[clang] [compiler-rt] [compiler-rt] Realtime Sanitizer: Introduce Realtime Sanitizer (RTSan) backend (PR #92460)

[Chris Apple via llvm-commits]

cjappl wrote:

There are 3 errors I see:

Mostly it's this `llvm_gtest` issue:
```
ninja: error: 'compiler-rt/lib/rtsan/tests/llvm_gtest', needed by 'compiler-rt/lib/rtsan/tests/RtsanNoInstTestObjects.rtsan_preinit.cpp.x86_64.o', missing and no known rule to make it
```

On fuchsia it is a parameter type issue:
```
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/rtsan_interceptors.cpp:55:22: error: use of undeclared identifier '__unsanitized_open'; did you mean '__unsanitized_memset'?
   55 |   const int result = REAL(open)(path, oflag, mode);
      |                      ^~~~~~~~~~
      |                      __unsanitized_memset
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/../interception/interception.h:241:18: note: expanded from macro 'REAL'
  241 | # define REAL(x) __unsanitized_##x
      |                  ^
<scratch space>:138:1: note: expanded from here
  138 | __unsanitized_open
      | ^
/usr/local/fuchsia/sdk/arch/x64/sysroot/include/zircon/sanitizer.h:34:18: note: '__unsanitized_memset' declared here
   34 | __typeof(memset) __unsanitized_memset;
      |                  ^
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/rtsan_interceptors.cpp:55:33: error: cannot initialize a parameter of type 'void *' with an lvalue of type 'const char *'
   55 |   const int result = REAL(open)(path, oflag, mode);
      |                                 ^~~~
/usr/local/fuchsia/sdk/arch/x64/sysroot/include/zircon/sanitizer.h:34:18: note: passing argument to parameter here
   34 | __typeof(memset) __unsanitized_memset;
      |                  ^
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/rtsan_interceptors.cpp:69:22: error: use of undeclared identifier '__unsanitized_openat'
   69 |   const int result = REAL(openat)(fd, path, oflag, mode);
      |                      ^
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/../interception/interception.h:241:18: note: expanded from macro 'REAL'
  241 | # define REAL(x) __unsanitized_##x
      |                  ^
<scratch space>:141:1: note: expanded from here
  141 | __unsanitized_openat
      | ^
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/rtsan_interceptors.cpp:77:22: error: use of undeclared identifier '__unsanitized_creat'
   77 |   const int result = REAL(creat)(path, mode);
      |                      ^
/var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/compiler-rt/lib/rtsan/../interception/interception.h:241:18: note: expanded from macro 'REAL'
  241 | # define REAL(x) __unsanitized_##x
      |                  ^
<scratch space>:144:1: note: expanded from here
  144 | __unsanitized_creat
      | ^
Step 6 (build) failure: build (failure)
...
```

On windows (which I think we should just disable support for, for now:

```
C:\b\slave\sanitizer-windows\llvm-project\compiler-rt\lib\rtsan\rtsan_context.cpp(19): fatal error C1083: Cannot open include file: 'pthread.h': No such file or directory
```


Working to see if I can fix the llvm_gtest issue right now. I would love advice on Fuchsia and disabling rtsan for windows.

https://github.com/llvm/llvm-project/pull/92460