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Generalize BuildVectorSDNode::isConstantSplat to use APInts and handle

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arbitrary vector sizes.  Add an optional MinSplatBits parameter to specify
a minimum for the splat element size.  Update the PPC target to use the
revised interface.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65899 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson 2009-03-02 23:24:16 +00:00
parent 52349a919b
commit 24e338e8a3
3 changed files with 69 additions and 90 deletions
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19
include/llvm/CodeGen/SelectionDAGNodes.h
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@ -1933,13 +1933,18 @@ public:
/// BUILD_VECTORs.
class BuildVectorSDNode : public SDNode {
public:
/// isConstantSplat - check if this is a constant splat, and if so, return
/// the splat element value in SplatBits. Any undefined bits in that value
/// are set to zero, and the corresponding bits in the SplatUndef mask are
/// set. The SplatSize value is set to the splat element size in bytes.
/// HasAnyUndefs is set to true if any bits in the vector are undefined.
bool isConstantSplat(unsigned &SplatBits, unsigned &SplatUndef,
unsigned &SplatSize, bool &HasAnyUndefs);
/// isConstantSplat - Check if this is a constant splat, and if so, find the
/// smallest element size that splats the vector. If MinSplatBits is
/// nonzero, the element size must be at least that large. Note that the
/// splat element may be the entire vector (i.e., a one element vector).
/// Returns the splat element value in SplatValue. Any undefined bits in
/// that value are zero, and the corresponding bits in the SplatUndef mask
/// are set. The SplatBitSize value is set to the splat element size in
/// bits. HasAnyUndefs is set to true if any bits in the vector are
/// undefined.
bool isConstantSplat(APInt &SplatValue, APInt &SplatUndef,
unsigned &SplatBitSize, bool &HasAnyUndefs,
unsigned MinSplatBits = 0);
static inline bool classof(const BuildVectorSDNode *) { return true; }
static inline bool classof(const SDNode *N) {

121
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -5555,93 +5555,64 @@ const Type *ConstantPoolSDNode::getType() const {
return Val.ConstVal->getType();
}
// If this is a splat (repetition) of a value across the whole vector, return
// the smallest size that splats it. For example, "0x01010101010101..." is a
// splat of 0x01, 0x0101, and 0x01010101. We return SplatBits = 0x01 and
// SplatSize = 1 byte.
bool BuildVectorSDNode::isConstantSplat(unsigned &SplatBits,
unsigned &SplatUndef,
unsigned &SplatSize,
bool &HasAnyUndefs) {
uint64_t Bits128[2];
uint64_t Undef128[2];
bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue,
APInt &SplatUndef,
unsigned &SplatBitSize,
bool &HasAnyUndefs,
unsigned MinSplatBits) {
MVT VT = getValueType(0);
assert(VT.isVector() && "Expected a vector type");
unsigned sz = VT.getSizeInBits();
if (MinSplatBits > sz)
return false;
// If this is a vector of constants or undefs, get the bits. A bit in
// UndefBits is set if the corresponding element of the vector is an
// ISD::UNDEF value. For undefs, the corresponding VectorBits values are
// zero.
SplatValue = APInt(sz, 0);
SplatUndef = APInt(sz, 0);
// Start with zero'd results.
Bits128[0] = Bits128[1] = Undef128[0] = Undef128[1] = 0;
unsigned EltBitSize = getOperand(0).getValueType().getSizeInBits();
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
// Get the bits. Bits with undefined values (when the corresponding element
// of the vector is an ISD::UNDEF value) are set in SplatUndef and cleared
// in SplatValue. If any of the values are not constant, give up and return
// false.
unsigned int nOps = getNumOperands();
assert(nOps > 0 && "isConstantSplat has 0-size build vector");
unsigned EltBitSize = VT.getVectorElementType().getSizeInBits();
for (unsigned i = 0; i < nOps; ++i) {
SDValue OpVal = getOperand(i);
unsigned BitPos = i * EltBitSize;
unsigned PartNo = i >= e/2; // In the upper 128 bits?
unsigned SlotNo = e/2 - (i & (e/2-1))-1; // Which subpiece of the uint64_t.
uint64_t EltBits = 0;
if (OpVal.getOpcode() == ISD::UNDEF) {
uint64_t EltUndefBits = ~0U >> (32-EltBitSize);
Undef128[PartNo] |= EltUndefBits << (SlotNo*EltBitSize);
continue;
} else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(OpVal)) {
EltBits = CN->getZExtValue() & (~0U >> (32-EltBitSize));
} else if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(OpVal)) {
assert(CN->getValueType(0) == MVT::f32 &&
"Only one legal FP vector type!");
EltBits = FloatToBits(CN->getValueAPF().convertToFloat());
} else {
// Nonconstant element.
if (OpVal.getOpcode() == ISD::UNDEF)
SplatUndef |= APInt::getBitsSet(sz, BitPos, BitPos +EltBitSize);
else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(OpVal))
SplatValue |= APInt(CN->getAPIntValue()).zext(sz) << BitPos;
else if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(OpVal))
SplatValue |= CN->getValueAPF().bitcastToAPInt().zext(sz) << BitPos;
else
return false;
}
Bits128[PartNo] |= EltBits << (SlotNo*EltBitSize);
}
// Don't let undefs prevent splats from matching. See if the top 64-bits are
// the same as the lower 64-bits, ignoring undefs.
if ((Bits128[0] & ~Undef128[1]) != (Bits128[1] & ~Undef128[0]))
return false; // Can't be a splat if two pieces don't match.
// The build_vector is all constants or undefs. Find the smallest element
// size that splats the vector.
uint64_t Bits64 = Bits128[0] | Bits128[1];
uint64_t Undef64 = Undef128[0] & Undef128[1];
HasAnyUndefs = (SplatUndef != 0);
while (sz > 8) {
// Check that the top 32-bits are the same as the lower 32-bits, ignoring
// undefs.
if ((Bits64 & (~Undef64 >> 32)) != ((Bits64 >> 32) & ~Undef64))
return false; // Can't be a splat if two pieces don't match.
unsigned HalfSize = sz / 2;
APInt HighValue = APInt(SplatValue).lshr(HalfSize).trunc(HalfSize);
APInt LowValue = APInt(SplatValue).trunc(HalfSize);
APInt HighUndef = APInt(SplatUndef).lshr(HalfSize).trunc(HalfSize);
APInt LowUndef = APInt(SplatUndef).trunc(HalfSize);
HasAnyUndefs = (Undef128[0] | Undef128[1]) != 0;
// If the two halves do not match (ignoring undef bits), stop here.
if ((HighValue & ~LowUndef) != (LowValue & ~HighUndef) ||
MinSplatBits > HalfSize)
break;
uint32_t Bits32 = uint32_t(Bits64) | uint32_t(Bits64 >> 32);
uint32_t Undef32 = uint32_t(Undef64) & uint32_t(Undef64 >> 32);
// If the top 16-bits are different than the lower 16-bits, ignoring
// undefs, we have an i32 splat.
if ((Bits32 & (~Undef32 >> 16)) != ((Bits32 >> 16) & ~Undef32)) {
SplatBits = Bits32;
SplatUndef = Undef32;
SplatSize = 4;
return true;
SplatValue = HighValue | LowValue;
SplatUndef = HighUndef & LowUndef;
sz = HalfSize;
}
uint16_t Bits16 = uint16_t(Bits32) | uint16_t(Bits32 >> 16);
uint16_t Undef16 = uint16_t(Undef32) & uint16_t(Undef32 >> 16);
// If the top 8-bits are different than the lower 8-bits, ignoring
// undefs, we have an i16 splat.
if ((Bits16 & (uint16_t(~Undef16) >> 8)) != ((Bits16 >> 8) & ~Undef16)) {
SplatBits = Bits16;
SplatUndef = Undef16;
SplatSize = 2;
return true;
}
// Otherwise, we have an 8-bit splat.
SplatBits = uint8_t(Bits16) | uint8_t(Bits16 >> 8);
SplatUndef = uint8_t(Undef16) & uint8_t(Undef16 >> 8);
SplatSize = 1;
SplatBitSize = sz;
return true;
}

