[Bug target/113341] Using GCC as the bootstrap compiler breaks LLVM on 32-bit PowerPC

["glaubitz at physik dot fu-berlin.de" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113341

--- Comment #13 from John Paul Adrian Glaubitz <glaubitz at physik dot fu-berlin.de> ---
(In reply to Andrew Pinski from comment #7)
> `-fno-lifetime-dse` is already used but I get the feeling there might be
> strict aliasing issues in the code though.  What happens if you add
> -fno-strict-aliasing ?
> 
> This code gives me strict aliasing violation vibes:
> ```
> T **getAddressOfPointer(ExternalASTSource *Source) const {
>     // Ensure the integer is in pointer form.
>     (void)get(Source);
>     return reinterpret_cast<T**>(&Ptr);
>   }
> ```

I tried with the following diff but that did not fix the issue:

diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake
b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 5ca580fbb59c..51c470dcc3ed 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -679,7 +679,7 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   # crash if LLVM is built with GCC and LTO enabled (#57740).  Until
   # these bugs are fixed, we need to disable dead store eliminations
   # based on object lifetime.
-  append("-fno-lifetime-dse" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+  append("-fno-lifetime-dse -fno-strict-aliasing" CMAKE_C_FLAGS
CMAKE_CXX_FLAGS)
 endif ()

 # Modules enablement for GCC-compatible compilers: