A code in calculate_dep for binary ops when processing AShr is

trying to look for dependency of operands of its operands (sort
of double reference) and hit the case the dependency is not set
yet. Check for this case and bail-out.

Change-Id: I1ec9d12e95045fc26b82677c245db1b570e30451

Author: itsimbal

IGC/Compiler/CISACodeGen/WIAnalysis.cpp

@@ -640,6 +640,24 @@ void WIAnalysisRunner::calculate_dep(const Value* val)
         {
             // We do not calculate non-PhiNode instruction that have unset operands
             if (unsetOpNum > 0) return;
+
+            // We have all operands set. Check a special case from calculate_dep for
+            // binary ops (see the details below). It checks for ASHR+ADD and ASHR+SHL
+            // cases, and in particular it accesses dependency for ADD operands. It
+            // could happen these operands are not processed yet and in such case
+            // getDependency raises the assertion. Thus check if dependency is set.
+            // Currently we need to check dependency for ASHR->ADD operands only.
+            // For SHR, its operands are checked to be constant so skip this case.
+            // This code could be extended further depending on requirements.
+            if (inst->getOpcode() == Instruction::AShr)
+            {
+                BinaryOperator* op0 = dyn_cast<BinaryOperator>(inst->getOperand(0));
+                if (op0 && op0->getOpcode() == Instruction::Add &&
+                    !hasDependency(op0->getOperand(1)))
+                {
+                    return;
+                }
+            }
         }
         orig = WIAnalysis::UNIFORM;
     }