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 
     17 //===----------------------------------------------------------------------===//
     18 //  Vector Mask Decoding
     19 //===----------------------------------------------------------------------===//
     20 
     21 namespace llvm {
     22 
     23 void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     24   // Defaults the copying the dest value.
     25   ShuffleMask.push_back(0);
     26   ShuffleMask.push_back(1);
     27   ShuffleMask.push_back(2);
     28   ShuffleMask.push_back(3);
     29 
     30   // Decode the immediate.
     31   unsigned ZMask = Imm & 15;
     32   unsigned CountD = (Imm >> 4) & 3;
     33   unsigned CountS = (Imm >> 6) & 3;
     34 
     35   // CountS selects which input element to use.
     36   unsigned InVal = 4+CountS;
     37   // CountD specifies which element of destination to update.
     38   ShuffleMask[CountD] = InVal;
     39   // ZMask zaps values, potentially overriding the CountD elt.
     40   if (ZMask & 1) ShuffleMask[0] = SM_SentinelZero;
     41   if (ZMask & 2) ShuffleMask[1] = SM_SentinelZero;
     42   if (ZMask & 4) ShuffleMask[2] = SM_SentinelZero;
     43   if (ZMask & 8) ShuffleMask[3] = SM_SentinelZero;
     44 }
     45 
     46 // <3,1> or <6,7,2,3>
     47 void DecodeMOVHLPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
     48   for (unsigned i = NElts/2; i != NElts; ++i)
     49     ShuffleMask.push_back(NElts+i);
     50 
     51   for (unsigned i = NElts/2; i != NElts; ++i)
     52     ShuffleMask.push_back(i);
     53 }
     54 
     55 // <0,2> or <0,1,4,5>
     56 void DecodeMOVLHPSMask(unsigned NElts, SmallVectorImpl<int> &ShuffleMask) {
     57   for (unsigned i = 0; i != NElts/2; ++i)
     58     ShuffleMask.push_back(i);
     59 
     60   for (unsigned i = 0; i != NElts/2; ++i)
     61     ShuffleMask.push_back(NElts+i);
     62 }
     63 
     64 /// DecodePSHUFMask - This decodes the shuffle masks for pshufd, and vpermilp*.
     65 /// VT indicates the type of the vector allowing it to handle different
     66 /// datatypes and vector widths.
     67 void DecodePSHUFMask(EVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     68   unsigned NumElts = VT.getVectorNumElements();
     69 
     70   unsigned NumLanes = VT.getSizeInBits() / 128;
     71   unsigned NumLaneElts = NumElts / NumLanes;
     72 
     73   int NewImm = Imm;
     74   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
     75     for (unsigned i = 0; i != NumLaneElts; ++i) {
     76       ShuffleMask.push_back(NewImm % NumLaneElts + l);
     77       NewImm /= NumLaneElts;
     78     }
     79     if (NumLaneElts == 4) NewImm = Imm; // reload imm
     80   }
     81 }
     82 
     83 void DecodePSHUFHWMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     84   ShuffleMask.push_back(0);
     85   ShuffleMask.push_back(1);
     86   ShuffleMask.push_back(2);
     87   ShuffleMask.push_back(3);
     88   for (unsigned i = 0; i != 4; ++i) {
     89     ShuffleMask.push_back(4+(Imm & 3));
     90     Imm >>= 2;
     91   }
     92 }
     93 
     94 void DecodePSHUFLWMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
     95   for (unsigned i = 0; i != 4; ++i) {
     96     ShuffleMask.push_back((Imm & 3));
     97     Imm >>= 2;
     98   }
     99   ShuffleMask.push_back(4);
    100   ShuffleMask.push_back(5);
    101   ShuffleMask.push_back(6);
    102   ShuffleMask.push_back(7);
    103 }
    104 
    105 /// DecodeSHUFPMask - This decodes the shuffle masks for shufp*. VT indicates
    106 /// the type of the vector allowing it to handle different datatypes and vector
    107 /// widths.
