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Recognize more BUILD_VECTORs and VECTOR_SHUFFLEs that can be implemented by

copying VFP subregs.  This exposed a bunch of dead code in the *spill-q.ll
tests, so I tweaked those tests to keep that code from being optimized away.
Radar 7872877.

llvm-svn: 104415
This commit is contained in:
Bob Wilson 2010-05-22 00:23:12 +00:00
parent 165bcdf8a8
commit b8ebb375b6
4 changed files with 119 additions and 31 deletions

View File

@ -2810,21 +2810,60 @@ static SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
}
}
// If there are only 2 elements in a 128-bit vector, insert them into an
// undef vector. This handles the common case for 128-bit vector argument
// passing, where the insertions should be translated to subreg accesses
// with no real instructions.
if (VT.is128BitVector() && Op.getNumOperands() == 2) {
SDValue Val = DAG.getUNDEF(VT);
SDValue Op0 = Op.getOperand(0);
SDValue Op1 = Op.getOperand(1);
if (Op0.getOpcode() != ISD::UNDEF)
Val = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, VT, Val, Op0,
DAG.getIntPtrConstant(0));
if (Op1.getOpcode() != ISD::UNDEF)
Val = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, VT, Val, Op1,
DAG.getIntPtrConstant(1));
return Val;
// Scan through the operands to see if only one value is used.
unsigned NumElts = VT.getVectorNumElements();
bool isOnlyLowElement = true;
bool usesOnlyOneValue = true;
bool isConstant = true;
SDValue Value;
for (unsigned i = 0; i < NumElts; ++i) {
SDValue V = Op.getOperand(i);
if (V.getOpcode() == ISD::UNDEF)
continue;
if (i > 0)
isOnlyLowElement = false;
if (!isa<ConstantFPSDNode>(V) && !isa<ConstantSDNode>(V))
isConstant = false;
if (!Value.getNode())
Value = V;
else if (V != Value)
usesOnlyOneValue = false;
}
if (!Value.getNode())
return DAG.getUNDEF(VT);
if (isOnlyLowElement)
return DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, VT, Value);
// If all elements are constants, fall back to the default expansion, which
// will generate a load from the constant pool.
if (isConstant)
return SDValue();
// Use VDUP for non-constant splats.
if (usesOnlyOneValue)
return DAG.getNode(ARMISD::VDUP, dl, VT, Value);
// Vectors with 32- or 64-bit elements can be built by directly assigning
// the subregisters.
unsigned EltSize = VT.getVectorElementType().getSizeInBits();
if (EltSize >= 32) {
// Do the expansion with floating-point types, since that is what the VFP
// registers are defined to use, and since i64 is not legal.
EVT EltVT = EVT::getFloatingPointVT(EltSize);
EVT VecVT = EVT::getVectorVT(*DAG.getContext(), EltVT, NumElts);
SDValue Val = DAG.getUNDEF(VecVT);
for (unsigned i = 0; i < NumElts; ++i) {
SDValue Elt = Op.getOperand(i);
if (Elt.getOpcode() == ISD::UNDEF)
continue;
Elt = DAG.getNode(ISD::BIT_CONVERT, dl, EltVT, Elt);
Val = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, VecVT, Val, Elt,
DAG.getConstant(i, MVT::i32));
}
return DAG.getNode(ISD::BIT_CONVERT, dl, VT, Val);
}
return SDValue();
@ -3014,8 +3053,8 @@ static SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) {
// If the shuffle is not directly supported and it has 4 elements, use
// the PerfectShuffle-generated table to synthesize it from other shuffles.
if (VT.getVectorNumElements() == 4 &&
(VT.is128BitVector() || VT.is64BitVector())) {
unsigned NumElts = VT.getVectorNumElements();
if (NumElts == 4) {
unsigned PFIndexes[4];
for (unsigned i = 0; i != 4; ++i) {
if (ShuffleMask[i] < 0)
@ -3027,7 +3066,6 @@ static SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) {
// Compute the index in the perfect shuffle table.
unsigned PFTableIndex =
PFIndexes[0]*9*9*9+PFIndexes[1]*9*9+PFIndexes[2]*9+PFIndexes[3];
unsigned PFEntry = PerfectShuffleTable[PFTableIndex];
unsigned Cost = (PFEntry >> 30);
@ -3035,19 +3073,24 @@ static SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) {
return GeneratePerfectShuffle(PFEntry, V1, V2, DAG, dl);
}
// v2f64 and v2i64 shuffles are just register copies.
if (VT == MVT::v2f64 || VT == MVT::v2i64) {
// Do the expansion as f64 since i64 is not legal.
V1 = DAG.getNode(ISD::BIT_CONVERT, dl, MVT::v2f64, V1);
V2 = DAG.getNode(ISD::BIT_CONVERT, dl, MVT::v2f64, V2);
SDValue Val = DAG.getUNDEF(MVT::v2f64);
for (unsigned i = 0; i < 2; ++i) {
// Implement shuffles with 32- or 64-bit elements as subreg copies.
unsigned EltSize = VT.getVectorElementType().getSizeInBits();
if (EltSize >= 32) {
// Do the expansion with floating-point types, since that is what the VFP
// registers are defined to use, and since i64 is not legal.
EVT EltVT = EVT::getFloatingPointVT(EltSize);
EVT VecVT = EVT::getVectorVT(*DAG.getContext(), EltVT, NumElts);
V1 = DAG.getNode(ISD::BIT_CONVERT, dl, VecVT, V1);
V2 = DAG.getNode(ISD::BIT_CONVERT, dl, VecVT, V2);
SDValue Val = DAG.getUNDEF(VecVT);
for (unsigned i = 0; i < NumElts; ++i) {
if (ShuffleMask[i] < 0)
continue;
SDValue Elt = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, MVT::f64,
ShuffleMask[i] < 2 ? V1 : V2,
DAG.getConstant(ShuffleMask[i] & 1, MVT::i32));
Val = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, MVT::v2f64, Val,
SDValue Elt = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, EltVT,
ShuffleMask[i] < (int)NumElts ? V1 : V2,
DAG.getConstant(ShuffleMask[i] & (NumElts-1),
MVT::i32));
Val = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, VecVT, Val,
Elt, DAG.getConstant(i, MVT::i32));
}
return DAG.getNode(ISD::BIT_CONVERT, dl, VT, Val);

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@ -0,0 +1,43 @@
; RUN: llc < %s -march=arm -mcpu=cortex-a8 | FileCheck %s
; Radar 7872877
define arm_apcscc void @test(float* %fltp, i32 %packedValue, float* %table) nounwind {
entry:
%0 = load float* %fltp
%1 = insertelement <4 x float> undef, float %0, i32 0
%2 = shufflevector <4 x float> %1, <4 x float> undef, <4 x i32> zeroinitializer
%3 = shl i32 %packedValue, 16
%4 = ashr i32 %3, 30
%.sum = add i32 %4, 4
%5 = getelementptr inbounds float* %table, i32 %.sum
;CHECK: vldr.32 s
%6 = load float* %5, align 4
%tmp11 = insertelement <4 x float> undef, float %6, i32 0
%7 = shl i32 %packedValue, 18
%8 = ashr i32 %7, 30
%.sum12 = add i32 %8, 4
%9 = getelementptr inbounds float* %table, i32 %.sum12
;CHECK: vldr.32 s
%10 = load float* %9, align 4
%tmp9 = insertelement <4 x float> %tmp11, float %10, i32 1
%11 = shl i32 %packedValue, 20
%12 = ashr i32 %11, 30
%.sum13 = add i32 %12, 4
%13 = getelementptr inbounds float* %table, i32 %.sum13
;CHECK: vldr.32 s
%14 = load float* %13, align 4
%tmp7 = insertelement <4 x float> %tmp9, float %14, i32 2
%15 = shl i32 %packedValue, 22
%16 = ashr i32 %15, 30
%.sum14 = add i32 %16, 4
%17 = getelementptr inbounds float* %table, i32 %.sum14
;CHECK: vldr.32 s
%18 = load float* %17, align 4
%tmp5 = insertelement <4 x float> %tmp7, float %18, i32 3
%19 = fmul <4 x float> %tmp5, %2
%20 = bitcast float* %fltp to i8*
tail call void @llvm.arm.neon.vst1.v4f32(i8* %20, <4 x float> %19)
ret void
}
declare void @llvm.arm.neon.vst1.v4f32(i8*, <4 x float>) nounwind

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@ -46,7 +46,8 @@ bb4: ; preds = %bb193, %entry
%20 = shufflevector <2 x float> %19, <2 x float> undef, <4 x i32> zeroinitializer ; <<4 x float>> [#uses=1]
%21 = fadd <4 x float> zeroinitializer, %20 ; <<4 x float>> [#uses=2]
%22 = fcmp ogt <4 x float> %besterror.0.2264, %21 ; <<4 x i1>> [#uses=0]
br i1 undef, label %bb193, label %bb186
%tmp = extractelement <4 x i1> %22, i32 0
br i1 %tmp, label %bb193, label %bb186
bb186: ; preds = %bb4
br label %bb193

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@ -46,7 +46,8 @@ bb4: ; preds = %bb193, %entry
%20 = shufflevector <2 x float> %19, <2 x float> undef, <4 x i32> zeroinitializer ; <<4 x float>> [#uses=1]
%21 = fadd <4 x float> zeroinitializer, %20 ; <<4 x float>> [#uses=2]
%22 = fcmp ogt <4 x float> %besterror.0.2264, %21 ; <<4 x i1>> [#uses=0]
br i1 undef, label %bb193, label %bb186
%tmp = extractelement <4 x i1> %22, i32 0
br i1 %tmp, label %bb193, label %bb186
bb186: ; preds = %bb4
br label %bb193