19
lib/Target/PowerPC/PPCISelLowering.cpp
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@ -3167,13 +3167,16 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
BuildVectorSDNode *BVN = dyn_cast<BuildVectorSDNode>(Op.getNode());
assert(BVN != 0 && "Expected a BuildVectorSDNode in LowerBUILD_VECTOR");
// If this is a splat (repetition) of a value across the whole vector, return
// the smallest size that splats it. For example, "0x01010101010101..." is a
// splat of 0x01, 0x0101, and 0x01010101. We return SplatBits = 0x01 and
// SplatSize = 1 byte.
unsigned SplatBits, SplatUndef, SplatSize;
// Check if this is a splat of a constant value.
APInt APSplatBits, APSplatUndef;
unsigned SplatBitSize;
bool HasAnyUndefs;
if (BVN->isConstantSplat(SplatBits, SplatUndef, SplatSize, HasAnyUndefs)) {
if (BVN->isConstantSplat(APSplatBits, APSplatUndef, SplatBitSize,
HasAnyUndefs) &&
SplatBitSize <= 32) {
unsigned SplatBits = APSplatBits.getZExtValue();
unsigned SplatUndef = APSplatUndef.getZExtValue();
unsigned SplatSize = SplatBitSize / 8;
// First, handle single instruction cases.
@ -3189,7 +3192,8 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
}
// If the sign extended value is in the range [-16,15], use VSPLTI[bhw].
int32_t SextVal= int32_t(SplatBits << (32-8*SplatSize)) >> (32-8*SplatSize);
int32_t SextVal= (int32_t(SplatBits << (32-SplatBitSize)) >>
(32-SplatBitSize));
if (SextVal >= -16 && SextVal <= 15)
return BuildSplatI(SextVal, SplatSize, Op.getValueType(), DAG, dl);
@ -3221,7 +3225,6 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
}
// Check to see if this is a wide variety of vsplti*, binop self cases.
unsigned SplatBitSize = SplatSize*8;
static const signed char SplatCsts[] = {
-1, 1, -2, 2, -3, 3, -4, 4, -5, 5, -6, 6, -7, 7,
-8, 8, -9, 9, -10, 10, -11, 11, -12, 12, -13, 13, 14, -14, 15, -15, -16