Add profiling support, through the rustc -Z profile flag.

When -Z profile is passed, the GCDAProfiling LLVM pass is added
to the pipeline, which uses debug information to instrument the IR.
After compiling with -Z profile, the $(OUT_DIR)/$(CRATE_NAME).gcno
file is created, containing initial profiling information.
After running the program built, the $(OUT_DIR)/$(CRATE_NAME).gcda
file is created, containing branch counters.

The created *.gcno and *.gcda files can be processed using
the "llvm-cov gcov" and "lcov" tools. The profiling data LLVM
generates does not faithfully follow the GCC's format for *.gcno
and *.gcda files, and so it will probably not work with other tools
(such as gcov itself) that consume these files.

configure

@@ -452,6 +452,7 @@ opt vendor 0 "enable usage of vendored Rust crates"
 opt sanitizers 0 "build the sanitizer runtimes (asan, lsan, msan, tsan)"
 opt dist-src 1 "when building tarballs enables building a source tarball"
 opt cargo-openssl-static 0 "static openssl in cargo"
+opt profiler 0 "build the profiler runtime"
 
 # Optimization and debugging options. These may be overridden by the release channel, etc.
 opt_nosave optimize 1 "build optimized rust code"

src/bootstrap/check.rs

@@ -268,6 +268,10 @@ pub fn compiletest(build: &Build,
         cmd.env("SANITIZER_SUPPORT", "1");
     }
 
+    if build.config.profiler {
+        cmd.env("PROFILER_SUPPORT", "1");
+    }
+
     cmd.arg("--adb-path").arg("adb");
     cmd.arg("--adb-test-dir").arg(ADB_TEST_DIR);
     if target.contains("android") {

src/bootstrap/config.rs

@@ -50,6 +50,7 @@ pub struct Config {
     pub full_bootstrap: bool,
     pub extended: bool,
     pub sanitizers: bool,
+    pub profiler: bool,
 
     // llvm codegen options
     pub llvm_assertions: bool,
@@ -158,6 +159,7 @@ struct Build {
     extended: Option<bool>,
     verbose: Option<usize>,
     sanitizers: Option<bool>,
+    profiler: Option<bool>,
     openssl_static: Option<bool>,
 }
 
@@ -311,6 +313,7 @@ impl Config {
         set(&mut config.extended, build.extended);
         set(&mut config.verbose, build.verbose);
         set(&mut config.sanitizers, build.sanitizers);
+        set(&mut config.profiler, build.profiler);
         set(&mut config.openssl_static, build.openssl_static);
 
         if let Some(ref install) = toml.install {
@@ -462,6 +465,7 @@ impl Config {
                 ("FULL_BOOTSTRAP", self.full_bootstrap),
                 ("EXTENDED", self.extended),
                 ("SANITIZERS", self.sanitizers),
+                ("PROFILER", self.profiler),
                 ("DIST_SRC", self.rust_dist_src),
                 ("CARGO_OPENSSL_STATIC", self.openssl_static),
             }

src/bootstrap/config.toml.example

@@ -147,6 +147,9 @@
 # Build the sanitizer runtimes
 #sanitizers = false
 
+# Build the profiler runtime
+#profiler = false
+
 # Indicates whether the OpenSSL linked into Cargo will be statically linked or
 # not. If static linkage is specified then the build system will download a
 # known-good version of OpenSSL, compile it, and link it to Cargo.

src/bootstrap/lib.rs

@@ -667,6 +667,9 @@ impl Build {
         if self.config.backtrace {
             features.push_str(" backtrace");
         }
+        if self.config.profiler {
+            features.push_str(" profiler");
+        }
         return features
     }
 

