350 lines
11 KiB
C++
350 lines
11 KiB
C++
//===-- X86ShuffleDecodeConstantPool.cpp - X86 shuffle decode -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Define several functions to decode x86 specific shuffle semantics using
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// constants from the constant pool.
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//
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//===----------------------------------------------------------------------===//
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#include "Utils/X86ShuffleDecode.h"
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#include "llvm/ADT/APInt.h"
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#include "llvm/IR/Constants.h"
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//===----------------------------------------------------------------------===//
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// Vector Mask Decoding
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//===----------------------------------------------------------------------===//
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namespace llvm {
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static bool extractConstantMask(const Constant *C, unsigned MaskEltSizeInBits,
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APInt &UndefElts,
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SmallVectorImpl<uint64_t> &RawMask) {
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// It is not an error for shuffle masks to not be a vector of
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// MaskEltSizeInBits because the constant pool uniques constants by their
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// bit representation.
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// e.g. the following take up the same space in the constant pool:
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// i128 -170141183420855150465331762880109871104
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//
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// <2 x i64> <i64 -9223372034707292160, i64 -9223372034707292160>
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//
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// <4 x i32> <i32 -2147483648, i32 -2147483648,
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// i32 -2147483648, i32 -2147483648>
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Type *CstTy = C->getType();
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if (!CstTy->isVectorTy())
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return false;
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Type *CstEltTy = CstTy->getVectorElementType();
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if (!CstEltTy->isIntegerTy())
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return false;
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unsigned CstSizeInBits = CstTy->getPrimitiveSizeInBits();
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unsigned CstEltSizeInBits = CstTy->getScalarSizeInBits();
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unsigned NumCstElts = CstTy->getVectorNumElements();
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assert((CstSizeInBits % MaskEltSizeInBits) == 0 &&
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"Unaligned shuffle mask size");
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unsigned NumMaskElts = CstSizeInBits / MaskEltSizeInBits;
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UndefElts = APInt(NumMaskElts, 0);
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RawMask.resize(NumMaskElts, 0);
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// Fast path - if the constants match the mask size then copy direct.
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if (MaskEltSizeInBits == CstEltSizeInBits) {
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assert(NumCstElts == NumMaskElts && "Unaligned shuffle mask size");
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for (unsigned i = 0; i != NumMaskElts; ++i) {
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Constant *COp = C->getAggregateElement(i);
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if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
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return false;
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if (isa<UndefValue>(COp)) {
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UndefElts.setBit(i);
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RawMask[i] = 0;
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continue;
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}
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auto *Elt = cast<ConstantInt>(COp);
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RawMask[i] = Elt->getValue().getZExtValue();
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}
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return true;
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}
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// Extract all the undef/constant element data and pack into single bitsets.
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APInt UndefBits(CstSizeInBits, 0);
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APInt MaskBits(CstSizeInBits, 0);
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for (unsigned i = 0; i != NumCstElts; ++i) {
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Constant *COp = C->getAggregateElement(i);
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if (!COp || (!isa<UndefValue>(COp) && !isa<ConstantInt>(COp)))
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return false;
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unsigned BitOffset = i * CstEltSizeInBits;
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if (isa<UndefValue>(COp)) {
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UndefBits.setBits(BitOffset, BitOffset + CstEltSizeInBits);
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continue;
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}
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MaskBits.insertBits(cast<ConstantInt>(COp)->getValue(), BitOffset);
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}
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// Now extract the undef/constant bit data into the raw shuffle masks.
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for (unsigned i = 0; i != NumMaskElts; ++i) {
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unsigned BitOffset = i * MaskEltSizeInBits;
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APInt EltUndef = UndefBits.extractBits(MaskEltSizeInBits, BitOffset);
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// Only treat the element as UNDEF if all bits are UNDEF, otherwise
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// treat it as zero.
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if (EltUndef.isAllOnesValue()) {
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UndefElts.setBit(i);
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RawMask[i] = 0;
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continue;
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}
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APInt EltBits = MaskBits.extractBits(MaskEltSizeInBits, BitOffset);
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RawMask[i] = EltBits.getZExtValue();
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}
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return true;
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}
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void DecodePSHUFBMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
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Type *MaskTy = C->getType();
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unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
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(void)MaskTySize;
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assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
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"Unexpected vector size.");
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// The shuffle mask requires a byte vector.
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APInt UndefElts;
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SmallVector<uint64_t, 64> RawMask;
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if (!extractConstantMask(C, 8, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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assert((NumElts == 16 || NumElts == 32 || NumElts == 64) &&
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"Unexpected number of vector elements.");
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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uint64_t Element = RawMask[i];
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// If the high bit (7) of the byte is set, the element is zeroed.
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if (Element & (1 << 7))
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ShuffleMask.push_back(SM_SentinelZero);
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else {
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// For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
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// lane of the vector we're inside.
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unsigned Base = i & ~0xf;
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// Only the least significant 4 bits of the byte are used.
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int Index = Base + (Element & 0xf);
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ShuffleMask.push_back(Index);
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}
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}
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}
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void DecodeVPERMILPMask(const Constant *C, unsigned ElSize,
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SmallVectorImpl<int> &ShuffleMask) {
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Type *MaskTy = C->getType();
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unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
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(void)MaskTySize;
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assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
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"Unexpected vector size.");
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assert((ElSize == 32 || ElSize == 64) && "Unexpected vector element size.");
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// The shuffle mask requires elements the same size as the target.
