Make scalar half-float variables even-word aligned on BDW.

Change-Id: I2b0ab81b1f72af4f84629c3c6ee3bfd1c57b0082

Author: weiyu-chen

visa/GraphColor.cpp

@@ -10507,6 +10507,18 @@ void GlobalRA::fixAlignment()
         }
     }
 
+    if (getGenxPlatform() == GENX_BDW)
+    {
+        // BDW requires even_word alignment for scalar HF variables
+        for (auto dcl : kernel.Declares)
+        {
+            if (dcl->getElemType() == Type_HF && dcl->getSubRegAlign() == Any)
+            {
+                setSubRegAlign(dcl, Even_Word);
+            }
+        }
+    }
+
     // ToDo: remove these as it should be done by HWConformity
     for (auto BB : kernel.fg)
     {

visa/HWConformity.cpp

@@ -7243,7 +7243,7 @@ void HWConformity::helperGenerateTempDst(
     G4_DstRegRegion *dstRegion = builder.Create_Dst_Opnd_From_Dcl(dcl, hStride);
     inst->setDest(dstRegion);
 
-    RegionDesc* region = builder.createRegionDesc(execSize*hStride, execSize, hStride);
+    RegionDesc* region = execSize == 1 ? builder.getRegionScalar() : builder.createRegionDesc(execSize*hStride, execSize, hStride);
     G4_SrcRegRegion *srcRegion = builder.Create_Src_Opnd_From_Dcl(dcl, region);
 
     //creating a mov from temp dst to final destination using original options of fixed instruction