src/doc/unstable-book/src/SUMMARY.md

@@ -2,6 +2,7 @@
 
 - [Compiler flags](compiler-flags.md)
     - [linker_flavor](compiler-flags/linker-flavor.md)
+    - [profile](compiler-flags/profile.md)
     - [remap_path_prefix](compiler-flags/remap-path-prefix.md)
 - [Language features](language-features.md)
     - [abi_msp430_interrupt](language-features/abi-msp430-interrupt.md)
@@ -71,6 +72,7 @@
     - [plugin_registrar](language-features/plugin-registrar.md)
     - [prelude_import](language-features/prelude-import.md)
     - [proc_macro](language-features/proc-macro.md)
+    - [profiler_runtime](language-features/profiler-runtime.md)
     - [quote](language-features/quote.md)
     - [relaxed_adts](language-features/relaxed-adts.md)
     - [repr_align](language-features/repr-align.md)
@@ -180,6 +182,7 @@
     - [print](library-features/print.md)
     - [proc_macro_internals](library-features/proc-macro-internals.md)
     - [process_try_wait](library-features/process-try-wait.md)
+    - [profiler_runtime_lib](library-features/sanitizer-runtime-lib.md)
     - [question_mark_carrier](library-features/question-mark-carrier.md)
     - [rand](library-features/rand.md)
     - [range_contains](library-features/range-contains.md)

src/doc/unstable-book/src/compiler-flags/profile.md

@@ -0,0 +1,5 @@
+# `profile`
+
+The tracking issue for this feature is: None
+
+------------------------

src/doc/unstable-book/src/language-features/profiler-runtime.md

@@ -0,0 +1,5 @@
+# `profiler_runtime`
+
+The tracking issue for this feature is: None.
+
+------------------------

src/doc/unstable-book/src/library-features/profiler-runtime-lib.md

@@ -0,0 +1,5 @@
+# `profiler_runtime_lib`
+
+This feature is internal to the Rust compiler and is not intended for general use.
+
+------------------------

src/libprofiler_builtins/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+authors = ["The Rust Project Developers"]
+build = "build.rs"
+name = "profiler_builtins"
+version = "0.0.0"
+
+[lib]
+name = "profiler_builtins"
+path = "lib.rs"
+test = false
+bench = false
+doc = false
+
+[dependencies]
+core = { path = "../libcore" }
+
+[build-dependencies]
+gcc = "0.3.27"

src/libprofiler_builtins/build.rs

@@ -0,0 +1,56 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Compiles the profiler part of the `compiler-rt` library.
+//!
+//! See the build.rs for libcompiler_builtins crate for details.
+
+extern crate gcc;
+
+use std::env;
+use std::path::Path;
+
+fn main() {
+    let target = env::var("TARGET").expect("TARGET was not set");
+    let cfg = &mut gcc::Config::new();
+
+    if target.contains("msvc") {
+        // Don't pull in extra libraries on MSVC
+        cfg.flag("/Zl");
+    } else {
+        // Turn off various features of gcc and such, mostly copying
+        // compiler-rt's build system already
+        cfg.flag("-fno-builtin");
+        cfg.flag("-fvisibility=hidden");
+        cfg.flag("-fomit-frame-pointer");
+        cfg.flag("-ffreestanding");
+        cfg.define("VISIBILITY_HIDDEN", None);
+    }
+
+    let profile_sources = &["GCDAProfiling.c",
+                            "InstrProfiling.c",
+                            "InstrProfilingBuffer.c",
+                            "InstrProfilingFile.c",
+                            "InstrProfilingMerge.c",
+                            "InstrProfilingMergeFile.c",
+                            "InstrProfilingPlatformDarwin.c",
+                            "InstrProfilingPlatformLinux.c",
+                            "InstrProfilingPlatformOther.c",
+                            "InstrProfilingRuntime.cc",
+                            "InstrProfilingUtil.c",
+                            "InstrProfilingValue.c",
+                            "InstrProfilingWriter.c"];
+
+    for src in profile_sources {
+        cfg.file(Path::new("../compiler-rt/lib/profile").join(src));
+    }
+
+    cfg.compile("libprofiler-rt.a");
+}

src/libprofiler_builtins/lib.rs

@@ -0,0 +1,20 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![no_std]
+#![cfg_attr(not(stage0), feature(profiler_runtime))]
+#![cfg_attr(not(stage0), profiler_runtime)]
+#![unstable(feature = "profiler_runtime_lib",
+            reason = "internal implementation detail of rustc right now",
+            issue = "0")]
+#![crate_name = "profiler_builtins"]
+#![crate_type = "rlib"]
+#![allow(unused_features)]
+#![feature(staged_api)]

src/librustc/middle/cstore.rs

@@ -220,6 +220,7 @@ pub trait CrateStore {
     fn is_panic_runtime(&self, cnum: CrateNum) -> bool;
     fn is_compiler_builtins(&self, cnum: CrateNum) -> bool;
     fn is_sanitizer_runtime(&self, cnum: CrateNum) -> bool;
+    fn is_profiler_runtime(&self, cnum: CrateNum) -> bool;
     fn panic_strategy(&self, cnum: CrateNum) -> PanicStrategy;
     fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate>;
     /// The name of the crate as it is referred to in source code of the current
@@ -356,6 +357,7 @@ impl CrateStore for DummyCrateStore {
     fn is_allocator(&self, cnum: CrateNum) -> bool { bug!("is_allocator") }
     fn is_panic_runtime(&self, cnum: CrateNum) -> bool { bug!("is_panic_runtime") }
     fn is_compiler_builtins(&self, cnum: CrateNum) -> bool { bug!("is_compiler_builtins") }
+    fn is_profiler_runtime(&self, cnum: CrateNum) -> bool { bug!("is_profiler_runtime") }
     fn is_sanitizer_runtime(&self, cnum: CrateNum) -> bool { bug!("is_sanitizer_runtime") }
     fn panic_strategy(&self, cnum: CrateNum) -> PanicStrategy {
         bug!("panic_strategy")

src/librustc/session/config.rs

@@ -1025,6 +1025,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "add a source pattern to the file path remapping config"),
     remap_path_prefix_to: Vec<String> = (vec![], parse_string_push, [TRACKED],
         "add a mapping target to the file path remapping config"),
+    profile: bool = (false, parse_bool, [TRACKED],
+                     "insert profiling code"),
 }
 
 pub fn default_lib_output() -> CrateType {

src/librustc_driver/driver.rs

@@ -203,7 +203,8 @@ pub fn compile_input(sess: &Session,
                 println!("Pre-trans");
                 tcx.print_debug_stats();
             }
-            let trans = phase_4_translate_to_llvm(tcx, analysis, &incremental_hashes_map);
+            let trans = phase_4_translate_to_llvm(tcx, analysis, &incremental_hashes_map,
+                                                  &outputs);
 
             if log_enabled!(::log::LogLevel::Info) {
                 println!("Post-trans");
@@ -1029,7 +1030,8 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
 /// be discarded.
 pub fn phase_4_translate_to_llvm<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                            analysis: ty::CrateAnalysis,
-                                           incremental_hashes_map: &IncrementalHashesMap)
+                                           incremental_hashes_map: &IncrementalHashesMap,
+                                           output_filenames: &OutputFilenames)
                                            -> trans::CrateTranslation {
     let time_passes = tcx.sess.time_passes();
 
@@ -1077,7 +1079,7 @@ pub fn phase_4_translate_to_llvm<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let translation =
         time(time_passes,
              "translation",
-             move || trans::trans_crate(tcx, analysis, &incremental_hashes_map));
+             move || trans::trans_crate(tcx, analysis, &incremental_hashes_map, output_filenames));
 
     time(time_passes,
          "assert dep graph",

src/librustc_llvm/ffi.rs

@@ -587,7 +587,9 @@ extern "C" {
     pub fn LLVMIsUndef(Val: ValueRef) -> Bool;
 
     // Operations on metadata
+    pub fn LLVMMDStringInContext(C: ContextRef, Str: *const c_char, SLen: c_uint) -> ValueRef;
     pub fn LLVMMDNodeInContext(C: ContextRef, Vals: *const ValueRef, Count: c_uint) -> ValueRef;
+    pub fn LLVMAddNamedMetadataOperand(M: ModuleRef, Name: *const c_char, Val: ValueRef);
 
