Rollup merge of rust-lang#73488 - richkadel:llvm-coverage-map-gen, r=tmandry

code coverage foundation for hash and num_counters

This PR is the next iteration after PR rust-lang#73011 (which is still waiting on bors to merge).

@wesleywiser - PTAL
r? @tmandry

(FYI, I'm also working on injecting the coverage maps, in another branch, while waiting for these to merge.)

Thanks!

Author: Manishearth

Diff for: src/librustc_codegen_llvm/intrinsic.rs

@@ -23,7 +23,6 @@ use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt};
 use rustc_middle::ty::{self, Ty};
 use rustc_middle::{bug, span_bug};
 use rustc_span::Span;
-use rustc_span::Symbol;
 use rustc_target::abi::{self, HasDataLayout, LayoutOf, Primitive};
 use rustc_target::spec::PanicStrategy;
 
@@ -141,26 +140,20 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                 self.call(llfn, &[], None)
             }
             "count_code_region" => {
-                if let ty::InstanceDef::Item(fn_def_id) = caller_instance.def {
-                    let caller_fn_path = tcx.def_path_str(fn_def_id);
-                    debug!(
-                        "count_code_region to llvm.instrprof.increment(fn_name={})",
-                        caller_fn_path
-                    );
-
-                    // FIXME(richkadel): (1) Replace raw function name with mangled function name;
-                    // (2) Replace hardcoded `1234` in `hash` with a computed hash (as discussed in)
-                    // the MCP (compiler-team/issues/278); and replace the hardcoded `1` for
-                    // `num_counters` with the actual number of counters per function (when the
-                    // changes are made to inject more than one counter per function).
-                    let (fn_name, _len_val) = self.const_str(Symbol::intern(&caller_fn_path));
-                    let index = args[0].immediate();
-                    let hash = self.const_u64(1234);
-                    let num_counters = self.const_u32(1);
-                    self.instrprof_increment(fn_name, hash, num_counters, index)
-                } else {
-                    bug!("intrinsic count_code_region: no src.instance");
-                }
+                // FIXME(richkadel): The current implementation assumes the MIR for the given
+                // caller_instance represents a single function. Validate and/or correct if inlining
+                // and/or monomorphization invalidates these assumptions.
+                let coverage_data = tcx.coverage_data(caller_instance.def_id());
+                let mangled_fn = tcx.symbol_name(caller_instance);
+                let (mangled_fn_name, _len_val) = self.const_str(mangled_fn.name);
+                let hash = self.const_u64(coverage_data.hash);
+                let num_counters = self.const_u32(coverage_data.num_counters);
+                let index = args[0].immediate();
+                debug!(
+                    "count_code_region to LLVM intrinsic instrprof.increment(fn_name={}, hash={:?}, num_counters={:?}, index={:?})",
+                    mangled_fn.name, hash, num_counters, index
+                );
+                self.instrprof_increment(mangled_fn_name, hash, num_counters, index)
             }
             "va_start" => self.va_start(args[0].immediate()),
             "va_end" => self.va_end(args[0].immediate()),

Diff for: src/librustc_metadata/locator.rs

@@ -488,6 +488,8 @@ impl<'a> CrateLocator<'a> {
                 && self.triple != TargetTriple::from_triple(config::host_triple())
             {
                 err.note(&format!("the `{}` target may not be installed", self.triple));
+            } else if self.crate_name == sym::profiler_builtins {
+                err.note(&"the compiler may have been built without the profiler runtime");
             }
             err.span_label(self.span, "can't find crate");
             err

Diff for: src/librustc_middle/hir/map/mod.rs

@@ -56,7 +56,7 @@ fn fn_sig<'hir>(node: Node<'hir>) -> Option<&'hir FnSig<'hir>> {
     }
 }
 
-fn associated_body<'hir>(node: Node<'hir>) -> Option<BodyId> {
+pub fn associated_body<'hir>(node: Node<'hir>) -> Option<BodyId> {
     match node {
         Node::Item(Item {
             kind: ItemKind::Const(_, body) | ItemKind::Static(.., body) | ItemKind::Fn(.., body),

Diff for: src/librustc_middle/ich/hcx.rs

@@ -67,13 +67,15 @@ impl<'a> StableHashingContext<'a> {
     /// Don't use it for anything else or you'll run the risk of
     /// leaking data out of the tracking system.
     #[inline]
-    pub fn new(
+    fn new_with_or_without_spans(
         sess: &'a Session,
         krate: &'a hir::Crate<'a>,
         definitions: &'a Definitions,
         cstore: &'a dyn CrateStore,
+        always_ignore_spans: bool,
     ) -> Self {
-        let hash_spans_initial = !sess.opts.debugging_opts.incremental_ignore_spans;
+        let hash_spans_initial =
+            !always_ignore_spans && !sess.opts.debugging_opts.incremental_ignore_spans;
 
