make __packed memory access default for gcc

It's always as good or better then memcpy()
but depends on gcc-specific extension.

solves https://github.com/facebook/zstd/issues/620

diff --git a/lib/lz4.c b/lib/lz4.c
index 4558117..c9c5a07 100644 (file)
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -63,16 +63,15 @@
  * Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable).
  *            This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
  * Method 2 : direct access. This method is portable but violate C standard.
- *            It can generate buggy code on targets which generate assembly depending on alignment.
+ *            It can generate buggy code on targets which assembly generation depends on alignment.
  *            But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6)
  * See https://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
  * Prefer these methods in priority order (0 > 1 > 2)
  */
-#ifndef LZ4_FORCE_MEMORY_ACCESS   /* can be defined externally, on command line for example */
+#ifndef LZ4_FORCE_MEMORY_ACCESS   /* can be defined externally */
 #  if defined(__GNUC__) && ( defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) )
 #    define LZ4_FORCE_MEMORY_ACCESS 2
-#  elif defined(__INTEL_COMPILER) || \
-  (defined(__GNUC__) && ( defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) ))
+#  elif defined(__INTEL_COMPILER) || defined(__GNUC__)
 #    define LZ4_FORCE_MEMORY_ACCESS 1
 #  endif
 #endif