     // Operations on scalar constants
     pub fn LLVMConstInt(IntTy: TypeRef, N: c_ulonglong, SignExtend: Bool) -> ValueRef;
@@ -1328,6 +1330,8 @@ extern "C" {
 
     pub fn LLVMRustAddModuleFlag(M: ModuleRef, name: *const c_char, value: u32);
 
+    pub fn LLVMRustMetadataAsValue(C: ContextRef, MD: MetadataRef) -> ValueRef;
+
     pub fn LLVMRustDIBuilderCreate(M: ModuleRef) -> DIBuilderRef;
 
     pub fn LLVMRustDIBuilderDispose(Builder: DIBuilderRef);

src/librustc_metadata/creader.rs

@@ -870,6 +870,33 @@ impl<'a> CrateLoader<'a> {
         }
     }
 
+    fn inject_profiler_runtime(&mut self) {
+        if self.sess.opts.debugging_opts.profile {
+            let mut uses_std = false;
+            self.cstore.iter_crate_data(|_, data| {
+                if data.name == "std" {
+                    uses_std = true;
+                }
+            });
+
+            if uses_std {
+                info!("loading profiler");
+
+                let symbol = Symbol::intern("profiler_builtins");
+                let dep_kind = DepKind::Implicit;
+                let (_, data) =
+                    self.resolve_crate(&None, symbol, symbol, None, DUMMY_SP,
+                                       PathKind::Crate, dep_kind);
+
+                // Sanity check the loaded crate to ensure it is indeed a profiler runtime
+                if !data.is_profiler_runtime() {
+                    self.sess.err(&format!("the crate `profiler_builtins` is not \
+                                            a profiler runtime"));
+                }
+            }
+        }
+    }
+
     fn inject_allocator_crate(&mut self) {
         // Make sure that we actually need an allocator, if none of our
         // dependencies need one then we definitely don't!
@@ -1071,6 +1098,7 @@ impl<'a> middle::cstore::CrateLoader for CrateLoader<'a> {
         // inject the sanitizer runtime before the allocator runtime because all
         // sanitizers force the use of the `alloc_system` allocator
         self.inject_sanitizer_runtime();
+        self.inject_profiler_runtime();
         self.inject_allocator_crate();
         self.inject_panic_runtime(krate);
 

src/librustc_metadata/cstore.rs

@@ -308,6 +308,11 @@ impl CrateMetadata {
         attr::contains_name(&attrs, "sanitizer_runtime")
     }
 
+    pub fn is_profiler_runtime(&self) -> bool {
+        let attrs = self.get_item_attrs(CRATE_DEF_INDEX);
+        attr::contains_name(&attrs, "profiler_runtime")
+    }
+
     pub fn is_no_builtins(&self) -> bool {
         let attrs = self.get_item_attrs(CRATE_DEF_INDEX);
         attr::contains_name(&attrs, "no_builtins")

src/librustc_metadata/cstore_impl.rs

@@ -275,6 +275,10 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).is_sanitizer_runtime()
     }
 
+    fn is_profiler_runtime(&self, cnum: CrateNum) -> bool {
+        self.get_crate_data(cnum).is_profiler_runtime()
+    }
+
     fn panic_strategy(&self, cnum: CrateNum) -> PanicStrategy {
         self.get_crate_data(cnum).panic_strategy()
     }

src/librustc_trans/back/link.rs

@@ -1074,6 +1074,9 @@ fn add_upstream_rust_crates(cmd: &mut Linker,
         // symbols from the dylib.
         let src = sess.cstore.used_crate_source(cnum);
         match data[cnum.as_usize() - 1] {
+            _ if sess.cstore.is_profiler_runtime(cnum) => {
+                add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
+            }
             _ if sess.cstore.is_sanitizer_runtime(cnum) => {
                 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
             }

src/librustc_trans/back/write.rs

@@ -699,6 +699,10 @@ pub fn run_passes(sess: &Session,
         }
     }
 
+    if sess.opts.debugging_opts.profile {
+        modules_config.passes.push("insert-gcov-profiling".to_owned())
+    }
+
     modules_config.opt_level = Some(get_llvm_opt_level(sess.opts.optimize));
     modules_config.opt_size = Some(get_llvm_opt_size(sess.opts.optimize));