019d75b44e
Adds support for LLVM [SafeStack] which provides backward edge control flow protection by separating the stack into two parts: data which is only accessed in provable safe ways is allocated on the normal stack (the "safe stack") and all other data is placed in a separate allocation (the "unsafe stack"). SafeStack support is enabled by passing `-Zsanitizer=safestack`. [SafeStack]: https://clang.llvm.org/docs/SafeStack.html
The files here use the LLVM FileCheck framework, documented at https://llvm.org/docs/CommandGuide/FileCheck.html.
One extension worth noting is the use of revisions as custom prefixes for FileCheck. If your codegen test has different behavior based on the chosen target or different compiler flags that you want to exercise, you can use a revisions annotation, like so:
// revisions: aaa bbb
// [bbb] compile-flags: --flags-for-bbb
After specifying those variations, you can write different expected, or
explicitly unexpected output by using <prefix>-SAME:
and <prefix>-NOT:
,
like so:
// CHECK: expected code
// aaa-SAME: emitted-only-for-aaa
// aaa-NOT: emitted-only-for-bbb
// bbb-NOT: emitted-only-for-aaa
// bbb-SAME: emitted-only-for-bbb