[llvm] r355084 - [X86][AVX] Remove superfluous insert_subvector(zero, bitcast(x)) -> bitcast(insert_subvector(zero, x)) fold

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Thu Feb 28 03:39:52 2019
New Revision: 355084

URL: http://llvm.org/viewvc/llvm-project?rev=355084&view=rev
Log:
[X86][AVX] Remove superfluous insert_subvector(zero, bitcast(x)) -> bitcast(insert_subvector(zero, x)) fold

This is caught by other existing bitcast folds.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=355084&r1=355083&r2=355084&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Feb 28 03:39:52 2019
@@ -41888,20 +41888,6 @@ static SDValue combineInsertSubvector(SD
                            getZeroVector(OpVT, Subtarget, DAG, dl),
                            Ins.getOperand(1), N->getOperand(2));
     }
-
-    // If we're inserting a bitcast into zeros, rewrite the insert and move the
-    // bitcast to the other side. This helps with detecting zero extending
-    // during isel.
-    // TODO: Is this useful for other indices than 0?
-    if (!IsI1Vector && SubVec.getOpcode() == ISD::BITCAST && IdxVal == 0) {
-      MVT CastVT = SubVec.getOperand(0).getSimpleValueType();
-      unsigned NumElems = OpVT.getSizeInBits() / CastVT.getScalarSizeInBits();
-      MVT NewVT = MVT::getVectorVT(CastVT.getVectorElementType(), NumElems);
-      SDValue Insert = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, NewVT,
-                                   DAG.getBitcast(NewVT, Vec),
-                                   SubVec.getOperand(0), N->getOperand(2));
-      return DAG.getBitcast(OpVT, Insert);
-    }
   }
 
   // Stop here if this is an i1 vector.