Merge pull request #2638 from rust-lang/tshepang/sembr

sembr sanitizers.md and improve it a bit

Author: tshepang

src/sanitizers.md

@@ -10,25 +10,26 @@ The rustc compiler contains support for following sanitizers:
 * [Hardware-assisted AddressSanitizer][clang-hwasan]  a tool similar to
   AddressSanitizer but based on partial hardware assistance.
 * [KernelControlFlowIntegrity][clang-kcfi] LLVM Kernel Control Flow Integrity
-  (KCFI) provides forward-edge control flow protection for operating systems
-  kernels.
+  (KCFI) provides forward-edge control flow protection for operating systems kernels.
 * [LeakSanitizer][clang-lsan] a run-time memory leak detector.
 * [MemorySanitizer][clang-msan] a detector of uninitialized reads.
 * [ThreadSanitizer][clang-tsan] a fast data race detector.
 
 ## How to use the sanitizers?
 
 To enable a sanitizer compile with `-Z sanitizer=...` option, where value is one
-of `address`, `cfi`, `hwaddress`, `kcfi`, `leak`, `memory` or `thread`. For more
-details on how to use sanitizers please refer to the sanitizer flag in [the
-unstable book](https://doc.rust-lang.org/unstable-book/).
+of `address`, `cfi`, `hwaddress`, `kcfi`, `leak`, `memory` or `thread`.
+For more details on how to use sanitizers,
+please refer to the sanitizer flag in [The Unstable Book].
+
+[The Unstable Book]: https://doc.rust-lang.org/unstable-book
 
 ## How are sanitizers implemented in rustc?
 
 The implementation of sanitizers (except CFI) relies almost entirely on LLVM.
 The rustc is an integration point for LLVM compile time instrumentation passes
-and runtime libraries. Highlight of the most important aspects of the
-implementation:
+and runtime libraries.
+Highlight of the most important aspects of the implementation:
 
 *  The sanitizer runtime libraries are part of the [compiler-rt] project, and
    [will be built][sanitizer-build] on [supported targets][sanitizer-targets]
@@ -43,23 +44,26 @@ implementation:
 
 *  During LLVM code generation, the functions intended for instrumentation are
    [marked][sanitizer-attribute] with appropriate LLVM attribute:
-   `SanitizeAddress`, `SanitizeHWAddress`, `SanitizeMemory`, or
-   `SanitizeThread`. By default all functions are instrumented, but this
+   `SanitizeAddress`, `SanitizeHWAddress`, `SanitizeMemory`, or `SanitizeThread`.
+   By default, all functions are instrumented, but this
    behaviour can be changed with `#[sanitize(xyz = "on|off|<other>")]`.
 
 *  The decision whether to perform instrumentation or not is possible only at a
-   function granularity. In the cases were those decision differ between
-   functions it might be necessary to inhibit inlining, both at [MIR
+   function granularity.
+   In the cases were those decision differ between
+   functions, it might be necessary to inhibit inlining, both at [MIR
    level][inline-mir] and [LLVM level][inline-llvm].
 
 *  The LLVM IR generated by rustc is instrumented by [dedicated LLVM
-   passes][sanitizer-pass], different for each sanitizer. Instrumentation
-   passes are invoked after optimization passes.
+   passes][sanitizer-pass], different for each sanitizer.
+   Instrumentation passes are invoked after optimization passes.
 
 *  When producing an executable, the sanitizer specific runtime library is
-   [linked in][sanitizer-link]. The libraries are searched for in the target
-   libdir. First relative to the overridden system root and subsequently
-   relative to the default system root. Fall-back to the default system root
+   [linked in][sanitizer-link].
+   The libraries are searched for in the target libdir.
+   First, the search is relative to the overridden system root, and subsequently,
+   it is relative to the default system root.
+   Fall-back to the default system root
    ensures that sanitizer runtimes remain available when using sysroot overrides
    constructed by cargo `-Z build-std` or xargo.
 
@@ -80,21 +84,20 @@ Sanitizers are validated by code generation tests in
 [`tests/ui/sanitizer/`][test-ui] directory.
 
 Testing sanitizer functionality requires the sanitizer runtimes (built when
-`sanitizer = true` in `bootstrap.toml`) and target providing support for particular
-sanitizer. When sanitizer is unsupported on given target, sanitizers tests will
-be ignored. This behaviour is controlled by compiletest `needs-sanitizer-*`
-directives.
+`sanitizer = true` in `bootstrap.toml`) and target providing support for particular a sanitizer.
+When a sanitizer is unsupported on a given target, sanitizer tests will be ignored.
+This behaviour is controlled by compiletest `needs-sanitizer-*` directives.
 
 [test-cg]: https://github.com/rust-lang/rust/tree/HEAD/tests/codegen-llvm
 [test-ui]: https://github.com/rust-lang/rust/tree/HEAD/tests/ui/sanitizer
 
-## Enabling sanitizer on a new target
+## Enabling a sanitizer on a new target
 
 To enable a sanitizer on a new target which is already supported by LLVM:
 
 1. Include the sanitizer in the list of `supported_sanitizers` in [the target
-   definition][target-definition]. `rustc --target .. -Zsanitizer=..` should now
-   recognize sanitizer as supported.
+   definition][target-definition].
+   `rustc --target .. -Zsanitizer=..` should now recognize the sanitizer as supported.
 2. [Build the runtime for the target and include it in the libdir.][sanitizer-targets]
 3. [Teach compiletest that your target now supports the sanitizer.][compiletest-definition]
    Tests marked with `needs-sanitizer-*` should now run on the target.