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SLPVectorizer: refactor reorderInputsAccordingToOpcode (NFC)

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This is intended to simplify the changes needed to solve PR25247.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 251085
This commit is contained in:
Mehdi Amini
2015-10-23 00:46:17 +00:00
parent 44dbf115fe
commit bf6ee32ca5
1 changed files with 82 additions and 53 deletions
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135
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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@@ -1943,6 +1943,59 @@ void BoUpSLP::reorderAltShuffleOperands(ArrayRef<Value *> VL,
}
}
// Return true if I should be commuted before adding it's left and right
// operands to the arrays Left and Right.
//
// The vectorizer is trying to either have all elements one side being
// instruction with the same opcode to enable further vectorization, or having
// a splat to lower the vectorizing cost.
static bool shouldReorderOperands(int i, Instruction &I,
SmallVectorImpl<Value *> &Left,
SmallVectorImpl<Value *> &Right) {
Value *VLeft = I.getOperand(0);
Value *VRight = I.getOperand(1);
Instruction *ILeft = dyn_cast<Instruction>(VLeft);
Instruction *IRight = dyn_cast<Instruction>(VRight);
// Sort two opcodes. In the code below we try to preserve the ability to use
// broadcast of values instead of individual inserts.
// vl1 = load
// vl2 = phi
// vr1 = load
// vr2 = vr2
// = vl1 x vr1
// = vl2 x vr2
// If we just sorted according to opcode we would leave the first line in
// tact but we would swap vl2 with vr2 because opcode(phi) > opcode(load).
// = vl1 x vr1
// = vr2 x vl2
// Because vr2 and vr1 are from the same load we loose the opportunity of a
// broadcast for the packed right side in the backend: we have [vr1, vl2]
// instead of [vr1, vr2=vr1].
if (ILeft && IRight) {
if (ILeft->getOpcode() > IRight->getOpcode() &&
Right[i - 1] != IRight) {
// Try not to destroy a broad cast for no apparent benefit.
return true;
} else if (ILeft->getOpcode() == IRight->getOpcode() &&
Right[i - 1] == ILeft) {
// Try preserve broadcasts.
return true;
} else if (ILeft->getOpcode() == IRight->getOpcode() &&
Left[i - 1] == IRight) {
// Try preserve broadcasts.
return true;
}
return false;
}
// One opcode, put the instruction on the right.
if (ILeft) {
return true;
}
return false;
}
void BoUpSLP::reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
SmallVectorImpl<Value *> &Left,
SmallVectorImpl<Value *> &Right) {
@@ -1951,28 +2004,42 @@ void BoUpSLP::reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
bool AllSameOpcodeLeft = true;
bool AllSameOpcodeRight = true;
for (unsigned i = 0, e = VL.size(); i != e; ++i) {
Instruction *I = cast<Instruction>(VL[i]);
Value *VLeft = I->getOperand(0);
Value *VRight = I->getOperand(1);
if (VL.size()) {
// Peel the first iteration out of the loop since there's nothing
// interesting to do anyway and it simplifies the checks
auto VLeft = cast<Instruction>(VL[0])->getOperand(0);
auto VRight = cast<Instruction>(VL[0])->getOperand(1);
OrigLeft.push_back(VLeft);
OrigRight.push_back(VRight);
if (!isa<Instruction>(VRight) && isa<Instruction>(VLeft))
// Favor having instruction to the right. FIXME: why?
std::swap(VLeft, VRight);
Left.push_back(VLeft);
Right.push_back(VRight);
}
for (unsigned i = 1, e = VL.size(); i != e; ++i) {
Instruction *I = cast<Instruction>(VL[i]);
Value *VLeft = I->getOperand(0);
Value *VRight = I->getOperand(1);
OrigLeft.push_back(VLeft);
OrigRight.push_back(VRight);
Instruction *ILeft = dyn_cast<Instruction>(VLeft);
Instruction *IRight = dyn_cast<Instruction>(VRight);
// Check whether all operands on one side have the same opcode. In this case
// we want to preserve the original order and not make things worse by
// reordering.
if (i && AllSameOpcodeLeft && ILeft) {
if (AllSameOpcodeLeft && ILeft) {
if (Instruction *PLeft = dyn_cast<Instruction>(OrigLeft[i - 1])) {
if (PLeft->getOpcode() != ILeft->getOpcode())
AllSameOpcodeLeft = false;
} else
AllSameOpcodeLeft = false;
}
if (i && AllSameOpcodeRight && IRight) {
if (AllSameOpcodeRight && IRight) {
if (Instruction *PRight = dyn_cast<Instruction>(OrigRight[i - 1])) {
if (PRight->getOpcode() != IRight->getOpcode())
AllSameOpcodeRight = false;
@@ -1980,54 +2047,16 @@ void BoUpSLP::reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
AllSameOpcodeRight = false;
}
// Sort two opcodes. In the code below we try to preserve the ability to use
// broadcast of values instead of individual inserts.
// vl1 = load
// vl2 = phi
// vr1 = load
// vr2 = vr2
// = vl1 x vr1
// = vl2 x vr2
// If we just sorted according to opcode we would leave the first line in
// tact but we would swap vl2 with vr2 because opcode(phi) > opcode(load).
// = vl1 x vr1
// = vr2 x vl2
// Because vr2 and vr1 are from the same load we loose the opportunity of a
// broadcast for the packed right side in the backend: we have [vr1, vl2]
// instead of [vr1, vr2=vr1].
if (ILeft && IRight) {
if (!i && ILeft->getOpcode() > IRight->getOpcode()) {
Left.push_back(IRight);
Right.push_back(ILeft);
} else if (i && ILeft->getOpcode() > IRight->getOpcode() &&
Right[i - 1] != IRight) {
// Try not to destroy a broad cast for no apparent benefit.
Left.push_back(IRight);
Right.push_back(ILeft);
} else if (i && ILeft->getOpcode() == IRight->getOpcode() &&
Right[i - 1] == ILeft) {
// Try preserve broadcasts.
Left.push_back(IRight);
Right.push_back(ILeft);
} else if (i && ILeft->getOpcode() == IRight->getOpcode() &&
Left[i - 1] == IRight) {
// Try preserve broadcasts.
Left.push_back(IRight);
Right.push_back(ILeft);
} else {
Left.push_back(ILeft);
Right.push_back(IRight);
}
continue;
// Commute to favor either a splat or maximizing having the same opcodes on
// one side.
if (shouldReorderOperands(i, *I, Left, Right)) {
Left.push_back(I->getOperand(1));
Right.push_back(I->getOperand(0));
} else {
Left.push_back(I->getOperand(0));
Right.push_back(I->getOperand(1));
}
// One opcode, put the instruction on the right.
if (ILeft) {
Left.push_back(VRight);
Right.push_back(ILeft);
continue;
}
Left.push_back(VLeft);
Right.push_back(VRight);
}
bool LeftBroadcast = isSplat(Left);