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APInt UndefElts;
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SmallVector<uint64_t, 16> RawMask;
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if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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unsigned NumEltsPerLane = 128 / ElSize;
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assert((NumElts == 2 || NumElts == 4 || NumElts == 8 || NumElts == 16) &&
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"Unexpected number of vector elements.");
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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int Index = i & ~(NumEltsPerLane - 1);
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uint64_t Element = RawMask[i];
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if (ElSize == 64)
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Index += (Element >> 1) & 0x1;
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else
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Index += Element & 0x3;
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ShuffleMask.push_back(Index);
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}
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}
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void DecodeVPERMIL2PMask(const Constant *C, unsigned M2Z, unsigned ElSize,
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SmallVectorImpl<int> &ShuffleMask) {
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Type *MaskTy = C->getType();
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unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
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(void)MaskTySize;
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assert((MaskTySize == 128 || MaskTySize == 256) && "Unexpected vector size.");
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// The shuffle mask requires elements the same size as the target.
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APInt UndefElts;
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SmallVector<uint64_t, 8> RawMask;
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if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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unsigned NumEltsPerLane = 128 / ElSize;
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assert((NumElts == 2 || NumElts == 4 || NumElts == 8) &&
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"Unexpected number of vector elements.");
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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// VPERMIL2 Operation.
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// Bits[3] - Match Bit.
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// Bits[2:1] - (Per Lane) PD Shuffle Mask.
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// Bits[2:0] - (Per Lane) PS Shuffle Mask.
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uint64_t Selector = RawMask[i];
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unsigned MatchBit = (Selector >> 3) & 0x1;
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// M2Z[0:1] MatchBit
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// 0Xb X Source selected by Selector index.
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// 10b 0 Source selected by Selector index.
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// 10b 1 Zero.
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// 11b 0 Zero.
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// 11b 1 Source selected by Selector index.
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if ((M2Z & 0x2) != 0u && MatchBit != (M2Z & 0x1)) {
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ShuffleMask.push_back(SM_SentinelZero);
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continue;
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}
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int Index = i & ~(NumEltsPerLane - 1);
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if (ElSize == 64)
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Index += (Selector >> 1) & 0x1;
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else
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Index += Selector & 0x3;
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int Src = (Selector >> 2) & 0x1;
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Index += Src * NumElts;
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ShuffleMask.push_back(Index);
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}
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}
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void DecodeVPPERMMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
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assert(C->getType()->getPrimitiveSizeInBits() == 128 &&
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"Unexpected vector size.");
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// The shuffle mask requires a byte vector.
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APInt UndefElts;
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SmallVector<uint64_t, 16> RawMask;
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if (!extractConstantMask(C, 8, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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assert(NumElts == 16 && "Unexpected number of vector elements.");
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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// VPPERM Operation
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// Bits[4:0] - Byte Index (0 - 31)
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// Bits[7:5] - Permute Operation
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//
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// Permute Operation:
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// 0 - Source byte (no logical operation).
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// 1 - Invert source byte.
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// 2 - Bit reverse of source byte.
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// 3 - Bit reverse of inverted source byte.
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// 4 - 00h (zero - fill).
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// 5 - FFh (ones - fill).
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// 6 - Most significant bit of source byte replicated in all bit positions.
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// 7 - Invert most significant bit of source byte and replicate in all bit
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// positions.
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uint64_t Element = RawMask[i];
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uint64_t Index = Element & 0x1F;
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uint64_t PermuteOp = (Element >> 5) & 0x7;
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if (PermuteOp == 4) {
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ShuffleMask.push_back(SM_SentinelZero);
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continue;
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}
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if (PermuteOp != 0) {
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ShuffleMask.clear();
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return;
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}
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ShuffleMask.push_back((int)Index);
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}
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}
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void DecodeVPERMVMask(const Constant *C, unsigned ElSize,
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SmallVectorImpl<int> &ShuffleMask) {
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Type *MaskTy = C->getType();
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unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
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(void)MaskTySize;
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assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
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"Unexpected vector size.");
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assert((ElSize == 8 || ElSize == 16 || ElSize == 32 || ElSize == 64) &&
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"Unexpected vector element size.");
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// The shuffle mask requires elements the same size as the target.
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APInt UndefElts;
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SmallVector<uint64_t, 64> RawMask;
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if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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int Index = RawMask[i] & (NumElts - 1);
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ShuffleMask.push_back(Index);
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}
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}
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void DecodeVPERMV3Mask(const Constant *C, unsigned ElSize,
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SmallVectorImpl<int> &ShuffleMask) {
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Type *MaskTy = C->getType();
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unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
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(void)MaskTySize;
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assert((MaskTySize == 128 || MaskTySize == 256 || MaskTySize == 512) &&
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"Unexpected vector size.");
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assert((ElSize == 8 || ElSize == 16 || ElSize == 32 || ElSize == 64) &&
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"Unexpected vector element size.");
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// The shuffle mask requires elements the same size as the target.
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APInt UndefElts;
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SmallVector<uint64_t, 64> RawMask;
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if (!extractConstantMask(C, ElSize, UndefElts, RawMask))
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return;
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unsigned NumElts = RawMask.size();
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for (unsigned i = 0; i != NumElts; ++i) {
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if (UndefElts[i]) {
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ShuffleMask.push_back(SM_SentinelUndef);
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continue;
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}
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int Index = RawMask[i] & (NumElts*2 - 1);
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ShuffleMask.push_back(Index);
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}
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}
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} // llvm namespace
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