Home | History | Annotate | Download | only in Utils
      1 //===-- X86ShuffleDecode.cpp - X86 shuffle decode logic -------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // Define several functions to decode x86 specific shuffle semantics into a
     11 // generic vector mask.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "X86ShuffleDecode.h"
     16 #include "llvm/CodeGen/MachineValueType.h"
     17 
     18 //===----------------------------------------------------------------------===//
     19 //  Vector Mask Decoding
     20 //===----------------------------------------------------------------------===//
     21 
     22 namespace llvm {
     23 
     24 void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     25   // Defaults the copying the dest value.
     26   ShuffleMask.push_back(0);
     27   ShuffleMask.push_back(1);
     28   ShuffleMask.push_back(2);
     29   ShuffleMask.push_back(3);
     30 
     31   // Decode the immediate.
     32   unsigned ZMask = Imm & 15;
     33   unsigned CountD = (Imm >> 4) & 3;
     34   unsigned CountS = (Imm >> 6) & 3;
     35 
     36   // CountS selects which input element to use.
     37   unsigned InVal = 4+CountS;
     38   // CountD specifies which element of destination to update.
     39   ShuffleMask[CountD] = InVal;
     40   // ZMask zaps values, potentially overriding the CountD elt.
     41   if (ZMask & 1) ShuffleMask[0] = SM_SentinelZero;
     42   if (ZMask & 2) ShuffleMask[1] = SM_SentinelZero;
     43   if (ZMask & 4) ShuffleMask[2] = SM_SentinelZero;
     44   if (ZMask & 8) ShuffleMask[3] = SM_SentinelZero;
     45 }
     46 
     47 // <3,1> or <6,7,2,3>
     48 void DecodeMOVHLPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
     49   for (unsigned i = NElts/2; i != NElts; ++i)
     50     ShuffleMask.push_back(NElts+i);
     51 
     52   for (unsigned i = NElts/2; i != NElts; ++i)
     53     ShuffleMask.push_back(i);
     54 }
     55 
     56 // <0,2> or <0,1,4,5>
     57 void DecodeMOVLHPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
     58   for (unsigned i = 0; i != NElts/2; ++i)
     59     ShuffleMask.push_back(i);
     60 
     61   for (unsigned i = 0; i != NElts/2; ++i)
     62     ShuffleMask.push_back(NElts+i);
     63 }
     64 
     65 void DecodePALIGNRMask(MVT VT, unsigned Imm,
     66                        SmallVectorImpl<int> &ShuffleMask) {
     67   unsigned NumElts = VT.getVectorNumElements();
     68   unsigned Offset = Imm * (VT.getVectorElementType().getSizeInBits() / 8);
     69 
     70   unsigned NumLanes = VT.getSizeInBits() / 128;
     71   unsigned NumLaneElts = NumElts / NumLanes;
     72 
     73   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
     74     for (unsigned i = 0; i != NumLaneElts; ++i) {
     75       unsigned Base = i + Offset;
     76       // if i+offset is out of this lane then we actually need the other source
     77       if (Base >= NumLaneElts) Base += NumElts - NumLaneElts;
     78       ShuffleMask.push_back(Base + l);
     79     }
     80   }
     81 }
     82 
     83 /// DecodePSHUFMask - This decodes the shuffle masks for pshufd, and vpermilp*.
     84 /// VT indicates the type of the vector allowing it to handle different
     85 /// datatypes and vector widths.
