[libc] Add tolower, toupper implementation.

[cgyurgyik]

Summary

Passes integration and libc checks!

[sivachandra]

libc/src/ctype/tolower.cpp

20

While this is smart, why should we not prefer a more readable approach like this:

return c + 'a' - 'A'; // 'a' - 'A' is a compile time constant so this is effectively just one add instruction.

libc/src/ctype/toupper.cpp

20

Same here.

[cgyurgyik]

Address Siva's comments.

libc/config/linux/aarch64/entrypoints.txt

 set(TARGET_LIBC_ENTRYPOINTS
     # ctype.h entrypoints
     libc.src.ctype.isalnum
     libc.src.ctype.isalpha
     libc.src.ctype.isblank
     libc.src.ctype.iscntrl
     libc.src.ctype.isdigit
     libc.src.ctype.isgraph
     libc.src.ctype.islower
     libc.src.ctype.isprint
     libc.src.ctype.ispunct
     libc.src.ctype.isspace
     libc.src.ctype.isupper
     libc.src.ctype.isxdigit
+    libc.src.ctype.tolower
+    libc.src.ctype.toupper
     
     # errno.h entrypoints
     libc.src.errno.__errno_location
 
     # string.h entrypoints
     libc.src.string.bzero
     libc.src.string.memchr
     libc.src.string.memcpy

libc/config/linux/api.td

let Functions = [
     "isdigit",
     "isgraph",
     "islower",
     "isprint",
     "ispunct",
     "isspace",
     "isupper",
     "isxdigit",
+    "tolower",
+    "toupper",
   ];
 }
 
 def MathErrHandlingMacro : MacroDef<"math_errhandling"> {
   let Defn = [{
     #ifndef math_errhandling
     #ifdef __FAST_MATH__
     #define math_errhandling 0

libc/config/linux/x86_64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.isdigit
     libc.src.ctype.isgraph
     libc.src.ctype.islower
     libc.src.ctype.isprint
     libc.src.ctype.ispunct
     libc.src.ctype.isspace
     libc.src.ctype.isupper
     libc.src.ctype.isxdigit
+    libc.src.ctype.tolower
+    libc.src.ctype.toupper
 
     # errno.h entrypoints
     libc.src.errno.__errno_location
 
     # signal.h entrypoints
     libc.src.signal.raise
     libc.src.signal.sigaction
     libc.src.signal.sigdelset

libc/spec/stdc.td

HeaderSpec CType = HeaderSpec<
               RetValSpec<IntType>,
               [ArgSpec<IntType>]
           >,
           FunctionSpec<
               "isxdigit",
               RetValSpec<IntType>,
               [ArgSpec<IntType>]
           >,
+          FunctionSpec<
+              "tolower",
+              RetValSpec<IntType>,
+              [ArgSpec<IntType>]
+          >,
+          FunctionSpec<
+              "toupper",
+              RetValSpec<IntType>,
+              [ArgSpec<IntType>]
+          >,
       ]
   >;
      
   HeaderSpec String = HeaderSpec<
       "string.h",
       [
           Macro<"NULL">,
       ],

libc/src/ctype/CMakeLists.txt

 )
 
 add_entrypoint_object(
   islower
   SRCS
     islower.cpp
   HDRS
     islower.h
+  DEPENDS
+    .ctype_utils
 )
 
 add_entrypoint_object(
   isprint
   SRCS
     isprint.cpp
   HDRS
     isprint.h

 )
 
 add_entrypoint_object(
   isupper
   SRCS
     isupper.cpp
   HDRS
     isupper.h
+  DEPENDS
+    .ctype_utils
 )
 
 add_entrypoint_object(
   isxdigit
   SRCS
     isxdigit.cpp
   HDRS
     isxdigit.h
   DEPENDS
     .ctype_utils
 )
+
+add_entrypoint_object(
+  tolower
+  SRCS
+    tolower.cpp
+  HDRS
+    tolower.h
+  DEPENDS
+    .ctype_utils
+)
+
+add_entrypoint_object(
+  toupper
+  SRCS
+    toupper.cpp
+  HDRS
+    toupper.h
+  DEPENDS
+    .ctype_utils
+)

libc/src/ctype/ctype_utils.h

 namespace internal {
 
 // ------------------------------------------------------
 // Rationale: Since these classification functions are
 // called in other functions, we will avoid the overhead
 // of a function call by inlining them.
 // ------------------------------------------------------
 
-static inline int isdigit(unsigned ch) { return (ch - '0') < 10; }
-
 static inline int isalpha(unsigned ch) { return (ch | 32) - 'a' < 26; }
 
+static inline int isdigit(unsigned ch) { return (ch - '0') < 10; }
+
 static inline int isalnum(unsigned ch) { return isalpha(ch) || isdigit(ch); }
 
 static inline int isgraph(unsigned ch) { return 0x20 < ch && ch < 0x7f; }
 
+static inline int islower(unsigned ch) { return (ch - 'a') < 26; }
+
+static inline int isupper(unsigned ch) { return (ch - 'A') < 26; }
+
 } // namespace internal
 } // namespace __llvm_libc
 
