How Is Arm_Neon. H Generated or Maintained?
There Is Arm_Neon. H in Android Ndk: $Android_Ndk_Root/Toolchains/Llvm/Prebuilt/Linux-X86_64/Lib64/Clang/9.0.9/Include/Arm_Neon. H the Arm_Neon. H Content Is...
There is arm_neon.h in Android NDK:
$ANDROID_NDK_ROOT/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/9.0.9/include/arm_neon.h
The arm_neon.h content is very long (for me), say, in NDK-r21e, with 73681 lines:
I wonder how is the arm_neon.h generated from Clang compiler ? Is it generated from some scripts? (Sorry for my poor knowledge for LLVM)
1 Answer
For Clang compiler, there is arm_neon.td as source file, and CMake generates arm_neon.h file.
To be precise:
- there is
llvm-project/clang/include/clang/Basic/arm_neon.td - there is
llvm-project/clang/lib/Headers/CMakeLists.txt, providing:
# Generate header files and copy them to the build directory
if(ARM IN_LIST LLVM_TARGETS_TO_BUILD OR AArch64 IN_LIST LLVM_TARGETS_TO_BUILD)
# Generate arm_neon.h
clang_generate_header(-gen-arm-neon arm_neon.td arm_neon.h)
# Generate arm_fp16.h
clang_generate_header(-gen-arm-fp16 arm_fp16.td arm_fp16.h)
# Generate arm_sve.h
clang_generate_header(-gen-arm-sve-header arm_sve.td arm_sve.h)
# Generate arm_bf16.h
clang_generate_header(-gen-arm-bf16 arm_bf16.td arm_bf16.h)
# Generate arm_mve.h
clang_generate_header(-gen-arm-mve-header arm_mve.td arm_mve.h)
# Generate arm_cde.h
clang_generate_header(-gen-arm-cde-header arm_cde.td arm_cde.h)
endif()
- From the git commit history, there wasn't
arm_neon.tdin the early times:
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