[Beignet] [PATCH] GBE: Fix a bug in encoding MATH instruction

[Ruiling Song]

For std::vector, a push_back may cause memory relocation if no enough
memory in the vector pool. And iterator or pointer got previously will
become invalid after relocation.

Here in GenEncoder::next(), which will call push_back(), memory
relocation may occur. Then relocation will make 'insn' point to
invalid memory that does not belong to GenEncoder::store anymore.
Then, the setting of execution_width will fail.

Signed-off-by: Ruiling Song <ruiling.song at intel.com>
---
 backend/src/backend/gen_encoder.cpp |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/backend/src/backend/gen_encoder.cpp b/backend/src/backend/gen_encoder.cpp
index 3d8afe8..ae981b2 100644
--- a/backend/src/backend/gen_encoder.cpp
+++ b/backend/src/backend/gen_encoder.cpp
@@ -1010,7 +1010,9 @@ namespace gbe
 
      if (function == GEN_MATH_FUNCTION_INT_DIV_QUOTIENT ||
          function == GEN_MATH_FUNCTION_INT_DIV_REMAINDER) {
-        if(insn->header.execution_size == GEN_WIDTH_16) {
+        insn->header.execution_size = GEN_WIDTH_8;
+
+        if(this->curr.execWidth == 16) {
           GenInstruction *insn2 = this->next(GEN_OPCODE_MATH);
           GenRegister new_dest, new_src0, new_src1;
           new_dest = GenRegister::QnPhysical(dst, 1);
@@ -1024,7 +1026,6 @@ namespace gbe
           this->setSrc1(insn2, new_src1);
         }
 
-        insn->header.execution_size = GEN_WIDTH_8;
      }
   }
 
-- 
1.7.9.5