llvm-6502/lib/Target/X86/Utils/X86ShuffleDecode.cpp
Chandler Carruth 08780d4c1d [x86] Teach the x86 DAG combiner to form MOVSLDUP and MOVSHDUP
instructions when it finds an appropriate pattern.

These are lovely instructions, and its a shame to not use them. =] They
are fast, and can hand loads folded into their operands, etc.

I've also plumbed the comment shuffle decoding through the various
layers so that the test cases are printed nicely.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217758 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-15 11:15:23 +00:00

293 lines
10 KiB
C++

//===-- X86ShuffleDecode.cpp - X86 shuffle decode logic -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Define several functions to decode x86 specific shuffle semantics into a
// generic vector mask.
//
//===----------------------------------------------------------------------===//
#include "X86ShuffleDecode.h"
#include "llvm/IR/Constants.h"
#include "llvm/CodeGen/MachineValueType.h"
//===----------------------------------------------------------------------===//
// Vector Mask Decoding
//===----------------------------------------------------------------------===//
namespace llvm {
void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
// Defaults the copying the dest value.
ShuffleMask.push_back(0);
ShuffleMask.push_back(1);
ShuffleMask.push_back(2);
ShuffleMask.push_back(3);
// Decode the immediate.
unsigned ZMask = Imm & 15;
unsigned CountD = (Imm >> 4) & 3;
unsigned CountS = (Imm >> 6) & 3;
// CountS selects which input element to use.
unsigned InVal = 4+CountS;
// CountD specifies which element of destination to update.
ShuffleMask[CountD] = InVal;
// ZMask zaps values, potentially overriding the CountD elt.
if (ZMask & 1) ShuffleMask[0] = SM_SentinelZero;
if (ZMask & 2) ShuffleMask[1] = SM_SentinelZero;
if (ZMask & 4) ShuffleMask[2] = SM_SentinelZero;
if (ZMask & 8) ShuffleMask[3] = SM_SentinelZero;
}
// <3,1> or <6,7,2,3>
void DecodeMOVHLPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
for (unsigned i = NElts/2; i != NElts; ++i)
ShuffleMask.push_back(NElts+i);
for (unsigned i = NElts/2; i != NElts; ++i)
ShuffleMask.push_back(i);
}
// <0,2> or <0,1,4,5>
void DecodeMOVLHPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
for (unsigned i = 0; i != NElts/2; ++i)
ShuffleMask.push_back(i);
for (unsigned i = 0; i != NElts/2; ++i)
ShuffleMask.push_back(NElts+i);
}
void DecodeMOVSLDUPMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
for (int i = 0, e = NumElts / 2; i < e; ++i) {
ShuffleMask.push_back(2 * i);
ShuffleMask.push_back(2 * i);
}
}
void DecodeMOVSHDUPMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
for (int i = 0, e = NumElts / 2; i < e; ++i) {
ShuffleMask.push_back(2 * i + 1);
ShuffleMask.push_back(2 * i + 1);
}
}
void DecodePALIGNRMask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
unsigned Offset = Imm * (VT.getVectorElementType().getSizeInBits() / 8);
unsigned NumLanes = VT.getSizeInBits() / 128;
unsigned NumLaneElts = NumElts / NumLanes;
for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
for (unsigned i = 0; i != NumLaneElts; ++i) {
unsigned Base = i + Offset;
// if i+offset is out of this lane then we actually need the other source
if (Base >= NumLaneElts) Base += NumElts - NumLaneElts;
ShuffleMask.push_back(Base + l);
}
}
}
/// DecodePSHUFMask - This decodes the shuffle masks for pshufd, and vpermilp*.
/// VT indicates the type of the vector allowing it to handle different
/// datatypes and vector widths.
void DecodePSHUFMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
unsigned NumLanes = VT.getSizeInBits() / 128;
unsigned NumLaneElts = NumElts / NumLanes;
unsigned NewImm = Imm;
for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
for (unsigned i = 0; i != NumLaneElts; ++i) {
ShuffleMask.push_back(NewImm % NumLaneElts + l);
NewImm /= NumLaneElts;
}
if (NumLaneElts == 4) NewImm = Imm; // reload imm
}
}
void DecodePSHUFHWMask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
for (unsigned l = 0; l != NumElts; l += 8) {
unsigned NewImm = Imm;
for (unsigned i = 0, e = 4; i != e; ++i) {
ShuffleMask.push_back(l + i);
}
for (unsigned i = 4, e = 8; i != e; ++i) {
ShuffleMask.push_back(l + 4 + (NewImm & 3));
NewImm >>= 2;
}
}
}
void DecodePSHUFLWMask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
for (unsigned l = 0; l != NumElts; l += 8) {
unsigned NewImm = Imm;
for (unsigned i = 0, e = 4; i != e; ++i) {
ShuffleMask.push_back(l + (NewImm & 3));
NewImm >>= 2;
}
for (unsigned i = 4, e = 8; i != e; ++i) {
ShuffleMask.push_back(l + i);
}
}
}
/// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
