[libc] Add float.h header. (#78737)

libc/config/baremetal/arm/headers.txt

@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.fenv
     libc.include.errno
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.stdio

libc/config/baremetal/riscv/headers.txt

@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.fenv
     libc.include.errno
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.stdio

libc/config/darwin/arm/headers.txt

@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.errno
     libc.include.fenv
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.stdlib

libc/config/darwin/x86_64/headers.txt

@@ -3,6 +3,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.errno
     # Fenv is currently disabled.
     #libc.include.fenv
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.stdlib

libc/config/gpu/headers.txt

@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.string
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.fenv

libc/config/linux/aarch64/headers.txt

@@ -4,6 +4,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.errno
     libc.include.features
     libc.include.fenv
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.pthread

libc/config/linux/arm/headers.txt

@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.fenv
     libc.include.errno
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.stdlib

libc/config/linux/riscv/headers.txt

@@ -6,6 +6,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fcntl
     libc.include.features
     libc.include.fenv
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.pthread

libc/config/linux/x86_64/headers.txt

@@ -6,6 +6,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.fcntl
     libc.include.features
     libc.include.fenv
+    libc.include.float
     libc.include.inttypes
     libc.include.math
     libc.include.pthread

libc/include/CMakeLists.txt

@@ -75,6 +75,14 @@ add_gen_header(
     .llvm-libc-types.imaxdiv_t
 )
 
+add_gen_header(
+  float
+  DEF_FILE float.h.def
+  GEN_HDR float.h
+  DEPENDS
+    .llvm-libc-macros.float_macros
+)
+
 add_gen_header(
   math
   DEF_FILE math.h.def

libc/include/float.h.def

@@ -0,0 +1,14 @@
+//===-- C standard library header float.h ---------------------------------===//
+//
+// 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_FLOAT_H
+#define LLVM_LIBC_FLOAT_H
+
+#include <llvm-libc-macros/float-macros.h>
+
+#endif // LLVM_LIBC_FLOAT_H

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

@@ -67,6 +67,12 @@ add_macro_header(
     file-seek-macros.h
 )
 
+add_macro_header(
+  float_macros
+  HDR
+    float-macros.h
+)
+
 add_macro_header(
   math_macros
   HDR

libc/include/llvm-libc-macros/float-macros.h

@@ -0,0 +1,21 @@
+//===-- Definition of macros from float.h ---------------------------------===//
+//
+// 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_MACROS_FLOAT_MACROS_H
+#define __LLVM_LIBC_MACROS_FLOAT_MACROS_H
+
+#undef FLT_MANT_DIG
+#define FLT_MANT_DIG __FLT_MANT_DIG__
+
+#undef DBL_MANT_DIG
+#define DBL_MANT_DIG __DBL_MANT_DIG__
+
+#undef LDBL_MANT_DIG
+#define LDBL_MANT_DIG __LDBL_MANT_DIG__
+
+#endif // __LLVM_LIBC_MACROS_FLOAT_MACROS_H

libc/spec/stdc.td

@@ -847,6 +847,15 @@ def StdC : StandardSpec<"stdc"> {
       ]
   >;
 
+  HeaderSpec Float = HeaderSpec<
+      "float.h",
+      [
+        Macro<"FLT_MANT_DIG">,
+        Macro<"DBL_MANT_DIG">,
+        Macro<"LDBL_MANT_DIG">,
+      ]
+  >;
+
   NamedType SigAtomicT = NamedType<"sig_atomic_t">;
   HeaderSpec Signal = HeaderSpec<
       "signal.h",
@@ -1149,6 +1158,7 @@ def StdC : StandardSpec<"stdc"> {
     CType,
     Errno,
     Fenv,
+    Float,
     Math,
     String,
     StdIO,