Add MIPS SIMD Arch (MSA) optimized MirrorRow function

source/cpu_id.cc

 /*
  *  Copyright 2011 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 241 matching lines @@
 #endif
 #if defined(__mips__) && defined(__linux__)
 #if defined(__mips_dspr2)
   cpu_info |= kCpuHasDSPR2;
 #endif
   cpu_info |= kCpuHasMIPS;
   if (getenv("LIBYUV_DISABLE_DSPR2")) {
     cpu_info &= ~kCpuHasDSPR2;
   }
 #endif
+#if defined(__mips__) && defined(__linux__)

[fbarchard1, 2016/09/14 01:48:04]

this code block can be moved inside the previous
#if defined(__mips__) && defined(__linux__)
and share the 
cpu_info |= kCpuHasMIPS;

[manojkumar.bhosale, 2016/09/14 12:45:30]

Done.

+#if defined(__mips_msa)
+  cpu_info |= kCpuHasMSA;

[fbarchard1, 2016/09/14 01:48:04]

this is a compile time test.  If built with MSA, but run on a cpu that doesnt
have it, can it be runtime detected and fall back on C code?

also note that this code current uses a constant that enables the DSPR2 code,
but that change should be in the .h

[manojkumar.bhosale, 2016/09/14 12:45:30]

Done.

+#endif
+  cpu_info |= kCpuHasMIPS;
+  if (getenv("LIBYUV_DISABLE_MSA")) {
+    cpu_info &= ~kCpuHasMSA;
+  }
+#endif
 #if defined(__arm__) || defined(__aarch64__)
 // gcc -mfpu=neon defines __ARM_NEON__
 // __ARM_NEON__ generates code that requires Neon.  NaCL also requires Neon.
 // For Linux, /proc/cpuinfo can be tested but without that assume Neon.
 #if defined(__ARM_NEON__) || defined(__native_client__) || !defined(__linux__)
   cpu_info = kCpuHasNEON;
 // For aarch64(arm64), /proc/cpuinfo's feature is not complete, e.g. no neon
 // flag in it.
 // So for aarch64, neon enabling is hard coded here.
 #endif
@@ skipping 19 matching lines @@
 // Note that use of this function is not thread safe.
 LIBYUV_API
 void MaskCpuFlags(int enable_flags) {
   cpu_info_ = InitCpuFlags() & enable_flags;
 }
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif