link to build-and-run, fix em-dash

src/how-to-build-and-run.md

@@ -110,6 +110,8 @@ This is just a subset of the full rustc build. The **full** rustc build
 - Build libstd with stage2 compiler.
 - Build librustdoc and a bunch of other things.
 
+<a name=toolchain></a>
+
 ### Creating a rustup toolchain
 
 Once you have successfully built rustc, you will have created a bunch
@@ -125,6 +127,12 @@ to run the entire test suite).
 > rustup toolchain link stage2 build/<host-triple>/stage2
 ```
 
+The `<host-triple>` would typically be one of the following:
+
+- Linux: `x86_64-unknown-linux-gnu`
+- Mac: `x86_64-apple-darwin`
+- Windows: `x86_64-pc-windows-msvc`
+
 Now you can run the rustc you built with. If you run with `-vV`, you
 should see a version number ending in `-dev`, indicating a build from
 your local environment:

src/profiling/with_perf.md

@@ -12,7 +12,7 @@ This is a guide for how to profile rustc with [perf](https://perf.wiki.kernel.or
   - leave everything else the defaults
 - Run `./x.py build` to get a full build
 - Make a rustup toolchain (let's call it `rust-prof`) pointing to that result
-  - `rustup toolchain link <path-to-toolchain>`
+  - see [the "build and run" section for instructions](../how-to-build-and-run.html#toolchain)
   
 ## Gathering a perf profile
 
@@ -118,7 +118,7 @@ the `cargo rustc` command, like so:
 
 ```bash
 > touch src/lib.rs
-> CARGO_INCREMENTAL=0 perf record -F99 --call-graph dwarf cargo rustc --profile check --lib — -Zborrowck=mir
+> CARGO_INCREMENTAL=0 perf record -F99 --call-graph dwarf cargo rustc --profile check --lib -- -Zborrowck=mir
 ```
 
 [pf]: https://github.com/nikomatsakis/perf-focus