         StableHashingContext {
             sess,
@@ -88,6 +90,33 @@ impl<'a> StableHashingContext<'a> {
         }
     }
 
+    #[inline]
+    pub fn new(
+        sess: &'a Session,
+        krate: &'a hir::Crate<'a>,
+        definitions: &'a Definitions,
+        cstore: &'a dyn CrateStore,
+    ) -> Self {
+        Self::new_with_or_without_spans(
+            sess,
+            krate,
+            definitions,
+            cstore,
+            /*always_ignore_spans=*/ false,
+        )
+    }
+
+    #[inline]
+    pub fn ignore_spans(
+        sess: &'a Session,
+        krate: &'a hir::Crate<'a>,
+        definitions: &'a Definitions,
+        cstore: &'a dyn CrateStore,
+    ) -> Self {
+        let always_ignore_spans = true;
+        Self::new_with_or_without_spans(sess, krate, definitions, cstore, always_ignore_spans)
+    }
+
     #[inline]
     pub fn sess(&self) -> &'a Session {
         self.sess

Diff for: src/librustc_middle/mir/mod.rs

@@ -164,8 +164,8 @@ pub struct Body<'tcx> {
     /// The user may be writing e.g. `&[(SOME_CELL, 42)][i].1` and this would get promoted, because
     /// we'd statically know that no thing with interior mutability will ever be available to the
     /// user without some serious unsafe code.  Now this means that our promoted is actually
-    /// `&[(SOME_CELL, 42)]` and the MIR using it will do the `&promoted[i].1` projection because the
-    /// index may be a runtime value. Such a promoted value is illegal because it has reachable
+    /// `&[(SOME_CELL, 42)]` and the MIR using it will do the `&promoted[i].1` projection because
+    /// the index may be a runtime value. Such a promoted value is illegal because it has reachable
     /// interior mutability. This flag just makes this situation very obvious where the previous
     /// implementation without the flag hid this situation silently.
     /// FIXME(oli-obk): rewrite the promoted during promotion to eliminate the cell components.
@@ -2921,3 +2921,18 @@ impl Location {
         }
     }
 }
+
+/// Coverage data associated with each function (MIR) instrumented with coverage counters, when
+/// compiled with `-Zinstrument_coverage`. The query `tcx.coverage_data(DefId)` computes these
+/// values on demand (during code generation). This query is only valid after executing the MIR pass
+/// `InstrumentCoverage`.
+#[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
+pub struct CoverageData {
+    /// A hash value that can be used by the consumer of the coverage profile data to detect
+    /// changes to the instrumented source of the associated MIR body (typically, for an
+    /// individual function).
+    pub hash: u64,
+
+    /// The total number of coverage region counters added to the MIR `Body`.
+    pub num_counters: u32,
+}

Diff for: src/librustc_middle/query/mod.rs

@@ -231,6 +231,12 @@ rustc_queries! {
             cache_on_disk_if { key.is_local() }
         }
 
+        query coverage_data(key: DefId) -> mir::CoverageData {
+            desc { |tcx| "retrieving coverage data from MIR for `{}`", tcx.def_path_str(key) }
+            storage(ArenaCacheSelector<'tcx>)
+            cache_on_disk_if { key.is_local() }
+        }
+
         query promoted_mir(key: DefId) -> IndexVec<mir::Promoted, mir::Body<'tcx>> {
             desc { |tcx| "optimizing promoted MIR for `{}`", tcx.def_path_str(key) }
             storage(ArenaCacheSelector<'tcx>)

Diff for: src/librustc_middle/ty/context.rs

@@ -1307,6 +1307,13 @@ impl<'tcx> TyCtxt<'tcx> {
         StableHashingContext::new(self.sess, krate, self.definitions, &*self.cstore)
     }
 
+    #[inline(always)]
+    pub fn create_no_span_stable_hashing_context(self) -> StableHashingContext<'tcx> {
+        let krate = self.gcx.untracked_crate;
+
+        StableHashingContext::ignore_spans(self.sess, krate, self.definitions, &*self.cstore)
+    }
+
     // This method makes sure that we have a DepNode and a Fingerprint for
     // every upstream crate. It needs to be called once right after the tcx is
     // created.