[Autobackout][FuncReg]Revert of change: bf60373

relax ACC substitution constraints

Change-Id: Iaa29487e7cd56ca2d5565a3beb59be7218e75d5a

Author: bcheng0127

visa/Gen4_IR.cpp

@@ -7822,6 +7822,11 @@ bool G4_INST::canSrcBeAcc(Gen4_Operand_Number opndNum) const
     }
 
     G4_SrcRegRegion* src = getSrc(srcId)->asSrcRegRegion();
+    if (srcId == 1 && src->getModifier() != Mod_src_undef)
+    {
+        // src1 acc does not support modifiers
+        return false;
+    }
     if (!src->getRegion()->isContiguous(getExecSize()))
     {
         return false;
@@ -7912,7 +7917,7 @@ bool G4_INST::canSrcBeAcc(Gen4_Operand_Number opndNum) const
     case G4_mad:
         // no int acc if it's used as mul operand
         return builder.canMadHaveAcc() &&
-            (IS_FTYPE(src->getType()) || (src->getType() == Type_DF));
+            ((srcId == 1 && (IS_FTYPE(src->getType()) || (src->getType() == Type_DF))) || (srcId == 0 && src->getModifier() == Mod_src_undef));
     case G4_csel:
         return builder.canMadHaveAcc();
     case G4_mul:

visa/HWConformity.cpp

@@ -4392,10 +4392,7 @@ static bool isAccCandidate(G4_INST* inst, G4_Kernel& kernel, int& lastUse, bool&
         }
         else if (opndNum != Opnd_src0)
         {
-            if (!useInst->canSwapSource())
-            {
-                return false;
-            }
+            return false;
         }
 
         if (useInst->getSingleDef(opndNum) == nullptr)
@@ -4506,22 +4503,6 @@ static bool replaceDstWithAcc(G4_INST* inst, int accNum, IR_Builder& builder)
                 return false;
             }
         }
-
-        if (useInst->getNumSrc() == 2)
-        {
-            if (use.second != Opnd_src0)
-            {
-                if (useInst->canSwapSource() && !useInst->getSrc(0)->isAccReg())
-                {
-                    useInst->swapSrc(0, 1);
-                    use.second = Opnd_src0;
-                }
-                else
-                {
-                    return false;
-                }
-            }
-        }
     }
 
     // at this point acc substitution must succeed