[compiler-rt][builtins][RISCV] Set COMPILER_RT_HAS_FLOAT16 for RISC-V compiler-rt tests, fixes test__extendhfsf2

[luismarques]

Summary

Since D92241, compiler-rt/cmake/builtin-config-ix.cmake automatically tests the host compiler for support of _Float16 and conditionally defines COMPILER_RT_HAS_FLOAT16. That defines the macro while the compiler-rt builtins are being built. To also define it during the compiler-rt test runs requires whitelisting the architecture in compiler-rt/test/builtins/CMakeLists.txt, as done in this patch. That seems brittle. Ideally, we'd move to a solution where the target compiler was automatically tested as well, but I'm not sure how feasible that is with the current CMake setup.

For now, this patch whitelists RISC-V, fixing errors in test__extendhfsf2. Alternate solutions that fix the root issue are welcome, though.

[MaskRay]

Why does this fix compiler-rt/test/builtins/Unit/extendhftf2_test.c? The test is skipped when COMPILER_RT_HAS_FLOAT16 is undefined.

[luismarques]

In D129432#3640892, @MaskRay wrote:

Why does this fix compiler-rt/test/builtins/Unit/extendhftf2_test.c? The test is skipped when COMPILER_RT_HAS_FLOAT16 is undefined.

This is not a fix for extendhftf2_test.c, it's a fix for extendhfsf2_test.c.

[MaskRay]

In D129432#3640946, @luismarques wrote:

In D129432#3640892, @MaskRay wrote:

Why does this fix compiler-rt/test/builtins/Unit/extendhftf2_test.c? The test is skipped when COMPILER_RT_HAS_FLOAT16 is undefined.

This is not a fix for extendhftf2_test.c, it's a fix for extendhfsf2_test.c.

"Since D92241, we have a CMake test to automatically define COMPILER_RT_HAS_FLOAT16 when the host compiler supports _Float16." "a CMake test" isn't clear. Clarify it.

compiler-rt/test/builtins/CMakeLists.txt

if (${arch} STREQUAL "armhf")
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
   if (${arch} STREQUAL "riscv32")
     list(APPEND BUILTINS_TEST_TARGET_CFLAGS -fforce-enable-int128)
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
-  if (${arch} MATCHES "arm|aarch64|arm64" AND COMPILER_RT_HAS_FLOAT16)
+  if (${arch} MATCHES "arm|aarch64|arm64|riscv32|riscv64" AND COMPILER_RT_HAS_FLOAT16)
     list(APPEND BUILTINS_TEST_TARGET_CFLAGS -DCOMPILER_RT_HAS_FLOAT16)
     string(REPLACE ";" " " BUILTINS_TEST_TARGET_CFLAGS "${BUILTINS_TEST_TARGET_CFLAGS}")
   endif()
 
   if(COMPILER_RT_ENABLE_CET)
     if(NOT arch MATCHES "i?86|x86_64|AMD64")
       message(SEND_ERROR "${arch} does not support CET")
     endif()