Cleaning redundant generic addrspacecast instructions

Change-Id: I53a25fd14d04bb54f8ae9678cf0aa9d36ecd0fd4

Author: grey-eminence

IGC/Compiler/Optimizer/OpenCLPasses/GenericAddressResolution/GenericAddressDynamicResolution.cpp

@@ -218,6 +218,31 @@ bool GenericAddressDynamicResolution::runOnFunction(Function& F)
         }
     } while (changed);
 
+    // Cleaning redundant addrspacecast instructions
+    // %1 = addrspacecast i32 * %buf to i32 addrspace(4) *
+    // %2 = ptrtoint i32 addrspace(4) * %1 to i64
+    // ->
+    // %2 = ptrtoint i32 * %buf to i64
+    for (inst_iterator i = inst_begin(F); i != inst_end(F); ++i)
+    {
+        if (AddrSpaceCastInst* addrSpaceCastInst = llvm::dyn_cast<AddrSpaceCastInst>(&*i))
+        {
+            if (addrSpaceCastInst->getSrcAddressSpace() == ADDRESS_SPACE_PRIVATE
+                && addrSpaceCastInst->getDestAddressSpace() == ADDRESS_SPACE_GENERIC
+                && addrSpaceCastInst->hasOneUse())
+            {
+                if (PtrToIntInst* ptrtoint = llvm::dyn_cast<PtrToIntInst>(*addrSpaceCastInst->user_begin()))
+                {
+                    IRBuilder<> builder(addrSpaceCastInst);
+                    Value* newPtrToInt = builder.CreatePtrToInt(addrSpaceCastInst->getOperand(0), ptrtoint->getDestTy());
+                    ptrtoint->replaceAllUsesWith(newPtrToInt);
+                    ptrtoint->eraseFromParent();
+                    modified = true;
+                }
+            }
+        }
+    }
+
     return modified;
 }