[Fuchsia] Apply armv8m flags for runtimes (#100656)

These are needed for cortex-m33. Ideally in the future we'd have
separate multilibs for different ABI configs and we wouldn't need to
explicitly set cortex-m33 manually. The driver should handle it.

Author: PiJoules

clang/cmake/caches/Fuchsia-stage2.cmake

@@ -309,7 +309,7 @@ foreach(target armv6m-unknown-eabi;armv7m-unknown-eabi;armv8m.main-unknown-eabi)
   foreach(lang C;CXX;ASM)
     set(BUILTINS_${target}_CMAKE_${lang}_local_flags "--target=${target} -mthumb")
     if(${target} STREQUAL "armv8m.main-unknown-eabi")
-      set(BUILTINS_${target}_CMAKE_${lang}_local_flags "${BUILTINS_${target}_CMAKE_${lang}_local_flags} -mfloat-abi=hard -march=armv8m.main+fp+dsp -mcpu=cortex-m33" CACHE STRING "")
+      set(BUILTINS_${target}_CMAKE_${lang}_local_flags "${BUILTINS_${target}_CMAKE_${lang}_local_flags} -mfloat-abi=softfp -march=armv8m.main+fp+dsp -mcpu=cortex-m33" CACHE STRING "")
     endif()
     set(BUILTINS_${target}_CMAKE_${lang}_FLAGS "${BUILTINS_${target}_CMAKE_${lang}_local_flags}" CACHE STRING "")
   endforeach()
@@ -327,7 +327,11 @@ foreach(target armv6m-unknown-eabi;armv7m-unknown-eabi;armv8m.main-unknown-eabi)
   foreach(lang C;CXX;ASM)
     # TODO: The preprocessor defines workaround various issues in libc and libc++ integration.
     # These should be addressed and removed over time.
-    set(RUNTIMES_${target}_CMAKE_${lang}_FLAGS "--target=${target} -mthumb -Wno-atomic-alignment \"-Dvfprintf(stream, format, vlist)=vprintf(format, vlist)\" \"-Dfprintf(stream, format, ...)=printf(format)\" \"-Dtimeval=struct timeval{int tv_sec; int tv_usec;}\" \"-Dgettimeofday(tv, tz)\" -D_LIBCPP_PRINT=1" CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_${lang}_local_flags "--target=${target} -mthumb -Wno-atomic-alignment \"-Dvfprintf(stream, format, vlist)=vprintf(format, vlist)\" \"-Dfprintf(stream, format, ...)=printf(format)\" \"-Dtimeval=struct timeval{int tv_sec; int tv_usec;}\" \"-Dgettimeofday(tv, tz)\" -D_LIBCPP_PRINT=1")
+    if(${target} STREQUAL "armv8m.main-unknown-eabi")
+      set(RUNTIMES_${target}_CMAKE_${lang}_local_flags "${RUNTIMES_${target}_CMAKE_${lang}_local_flags} -mfloat-abi=softfp -march=armv8m.main+fp+dsp -mcpu=cortex-m33" CACHE STRING "")
+    endif()
+    set(RUNTIMES_${target}_CMAKE_${lang}_FLAGS "${RUNTIMES_${target}_CMAKE_${lang}_local_flags}" CACHE STRING "")
   endforeach()
   foreach(type SHARED;MODULE;EXE)
     set(RUNTIMES_${target}_CMAKE_${type}_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")