[Beignet] [PATCH] GBE: don't split instruction for some special case.

[Zhigang Gong]

If the src and dst are the same byte vector or the src
is scalar, we don't need to split the instruction.

Thus the following instructions:
(     269)  (-f1) sel(8)    g95<2>:B        g100<16,8,2>:B  0W              { align1 WE_normal 1Q };
(     271)  (-f1) sel(8)    g95.16<2>:B     g100.16<16,8,2>:B 0W            { align1 WE_normal 2Q };

could be optimized to one sind16 instruction:
(     263)  (-f1) sel(16)   g95<2>:B        g100<16,8,2>:B  0W              { align1 WE_normal 1H };

Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
 backend/src/backend/gen_encoder.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/backend/src/backend/gen_encoder.cpp b/backend/src/backend/gen_encoder.cpp
index 51e999e..094c894 100644
--- a/backend/src/backend/gen_encoder.cpp
+++ b/backend/src/backend/gen_encoder.cpp
@@ -69,6 +69,10 @@ namespace gbe
 
   INLINE bool needToSplitAlu1(GenEncoder *p, GenRegister dst, GenRegister src) {
     if (p->curr.execWidth != 16 || src.hstride == GEN_HORIZONTAL_STRIDE_0) return false;
+    if (isVectorOfBytes(dst) == true &&
+        ((isVectorOfBytes(src) == true && src.hstride == dst.hstride)
+          || src.hstride == GEN_HORIZONTAL_STRIDE_0))
+      return false;
     if (isVectorOfBytes(dst) == true) return true;
     if (isVectorOfBytes(src) == true) return true;
     return false;
@@ -79,7 +83,13 @@ namespace gbe
          (src0.hstride == GEN_HORIZONTAL_STRIDE_0 &&
           src1.hstride == GEN_HORIZONTAL_STRIDE_0))
       return false;
-    if (isVectorOfBytes(dst) == true) return true;
+    if (isVectorOfBytes(dst) == true &&
+        ((isVectorOfBytes(src0) == true && src0.hstride == dst.hstride) ||
+          src0.hstride == GEN_HORIZONTAL_STRIDE_0) &&
+        ((isVectorOfBytes(src1) == true && src1.hstride == dst.hstride) ||
+          src1.hstride == GEN_HORIZONTAL_STRIDE_0))
+      return false;
+    if (isVectorOfBytes(dst) == true ) return true;
     if (isVectorOfBytes(src0) == true) return true;
     if (isVectorOfBytes(src1) == true) return true;
     return false;
-- 
1.8.3.2