[Beignet] [PATCH V2] GBE: fix one illegal instruction when replace a uniform dst.

[Zhigang Gong]

When the dst is a uniform value, we replace it with a vector value, then
copy the vector value back may generate an illegal instruction as below
at address 18:

    (14      )  mov(16)         g124<1>:F       g127.7<0,1,0>:F                 { align1 WE_all 1H };
    (16      )  send(16)        g122<1>:UW      g124<8,8,1>:UD
                data (bti: 1, rgba: 14, SIMD16, legacy, Untyped Surface Read) mlen 2 rlen 2 { align1 WE_all 1H };
    (18      )  mov(1)          g127.6<1>:F     g122<8,8,1>:F                   { align1 WE_all };

This patch could fix this issue and generate correct instruction as below:

    (      14)  mov(16)         g124<1>:UD      g127.7<0,1,0>:UD                { align1 WE_all 1H };
    (      16)  send(16)        g122<1>:UW      g124<8,8,1>:UD
                data (bti: 1, rgba: 14, SIMD16, legacy, Untyped Surface Read) mlen 2 rlen 2 { align1 WE_all 1H };
    (      18)  mov(1)          g127.6<1>:UD    g122<0,1,0>:UD                  { align1 WE_all };

Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
 backend/src/backend/gen_insn_selection.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/backend/src/backend/gen_insn_selection.cpp b/backend/src/backend/gen_insn_selection.cpp
index 9886357..b651c19 100644
--- a/backend/src/backend/gen_insn_selection.cpp
+++ b/backend/src/backend/gen_insn_selection.cpp
@@ -945,9 +945,11 @@ namespace gbe
       SelectionInstruction *mov = this->create(SEL_OP_MOV, 1, 1);
       mov->dst(0) = GenRegister::retype(insn->dst(regID), gr.type);
       mov->state = GenInstructionState(simdWidth);
-      if (simdWidth == 1)
+      if (simdWidth == 1) {
         mov->state.noMask = 1;
-      mov->src(0) = gr;
+        mov->src(0) = GenRegister::retype(GenRegister::vec1(GEN_GENERAL_REGISTER_FILE, gr.reg()), gr.type);
+      } else
+        mov->src(0) = gr;
       insn->append(*mov);
     }
     insn->dst(regID) = gr;
-- 
1.8.3.2