llvm updates (#1761)

Author: tshepang

src/backend/updating-llvm.md

@@ -2,7 +2,7 @@
 
 <!-- toc -->
 
-<!-- date-check: Feb 2023 -->
+<!-- date-check: Jul 2023 -->
 There is no formal policy about when to update LLVM or what it can be updated to,
 but a few guidelines are applied:
 
@@ -52,7 +52,7 @@ An example PR:
 
 ## New LLVM Release Updates
 
-<!-- date-check: Aug 2022 -->
+<!-- date-check: Jul 2023 -->
 
 Unlike bugfixes,
 updating to a new release of LLVM typically requires a lot more work.
@@ -139,6 +139,7 @@ so let's go through each in detail.
    > - [LLVM 13](https://github.com/rust-lang/rust/pull/87570)
    > - [LLVM 14](https://github.com/rust-lang/rust/pull/93577)
    > - [LLVM 15](https://github.com/rust-lang/rust/pull/99464)
+   > - [LLVM 16](https://github.com/rust-lang/rust/pull/109474)
 
    Note that sometimes it's easiest to land [`llvm-wrapper`] compatibility as a PR
    before actually updating `src/llvm-project`.

src/llvm-coverage-instrumentation.md

@@ -223,7 +223,7 @@ details of the [_LLVM Coverage Mapping Format_][coverage-mapping-format]
 (Version 6).[^llvm-and-covmap-versions]
 
 [^llvm-and-covmap-versions]:
-The Rust compiler (as of <!-- date-check: --> Feb 2023) supports _LLVM Coverage Mapping Format_ 6.
+The Rust compiler (as of <!-- date-check: --> Jul 2023) supports _LLVM Coverage Mapping Format_ 6.
 The Rust compiler will automatically use the most up-to-date coverage mapping format
 version that is compatible with the compiler's built-in version of LLVM.