commit db492316399a0edc26788265c7fce78c63a0f838
Author: Dimitry Andric <dimitry@andric.com>
Date:   Wed May 3 17:53:59 2023 +0200

    [clang][BFloat] Avoid redefining bfloat16_t in arm_neon.h
    
    As of https://reviews.llvm.org/D79708, clang-tblgen generates `arm_neon.h`,
    `arm_sve.h` and `arm_bf16.h`, and all those generated files will contain a
    typedef of `bfloat16_t`. However, `arm_neon.h` and `arm_sve.h` include
    `arm_bf16.h` immediately before their own typedef:
    
        #include <arm_bf16.h>
        typedef __bf16 bfloat16_t;
    
    With a recent version of clang (I used 16.0.1) this results in warnings:
    
        /usr/lib/clang/16/include/arm_neon.h:38:16: error: redefinition of typedef 'bfloat16_t' is a C11 feature [-Werror,-Wtypedef-redefinition]
    
    Since `arm_bf16.h` is very likely supposed to be the one true place where
    `bfloat16_t` is defined, I propose to delete the duplicate typedefs from the
    generated `arm_neon.h` and `arm_sve.h`.
    
    Reviewed By: sdesmalen, simonbutcher
    
    Differential Revision: https://reviews.llvm.org/D148822

diff --git clang/utils/TableGen/NeonEmitter.cpp clang/utils/TableGen/NeonEmitter.cpp
index 51bb774c6da9..6ef5790731a6 100644
--- clang/utils/TableGen/NeonEmitter.cpp
+++ clang/utils/TableGen/NeonEmitter.cpp
@@ -2353,7 +2353,6 @@ void NeonEmitter::run(raw_ostream &OS) {
   OS << "#include <stdint.h>\n\n";
 
   OS << "#include <arm_bf16.h>\n";
-  OS << "typedef __bf16 bfloat16_t;\n";
 
   // Emit NEON-specific scalar typedefs.
   OS << "typedef float float32_t;\n";
diff --git clang/utils/TableGen/SveEmitter.cpp clang/utils/TableGen/SveEmitter.cpp
index bc50cbad4b54..d5d3f5fe558a 100644
--- clang/utils/TableGen/SveEmitter.cpp
+++ clang/utils/TableGen/SveEmitter.cpp
@@ -1103,7 +1103,6 @@ void SVEEmitter::createHeader(raw_ostream &OS) {
   OS << "typedef __SVBFloat16_t svbfloat16_t;\n";
 
   OS << "#include <arm_bf16.h>\n";
-  OS << "typedef __bf16 bfloat16_t;\n";
 
   OS << "typedef __SVFloat32_t svfloat32_t;\n";
   OS << "typedef __SVFloat64_t svfloat64_t;\n";