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AVX2: Build splat vectors by broadcasting a scalar from the constant pool.

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Previously we used three instructions to broadcast an immediate value into a
vector register.
On Sandybridge we continue to load the broadcasted value from the constant pool.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154284 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2012-04-08 12:54:54 +00:00
parent 864737cc51
commit 9d68b06bc5
3 changed files with 106 additions and 32 deletions
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96
lib/Target/X86/X86ISelLowering.cpp
View File

@ -4852,41 +4852,41 @@ static SDValue EltsFromConsecutiveLoads(EVT VT, SmallVectorImpl<SDValue> &Elts,
return SDValue();
}
/// isVectorBroadcast - Check if the node chain is suitable to be xformed to
/// a vbroadcast node. We support two patterns:
/// 1. A splat BUILD_VECTOR which uses a single scalar load.
/// LowerVectorBroadcast - Attempt to use the vbroadcast instruction
/// to generate a splat value for the following cases:
/// 1. A splat BUILD_VECTOR which uses a single scalar load, or a constant.
/// 2. A splat shuffle which uses a scalar_to_vector node which comes from
/// a scalar load.
/// The scalar load node is returned when a pattern is found,
/// a scalar load, or a constant.
/// The VBROADCAST node is returned when a pattern is found,
/// or SDValue() otherwise.
static SDValue isVectorBroadcast(SDValue &Op, const X86Subtarget *Subtarget) {
static SDValue LowerVectorBroadcast(SDValue &Op, const X86Subtarget *Subtarget,
DebugLoc &dl, SelectionDAG &DAG) {
if (!Subtarget->hasAVX())
return SDValue();
EVT VT = Op.getValueType();
SDValue V = Op;
if (V.hasOneUse() && V.getOpcode() == ISD::BITCAST)
V = V.getOperand(0);
//A suspected load to be broadcasted.
SDValue Ld;
bool ConstSplatVal;
switch (V.getOpcode()) {
switch (Op.getOpcode()) {
default:
// Unknown pattern found.
return SDValue();
case ISD::BUILD_VECTOR: {
// The BUILD_VECTOR node must be a splat.
if (!isSplatVector(V.getNode()))
if (!isSplatVector(Op.getNode()))
return SDValue();
Ld = V.getOperand(0);
Ld = Op.getOperand(0);
ConstSplatVal = (Ld.getOpcode() == ISD::Constant ||
Ld.getOpcode() == ISD::ConstantFP);
// The suspected load node has several users. Make sure that all
// of its users are from the BUILD_VECTOR node.
if (!Ld->hasNUsesOfValue(VT.getVectorNumElements(), 0))
// Constants may have multiple users.
if (!ConstSplatVal && !Ld->hasNUsesOfValue(VT.getVectorNumElements(), 0))
return SDValue();
break;
}
@ -4904,15 +4904,57 @@ static SDValue isVectorBroadcast(SDValue &Op, const X86Subtarget *Subtarget) {
return SDValue();
Ld = Sc.getOperand(0);
ConstSplatVal = (Ld.getOpcode() == ISD::Constant ||
Ld.getOpcode() == ISD::ConstantFP);
// The scalar_to_vector node and the suspected
// load node must have exactly one user.
if (!Sc.hasOneUse() || !Ld.hasOneUse())
// Constants may have multiple users.
if (!ConstSplatVal && (!Sc.hasOneUse() || !Ld.hasOneUse()))
return SDValue();
break;
}
}
bool Is256 = VT.getSizeInBits() == 256;
bool Is128 = VT.getSizeInBits() == 128;
// Handle the broadcasting a single constant scalar from the constant pool
// into a vector. On Sandybridge it is still better to load a constant vector
// from the constant pool and not to broadcast it from a scalar.
if (ConstSplatVal && Subtarget->hasAVX2()) {
EVT CVT = Ld.getValueType();
assert(!CVT.isVector() && "Must not broadcast a vector type");
unsigned ScalarSize = CVT.getSizeInBits();
if ((Is256 && (ScalarSize == 32 || ScalarSize == 64)) ||
(Is128 && (ScalarSize == 32))) {
// This is the type of the load operation for the constant that we save
// in the constant pool. We can't load float values from the constant pool
// because the DAG has to be legal at this stage.
MVT LdTy = (ScalarSize == 32 ? MVT::i32 : MVT::i64);
const Constant *C = 0;
if (ConstantSDNode *CI = dyn_cast<ConstantSDNode>(Ld))
C = CI->getConstantIntValue();
else if (ConstantFPSDNode *CF = dyn_cast<ConstantFPSDNode>(Ld))
C = CF->getConstantFPValue();
assert(C && "Invalid constant type");
SDValue CP = DAG.getConstantPool(C, LdTy);
unsigned Alignment = cast<ConstantPoolSDNode>(CP)->getAlignment();
Ld = DAG.getLoad(LdTy, dl, DAG.getEntryNode(), CP,
MachinePointerInfo::getConstantPool(),
false, false, false, Alignment);
// Bitcast the loaded constant back to the requested type.
Ld = DAG.getNode(ISD::BITCAST, dl, CVT, Ld);
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, Ld);
}
}
// The scalar source must be a normal load.
if (!ISD::isNormalLoad(Ld.getNode()))
return SDValue();
@ -4921,28 +4963,26 @@ static SDValue isVectorBroadcast(SDValue &Op, const X86Subtarget *Subtarget) {
if (Ld->hasAnyUseOfValue(1))
return SDValue();
bool Is256 = VT.getSizeInBits() == 256;
bool Is128 = VT.getSizeInBits() == 128;
unsigned ScalarSize = Ld.getValueType().getSizeInBits();
// VBroadcast to YMM
if (Is256 && (ScalarSize == 32 || ScalarSize == 64))
return Ld;
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, Ld);
// VBroadcast to XMM
if (Is128 && (ScalarSize == 32))
return Ld;
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, Ld);
// The integer check is needed for the 64-bit into 128-bit so it doesn't match
// double since there is vbroadcastsd xmm
if (Subtarget->hasAVX2() && Ld.getValueType().isInteger()) {
// VBroadcast to YMM
if (Is256 && (ScalarSize == 8 || ScalarSize == 16))
return Ld;
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, Ld);
// VBroadcast to XMM
if (Is128 && (ScalarSize == 8 || ScalarSize == 16 || ScalarSize == 64))
return Ld;
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, Ld);
}
// Unsupported broadcast.
@ -4977,9 +5017,9 @@ X86TargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) const {
return getOnesVector(VT, Subtarget->hasAVX2(), DAG, dl);
}
SDValue LD = isVectorBroadcast(Op, Subtarget);
if (LD.getNode())
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, LD);
SDValue Broadcast = LowerVectorBroadcast(Op, Subtarget, dl, DAG);
if (Broadcast.getNode())
return Broadcast;
unsigned EVTBits = ExtVT.getSizeInBits();
@ -6205,9 +6245,9 @@ SDValue NormalizeVectorShuffle(SDValue Op, SelectionDAG &DAG,
int Size = VT.getSizeInBits();
// Use vbroadcast whenever the splat comes from a foldable load
SDValue LD = isVectorBroadcast(Op, Subtarget);
if (LD.getNode())
return DAG.getNode(X86ISD::VBROADCAST, dl, VT, LD);
SDValue Broadcast = LowerVectorBroadcast(Op, Subtarget, dl, DAG);
if (Broadcast.getNode())
return Broadcast;
// Handle splats by matching through known shuffle masks
if ((Size == 128 && NumElem <= 4) ||

