1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "opto/ad.hpp"
  27 #include "opto/compile.hpp"
  28 #include "opto/regmask.hpp"
  29 
  30 #define RM_SIZE _RM_SIZE /* a constant private to the class RegMask */
  31 
  32 //-------------Non-zero bit search methods used by RegMask---------------------
  33 // Find lowest 1, or return 32 if empty
  34 int find_lowest_bit( uint32_t mask ) {
  35   int n = 0;
  36   if( (mask & 0xffff) == 0 ) {
  37     mask >>= 16;
  38     n += 16;
  39   }
  40   if( (mask & 0xff) == 0 ) {
  41     mask >>= 8;
  42     n += 8;
  43   }
  44   if( (mask & 0xf) == 0 ) {
  45     mask >>= 4;
  46     n += 4;
  47   }
  48   if( (mask & 0x3) == 0 ) {
  49     mask >>= 2;
  50     n += 2;
  51   }
  52   if( (mask & 0x1) == 0 ) {
  53     mask >>= 1;
  54      n += 1;
  55   }
  56   if( mask == 0 ) {
  57     n = 32;
  58   }
  59   return n;
  60 }
  61 
  62 // Find highest 1, or return 32 if empty
  63 int find_hihghest_bit( uint32_t mask ) {
  64   int n = 0;
  65   if( mask > 0xffff ) {
  66     mask >>= 16;
  67     n += 16;
  68   }
  69   if( mask > 0xff ) {
  70     mask >>= 8;
  71     n += 8;
  72   }
  73   if( mask > 0xf ) {
  74     mask >>= 4;
  75     n += 4;
  76   }
  77   if( mask > 0x3 ) {
  78     mask >>= 2;
  79     n += 2;
  80   }
  81   if( mask > 0x1 ) {
  82     mask >>= 1;
  83     n += 1;
  84   }
  85   if( mask == 0 ) {
  86     n = 32;
  87   }
  88   return n;
  89 }
  90 
  91 //------------------------------dump-------------------------------------------
  92 
  93 #ifndef PRODUCT
  94 void OptoReg::dump(int r, outputStream *st) {
  95   switch (r) {
  96   case Special: st->print("r---"); break;
  97   case Bad:     st->print("rBAD"); break;
  98   default:
  99     if (r < _last_Mach_Reg) st->print("%s", Matcher::regName[r]);
 100     else st->print("rS%d",r);
 101     break;
 102   }
 103 }
 104 #endif
 105 
 106 
 107 //=============================================================================
 108 const RegMask RegMask::Empty(
 109 # define BODY(I) 0,
 110   FORALL_BODY
 111 # undef BODY
 112   0
 113 );
 114 
 115 //=============================================================================
 116 bool RegMask::is_vector(uint ireg) {
 117   return (ireg == Op_VecS || ireg == Op_VecD ||
 118           ireg == Op_VecX || ireg == Op_VecY || ireg == Op_VecZ );
 119 }
 120 
 121 int RegMask::num_registers(uint ireg) {
 122     switch(ireg) {
 123       case Op_VecZ:
 124         return 16;
 125       case Op_VecY:
 126         return 8;
 127       case Op_VecX:
 128         return 4;
 129       case Op_VecD:
 130       case Op_RegD:
 131       case Op_RegL:
 132 #ifdef _LP64
 133       case Op_RegP:
 134 #endif
 135         return 2;
 136     }
 137     // Op_VecS and the rest ideal registers.
 138     return 1;
 139 }
 140 
 141 //------------------------------find_first_pair--------------------------------
 142 // Find the lowest-numbered register pair in the mask.  Return the
 143 // HIGHEST register number in the pair, or BAD if no pairs.