 #endif //  LLVM_LIBC_SRC_CTYPE_CTYPE_UTILS_H

libc/src/ctype/islower.cpp

 //===-- Implementation of islower------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/islower.h"
+#include "src/ctype/ctype_utils.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
-int LLVM_LIBC_ENTRYPOINT(islower)(int c) {
-  const unsigned ch = c;
-  return (ch - 'a') < 26;
-}
+int LLVM_LIBC_ENTRYPOINT(islower)(int c) { return internal::islower(c); }
 
 } // namespace __llvm_libc

libc/src/ctype/isupper.cpp

 //===-- Implementation of isupper------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/isupper.h"
+#include "src/ctype/ctype_utils.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
-int LLVM_LIBC_ENTRYPOINT(isupper)(int c) {
-  const unsigned ch = c;
-  return (ch - 'A') < 26;
-}
+int LLVM_LIBC_ENTRYPOINT(isupper)(int c) { return internal::isupper(c); }
 
 } // namespace __llvm_libc

libc/src/ctype/tolower.h

+//===-- Implementation header for tolower -------------------------*-C++-*-===//
+//
+// 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_SRC_CTYPE_TOLOWER_H
+#define LLVM_LIBC_SRC_CTYPE_TOLOWER_H
+
+namespace __llvm_libc {
+
+int tolower(int c);
+
+} // namespace __llvm_libc
+
+#endif //  LLVM_LIBC_SRC_CTYPE_TOLOWER_H

libc/src/ctype/tolower.cpp

-//===-- Implementation of islower------------------------------------------===//
+//===-- Implementation of tolower------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/ctype/islower.h"
+#include "src/ctype/tolower.h"
+#include "src/ctype/ctype_utils.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
-int LLVM_LIBC_ENTRYPOINT(islower)(int c) {
-  const unsigned ch = c;
-  return (ch - 'a') < 26;
+int LLVM_LIBC_ENTRYPOINT(tolower)(int c) {
+  if (internal::isupper(c))
+    return c + 'a' - 'A';
+  return c;
 }
 
 } // namespace __llvm_libc

libc/src/ctype/toupper.h

+//===-- Implementation header for toupper -------------------------*-C++-*-===//
+//
+// 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_SRC_CTYPE_TOUPPER_H
+#define LLVM_LIBC_SRC_CTYPE_TOUPPER_H
+
+namespace __llvm_libc {
+
+int toupper(int c);
+
+} // namespace __llvm_libc
+
+#endif //  LLVM_LIBC_SRC_CTYPE_TOUPPER_H

libc/src/ctype/toupper.cpp

-//===-- Implementation of islower------------------------------------------===//
+//===-- Implementation of toupper------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/ctype/islower.h"
+#include "src/ctype/toupper.h"
+#include "src/ctype/ctype_utils.h"
 
 #include "src/__support/common.h"
 
 namespace __llvm_libc {
 
 // TODO: Currently restricted to default locale.
 // These should be extended using locale information.
-int LLVM_LIBC_ENTRYPOINT(islower)(int c) {
-  const unsigned ch = c;
-  return (ch - 'a') < 26;
+int LLVM_LIBC_ENTRYPOINT(toupper)(int c) {
+  if (internal::islower(c))
+    return c + 'A' - 'a';
+  return c;
 }
 
 } // namespace __llvm_libc

libc/test/src/ctype/CMakeLists.txt

add_libc_unittest(
   isxdigit
   SUITE
     libc_ctype_unittests
   SRCS
     isxdigit_test.cpp
   DEPENDS
     libc.src.ctype.isxdigit
 )
+
+add_libc_unittest(
+  tolower
+  SUITE
+    libc_ctype_unittests
+  SRCS
+    tolower_test.cpp
+  DEPENDS
+    libc.src.ctype.tolower
+)
+
+add_libc_unittest(
+  toupper
+  SUITE
+    libc_ctype_unittests
+  SRCS
+    toupper_test.cpp
+  DEPENDS
+    libc.src.ctype.toupper
+)

libc/test/src/ctype/tolower_test.cpp

+//===-- Unittests for tolower----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/ctype/tolower.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(ToLower, DefaultLocale) {
+  for (int ch = 0; ch < 255; ++ch) {
+    // This follows pattern 'A' + 32 = 'a'.
+    if ('A' <= ch && ch <= 'Z')
+      EXPECT_EQ(__llvm_libc::tolower(ch), ch + 32);
+    else
+      EXPECT_EQ(__llvm_libc::tolower(ch), ch);
+  }
+}

libc/test/src/ctype/toupper_test.cpp

+//===-- Unittests for toupper----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/ctype/toupper.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(ToUpper, DefaultLocale) {
+  for (int ch = 0; ch < 255; ++ch) {
+    // This follows pattern 'a' - 32 = 'A'.
+    if ('a' <= ch && ch <= 'z')
+      EXPECT_EQ(__llvm_libc::toupper(ch), ch - 32);
+    else
+      EXPECT_EQ(__llvm_libc::toupper(ch), ch);
+  }
+}