[Target] Don't register AArch64 target tags without LLVM compiler sup…

…port (#16897)

This commit aims to fix the issue described here:
#16425 (comment) by
conditionally registering the target tags based on the availability of
the LLVM AArch64 backend. It's possible to extract the targets LLVM
has been compiled for using `llvm-config --targets-built`.

Change-Id: I20b608aea9ea554b0c0388ee884621305d2d59b9

cmake/modules/LLVM.cmake

@@ -41,6 +41,7 @@ if(NOT ${USE_LLVM} MATCHES ${IS_FALSE_PATTERN})
   if (${TVM_MLIR_VERSION})
     add_definitions(-DTVM_MLIR_VERSION=${TVM_MLIR_VERSION})
   endif()
+  add_definitions(-DTVM_LLVM_HAS_AARCH64_TARGET=${TVM_LLVM_HAS_AARCH64_TARGET})
   tvm_file_glob(GLOB COMPILER_LLVM_SRCS src/target/llvm/*.cc)
   list(APPEND TVM_LINKER_LIBS ${LLVM_LIBS})
   list(APPEND COMPILER_SRCS ${COMPILER_LLVM_SRCS})

cmake/utils/FindLLVM.cmake

@@ -64,6 +64,10 @@ macro(find_llvm use_llvm)
     endif()
     set(TVM_LLVM_VERSION ${LLVM_VERSION_MAJOR}${LLVM_VERSION_MINOR})
     set(TVM_INFO_LLVM_VERSION "${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
+    set(TVM_LLVM_HAS_AARCH64_TARGET 0)
+    if(DEFINED LLVM_TARGETS_TO_BUILD AND "AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
+      set(TVM_LLVM_HAS_AARCH64_TARGET 1)
+    endif()
   else()
     # use llvm config
     message(STATUS "Use llvm-config=" ${LLVM_CONFIG})
@@ -118,6 +122,13 @@ macro(find_llvm use_llvm)
     if(NOT "${__llvm_exit_code}" STREQUAL "0")
       message(FATAL_ERROR "Fatal error executing: ${LLVM_CONFIG} --cmakedir")
     endif()
+    execute_process(COMMAND ${LLVM_CONFIG} --targets-built
+      RESULT_VARIABLE __llvm_exit_code
+      OUTPUT_VARIABLE __llvm_targets_built
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    if(NOT "${__llvm_exit_code}" STREQUAL "0")
+      message(FATAL_ERROR "Fatal error executing: ${LLVM_CONFIG} --targets-built")
+    endif()
     cmake_path(SET "__llvm_cmakedir" "${__llvm_cmakedir}")
     message(STATUS "LLVM cmakedir: ${__llvm_cmakedir}")
     # map prefix => $
@@ -152,6 +163,12 @@ macro(find_llvm use_llvm)
       string(REPLACE "$" ${__llvm_prefix} __lib_with_prefix "${__flag}")
       list(APPEND LLVM_LIBS "${__lib_with_prefix}")
     endforeach()
+    # targets built
+    set(TVM_LLVM_HAS_AARCH64_TARGET 0)
+    separate_arguments(BUILT_TARGET_LIST NATIVE_COMMAND ${__llvm_targets_built})
+    if("AArch64" IN_LIST BUILT_TARGET_LIST)
+      set(TVM_LLVM_HAS_AARCH64_TARGET 1)
+    endif()
     if (${USE_MLIR})
       if (EXISTS "${__llvm_libdir}/libMLIRPresburger.a")
         if (EXISTS "${__llvm_libdir}/libMLIRSupport.a")
@@ -203,4 +220,5 @@ macro(find_llvm use_llvm)
   if (${TVM_LLVM_VERSION} LESS 40)
     message(FATAL_ERROR "TVM requires LLVM 4.0 or higher.")
   endif()
+  message(STATUS "Found TVM_LLVM_HAS_AARCH64_TARGET=" ${TVM_LLVM_HAS_AARCH64_TARGET})
 endmacro(find_llvm)

src/target/parsers/aprofile.cc

@@ -94,8 +94,8 @@ static TargetFeatures GetFeatures(TargetJSON target) {
   Array<String> targets = llvm_backend.GetAllLLVMTargets();
   if ((IsAArch64(mtriple) && !CheckContains(targets, "aarch64")) ||
       (IsAArch32(mtriple, mcpu) && !CheckContains(targets, "arm"))) {
-    LOG(WARNING) << "Cannot parse target features. LLVM was not compiled with support for "
-                    "Arm(R)-based targets.";
+    LOG(WARNING) << "Cannot parse target features for target: " << target
+                 << ". LLVM was not compiled with support for Arm(R)-based targets.";
     return {};
   }
 
@@ -115,7 +115,8 @@ static TargetFeatures GetFeatures(TargetJSON target) {
           {"has_sme", Bool(has_feature("sme"))}};
 #endif
 
-  LOG(WARNING) << "Cannot parse Arm(R)-based target features without LLVM support.";
+  LOG(WARNING) << "Cannot parse Arm(R)-based target features for target " << target
+               << " without LLVM support.";
   return {};
 }
 

src/target/tag.cc

@@ -70,6 +70,7 @@ Target TargetTag::AddTag(String name, Map<String, ObjectRef> config, bool overri
 
 /**********  Register Target tags  **********/
 
+#if TVM_LLVM_HAS_AARCH64_TARGET
 TVM_REGISTER_TARGET_TAG("raspberry-pi/4b-aarch64")
     .set_config({{"kind", String("llvm")},
                  {"mtriple", String("aarch64-linux-gnu")},
@@ -130,7 +131,8 @@ TVM_REGISTER_TARGET_TAG("nvidia/jetson-agx-orin-64gb")
                                                  {"mtriple", String("aarch64-linux-gnu")},
                                                  {"mcpu", String("cortex-a78")},
                                                  {"num-cores", Integer(12)}}}});
-#endif
+#endif  // TVM_LLVM_VERSION >= 110
+#endif  // TVM_LLVM_HAS_AARCH64_TARGET
 
 #define TVM_REGISTER_CUDA_TAG(Name, Arch, SharedMem, RegPerBlock) \
   TVM_REGISTER_TARGET_TAG(Name).set_config({                      \
@@ -437,9 +439,11 @@ TVM_REGISTER_TAG_AWS_C5("aws/cpu/c5.24xlarge", 48, "cascadelake");
                                        {"mtriple", String("arm64-apple-macos")}, \
                                        {"mcpu", String("apple-latest")}}}});
 
+#if TVM_LLVM_HAS_AARCH64_TARGET
 TVM_REGISTER_METAL_GPU_TAG("apple/m1-gpu", 1024, 32768, 32);
 TVM_REGISTER_METAL_GPU_TAG("apple/m1-gpu-restricted", 256, 32768, 32);
 TVM_REGISTER_METAL_GPU_TAG("apple/m2-gpu", 1024, 32768, 32);
+#endif  // TVM_LLVM_HAS_AARCH64_TARGET
 
 #undef TVM_REGISTER_METAL_TAG