 144 OptoReg::Name RegMask::find_first_pair() const {
 145   verify_pairs();
 146   for( int i = 0; i < RM_SIZE; i++ ) {
 147     if( _A[i] ) {               // Found some bits
 148       int bit = _A[i] & -_A[i]; // Extract low bit
 149       // Convert to bit number, return hi bit in pair
 150       return OptoReg::Name((i<<_LogWordBits)+find_lowest_bit(bit)+1);
 151     }
 152   }
 153   return OptoReg::Bad;
 154 }
 155 
 156 //------------------------------ClearToPairs-----------------------------------
 157 // Clear out partial bits; leave only bit pairs
 158 void RegMask::clear_to_pairs() {
 159   for( int i = 0; i < RM_SIZE; i++ ) {
 160     int bits = _A[i];
 161     bits &= ((bits & 0x55555555)<<1); // 1 hi-bit set for each pair
 162     bits |= (bits>>1);          // Smear 1 hi-bit into a pair
 163     _A[i] = bits;
 164   }
 165   verify_pairs();
 166 }
 167 
 168 //------------------------------SmearToPairs-----------------------------------
 169 // Smear out partial bits; leave only bit pairs
 170 void RegMask::smear_to_pairs() {
 171   for( int i = 0; i < RM_SIZE; i++ ) {
 172     int bits = _A[i];
 173     bits |= ((bits & 0x55555555)<<1); // Smear lo bit hi per pair
 174     bits |= ((bits & 0xAAAAAAAA)>>1); // Smear hi bit lo per pair
 175     _A[i] = bits;
 176   }
 177   verify_pairs();
 178 }
 179 
 180 //------------------------------is_aligned_pairs-------------------------------
 181 bool RegMask::is_aligned_pairs() const {
 182   // Assert that the register mask contains only bit pairs.
 183   for( int i = 0; i < RM_SIZE; i++ ) {
 184     int bits = _A[i];
 185     while( bits ) {             // Check bits for pairing
 186       int bit = bits & -bits;   // Extract low bit
 187       // Low bit is not odd means its mis-aligned.
 188       if( (bit & 0x55555555) == 0 ) return false;
 189       bits -= bit;              // Remove bit from mask
 190       // Check for aligned adjacent bit
 191       if( (bits & (bit<<1)) == 0 ) return false;
 192       bits -= (bit<<1);         // Remove other halve of pair
 193     }
 194   }
 195   return true;
 196 }
 197 
 198 //------------------------------is_bound1--------------------------------------
 199 // Return TRUE if the mask contains a single bit
 200 int RegMask::is_bound1() const {
 201   if( is_AllStack() ) return false;
 202   int bit = -1;                 // Set to hold the one bit allowed
 203   for( int i = 0; i < RM_SIZE; i++ ) {
 204     if( _A[i] ) {               // Found some bits
 205       if( bit != -1 ) return false; // Already had bits, so fail
 206       bit = _A[i] & -_A[i];     // Extract 1 bit from mask
 207       if( bit != _A[i] ) return false; // Found many bits, so fail
 208     }
 209   }
 210   // True for both the empty mask and for a single bit
 211   return true;
 212 }
 213 
 214 //------------------------------is_bound2--------------------------------------
 215 // Return TRUE if the mask contains an adjacent pair of bits and no other bits.
 216 int RegMask::is_bound_pair() const {
 217   if( is_AllStack() ) return false;
 218 
 219   int bit = -1;                 // Set to hold the one bit allowed
 220   for( int i = 0; i < RM_SIZE; i++ ) {
 221     if( _A[i] ) {               // Found some bits
 222       if( bit != -1 ) return false; // Already had bits, so fail
 223       bit = _A[i] & -(_A[i]);   // Extract 1 bit from mask
 224       if( (bit << 1) != 0 ) {   // Bit pair stays in same word?
 225         if( (bit | (bit<<1)) != _A[i] )
 226           return false;         // Require adjacent bit pair and no more bits
 227       } else {                  // Else its a split-pair case
 228         if( bit != _A[i] ) return false; // Found many bits, so fail
 229         i++;                    // Skip iteration forward
 230         if( i >= RM_SIZE || _A[i] != 1 )
 231           return false; // Require 1 lo bit in next word
 232       }
 233     }
 234   }
 235   // True for both the empty mask and for a bit pair
 236   return true;
 237 }
 238 
 239 // only indicies of power 2 are accessed, so index 3 is only filled in for storage.
 240 static int low_bits[5] = { 0x55555555, 0x11111111, 0x01010101, 0x00000000, 0x00010001 };
 241 //------------------------------find_first_set---------------------------------
 242 // Find the lowest-numbered register set in the mask.  Return the
 243 // HIGHEST register number in the set, or BAD if no sets.
 244 // Works also for size 1.
