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
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