Track -Cprofile-use and -Cprofile-sample-use values by file hash, not file path

Author: Kobzol

Cargo.lock

@@ -4032,6 +4032,7 @@ dependencies = [
  "rustc_ty_utils",
  "rustc_typeck",
  "smallvec",
+ "tempfile",
  "tracing",
  "winapi",
 ]

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -304,7 +304,7 @@ impl<'a> GccLinker<'a> {
         };
 
         if let Some(path) = &self.sess.opts.unstable_opts.profile_sample_use {
-            self.linker_arg(&format!("-plugin-opt=sample-profile={}", path.display()));
+            self.linker_arg(&format!("-plugin-opt=sample-profile={}", path.as_path().display()));
         };
         self.linker_args(&[
             &format!("-plugin-opt={}", opt_level),

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -180,8 +180,11 @@ impl ModuleConfig {
                 sess.opts.cg.profile_generate.clone(),
                 SwitchWithOptPath::Disabled
             ),
-            pgo_use: if_regular!(sess.opts.cg.profile_use.clone(), None),
-            pgo_sample_use: if_regular!(sess.opts.unstable_opts.profile_sample_use.clone(), None),
+            pgo_use: if_regular!(sess.opts.cg.profile_use.clone().map(|p| p.into()), None),
+            pgo_sample_use: if_regular!(
+                sess.opts.unstable_opts.profile_sample_use.clone().map(|p| p.into()),
+                None
+            ),
             debug_info_for_profiling: sess.opts.unstable_opts.debug_info_for_profiling,
             instrument_coverage: if_regular!(sess.instrument_coverage(), false),
             instrument_gcov: if_regular!(

compiler/rustc_interface/Cargo.toml

@@ -55,6 +55,7 @@ winapi = { version = "0.3", features = ["libloaderapi"] }
 
 [dev-dependencies]
 rustc_target = { path = "../rustc_target" }
+tempfile = "3.2"
 
 [features]
 llvm = ['rustc_codegen_llvm']

compiler/rustc_interface/src/tests.rs

@@ -16,7 +16,7 @@ use rustc_session::config::{
 use rustc_session::config::{CFGuard, ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
-use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
+use rustc_session::utils::{CanonicalizedPath, ContentHashedFilePath, NativeLib, NativeLibKind};
 use rustc_session::{build_session, getopts, DiagnosticOutput, Session};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
@@ -594,7 +594,6 @@ fn test_codegen_options_tracking_hash() {
     tracked!(passes, vec![String::from("1"), String::from("2")]);
     tracked!(prefer_dynamic, true);
     tracked!(profile_generate, SwitchWithOptPath::Enabled(None));
-    tracked!(profile_use, Some(PathBuf::from("abc")));
     tracked!(relocation_model, Some(RelocModel::Pic));
     tracked!(soft_float, true);
     tracked!(split_debuginfo, Some(SplitDebuginfo::Packed));
@@ -777,7 +776,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(profile, true);
     tracked!(profile_emit, Some(PathBuf::from("abc")));
     tracked!(profiler_runtime, "abc".to_string());
-    tracked!(profile_sample_use, Some(PathBuf::from("abc")));
     tracked!(relax_elf_relocations, Some(true));
     tracked!(relro_level, Some(RelroLevel::Full));
     tracked!(remap_cwd_prefix, Some(PathBuf::from("abc")));
@@ -818,6 +816,41 @@ fn test_unstable_options_tracking_hash() {
     tracked_no_crate_hash!(no_codegen, true);
 }
 
+#[test]
+fn test_hashed_file_different_hash() {
+    let tempdir = tempfile::TempDir::new().unwrap();
+
+    let mut options = Options::default();
+
+    macro_rules! check {
+        ($opt: expr, $file: expr) => {
+            let path = tempdir.path().join($file);
+
+            // Write some data into the file
+            std::fs::write(&path, &[1, 2, 3]).unwrap();
+
+            // The hash is calculated now
+            *$opt = Some(ContentHashedFilePath::new(path.clone()));
+
+            let hash_no_crate = options.dep_tracking_hash(false);
+            let hash_crate = options.dep_tracking_hash(true);
+
+            // Write different data into the file
+            std::fs::write(&path, &[1, 2, 3, 4]).unwrap();
+
+            // The hash is re-calculated now
+            *$opt = Some(ContentHashedFilePath::new(path));
+
+            // Check that the hash has changed
+            assert_ne!(options.dep_tracking_hash(true), hash_crate);
+            assert_ne!(options.dep_tracking_hash(false), hash_no_crate);
+        };
+    }
+
+    check!(&mut options.cg.profile_use, "profile-instr.profdata");
+    check!(&mut options.unstable_opts.profile_sample_use, "profile-sample.profdata");
+}
+
 #[test]
 fn test_edition_parsing() {
     // test default edition

compiler/rustc_session/src/options.rs

@@ -3,7 +3,7 @@ use crate::config::*;
 use crate::early_error;
 use crate::lint;
 use crate::search_paths::SearchPath;
-use crate::utils::NativeLib;
+use crate::utils::{ContentHashedFilePath, NativeLib};
 use rustc_errors::LanguageIdentifier;
 use rustc_target::spec::{CodeModel, LinkerFlavor, MergeFunctions, PanicStrategy, SanitizerSet};
 use rustc_target::spec::{
@@ -364,6 +364,7 @@ mod desc {
     pub const parse_string_push: &str = parse_string;
     pub const parse_opt_langid: &str = "a language identifier";
     pub const parse_opt_pathbuf: &str = "a path";
+    pub const parse_opt_hashed_filepath: &str = "a path";
     pub const parse_list: &str = "a space-separated list of strings";
     pub const parse_list_with_polarity: &str =
         "a comma-separated list of strings, with elements beginning with + or -";
@@ -509,6 +510,19 @@ mod parse {
         }
     }
 