    108 void DecodeSHUFPMask(EVT VT, unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
    109   unsigned NumElts = VT.getVectorNumElements();
    110 
    111   unsigned NumLanes = VT.getSizeInBits() / 128;
    112   unsigned NumLaneElts = NumElts / NumLanes;
    113 
    114   int NewImm = Imm;
    115   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    116     // Part that reads from dest.
    117     for (unsigned i = 0; i != NumLaneElts/2; ++i) {
    118       ShuffleMask.push_back(NewImm % NumLaneElts + l);
    119       NewImm /= NumLaneElts;
    120     }
    121     // Part that reads from src.
    122     for (unsigned i = 0; i != NumLaneElts/2; ++i) {
    123       ShuffleMask.push_back(NewImm % NumLaneElts + NumElts + l);
    124       NewImm /= NumLaneElts;
    125     }
    126     if (NumLaneElts == 4) NewImm = Imm; // reload imm
    127   }
    128 }
    129 
    130 /// DecodeUNPCKHMask - This decodes the shuffle masks for unpckhps/unpckhpd
    131 /// and punpckh*. VT indicates the type of the vector allowing it to handle
    132 /// different datatypes and vector widths.
    133 void DecodeUNPCKHMask(EVT VT, SmallVectorImpl<int> &ShuffleMask) {
    134   unsigned NumElts = VT.getVectorNumElements();
    135 
    136   // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
    137   // independently on 128-bit lanes.
    138   unsigned NumLanes = VT.getSizeInBits() / 128;
    139   if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
    140   unsigned NumLaneElts = NumElts / NumLanes;
    141 
    142   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    143     for (unsigned i = l + NumLaneElts/2, e = l + NumLaneElts; i != e; ++i) {
    144       ShuffleMask.push_back(i);          // Reads from dest/src1
    145       ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
    146     }
    147   }
    148 }
    149 
    150 /// DecodeUNPCKLMask - This decodes the shuffle masks for unpcklps/unpcklpd
    151 /// and punpckl*. VT indicates the type of the vector allowing it to handle
    152 /// different datatypes and vector widths.
    153 void DecodeUNPCKLMask(EVT VT, SmallVectorImpl<int> &ShuffleMask) {
    154   unsigned NumElts = VT.getVectorNumElements();
    155 
    156   // Handle 128 and 256-bit vector lengths. AVX defines UNPCK* to operate
    157   // independently on 128-bit lanes.
    158   unsigned NumLanes = VT.getSizeInBits() / 128;
    159   if (NumLanes == 0 ) NumLanes = 1;  // Handle MMX
    160   unsigned NumLaneElts = NumElts / NumLanes;
    161 
    162   for (unsigned l = 0; l != NumElts; l += NumLaneElts) {
    163     for (unsigned i = l, e = l + NumLaneElts/2; i != e; ++i) {
    164       ShuffleMask.push_back(i);          // Reads from dest/src1
    165       ShuffleMask.push_back(i+NumElts);  // Reads from src/src2
    166     }
    167   }
    168 }
    169 
    170 void DecodeVPERM2X128Mask(EVT VT, unsigned Imm,
    171                           SmallVectorImpl<int> &ShuffleMask) {
    172   if (Imm & 0x88)
    173     return; // Not a shuffle
    174 
    175   unsigned HalfSize = VT.getVectorNumElements()/2;
    176   unsigned FstHalfBegin = (Imm & 0x3) * HalfSize;
    177   unsigned SndHalfBegin = ((Imm >> 4) & 0x3) * HalfSize;
    178 
    179   for (int i = FstHalfBegin, e = FstHalfBegin+HalfSize; i != e; ++i)
    180     ShuffleMask.push_back(i);
    181   for (int i = SndHalfBegin, e = SndHalfBegin+HalfSize; i != e; ++i)
    182     ShuffleMask.push_back(i);
    183 }
    184 
    185 } // llvm namespace
    186