[libc][NFC] move memmove implementation

[gchatelet]

Summary

Moving memmove implementation to its own file for symmetry with other mem functions.

libc/src/string/CMakeLists.txt

 # memmove
 # ------------------------------------------------------------------------------
 
 function(add_memmove memmove_name)
   add_implementation(memmove ${memmove_name}
     SRCS ${LIBC_SOURCE_DIR}/src/string/memmove.cpp
     HDRS ${LIBC_SOURCE_DIR}/src/string/memmove.h
     DEPENDS
-      .memory_utils.memory_utils
+      .memory_utils.memcpy_implementation
       libc.include.string
     ${ARGN}
   )
 endfunction()
 
 if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
   add_memmove(memmove_x86_64_opt_sse2   COMPILE_OPTIONS -march=k8             REQUIRE SSE2)
   add_memmove(memmove_x86_64_opt_sse4   COMPILE_OPTIONS -march=nehalem        REQUIRE SSE4_2)

libc/src/string/memmove.cpp

 //===-- Implementation of memmove -----------------------------------------===//
 //
 // 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/string/memmove.h"
-
-#include "src/__support/common.h"
-#include "src/string/memory_utils/op_aarch64.h"
-#include "src/string/memory_utils/op_builtin.h"
-#include "src/string/memory_utils/op_generic.h"
-#include "src/string/memory_utils/op_x86.h"
-#include <stddef.h> // size_t, ptrdiff_t
-
-#include <stdio.h>
+#include "src/string/memory_utils/memmove_implementations.h"
+#include <stddef.h> // size_t
 
 namespace __llvm_libc {
 
-[[maybe_unused]] static inline void
-inline_memmove_embedded_tiny(Ptr dst, CPtr src, size_t count) {
-  if ((count == 0) || (dst == src))
-    return;
-  if (dst < src) {
-#pragma nounroll
-    for (size_t offset = 0; offset < count; ++offset)
-      builtin::Memcpy<1>::block(dst + offset, src + offset);
-  } else {
-#pragma nounroll
-    for (ptrdiff_t offset = count - 1; offset >= 0; --offset)
-      builtin::Memcpy<1>::block(dst + offset, src + offset);
-  }
-}
-
-template <size_t MaxSize>
-[[maybe_unused]] static inline void inline_memmove_generic(Ptr dst, CPtr src,
-                                                           size_t count) {
-  if (count == 0)
-    return;
-  if (count == 1)
-    return generic::Memmove<1, MaxSize>::block(dst, src);
-  if (count <= 4)
-    return generic::Memmove<2, MaxSize>::head_tail(dst, src, count);
-  if (count <= 8)
-    return generic::Memmove<4, MaxSize>::head_tail(dst, src, count);
-  if (count <= 16)
-    return generic::Memmove<8, MaxSize>::head_tail(dst, src, count);
-  if (count <= 32)
-    return generic::Memmove<16, MaxSize>::head_tail(dst, src, count);
-  if (count <= 64)
-    return generic::Memmove<32, MaxSize>::head_tail(dst, src, count);
-  if (count <= 128)
-    return generic::Memmove<64, MaxSize>::head_tail(dst, src, count);
-  if (dst < src) {
-    generic::Memmove<32, MaxSize>::template align_forward<Arg::Src>(dst, src,
-                                                                    count);
-    return generic::Memmove<64, MaxSize>::loop_and_tail_forward(dst, src,
-                                                                count);
-  } else {
-    generic::Memmove<32, MaxSize>::template align_backward<Arg::Src>(dst, src,
-                                                                     count);
-    return generic::Memmove<64, MaxSize>::loop_and_tail_backward(dst, src,
-                                                                 count);
-  }
-}
-
-static inline void inline_memmove(Ptr dst, CPtr src, size_t count) {
-#if defined(LLVM_LIBC_ARCH_X86) || defined(LLVM_LIBC_ARCH_AARCH64)
-#if defined(LLVM_LIBC_ARCH_X86)
-  static constexpr size_t kMaxSize = x86::kAvx512F ? 64
-                                     : x86::kAvx   ? 32
-                                     : x86::kSse2  ? 16
-                                                   : 8;
-#elif defined(LLVM_LIBC_ARCH_AARCH64)
-  static constexpr size_t kMaxSize = aarch64::kNeon ? 16 : 8;
-#endif
-  // return inline_memmove_generic<kMaxSize>(dst, src, count);
-  if (count == 0)
-    return;
-  if (count == 1)
-    return generic::Memmove<1, kMaxSize>::block(dst, src);
-  if (count <= 4)
-    return generic::Memmove<2, kMaxSize>::head_tail(dst, src, count);
-  if (count <= 8)
-    return generic::Memmove<4, kMaxSize>::head_tail(dst, src, count);
-  if (count <= 16)
-    return generic::Memmove<8, kMaxSize>::head_tail(dst, src, count);
-  if (count <= 32)
-    return generic::Memmove<16, kMaxSize>::head_tail(dst, src, count);
-  if (count <= 64)
-    return generic::Memmove<32, kMaxSize>::head_tail(dst, src, count);
-  if (count <= 128)
-    return generic::Memmove<64, kMaxSize>::head_tail(dst, src, count);
-  if (dst < src) {
-    generic::Memmove<32, kMaxSize>::align_forward<Arg::Src>(dst, src, count);
-    return generic::Memmove<64, kMaxSize>::loop_and_tail_forward(dst, src,
-                                                                 count);
-  } else {
-    generic::Memmove<32, kMaxSize>::align_backward<Arg::Src>(dst, src, count);
-    return generic::Memmove<64, kMaxSize>::loop_and_tail_backward(dst, src,
-                                                                  count);
-  }
-#elif defined(LLVM_LIBC_ARCH_ARM)
-  return inline_memmove_embedded_tiny(dst, src, count);
-#else
-#error "Unsupported platform"
-#endif
-}
-
 LLVM_LIBC_FUNCTION(void *, memmove,
                    (void *dst, const void *src, size_t count)) {
-  inline_memmove(reinterpret_cast<Ptr>(dst), reinterpret_cast<CPtr>(src),
-                 count);
+  inline_memmove(dst, src, count);
   return dst;
 }
 
