Auto merge of #74091 - richkadel:llvm-coverage-map-gen-4, r=tmandry

Generating the coverage map

@tmandry @wesleywiser

rustc now generates the coverage map and can support (limited)
coverage report generation, at the function level.

Example commands to generate a coverage report:
```shell
$ BUILD=$HOME/rust/build/x86_64-unknown-linux-gnu
$ $BUILD/stage1/bin/rustc -Zinstrument-coverage \
$HOME/rust/src/test/run-make-fulldeps/instrument-coverage/main.rs
$ LLVM_PROFILE_FILE="main.profraw" ./main
called
$ $BUILD/llvm/bin/llvm-profdata merge -sparse main.profraw -o main.profdata
$ $BUILD/llvm/bin/llvm-cov show --instr-profile=main.profdata main
```
![rust coverage report only 20200706](https://user-images.githubusercontent.com/3827298/86697299-1cbe8f80-bfc3-11ea-8955-451b48626991.png)

r? @wesleywiser

Rust compiler MCP rust-lang/compiler-team#278
Relevant issue: #34701 - Implement support for LLVMs code coverage instrumentation

3 files changed, 6 insertions, 0 deletions

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index a8161c9bfb8..70e5f6ac26f 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -370,6 +370,7 @@ impl<'a> Builder<'a> {
                 tool::Cargo,
                 tool::Rls,
                 tool::RustAnalyzer,
+                tool::RustDemangler,
                 tool::Rustdoc,
                 tool::Clippy,
                 tool::CargoClippy,
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index b6641180c92..b76d80aa509 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1022,6 +1022,10 @@ impl Step for Compiletest {
             cmd.arg("--rustdoc-path").arg(builder.rustdoc(compiler));
         }
 
+        if mode == "run-make" && suite.ends_with("fulldeps") {
+            cmd.arg("--rust-demangler-path").arg(builder.tool_exe(Tool::RustDemangler));
+        }
+
         cmd.arg("--src-base").arg(builder.src.join("src/test").join(suite));
         cmd.arg("--build-base").arg(testdir(builder, compiler.host).join(suite));
         cmd.arg("--stage-id").arg(format!("stage{}-{}", compiler.stage, target));
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index f66061975d6..fe3f1e78029 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -361,6 +361,7 @@ bootstrap_tool!(
     Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true;
     BuildManifest, "src/tools/build-manifest", "build-manifest";
     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
+    RustDemangler, "src/tools/rust-demangler", "rust-demangler";
     RustInstaller, "src/tools/rust-installer", "fabricate", is_external_tool = true;
     RustdocTheme, "src/tools/rustdoc-themes", "rustdoc-themes";
     ExpandYamlAnchors, "src/tools/expand-yaml-anchors", "expand-yaml-anchors";