21
test/CodeGen/X86/avx-vbroadcast.ll
View File

@ -47,7 +47,7 @@ entry:
;;;; 128-bit versions
; CHECK: vbroadcastss (%
define <4 x float> @E(float* %ptr) nounwind uwtable readnone ssp {
define <4 x float> @e(float* %ptr) nounwind uwtable readnone ssp {
entry:
%q = load float* %ptr, align 4
%vecinit.i = insertelement <4 x float> undef, float %q, i32 0
@ -57,6 +57,19 @@ entry:
ret <4 x float> %vecinit6.i
}
; CHECK: _e2
; CHECK-NOT: vbroadcastss
; CHECK: ret
define <4 x float> @_e2(float* %ptr) nounwind uwtable readnone ssp {
%vecinit.i = insertelement <4 x float> undef, float 0xbf80000000000000, i32 0
%vecinit2.i = insertelement <4 x float> %vecinit.i, float 0xbf80000000000000, i32 1
%vecinit4.i = insertelement <4 x float> %vecinit2.i, float 0xbf80000000000000, i32 2
%vecinit6.i = insertelement <4 x float> %vecinit4.i, float 0xbf80000000000000, i32 3
ret <4 x float> %vecinit6.i
}
; CHECK: vbroadcastss (%
define <4 x i32> @F(i32* %ptr) nounwind uwtable readnone ssp {
entry:
@ -71,7 +84,7 @@ entry:
; Unsupported vbroadcasts
; CHECK: _G
; CHECK-NOT: vbroadcastsd (%
; CHECK-NOT: broadcast (%
; CHECK: ret
define <2 x i64> @G(i64* %ptr) nounwind uwtable readnone ssp {
entry:
@ -82,7 +95,7 @@ entry:
}
; CHECK: _H
; CHECK-NOT: vbroadcastss
; CHECK-NOT: broadcast
; CHECK: ret
define <4 x i32> @H(<4 x i32> %a) {
%x = shufflevector <4 x i32> %a, <4 x i32> undef, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
@ -90,7 +103,7 @@ define <4 x i32> @H(<4 x i32> %a) {
}
; CHECK: _I
; CHECK-NOT: vbroadcastsd (%
; CHECK-NOT: broadcast (%
; CHECK: ret
define <2 x double> @I(double* %ptr) nounwind uwtable readnone ssp {
entry:

21
test/CodeGen/X86/avx2-vbroadcast.ll
View File

@ -150,3 +150,24 @@ entry:
%vecinit2.i = insertelement <2 x double> %vecinit.i, double %q, i32 1
ret <2 x double> %vecinit2.i
}
; CHECK: V111
; CHECK: vpbroadcastd
; CHECK: ret
define <8 x i32> @V111(<8 x i32> %in) nounwind uwtable readnone ssp {
entry:
%g = add <8 x i32> %in, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
ret <8 x i32> %g
}
; CHECK: _e2
; CHECK: vbroadcastss
; CHECK: ret
define <4 x float> @_e2(float* %ptr) nounwind uwtable readnone ssp {
%vecinit.i = insertelement <4 x float> undef, float 0xbf80000000000000, i32 0
%vecinit2.i = insertelement <4 x float> %vecinit.i, float 0xbf80000000000000, i32 1
%vecinit4.i = insertelement <4 x float> %vecinit2.i, float 0xbf80000000000000, i32 2
%vecinit6.i = insertelement <4 x float> %vecinit4.i, float 0xbf80000000000000, i32 3
ret <4 x float> %vecinit6.i
}