+    pub(crate) fn parse_opt_hashed_filepath(
+        slot: &mut Option<ContentHashedFilePath>,
+        v: Option<&str>,
+    ) -> bool {
+        match v {
+            Some(s) => {
+                *slot = Some(ContentHashedFilePath::new(PathBuf::from(s)));
+                true
+            }
+            None => false,
+        }
+    }
+
     pub(crate) fn parse_string_push(slot: &mut Vec<String>, v: Option<&str>) -> bool {
         match v {
             Some(s) => {
@@ -1176,7 +1190,7 @@ options! {
     profile_generate: SwitchWithOptPath = (SwitchWithOptPath::Disabled,
         parse_switch_with_opt_path, [TRACKED],
         "compile the program with profiling instrumentation"),
-    profile_use: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
+    profile_use: Option<ContentHashedFilePath> = (None, parse_opt_hashed_filepath, [TRACKED],
         "use the given `.profdata` file for profile-guided optimization"),
     #[rustc_lint_opt_deny_field_access("use `Session::relocation_model` instead of this field")]
     relocation_model: Option<RelocModel> = (None, parse_relocation_model, [TRACKED],
@@ -1488,7 +1502,7 @@ options! {
         (default based on relative source path)"),
     profiler_runtime: String = (String::from("profiler_builtins"), parse_string, [TRACKED],
         "name of the profiler runtime crate to automatically inject (default: `profiler_builtins`)"),
-    profile_sample_use: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
+    profile_sample_use: Option<ContentHashedFilePath> = (None, parse_opt_hashed_filepath, [TRACKED],
         "use the given `.prof` file for sampled profile-guided optimization (also known as AutoFDO)"),
     query_dep_graph: bool = (false, parse_bool, [UNTRACKED],
         "enable queries of the dependency graph for regression testing (default: no)"),

compiler/rustc_session/src/session.rs

@@ -1459,20 +1459,20 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
     // 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.cg.profile_use {
-        if !path.exists() {
+        if !path.as_path().exists() {
             sess.err(&format!(
                 "File `{}` passed to `-C profile-use` does not exist.",
-                path.display()
+                path.as_path().display()
             ));
         }
     }
 
     // Do the same for sample profile data.
     if let Some(ref path) = sess.opts.unstable_opts.profile_sample_use {
-        if !path.exists() {
+        if !path.as_path().exists() {
             sess.err(&format!(
                 "File `{}` passed to `-C profile-sample-use` does not exist.",
-                path.display()
+                path.as_path().display()
             ));
         }
     }

compiler/rustc_session/src/utils.rs

@@ -1,5 +1,11 @@
+use crate::config::dep_tracking::DepTrackingHash;
+use crate::config::ErrorOutputType;
 use crate::session::Session;
 use rustc_data_structures::profiling::VerboseTimingGuard;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use std::collections::hash_map::DefaultHasher;
+use std::fs::File;
+use std::io::Read;
 use std::path::{Path, PathBuf};
 
 impl Session {
@@ -91,3 +97,59 @@ impl CanonicalizedPath {
         &self.original
     }
 }
+
+/// A path that should be invalidated when the file that it points to has changed.
+/// `ContentHashedFilePath` is identified by its contents only, so even if the filepath itself
+/// changes, but the contents stay the same, it will contain the same hash.
+#[derive(Clone, Debug)]
+pub struct ContentHashedFilePath {
+    path: PathBuf,
+    hash: (u64, u64),
+}
+
+impl ContentHashedFilePath {
+    pub fn new(path: PathBuf) -> Self {
+        // If the file does not exist or couldn't be hashed, just use a placeholder hash
+        let hash = hash_file(&path).unwrap_or((0, 0));
+        Self { path, hash }
+    }
+
+    pub fn as_path(&self) -> &Path {
+        self.path.as_path()
+    }
+}
+
+impl From<ContentHashedFilePath> for PathBuf {
+    fn from(path: ContentHashedFilePath) -> Self {
+        path.path
+    }
+}
+
+impl DepTrackingHash for ContentHashedFilePath {
+    fn hash(
+        &self,
+        hasher: &mut DefaultHasher,
+        _error_format: ErrorOutputType,
+        _for_crate_hash: bool,
+    ) {
+        std::hash::Hash::hash(&self.hash, hasher);
+    }
+}
+
+fn hash_file(path: &Path) -> std::io::Result<(u64, u64)> {
+    let mut hasher = StableHasher::new();
+
+    let mut file = File::open(path)?;
+    let mut buffer = [0; 128 * 1024];
+
+    loop {
+        let count = file.read(&mut buffer)?;
+        if count == 0 {
+            break;
+        }
+
+        buffer[..count].hash_stable(&mut (), &mut hasher);
+    }
+
+    Ok(hasher.finalize())
+}