[libc] Fix generated float128 header for aarch64 target.

Author: lntue

libc/config/linux/api.td

@@ -55,7 +55,7 @@ def IntTypesAPI : PublicAPI<"inttypes.h"> {
 }
 
 def MathAPI : PublicAPI<"math.h"> {
-  let Types = ["double_t", "float_t"];
+  let Types = ["double_t", "float_t", "float128"];
 }
 
 def FenvAPI: PublicAPI<"fenv.h"> {

libc/include/CMakeLists.txt

@@ -92,6 +92,7 @@ add_gen_header(
     .llvm-libc-macros.math_macros
     .llvm-libc-types.double_t
     .llvm-libc-types.float_t
+    .llvm-libc-types.float128
 )
 
 # TODO: This should be conditional on POSIX networking being included.

libc/include/llvm-libc-types/CMakeLists.txt

@@ -96,3 +96,4 @@ add_header(rpc_opcodes_t HDR rpc_opcodes_t.h)
 add_header(ACTION HDR ACTION.h)
 add_header(ENTRY HDR ENTRY.h)
 add_header(struct_hsearch_data HDR struct_hsearch_data.h)
+add_header(float128 HDR float128.h)

libc/include/llvm-libc-types/float128.h

@@ -0,0 +1,30 @@
+//===-- Definition of float128 type ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __LLVM_LIBC_TYPES_FLOAT128_H__
+#define __LLVM_LIBC_TYPES_FLOAT128_H__
+
+#if defined(__clang__)
+#define LIBC_COMPILER_IS_CLANG
+#define LIBC_COMPILER_CLANG_VER (__clang_major__ * 100 + __clang_minor__)
+#elif defined(__GNUC__)
+#define LIBC_COMPILER_IS_GCC
+#define LIBC_COMPILER_GCC_VER (__GNUC__ * 100 + __GNUC_MINOR__)
+#endif
+
+#if (defined(LIBC_COMPILER_GCC_VER) && (LIBC_COMPILER_GCC_VER >= 1301)) &&     \
+    (defined(__aarch64__) || defined(__riscv) || defined(__x86_64__))
+typedef _Float128 float128;
+#elif (defined(LIBC_COMPILER_CLANG_VER) && (LIBC_COMPILER_CLANG_VER >= 600)) &&\
+    (defined(__x86_64__) && !defined(__Fuchsia__))
+typedef __float128 float128;
+#elif (LDBL_MANT_DIG == 113) || (__LDBL_MANT_DIG__ == 113)
+typedef long double float128;
+#endif
+
+#endif // __LLVM_LIBC_TYPES_FLOAT128_H__

libc/spec/spec.td

@@ -51,7 +51,7 @@ def LongDoubleType : NamedType<"long double">;
 def CharType : NamedType<"char">;
 
 // TODO: Add compatibility layer to use C23 type _Float128 if possible.
-def Float128Type : NamedType<"__float128">;
+def Float128Type : NamedType<"float128">;
 
 // Common types
 def VoidPtr : PtrType<VoidType>;

libc/spec/stdc.td

@@ -352,6 +352,7 @@ def StdC : StandardSpec<"stdc"> {
       [
           NamedType<"float_t">,
           NamedType<"double_t">,
+          NamedType<"float128">,
       ],
       [], // Enumerations
       [

libc/src/__support/macros/properties/float.h

@@ -19,11 +19,11 @@
 #include <float.h> // LDBL_MANT_DIG
 
 // 'long double' properties.
-#if (LDBL_MANT_DIG == 53)
+#if (LDBL_MANT_DIG == 53) || (__LDBL_MANT_DIG__ == 53)
 #define LIBC_LONG_DOUBLE_IS_FLOAT64
-#elif (LDBL_MANT_DIG == 64)
+#elif (LDBL_MANT_DIG == 64) || (__LDBL_MANT_DIG__ == 64)
 #define LIBC_LONG_DOUBLE_IS_X86_FLOAT80
-#elif (LDBL_MANT_DIG == 113)
+#elif (LDBL_MANT_DIG == 113) || (__LDBL_MANT_DIG__ == 113)
 #define LIBC_LONG_DOUBLE_IS_FLOAT128
 #endif
 
@@ -53,6 +53,9 @@ using float16 = _Float16;
 #endif
 
 // float128 support.
+// If the definition of float128 here is updated, also update
+//   include/llvm-libc-types/float128.h
+// so that the type definition in generated header `math.h` matched.
 #if (defined(LIBC_COMPILER_GCC_VER) && (LIBC_COMPILER_GCC_VER >= 1301)) &&     \
     (defined(LIBC_TARGET_ARCH_IS_AARCH64) ||                                   \
      defined(LIBC_TARGET_ARCH_IS_ANY_RISCV) ||                                 \