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/matcher.hpp"
  29 #include "opto/node.hpp"
  30 #include "opto/regmask.hpp"
  31 
  32 #define RM_SIZE _RM_SIZE /* a constant private to the class RegMask */
  33 
  34 //-------------Non-zero bit search methods used by RegMask---------------------
  35 // Find lowest 1, or return 32 if empty
  36 int find_lowest_bit( uint32_t mask ) {
  37   int n = 0;
  38   if( (mask & 0xffff) == 0 ) {
  39     mask >>= 16;
  40     n += 16;
  41   }
  42   if( (mask & 0xff) == 0 ) {
  43     mask >>= 8;
  44     n += 8;
  45   }
  46   if( (mask & 0xf) == 0 ) {
  47     mask >>= 4;
  48     n += 4;
  49   }
  50   if( (mask & 0x3) == 0 ) {
  51     mask >>= 2;
  52     n += 2;
  53   }
  54   if( (mask & 0x1) == 0 ) {
  55     mask >>= 1;
  56      n += 1;
  57   }
  58   if( mask == 0 ) {
  59     n = 32;
  60   }
  61   return n;
  62 }
  63 
  64 // Find highest 1, or return 32 if empty
  65 int find_hihghest_bit( uint32_t mask ) {
  66   int n = 0;
  67   if( mask > 0xffff ) {
  68     mask >>= 16;
  69     n += 16;
  70   }
  71   if( mask > 0xff ) {
  72     mask >>= 8;
  73     n += 8;
  74   }
  75   if( mask > 0xf ) {
  76     mask >>= 4;
  77     n += 4;
  78   }
  79   if( mask > 0x3 ) {
  80     mask >>= 2;
  81     n += 2;
  82   }
  83   if( mask > 0x1 ) {
  84     mask >>= 1;
  85     n += 1;
  86   }
  87   if( mask == 0 ) {
  88     n = 32;
  89   }
  90   return n;
  91 }
  92 
  93 //------------------------------dump-------------------------------------------
  94 
  95 #ifndef PRODUCT
  96 void OptoReg::dump(int r, outputStream *st) {
  97   switch (r) {
  98   case Special: st->print("r---"); break;
  99   case Bad:     st->print("rBAD"); break;
 100   default:
 101     if (r < _last_Mach_Reg) st->print("%s", Matcher::regName[r]);
 102     else st->print("rS%d",r);
 103     break;
 104   }
 105 }
 106 #endif
 107 
 108 
 109 //=============================================================================
 110 const RegMask RegMask::Empty(
 111 # define BODY(I) 0,
 112   FORALL_BODY
 113 # undef BODY
 114   0
 115 );
 116 
 117 //=============================================================================
 118 bool RegMask::is_vector(uint ireg) {
 119   return (ireg == Op_VecS || ireg == Op_VecD ||
 120           ireg == Op_VecX || ireg == Op_VecY || ireg == Op_VecZ );
 121 }
 122 
 123 int RegMask::num_registers(uint ireg) {
 124     switch(ireg) {
 125       case Op_VecZ:
 126         return 16;
 127       case Op_VecY:
 128         return 8;
 129       case Op_VecX:
 130         return 4;
 131       case Op_VecD:
 132       case Op_RegD:
 133       case Op_RegL:
 134 #ifdef _LP64
 135       case Op_RegP:
 136 #endif
 137         return 2;
 138     }
 139     // Op_VecS and the rest ideal registers.
 140     return 1;
 141 }
 142 
 143 //------------------------------find_first_pair--------------------------------
 144 // Find the lowest-numbered register pair in the mask.  Return the
 145 // HIGHEST register number in the pair, or BAD if no pairs.