 245 OptoReg::Name RegMask::find_first_set(const int size) const {
 246   verify_sets(size);
 247   for (int i = 0; i < RM_SIZE; i++) {
 248     if (_A[i]) {                // Found some bits
 249       int bit = _A[i] & -_A[i]; // Extract low bit
 250       // Convert to bit number, return hi bit in pair
 251       return OptoReg::Name((i<<_LogWordBits)+find_lowest_bit(bit)+(size-1));
 252     }
 253   }
 254   return OptoReg::Bad;
 255 }
 256 
 257 //------------------------------clear_to_sets----------------------------------
 258 // Clear out partial bits; leave only aligned adjacent bit pairs
 259 void RegMask::clear_to_sets(const int size) {
 260   if (size == 1) return;
 261   assert(2 <= size && size <= 16, "update low bits table");
 262   assert(is_power_of_2(size), "sanity");
 263   int low_bits_mask = low_bits[size>>2];
 264   for (int i = 0; i < RM_SIZE; i++) {
 265     int bits = _A[i];
 266     int sets = (bits & low_bits_mask);
 267     for (int j = 1; j < size; j++) {
 268       sets = (bits & (sets<<1)); // filter bits which produce whole sets
 269     }
 270     sets |= (sets>>1);           // Smear 1 hi-bit into a set
 271     if (size > 2) {
 272       sets |= (sets>>2);         // Smear 2 hi-bits into a set
 273       if (size > 4) {
 274         sets |= (sets>>4);       // Smear 4 hi-bits into a set
 275         if (size > 8) {
 276           sets |= (sets>>8);     // Smear 8 hi-bits into a set
 277         }
 278       }
 279     }
 280     _A[i] = sets;
 281   }
 282   verify_sets(size);
 283 }
 284 
 285 //------------------------------smear_to_sets----------------------------------
 286 // Smear out partial bits to aligned adjacent bit sets
 287 void RegMask::smear_to_sets(const int size) {
 288   if (size == 1) return;
 289   assert(2 <= size && size <= 16, "update low bits table");
 290   assert(is_power_of_2(size), "sanity");
 291   int low_bits_mask = low_bits[size>>2];
 292   for (int i = 0; i < RM_SIZE; i++) {
 293     int bits = _A[i];
 294     int sets = 0;
 295     for (int j = 0; j < size; j++) {
 296       sets |= (bits & low_bits_mask);  // collect partial bits
 297       bits  = bits>>1;
 298     }
 299     sets |= (sets<<1);           // Smear 1 lo-bit  into a set
 300     if (size > 2) {
 301       sets |= (sets<<2);         // Smear 2 lo-bits into a set
 302       if (size > 4) {
 303         sets |= (sets<<4);       // Smear 4 lo-bits into a set
 304         if (size > 8) {
 305           sets |= (sets<<8);     // Smear 8 lo-bits into a set
 306         }
 307       }
 308     }
 309     _A[i] = sets;
 310   }
 311   verify_sets(size);
 312 }
 313 
 314 //------------------------------is_aligned_set--------------------------------
 315 bool RegMask::is_aligned_sets(const int size) const {
 316   if (size == 1) return true;
 317   assert(2 <= size && size <= 16, "update low bits table");
 318   assert(is_power_of_2(size), "sanity");
 319   int low_bits_mask = low_bits[size>>2];
 320   // Assert that the register mask contains only bit sets.
 321   for (int i = 0; i < RM_SIZE; i++) {
 322     int bits = _A[i];
 323     while (bits) {              // Check bits for pairing
 324       int bit = bits & -bits;   // Extract low bit
 325       // Low bit is not odd means its mis-aligned.
 326       if ((bit & low_bits_mask) == 0) return false;
 327       // Do extra work since (bit << size) may overflow.
 328       int hi_bit = bit << (size-1); // high bit
 329       int set = hi_bit + ((hi_bit-1) & ~(bit-1));
 330       // Check for aligned adjacent bits in this set
 331       if ((bits & set) != set) return false;
 332       bits -= set;  // Remove this set
 333     }
 334   }
 335   return true;
 336 }
 337 
 338 //------------------------------is_bound_set-----------------------------------
 339 // Return TRUE if the mask contains one adjacent set of bits and no other bits.
 340 // Works also for size 1.
 341 int RegMask::is_bound_set(const int size) const {
 342   if( is_AllStack() ) return false;
 343   assert(1 <= size && size <= 16, "update low bits table");
 344   int bit = -1;                 // Set to hold the one bit allowed
 345   for (int i = 0; i < RM_SIZE; i++) {
 346     if (_A[i] ) {               // Found some bits
 347       if (bit != -1)
 348        return false;            // Already had bits, so fail
 349       bit = _A[i] & -_A[i];     // Extract low bit from mask
 350       int hi_bit = bit << (size-1); // high bit
 351       if (hi_bit != 0) {        // Bit set stays in same word?
