Need the "compiler-rt" runtime for address sanitizer

[cbuttner]

Related to c3lang/c3c#1222

Specifically we need clang_rt.asan-x86_64.lib for address sanitizer support on windows. This library needs to be deployed next to c3c.exe so it can be linked against when --sanitize=address is enabled.

Here's the info on how to build:
https://clang.llvm.org/docs/AddressSanitizer.html#how-to-build

[cbuttner]

Looks like on Windows you have to build compiler-rt separately, after the LLVM build has finished.
So go into <root>/compiler-rt, mkdir build etc.
Configure with

-G <...>
-Thost=<...>
-DCMAKE_INSTALL_PREFIX=<...>
-DCMAKE_MSVC_RUNTIME_LIBRARY=<...>
-DCMAKE_MT=<...>
<whatever other general flags are needed...>
-DLLVM_CMAKE_DIR=<LLVM install path>

Where the LLVM install path is what is currently packaged up (contains bin, include, lib and share)

Then build and install like LLVM
cmake --build .
cmake --build . --target install (this will install into <install prefix>/lib/windows)

[lerno]

All we need is the library, so presumably a second build doing that then.

[cbuttner]

I think I figured out a better way, PR coming soon.

[cbuttner]

#4
I tested this, and it should build what is needed.

[cbuttner]

@lerno No need to build clang!

Go into <root>/runtimes and build with the following flags

set COMPILER_RT_CMAKE_CONFIGURE_FLAGS= ^
	-G "%CMAKE_GENERATOR%%CMAKE_GENERATOR_SUFFIX%" ^
	-Thost=x64 ^
	-DCMAKE_INSTALL_PREFIX=%LLVM_RELEASE_DIR%/lib/clang/18 ^
	-DCMAKE_MSVC_RUNTIME_LIBRARY=%CMAKE_CRT% ^
	-DCMAKE_MT=mt ^
	-DCMAKE_C_COMPILER_TARGET="x86_64-pc-windows-msvc" ^
	-DLLVM_ENABLE_RUNTIMES=compiler-rt ^
	-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON ^
	-DCOMPILER_RT_BUILD_BUILTINS=OFF

This part is also the same

cmake -B . %COMPILER_RT_CMAKE_CONFIGURE_FLAGS%
cmake --build . %CMAKE_BUILD_FLAGS%
cmake --build . --target install %CMAKE_BUILD_FLAGS%

Confirmed this actually works quite well, including the install step.

[lerno]

Can you do a pull request for a new setup?

[cbuttner]

#6