Changes in directory llvm/lib/CodeGen/SelectionDAG:
LegalizeDAG.cpp updated: 1.366 -> 1.367 --- Log message: Codegen insertelement with constant insertion points as scalar_to_vector and a shuffle. For this: void %test2(<4 x float>* %F, float %f) { %tmp = load <4 x float>* %F ; <<4 x float>> [#uses=2] %tmp3 = add <4 x float> %tmp, %tmp ; <<4 x float>> [#uses=1] %tmp2 = insertelement <4 x float> %tmp3, float %f, uint 2 ; <<4 x float>> [#uses=2] %tmp6 = add <4 x float> %tmp2, %tmp2 ; <<4 x float>> [#uses=1] store <4 x float> %tmp6, <4 x float>* %F ret void } we now get this on X86 (which will get better): _test2: movl 4(%esp), %eax movaps (%eax), %xmm0 addps %xmm0, %xmm0 movaps %xmm0, %xmm1 shufps $3, %xmm1, %xmm1 movaps %xmm0, %xmm2 shufps $1, %xmm2, %xmm2 unpcklps %xmm1, %xmm2 movss 8(%esp), %xmm1 unpcklps %xmm1, %xmm0 unpcklps %xmm2, %xmm0 addps %xmm0, %xmm0 movaps %xmm0, (%eax) ret instead of: _test2: subl $28, %esp movl 32(%esp), %eax movaps (%eax), %xmm0 addps %xmm0, %xmm0 movaps %xmm0, (%esp) movss 36(%esp), %xmm0 movss %xmm0, 8(%esp) movaps (%esp), %xmm0 addps %xmm0, %xmm0 movaps %xmm0, (%eax) addl $28, %esp ret --- Diffs of the changes: (+28 -0) LegalizeDAG.cpp | 28 ++++++++++++++++++++++++++++ 1 files changed, 28 insertions(+) Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp diff -u llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:1.366 llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:1.367 --- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:1.366 Sat Apr 15 20:36:45 2006 +++ llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp Mon Apr 17 14:21:01 2006 @@ -867,6 +867,34 @@ } // FALLTHROUGH case TargetLowering::Expand: { + // If the insert index is a constant, codegen this as a scalar_to_vector, + // then a shuffle that inserts it into the right position in the vector. + if (ConstantSDNode *InsertPos = dyn_cast<ConstantSDNode>(Tmp3)) { + SDOperand ScVec = DAG.getNode(ISD::SCALAR_TO_VECTOR, + Tmp1.getValueType(), Tmp2); + + unsigned NumElts = MVT::getVectorNumElements(Tmp1.getValueType()); + MVT::ValueType ShufMaskVT = MVT::getIntVectorWithNumElements(NumElts); + MVT::ValueType ShufMaskEltVT = MVT::getVectorBaseType(ShufMaskVT); + + // We generate a shuffle of InVec and ScVec, so the shuffle mask should + // be 0,1,2,3,4,5... with the appropriate element replaced with elt 0 of + // the RHS. + std::vector<SDOperand> ShufOps; + for (unsigned i = 0; i != NumElts; ++i) { + if (i != InsertPos->getValue()) + ShufOps.push_back(DAG.getConstant(i, ShufMaskEltVT)); + else + ShufOps.push_back(DAG.getConstant(NumElts, ShufMaskEltVT)); + } + SDOperand ShufMask = DAG.getNode(ISD::BUILD_VECTOR, ShufMaskVT,ShufOps); + + Result = DAG.getNode(ISD::VECTOR_SHUFFLE, Tmp1.getValueType(), + Tmp1, ScVec, ShufMask); + Result = LegalizeOp(Result); + break; + } + // If the target doesn't support this, we have to spill the input vector // to a temporary stack slot, update the element, then reload it. This is // badness. We could also load the value into a vector register (either _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits