[libc] Add a TableGen based header generator.

Summary:
* The Python header generator has been removed.
* Docs giving a highlevel overview of the header gen scheme have been
  added.

Reviewers: phosek, abrachet

Subscribers: mgorny, MaskRay, tschuett, libc-commits

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D70197

2 files changed, 252 insertions, 0 deletions

diff --git a/libc/spec/spec.td b/libc/spec/spec.td
new file mode 100644
index 00000000000..855dd6aaa77
--- /dev/null
+++ b/libc/spec/spec.td
@@ -0,0 +1,74 @@
+class Type {}
+
+class NamedType<string name> : Type {
+  string Name = name;
+}
+
+class Field<string name, Type type> {
+  string Name = name;
+  Type FieldType = type;
+}
+
+// Class to describe concrete structs specified by a standard.
+class Struct<string name> : NamedType<name> {
+  list<Field> Fields;
+}
+
+class PtrType<Type type> : Type {
+  Type PointeeType = type;
+}
+
+class ConstType<Type type> : Type {
+  Type UnqualifiedType = type;
+}
+
+class RestrictedPtrType<Type type> : Type {
+  Type PointeeType = type;
+}
+
+// Builtin types.
+def VarArgType : Type {}
+def VoidType : NamedType<"void">;
+def IntType : NamedType<"int">;
+def FloatType : NamedType<"float">;
+def DoubleType : NamedType<"double">;
+def LongDoubleType : NamedType<"long double">;
+def CharType : NamedType<"char">;
+
+class Macro<string name> {
+  string Name = name;
+}
+
+class Annotation {}
+
+class RetValSpec<Type type, list<Annotation> annotations = []> {
+  Type ReturnType = type;
+  list<Annotation> Annotations = annotations;
+}
+
+class ArgSpec<Type type, list<Annotation> annotations = [], string name = ""> {
+  Type ArgType = type;
+  list<Annotation> Annotations = annotations;
+  string Name = name;
+}
+
+class FunctionSpec<string name, RetValSpec return, list<ArgSpec> args> {
+  string Name = name;
+  RetValSpec Return = return;
+  list<ArgSpec> Args = args;
+}
+
+class HeaderSpec<string name,
+                list<Macro> macros,
+                list<Type> types,
+                list<FunctionSpec> functions> {
+  string Name = name;
+  list<FunctionSpec> Functions = functions;
+  list<Type> Types = types;
+  list<Macro> Macros = macros;
+}
+
+class StandardSpec<string name> {
+  string Name = name;
+  list<HeaderSpec> Headers;
+}
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
new file mode 100644
index 00000000000..154214dc516
--- /dev/null
+++ b/libc/spec/stdc.td
@@ -0,0 +1,178 @@
+def StdC : StandardSpec<"stdc"> {
+  PtrType VoidPtr = PtrType<VoidType>;
+  ConstType ConstVoidPtr = ConstType<VoidPtr>;
+  RestrictedPtrType VoidRestrictedPtr = RestrictedPtrType<VoidType>;
+  ConstType ConstVoidRestrictedPtr = ConstType<VoidRestrictedPtr>;
+
+  PtrType CharPtr = PtrType<CharType>;
+  ConstType ConstCharPtr = ConstType<CharPtr>;
+  RestrictedPtrType CharRestrictedPtr = RestrictedPtrType<CharType>;
+  ConstType ConstCharRestrictedPtr = ConstType<CharRestrictedPtr>;
+
+  NamedType SizeTType = NamedType<"size_t">;
+
+  HeaderSpec String = HeaderSpec<
+      "string.h",
+      [
+          Macro<"NULL">,
+      ],
+      [
+          SizeTType,
+      ],
+      [
+          FunctionSpec<
+              "memcpy",
+              RetValSpec<VoidPtr>, 
+              [ArgSpec<VoidRestrictedPtr>,
+               ArgSpec<ConstVoidRestrictedPtr>,
+               ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "memmove",
+              RetValSpec<VoidPtr>,
+              [ArgSpec<VoidPtr>, ArgSpec<ConstVoidPtr>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "memcmp",
+              RetValSpec<IntType>,
+              [ArgSpec<ConstVoidPtr>, ArgSpec<ConstVoidPtr>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "memchr",
+              RetValSpec<VoidPtr>,
+              [ArgSpec<ConstVoidPtr>, ArgSpec<IntType>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "memset",
+              RetValSpec<VoidPtr>,
+              [ArgSpec<VoidPtr>, ArgSpec<IntType>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "strcpy",
+              RetValSpec<CharPtr>, 
+              [ArgSpec<CharRestrictedPtr>, ArgSpec<ConstCharRestrictedPtr>]
+          >,
+          FunctionSpec<
+              "strncpy",
+              RetValSpec<CharPtr>, 
+              [ArgSpec<CharRestrictedPtr>,
+               ArgSpec<ConstCharRestrictedPtr>,
+               ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "strcat",
+              RetValSpec<CharPtr>, 
+              [ArgSpec<CharRestrictedPtr>, ArgSpec<ConstCharRestrictedPtr>]
+          >,
+          FunctionSpec<
+              "strncat",
+              RetValSpec<CharPtr>, 
+              [ArgSpec<CharPtr>, ArgSpec<ConstCharPtr>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "strcmp",
+              RetValSpec<IntType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strcoll",
+              RetValSpec<IntType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strncmp",
+              RetValSpec<IntType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>, ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "strxfrm",
+              RetValSpec<SizeTType>, 
+              [ArgSpec<CharRestrictedPtr>,
+               ArgSpec<ConstCharRestrictedPtr>,
+               ArgSpec<SizeTType>]
+          >,
+          FunctionSpec<
+              "strchr",
+              RetValSpec<CharPtr>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<IntType>]
+          >,
+          FunctionSpec<
+              "strcspn",
+              RetValSpec<SizeTType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strpbrk",
+              RetValSpec<CharPtr>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strrchr",
+              RetValSpec<CharPtr>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<IntType>]
+          >,
+          FunctionSpec<
+              "strspn",
+              RetValSpec<SizeTType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strstr",
+              RetValSpec<CharPtr>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
+          FunctionSpec<
+              "strtok",
+              RetValSpec<CharPtr>,
+              [ArgSpec<CharRestrictedPtr>, ArgSpec<ConstCharRestrictedPtr>]
+          >,
+          FunctionSpec<
+              "strerror",
+              RetValSpec<CharPtr>,
+              [ArgSpec<IntType>]
+          >,
+          FunctionSpec<
+              "strlen",
+              RetValSpec<SizeTType>,
+              [ArgSpec<ConstCharPtr>]
+          >,
+      ]
+  >;
+
+  HeaderSpec Math = HeaderSpec<
+      "math.h",
+      [], // Macros
+      [
+          NamedType<"float_t">,
+          NamedType<"double_t">,
+      ],
+      [
+          FunctionSpec<"acos", RetValSpec<DoubleType>, [ArgSpec<DoubleType>]>,
+          FunctionSpec<"acosl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>]>,
+      ]
+  >;
+
+  HeaderSpec StdIO = HeaderSpec<
+      "stdio.h",
+      [], // Macros
+      [ // Types
+          SizeTType,
+      ],
+      [
+          FunctionSpec<
+              "snprintf",
+              RetValSpec<IntType>,
+              [ArgSpec<CharPtr>,
+               ArgSpec<SizeTType>,
+               ArgSpec<ConstCharRestrictedPtr>,
+               ArgSpec<VarArgType>]
+          >,
+      ]
+  >;
+
+  let Headers = [
+    Math,
+    String,
+    StdIO,
+  ];
+}