Require 64-bit builds on x86 to use AcceleratedCrcMemcpyEngine

This also ensures that there is only one definition of
GetArchSpecificEngines by moving the condition to a common place.

PiperOrigin-RevId: 500038304
Change-Id: If0c55d701dfdc11a1a9c8c1b34eb220435529ffb

absl/crc/internal/crc_memcpy.h

@@ -21,6 +21,13 @@
 #include "absl/base/config.h"
 #include "absl/base/config.h"
 #include "absl/crc/crc32c.h"
 #include "absl/crc/crc32c.h"
 
 
+// Defined if the class AcceleratedCrcMemcpyEngine exists.
+#if defined(__x86_64__) && defined(__SSE4_2__)
+#define ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE 1
+#elif defined(_MSC_VER) && defined(__AVX__)
+#define ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE 1
+#endif
+
 namespace absl {
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 ABSL_NAMESPACE_BEGIN
 namespace crc_internal {
 namespace crc_internal {

absl/crc/internal/crc_memcpy_fallback.cc

@@ -54,7 +54,7 @@ absl::crc32c_t FallbackCrcMemcpyEngine::Compute(void* __restrict dst,
 }
 }
 
 
 // Compile the following only if we don't have
 // Compile the following only if we don't have
-#ifndef __SSE4_2__
+#ifndef ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE
 
 
 CrcMemcpy::ArchSpecificEngines CrcMemcpy::GetArchSpecificEngines() {
 CrcMemcpy::ArchSpecificEngines CrcMemcpy::GetArchSpecificEngines() {
   CrcMemcpy::ArchSpecificEngines engines;
   CrcMemcpy::ArchSpecificEngines engines;
@@ -68,7 +68,7 @@ std::unique_ptr<CrcMemcpyEngine> CrcMemcpy::GetTestEngine(int /*vector*/,
   return std::make_unique<FallbackCrcMemcpyEngine>();
   return std::make_unique<FallbackCrcMemcpyEngine>();
 }
 }
 
 
-#endif
+#endif  // ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE
 
 
 }  // namespace crc_internal
 }  // namespace crc_internal
 ABSL_NAMESPACE_END
 ABSL_NAMESPACE_END

absl/crc/internal/crc_memcpy_x86_64.cc

@@ -59,7 +59,7 @@
 #include "absl/crc/internal/crc_memcpy.h"
 #include "absl/crc/internal/crc_memcpy.h"
 #include "absl/strings/string_view.h"
 #include "absl/strings/string_view.h"
 
 
-#if defined(__SSE4_2__) || (defined(_MSC_VER) && defined(__AVX__))
+#ifdef ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE
 
 
 namespace absl {
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 ABSL_NAMESPACE_BEGIN
@@ -431,4 +431,4 @@ std::unique_ptr<CrcMemcpyEngine> CrcMemcpy::GetTestEngine(int vector,
 ABSL_NAMESPACE_END
 ABSL_NAMESPACE_END
 }  // namespace absl
 }  // namespace absl
 
 
-#endif  // defined(__SSE4_2__) || (defined(_MSC_VER) && defined(__AVX__))
+#endif  // ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE