[llvm] [BOLT] Enable cross compilation of runtime libraries (PR #101180)

[Gergely Bálint via llvm-commits]

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@@ -135,36 +134,168 @@ if (LLVM_INCLUDE_TESTS)
   endif()
 endif()
 
-if (BOLT_ENABLE_RUNTIME)
-  message(STATUS "Building BOLT runtime libraries for X86")
-  set(extra_args "")
-  if(CMAKE_SYSROOT)
-    list(APPEND extra_args -DCMAKE_SYSROOT=${CMAKE_SYSROOT})
+set(AARCH64_GNU_C_COMPILER aarch64-linux-gnu-gcc)
+set(AARCH64_GNU_CXX_COMPILER aarch64-linux-gnu-g++)
+set(X86_64_GNU_C_COMPILER x86_64-linux-gnu-gcc)
+set(X86_64_GNU_CXX_COMPILER x86_64-linux-gnu-g++)
+set(RISCV_GNU_C_COMPILER riscv64-linux-gnu-gcc)
+set(RISCV_GNU_CXX_COMPILER riscv64-linux-gnu-g++)
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bgergely0 wrote:

[As you can see here](https://github.com/bgergely0/llvm-project/blob/main/bolt/CMakeLists.txt#L241-L270) I only check for Clang and GNU compilers, and not something else. So the user would still not be able to compile with an arbitrary compiler, without adding support here.

What else should be supported? Is the limitation to only Clang/GNU not acceptable?

https://github.com/llvm/llvm-project/pull/101180