 } // namespace __llvm_libc

libc/src/string/memory_utils/CMakeLists.txt

 #TODO(michaelrj): split out the implementations from memory_utils
 add_header_library(
   memory_utils
   HDRS
     bcmp_implementations.h
     bzero_implementations.h
     memcmp_implementations.h
     memcpy_implementations.h
+    memmove_implementations.h
     memset_implementations.h
     op_aarch64.h
     op_builtin.h
     op_generic.h
     op_x86.h
     utils.h
   DEPS
     libc.src.__support.common
     libc.src.__support.CPP.bit
     libc.src.__support.CPP.cstddef
     libc.src.__support.CPP.type_traits
 )
 
 add_header_library(
   memcpy_implementation
   HDRS
     memcpy_implementations.h
   DEPS
     .memory_utils
 )
 
 add_header_library(
+  memmove_implementation
+  HDRS
+    memmove_implementations.h
+  DEPS
+    .memory_utils
+)
+
+add_header_library(
   memcmp_implementation
   HDRS
     memcmp_implementations.h
   DEPS
     .memory_utils
 )
 
 add_header_library(

libc/src/string/memory_utils/memmove_implementations.h

-//===-- Implementation of memmove -----------------------------------------===//
+//===-- Memmove implementation ----------------------------------*- 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
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/string/memmove.h"
+#ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_IMPLEMENTATIONS_H
+#define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_IMPLEMENTATIONS_H
 
 #include "src/__support/common.h"
 #include "src/string/memory_utils/op_aarch64.h"
 #include "src/string/memory_utils/op_builtin.h"
 #include "src/string/memory_utils/op_generic.h"
 #include "src/string/memory_utils/op_x86.h"
 #include <stddef.h> // size_t, ptrdiff_t
 
-#include <stdio.h>
-
 namespace __llvm_libc {
 
 [[maybe_unused]] static inline void
 inline_memmove_embedded_tiny(Ptr dst, CPtr src, size_t count) {
   if ((count == 0) || (dst == src))
     return;
   if (dst < src) {
 #pragma nounroll
#endif
   }
 #elif defined(LLVM_LIBC_ARCH_ARM)
   return inline_memmove_embedded_tiny(dst, src, count);
 #else
 #error "Unsupported platform"
 #endif
 }
 
-LLVM_LIBC_FUNCTION(void *, memmove,
-                   (void *dst, const void *src, size_t count)) {
+static inline void inline_memmove(void *dst, const void *src, size_t count) {
   inline_memmove(reinterpret_cast<Ptr>(dst), reinterpret_cast<CPtr>(src),
                  count);
-  return dst;
 }
 
 } // namespace __llvm_libc
+
+#endif /* LLVM_LIBC_SRC_STRING_MEMORY_UTILS_MEMMOVE_IMPLEMENTATIONS_H */

utils/bazel/llvm-project-overlay/libc/BUILD.bazel

hdrs = [
         "src/string/memory_utils/op_x86.h",
         "src/string/memory_utils/utils.h",
     ],
     textual_hdrs = [
         "src/string/memory_utils/bcmp_implementations.h",
         "src/string/memory_utils/bzero_implementations.h",
         "src/string/memory_utils/memcmp_implementations.h",
         "src/string/memory_utils/memcpy_implementations.h",
+        "src/string/memory_utils/memmove_implementations.h",
         "src/string/memory_utils/memset_implementations.h",
     ],
     deps = [
         ":__support_common",
         ":__support_cpp_array",
         ":__support_cpp_bit",
         ":__support_cpp_cstddef",
         ":__support_cpp_type_traits",

 
 libc_function(
     name = "memmove",
     srcs = ["src/string/memmove.cpp"],
     hdrs = ["src/string/memmove.h"],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
-        ":__support_integer_operations",
         ":string_memory_utils",
     ],
 )
 
 libc_function(
     name = "memcmp",
     srcs = ["src/string/memcmp.cpp"],
     hdrs = ["src/string/memcmp.h"],