[builtins] Add option to always build int128 routines

[smeenai]

Summary

32-bit targets don't build these by default, but e.g. armv7 and x86 can
build them just fine, and it's useful to have the int128 routines
available for certain applications. Add a CMake option to let us include
the int128 routines for architectures which would otherwise lack them.

[compnerd]

compiler-rt/lib/builtins/CMakeLists.txt

738

I think I prefer COMPILER_RT_ENABLE_SOFTWARE_INT128 as this would enable the software fallbacks for 128-bit integers right?

[smeenai]

compiler-rt/lib/builtins/CMakeLists.txt

738

Yup, sounds good.

[smeenai]

Rename per review comment

[phosek]

LGTM

compiler-rt/lib/builtins/CMakeLists.txt

set(ve_SOURCES
   ve/grow_stack.S
   ve/grow_stack_align.S
   ${GENERIC_TF_SOURCES}
   ${GENERIC_SOURCES})
 
 add_custom_target(builtins)
 set_target_properties(builtins PROPERTIES FOLDER "Compiler-RT Misc")
 
+option(COMPILER_RT_ENABLE_SOFTWARE_INT128
+  "Enable the int128 builtin routines for all targets."
+  OFF)
+
 if (APPLE)
   add_subdirectory(Darwin-excludes)
   add_subdirectory(macho_embedded)
   darwin_add_builtin_libraries(${BUILTIN_SUPPORTED_OS})
 else ()
   set(BUILTIN_CFLAGS "")
   add_security_warnings(BUILTIN_CFLAGS 0)
 
if (CAN_TARGET_${arch})
       # Needed for clear_cache on debug mode, due to r7's usage in inline asm.
       # Release mode already sets it via -O2/3, Debug mode doesn't.
       if (${arch} STREQUAL "armhf")
         list(APPEND BUILTIN_CFLAGS_${arch} -fomit-frame-pointer -DCOMPILER_RT_ARMHF_TARGET)
       endif()
 
       # For RISCV32, we must force enable int128 for compiling long
       # double routines.
-      if("${arch}" STREQUAL "riscv32")
+      if(COMPILER_RT_ENABLE_SOFTWARE_INT128 OR "${arch}" STREQUAL "riscv32")
         list(APPEND BUILTIN_CFLAGS_${arch} -fforce-enable-int128)
       endif()
 
       if(arch STREQUAL "aarch64")
         add_custom_target(
           lse_builtin_symlinks
           BYPRODUCTS ${lse_builtins}
           ${arm64_lse_commands}

compiler-rt/test/builtins/CMakeLists.txt

foreach(arch ${BUILTIN_TEST_ARCH})
   set(BUILTINS_TEST_TARGET_ARCH ${arch})
   string(TOLOWER "-${arch}-${OS_NAME}" BUILTINS_TEST_CONFIG_SUFFIX)
   get_test_cc_for_arch(${arch} BUILTINS_TEST_TARGET_CC BUILTINS_TEST_TARGET_CFLAGS)
   if (${arch} STREQUAL "armhf")
     list(APPEND BUILTINS_TEST_TARGET_CFLAGS -fomit-frame-pointer -DCOMPILER_RT_ARMHF_TARGET)
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
-  if (${arch} STREQUAL "riscv32")
+  if (COMPILER_RT_ENABLE_SOFTWARE_INT128 OR ${arch} STREQUAL "riscv32")
     list(APPEND BUILTINS_TEST_TARGET_CFLAGS -fforce-enable-int128)
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
   if(APPLE)
     # TODO: Support the new ABI on Apple platforms.
     if (${arch} MATCHES "arm|aarch64|arm64" AND COMPILER_RT_HAS_FLOAT16)
       list(APPEND BUILTINS_TEST_TARGET_CFLAGS -DCOMPILER_RT_HAS_FLOAT16)