     86 void DecodePSHUFMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     87   unsigned NumElts = VT.getVectorNumElements();
     88 
     89   unsigned NumLanes = VT.getSizeInBits() / 128;
     90   unsigned NumLaneElts = NumElts / NumLanes;
     91 
     92   unsigned NewImm = Imm;
     93   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
     94     for (unsigned i = 0; i != NumLaneElts; ++i) {
     95       ShuffleMask.push_back(NewImm % NumLaneElts + l);
     96       NewImm /= NumLaneElts;
     97     }
     98     if (NumLaneElts == 4) NewImm = Imm; // reload imm
     99   }
    100 }
    101 
    102 void DecodePSHUFHWMask(MVT VT, unsigned Imm,
    103                        SmallVectorImpl<int> &ShuffleMask) {
    104   unsigned NumElts = VT.getVectorNumElements();
    105 
    106   for (unsigned l = 0; l != NumElts; l += 8) {
    107     unsigned NewImm = Imm;
    108     for (unsigned i = 0, e = 4; i != e; ++i) {
    109       ShuffleMask.push_back(l + i);
    110     }
    111     for (unsigned i = 4, e = 8; i != e; ++i) {
    112       ShuffleMask.push_back(l + 4 + (NewImm & 3));
    113       NewImm >>= 2;
    114     }
    115   }
    116 }
    117 
    118 void DecodePSHUFLWMask(MVT VT, unsigned Imm,
    119                        SmallVectorImpl<int> &ShuffleMask) {
    120   unsigned NumElts = VT.getVectorNumElements();
    121 
    122   for (unsigned l = 0; l != NumElts; l += 8) {
    123     unsigned NewImm = Imm;
    124     for (unsigned i = 0, e = 4; i != e; ++i) {
    125       ShuffleMask.push_back(l + (NewImm & 3));
    126       NewImm >>= 2;
    127     }
    128     for (unsigned i = 4, e = 8; i != e; ++i) {
    129       ShuffleMask.push_back(l + i);
    130     }
    131   }
    132 }
    133 
    134 /// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
    135 /// the type of the vector allowing it to handle different datatypes and vector
    136 /// widths.
    137 void DecodeSHUFPMask(MVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
    138   unsigned NumElts = VT.getVectorNumElements();
    139 
    140   unsigned NumLanes = VT.getSizeInBits() / 128;
    141   unsigned NumLaneElts = NumElts / NumLanes;
    142 
    143   unsigned NewImm = Imm;
    144   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    145     // each half of a lane comes from different source
    146     for (unsigned s = 0; s != NumElts*2; s += NumElts) {
    147       for (unsigned i = 0; i != NumLaneElts/2; ++i) {
    148         ShuffleMask.push_back(NewImm % NumLaneElts + s + l);
    149         NewImm /= NumLaneElts;
    150       }
    151     }
    152     if (NumLaneElts == 4) NewImm = Imm; // reload imm
    153   }
    154 }
    155 
    156 /// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
    157 /// and punpckh*. VT indicates the type of the vector allowing it to handle
    158 /// different datatypes and vector widths.
    159 void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
    160   unsigned NumElts = VT.getVectorNumElements();
    161 
    162   // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
    163   // independently on 128-bit lanes.
    164   unsigned NumLanes = VT.getSizeInBits() / 128;
    165   if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
    166   unsigned NumLaneElts = NumElts / NumLanes;
    167 
    168   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    169     for (unsigned i = l + NumLaneElts/2, e = l + NumLaneElts; i != e; ++i) {
    170       ShuffleMask.push_back(i);          // Reads from dest/src1
    171       ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
    172     }
    173   }
    174 }
    175 
    176 /// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
    177 /// and punpckl*. VT indicates the type of the vector allowing it to handle
    178 /// different datatypes and vector widths.
    179 void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask) {
    180   unsigned NumElts = VT.getVectorNumElements();
    181 
    182   // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
    183   // independently on 128-bit lanes.
    184   unsigned NumLanes = VT.getSizeInBits() / 128;
    185   if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
    186   unsigned NumLaneElts = NumElts / NumLanes;
    187 
    188   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    189     for (unsigned i = l, e = l + NumLaneElts/2; i != e; ++i) {
    190       ShuffleMask.push_back(i);          // Reads from dest/src1
    191       ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
    192     }
    193   }
    194 }
    195 
    196 void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
    197                           SmallVectorImpl<int> &ShuffleMask) {
    198   if (Imm & 0x88)
    199     return; // Not a shuffle
    200 
    201   unsigned HalfSize = VT.getVectorNumElements()/2;
    202 
    203   for (unsigned l = 0; l != 2; ++l) {
    204     unsigned HalfBegin = ((Imm >> (l*4)) & 0x3) * HalfSize;
    205     for (unsigned i = HalfBegin, e = HalfBegin+HalfSize; i != e; ++i)
    206       ShuffleMask.push_back(i);
    207   }
    208 }
    209 
    210 /// DecodeVPERMMask - this decodes the shuffle masks for VPERMQ/VPERMPD.
    211 /// No VT provided since it only works on 256-bit, 4 element vectors.
    212 void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
    213   for (unsigned i = 0; i != 4; ++i) {
    214     ShuffleMask.push_back((Imm >> (2*i)) & 3);
    215   }
    216 }
    217 
    218 } // llvm namespace
    219