/back/write.rs

@@ -57,7 +57,7 @@ pub struct ModuleConfig {
     pub opt_size: Option<config::OptLevel>,
 
     pub pgo_gen: PgoGenerate,
-    pub pgo_use: String,
+    pub pgo_use: Option<PathBuf>,
 
     // Flags indicating which outputs to produce.
     pub emit_pre_lto_bc: bool,
@@ -95,7 +95,7 @@ impl ModuleConfig {
             opt_size: None,
 
             pgo_gen: PgoGenerate::Disabled,
-            pgo_use: String::new(),
+            pgo_use: None,
 
             emit_no_opt_bc: false,
             emit_pre_lto_bc: false,

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
+}