/// the type of the vector allowing it to handle different datatypes and vector
/// widths.
void DecodeSHUFPMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
unsigned NumLanes = VT.getSizeInBits() / 128;
unsigned NumLaneElts = NumElts / NumLanes;
unsigned NewImm = Imm;
for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
// each half of a lane comes from different source
for (unsigned s = 0; s != NumElts*2; s += NumElts) {
for (unsigned i = 0; i != NumLaneElts/2; ++i) {
ShuffleMask.push_back(NewImm % NumLaneElts + s + l);
NewImm /= NumLaneElts;
}
}
if (NumLaneElts == 4) NewImm = Imm; // reload imm
}
}
/// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
/// and punpckh*. VT indicates the type of the vector allowing it to handle
/// different datatypes and vector widths.
void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
// Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
// independently on 128-bit lanes.
unsigned NumLanes = VT.getSizeInBits() / 128;
if (NumLanes == 0 ) NumLanes = 1; // Handle MMX
unsigned NumLaneElts = NumElts / NumLanes;
for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
for (unsigned i = l + NumLaneElts/2, e = l + NumLaneElts; i != e; ++i) {
ShuffleMask.push_back(i); // Reads from dest/src1
ShuffleMask.push_back(i+NumElts); // Reads from src/src2
}
}
}
/// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
/// and punpckl*. VT indicates the type of the vector allowing it to handle
/// different datatypes and vector widths.
void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
unsigned NumElts = VT.getVectorNumElements();
// Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
// independently on 128-bit lanes.
unsigned NumLanes = VT.getSizeInBits() / 128;
if (NumLanes == 0 ) NumLanes = 1; // Handle MMX
unsigned NumLaneElts = NumElts / NumLanes;
for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
for (unsigned i = l, e = l + NumLaneElts/2; i != e; ++i) {
ShuffleMask.push_back(i); // Reads from dest/src1
ShuffleMask.push_back(i+NumElts); // Reads from src/src2
}
}
}
void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask) {
if (Imm & 0x88)
return; // Not a shuffle
unsigned HalfSize = VT.getVectorNumElements()/2;
for (unsigned l = 0; l != 2; ++l) {
unsigned HalfBegin = ((Imm >> (l*4)) & 0x3) * HalfSize;
for (unsigned i = HalfBegin, e = HalfBegin+HalfSize; i != e; ++i)
ShuffleMask.push_back(i);
}
}
void DecodePSHUFBMask(const ConstantDataSequential *C,
SmallVectorImpl<int> &ShuffleMask) {
Type *MaskTy = C->getType();
assert(MaskTy->isVectorTy() && "Expected a vector constant mask!");
assert(MaskTy->getVectorElementType()->isIntegerTy(8) &&
"Expected i8 constant mask elements!");
int NumElements = MaskTy->getVectorNumElements();
// FIXME: Add support for AVX-512.
assert((NumElements == 16 || NumElements == 32) &&
"Only 128-bit and 256-bit vectors supported!");
assert((unsigned)NumElements == C->getNumElements() &&
"Constant mask has a different number of elements!");
ShuffleMask.reserve(NumElements);
for (int i = 0; i < NumElements; ++i) {
// For AVX vectors with 32 bytes the base of the shuffle is the half of the
// vector we're inside.
int Base = i < 16 ? 0 : 16;
uint64_t Element = C->getElementAsInteger(i);
// If the high bit (7) of the byte is set, the element is zeroed.
if (Element & (1 << 7))
ShuffleMask.push_back(SM_SentinelZero);
else {
int Index = Base + Element;
assert((Index >= 0 && Index < NumElements) &&
"Out of bounds shuffle index for pshub instruction!");
ShuffleMask.push_back(Index);
}
}
}
void DecodePSHUFBMask(ArrayRef<uint64_t> RawMask,
SmallVectorImpl<int> &ShuffleMask) {
for (int i = 0, e = RawMask.size(); i < e; ++i) {
uint64_t M = RawMask[i];
// For AVX vectors with 32 bytes the base of the shuffle is the half of
// the vector we're inside.
int Base = i < 16 ? 0 : 16;
// If the high bit (7) of the byte is set, the element is zeroed.
if (M & (1 << 7))
ShuffleMask.push_back(SM_SentinelZero);
else {
int Index = Base + M;
assert((Index >= 0 && (unsigned)Index < RawMask.size()) &&
"Out of bounds shuffle index for pshub instruction!");
ShuffleMask.push_back(Index);
}
}
}
void DecodeBLENDMask(MVT VT, unsigned Imm,
SmallVectorImpl<int> &ShuffleMask) {
int NumElements = VT.getVectorNumElements();
for (int i = 0; i < NumElements; ++i)
ShuffleMask.push_back(((Imm >> i) & 1) ? NumElements + i : i);
}
/// DecodeVPERMMask - this decodes the shuffle masks for VPERMQ/VPERMPD.
/// No VT provided since it only works on 256-bit, 4 element vectors.
void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
for (unsigned i = 0; i != 4; ++i) {
ShuffleMask.push_back((Imm >> (2*i)) & 3);
}
}
} // llvm namespace