From: Yann Collet <cyan@fb.com>
Date: Thu, 30 Mar 2017 19:52:14 +0000 (-0700)
Subject: Changed memory strategy to __packed for gcc
X-Git-Tag: v1.2.0^2~69^2^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F640%2Fhead;p=thirdparty%2Fzstd.git

Changed memory strategy to __packed for gcc

Method 1 __packed is always as good or better than memcpy().
But it's not portable, as it depends on compiler extension.

For gcc, __pakced directive works fine.
Furthermore, gcc has serious performance issues with memcpy() on ARM 32 bits.
See #620
---

diff --git a/lib/common/mem.h b/lib/common/mem.h
index f049d181b..4773a8b93 100644
--- a/lib/common/mem.h
+++ b/lib/common/mem.h
@@ -89,8 +89,7 @@ MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (size
 #ifndef MEM_FORCE_MEMORY_ACCESS   /* can be defined externally, on command line for example */
 #  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 MEM_FORCE_MEMORY_ACCESS 2
-#  elif defined(__INTEL_COMPILER) /*|| defined(_MSC_VER)*/ || \
-  (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 MEM_FORCE_MEMORY_ACCESS 1
 #  endif
 #endif