 352         int set = hi_bit + ((hi_bit-1) & ~(bit-1));
 353         if (set != _A[i])
 354           return false;         // Require adjacent bit set and no more bits
 355       } else {                  // Else its a split-set case
 356         if (((-1) & ~(bit-1)) != _A[i])
 357           return false;         // Found many bits, so fail
 358         i++;                    // Skip iteration forward and check high part
 359         // The lower (32-size) bits should be 0 since it is split case.
 360         int clear_bit_size = 32-size;
 361         int shift_back_size = 32-clear_bit_size;
 362         int set = bit>>clear_bit_size;
 363         set = set & -set; // Remove sign extension.
 364         set = (((set << size) - 1) >> shift_back_size);
 365         if (i >= RM_SIZE || _A[i] != set)
 366           return false; // Require expected low bits in next word
 367       }
 368     }
 369   }
 370   // True for both the empty mask and for a bit set
 371   return true;
 372 }
 373 
 374 //------------------------------is_UP------------------------------------------
 375 // UP means register only, Register plus stack, or stack only is DOWN
 376 bool RegMask::is_UP() const {
 377   // Quick common case check for DOWN (any stack slot is legal)
 378   if( is_AllStack() )
 379     return false;
 380   // Slower check for any stack bits set (also DOWN)
 381   if( overlap(Matcher::STACK_ONLY_mask) )
 382     return false;
 383   // Not DOWN, so must be UP
 384   return true;
 385 }
 386 
 387 //------------------------------Size-------------------------------------------
 388 // Compute size of register mask in bits
 389 uint RegMask::Size() const {
 390   extern uint8_t bitsInByte[512];
 391   uint sum = 0;
 392   for( int i = 0; i < RM_SIZE; i++ )
 393     sum +=
 394       bitsInByte[(_A[i]>>24) & 0xff] +
 395       bitsInByte[(_A[i]>>16) & 0xff] +
 396       bitsInByte[(_A[i]>> 8) & 0xff] +
 397       bitsInByte[ _A[i]      & 0xff];
 398   return sum;
 399 }
 400 
 401 #ifndef PRODUCT
 402 //------------------------------print------------------------------------------
 403 void RegMask::dump(outputStream *st) const {
 404   st->print("[");
 405   RegMask rm = *this;           // Structure copy into local temp
 406 
 407   OptoReg::Name start = rm.find_first_elem(); // Get a register
 408   if (OptoReg::is_valid(start)) { // Check for empty mask
 409     rm.Remove(start);           // Yank from mask
 410     OptoReg::dump(start, st);   // Print register
 411     OptoReg::Name last = start;
 412 
 413     // Now I have printed an initial register.
 414     // Print adjacent registers as "rX-rZ" instead of "rX,rY,rZ".
 415     // Begin looping over the remaining registers.
 416     while (1) {                 //
 417       OptoReg::Name reg = rm.find_first_elem(); // Get a register
 418       if (!OptoReg::is_valid(reg))
 419         break;                  // Empty mask, end loop
 420       rm.Remove(reg);           // Yank from mask
 421 
 422       if (last+1 == reg) {      // See if they are adjacent
 423         // Adjacent registers just collect into long runs, no printing.
 424         last = reg;
 425       } else {                  // Ending some kind of run
 426         if (start == last) {    // 1-register run; no special printing
 427         } else if (start+1 == last) {
 428           st->print(",");       // 2-register run; print as "rX,rY"
 429           OptoReg::dump(last, st);
 430         } else {                // Multi-register run; print as "rX-rZ"
 431           st->print("-");
 432           OptoReg::dump(last, st);
 433         }
 434         st->print(",");         // Seperate start of new run
 435         start = last = reg;     // Start a new register run
 436         OptoReg::dump(start, st); // Print register
 437       } // End of if ending a register run or not
 438     } // End of while regmask not empty
 439 
 440     if (start == last) {        // 1-register run; no special printing
 441     } else if (start+1 == last) {
 442       st->print(",");           // 2-register run; print as "rX,rY"
 443       OptoReg::dump(last, st);
 444     } else {                    // Multi-register run; print as "rX-rZ"
 445       st->print("-");
 446       OptoReg::dump(last, st);
 447     }
 448     if (rm.is_AllStack()) st->print("...");
 449   }
 450   st->print("]");
 451 }
 452 #endif