[Beignet] [PATCH] Add the check for src and dst span different registers.

[junyan . he]

From: Junyan He <junyan...@linux.intel.com>

On IVB and HSW, When dst spans two registers, the source MUST
span two registers.  So the following instructions:
    mov (16) r104.0<2>:uw r126.0<8;8,1>:uw { Align1, H1 }
    mov (16) r104.1<2>:uw r111.0<8;8,1>:uw { Align1, H1 }
    mov (16) r106.0<2>:uw r110.0<8;8,1>:uw { Align1, H1 }
    mov (16) r106.1<2>:uw r109.0<8;8,1>:uw { Align1, H1 }
are illegal.
Add the check to split instruction into 2 SIMD8 instructions here.

TODO:
    These instructions are allowed on BDW, need to improve.

Signed-off-by: Junyan He <junyan...@linux.intel.com>
---
 backend/src/backend/gen_encoder.cpp |   41 +++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/backend/src/backend/gen_encoder.cpp 
b/backend/src/backend/gen_encoder.cpp
index 9058e2e..4d45811 100644
--- a/backend/src/backend/gen_encoder.cpp
+++ b/backend/src/backend/gen_encoder.cpp
@@ -87,6 +87,39 @@ namespace gbe
     return false;
   }
 
+  INLINE bool isSrcDstDiffSpan(GenRegister dst, GenRegister src) {
+    if (src.hstride == GEN_HORIZONTAL_STRIDE_0) return false;
+
+    uint32_t typeSz = typeSize(dst.type);
+    uint32_t horizontal = stride(dst.hstride);
+    uint32_t spans = (dst.subnr / (horizontal * typeSz)) * (horizontal * 
typeSz)  + horizontal * typeSz * 16;
+    uint32_t dstSpan = spans / GEN_REG_SIZE;
+    dstSpan = dstSpan + (spans % GEN_REG_SIZE == 0 ? 0 : 1);
+    if (dstSpan < 2) return false;
+
+    typeSz = typeSize(src.type);
+    horizontal = stride(src.hstride);
+    spans = (src.subnr / (horizontal * typeSz)) * (horizontal * typeSz)  + 
horizontal * typeSz * 16;
+    uint32_t srcSpan = (horizontal * typeSz * 16) / GEN_REG_SIZE;
+    srcSpan = srcSpan + (spans % GEN_REG_SIZE == 0 ? 0 : 1);
+
+    GBE_ASSERT(srcSpan <= 2);
+    GBE_ASSERT(dstSpan == 2);
+
+    if (srcSpan == dstSpan) return false;
+
+    /* Special case, dst is DW and src is w.
+       the case:
+       mov (16) r10.0<1>:d r12<8;8,1>:w
+       is allowed. */
+    if ((dst.type == GEN_TYPE_UD || dst.type == GEN_TYPE_D)
+          && (src.type == GEN_TYPE_UW || src.type == GEN_TYPE_W)
+          && dstSpan == 2 && srcSpan == 1
+          && dst.subnr == 0 && src.subnr == 0) return false;
+
+    return true;
+  }
+
   INLINE bool needToSplitAlu1(GenEncoder *p, GenRegister dst, GenRegister src) 
{
     if (p->curr.execWidth != 16) return false;
     if (isVectorOfLongs(dst) == true) return true;
@@ -97,6 +130,8 @@ namespace gbe
     if (isCrossMoreThan2(src) == true) return true;
     if (isVectorOfLongs(src) == true) return true;
 
+    if (isSrcDstDiffSpan(dst, src) == true) return true;
+
     if (isVectorOfBytes(dst) == true &&
         ((isVectorOfBytes(src) == true && src.hstride == dst.hstride)
           || src.hstride == GEN_HORIZONTAL_STRIDE_0))
@@ -120,6 +155,9 @@ namespace gbe
     if (isCrossMoreThan2(src0) == true) return true;
     if (isCrossMoreThan2(src1) == true) return true;
 
+    if (isSrcDstDiffSpan(dst, src0) == true) return true;
+    if (isSrcDstDiffSpan(dst, src1) == true) return true;
+
     if (isVectorOfBytes(dst) == true &&
         ((isVectorOfBytes(src0) == true && src0.hstride == dst.hstride) ||
          src0.hstride == GEN_HORIZONTAL_STRIDE_0) &&
@@ -149,6 +187,9 @@ namespace gbe
     if (isCrossMoreThan2(src0) == true) return true;
     if (isCrossMoreThan2(src1) == true) return true;
 
+    if (isSrcDstDiffSpan(dst, src0) == true) return true;
+    if (isSrcDstDiffSpan(dst, src1) == true) return true;
+
     if (src0.type == GEN_TYPE_D || src0.type == GEN_TYPE_UD || src0.type == 
GEN_TYPE_F)
       return true;
     if (src1.type == GEN_TYPE_D || src1.type == GEN_TYPE_UD || src1.type == 
GEN_TYPE_F)
-- 
1.7.9.5

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