[Bugfix] Preserve CUDA arch suffix (a/f) for SM12x — fixes NVFP4 NaN on desktop Blackwell (#37725)

Signed-off-by: Rob Tand <robert.tand@icloud.com>
Co-authored-by: Lucas Wilkinson <LucasWilkinson@users.noreply.github.com>

CMakeLists.txt

@@ -94,10 +94,10 @@ find_package(Torch REQUIRED)
 # This check must happen after find_package(Torch) because that's when CMAKE_CUDA_COMPILER_VERSION gets defined
 if(DEFINED CMAKE_CUDA_COMPILER_VERSION AND
    CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL 13.0)
-  set(CUDA_SUPPORTED_ARCHS "7.5;8.0;8.6;8.7;8.9;9.0;10.0;11.0;12.0")
+  set(CUDA_SUPPORTED_ARCHS "7.5;8.0;8.6;8.7;8.9;9.0;10.0;11.0;12.0;12.1")
 elseif(DEFINED CMAKE_CUDA_COMPILER_VERSION AND
    CMAKE_CUDA_COMPILER_VERSION VERSION_GREATER_EQUAL 12.8)
-  set(CUDA_SUPPORTED_ARCHS "7.0;7.2;7.5;8.0;8.6;8.7;8.9;9.0;10.0;10.1;12.0")
+  set(CUDA_SUPPORTED_ARCHS "7.0;7.2;7.5;8.0;8.6;8.7;8.9;9.0;10.0;10.1;12.0;12.1")
 else()
   set(CUDA_SUPPORTED_ARCHS "7.0;7.2;7.5;8.0;8.6;8.7;8.9;9.0")
 endif()

cmake/utils.cmake

@@ -173,8 +173,10 @@ print(candidates[0] if candidates else '')
 endfunction()
 
 # Macro for converting a `gencode` version number to a cmake version number.
+# Preserves architecture-specific suffixes (a/f) needed for correct
+# __CUDA_ARCH_FAMILY_SPECIFIC__ definition. E.g. "121a" -> "12.1a".
 macro(string_to_ver OUT_VER IN_STR)
-  string(REGEX REPLACE "\([0-9]+\)\([0-9]\)" "\\1.\\2" ${OUT_VER} ${IN_STR})
+  string(REGEX REPLACE "\([0-9]+\)\([0-9][af]?\)" "\\1.\\2" ${OUT_VER} ${IN_STR})
 endmacro()
 
 #
@@ -211,7 +213,7 @@ endmacro()
 function(extract_unique_cuda_archs_ascending OUT_ARCHES CUDA_ARCH_FLAGS)
   set(_CUDA_ARCHES)
   foreach(_ARCH ${CUDA_ARCH_FLAGS})
-    string(REGEX MATCH "arch=compute_\([0-9]+a?\)" _COMPUTE ${_ARCH})
+    string(REGEX MATCH "arch=compute_\([0-9]+[af]?\)" _COMPUTE ${_ARCH})
     if (_COMPUTE)
       set(_COMPUTE ${CMAKE_MATCH_1})
     endif()