 146 OptoReg::Name RegMask::find_first_pair() const {
 147   verify_pairs();
 148   for( int i = 0; i < RM_SIZE; i++ ) {
 149     if( _A[i] ) {               // Found some bits
 150       int bit = _A[i] & -_A[i]; // Extract low bit
 151       // Convert to bit number, return hi bit in pair
 152       return OptoReg::Name((i<<_LogWordBits)+find_lowest_bit(bit)+1);
 153     }
 154   }
 155   return OptoReg::Bad;
 156 }
 157 
 158 //------------------------------ClearToPairs-----------------------------------
 159 // Clear out partial bits; leave only bit pairs
 160 void RegMask::clear_to_pairs() {
 161   for( int i = 0; i < RM_SIZE; i++ ) {
 162     int bits = _A[i];
 163     bits &= ((bits & 0x55555555)<<1); // 1 hi-bit set for each pair
 164     bits |= (bits>>1);          // Smear 1 hi-bit into a pair
 165     _A[i] = bits;
 166   }
 167   verify_pairs();
 168 }
 169 
 170 //------------------------------SmearToPairs-----------------------------------
 171 // Smear out partial bits; leave only bit pairs
 172 void RegMask::smear_to_pairs() {
 173   for( int i = 0; i < RM_SIZE; i++ ) {
 174     int bits = _A[i];
 175     bits |= ((bits & 0x55555555)<<1); // Smear lo bit hi per pair
 176     bits |= ((bits & 0xAAAAAAAA)>>1); // Smear hi bit lo per pair
 177     _A[i] = bits;
 178   }
 179   verify_pairs();
 180 }
 181 
 182 //------------------------------is_aligned_pairs-------------------------------
 183 bool RegMask::is_aligned_pairs() const {
 184   // Assert that the register mask contains only bit pairs.
 185   for( int i = 0; i < RM_SIZE; i++ ) {
 186     int bits = _A[i];
 187     while( bits ) {             // Check bits for pairing
 188       int bit = bits & -bits;   // Extract low bit
 189       // Low bit is not odd means its mis-aligned.
 190       if( (bit & 0x55555555) == 0 ) return false;
 191       bits -= bit;              // Remove bit from mask
 192       // Check for aligned adjacent bit
 193       if( (bits & (bit<<1)) == 0 ) return false;
 194       bits -= (bit<<1);         // Remove other halve of pair
 195     }
 196   }
 197   return true;
 198 }
 199 
 200 //------------------------------is_bound1--------------------------------------
 201 // Return TRUE if the mask contains a single bit
 202 int RegMask::is_bound1() const {
 203   if( is_AllStack() ) return false;
 204   int bit = -1;                 // Set to hold the one bit allowed
 205   for( int i = 0; i < RM_SIZE; i++ ) {
 206     if( _A[i] ) {               // Found some bits
 207       if( bit != -1 ) return false; // Already had bits, so fail
 208       bit = _A[i] & -_A[i];     // Extract 1 bit from mask
 209       if( bit != _A[i] ) return false; // Found many bits, so fail
 210     }
 211   }
 212   // True for both the empty mask and for a single bit
 213   return true;
 214 }
 215 
 216 //------------------------------is_bound2--------------------------------------
 217 // Return TRUE if the mask contains an adjacent pair of bits and no other bits.
 218 int RegMask::is_bound_pair() const {
 219   if( is_AllStack() ) return false;
 220 
 221   int bit = -1;                 // Set to hold the one bit allowed
 222   for( int i = 0; i < RM_SIZE; i++ ) {
 223     if( _A[i] ) {               // Found some bits
 224       if( bit != -1 ) return false; // Already had bits, so fail
 225       bit = _A[i] & -(_A[i]);   // Extract 1 bit from mask
 226       if( (bit << 1) != 0 ) {   // Bit pair stays in same word?
 227         if( (bit | (bit<<1)) != _A[i] )
 228           return false;         // Require adjacent bit pair and no more bits
 229       } else {                  // Else its a split-pair case
 230         if( bit != _A[i] ) return false; // Found many bits, so fail
 231         i++;                    // Skip iteration forward
 232         if( i >= RM_SIZE || _A[i] != 1 )
 233           return false; // Require 1 lo bit in next word
 234       }
 235     }
 236   }
 237   // True for both the empty mask and for a bit pair
 238   return true;
 239 }
 240 
 241 // only indicies of power 2 are accessed, so index 3 is only filled in for storage.
 242 static int low_bits[5] = { 0x55555555, 0x11111111, 0x01010101, 0x00000000, 0x00010001 };
 243 //------------------------------find_first_set---------------------------------
 244 // Find the lowest-numbered register set in the mask.  Return the
 245 // HIGHEST register number in the set, or BAD if no sets.
 246 // Works also for size 1.
 247 OptoReg::Name RegMask::find_first_set(const int size) const {
 248   verify_sets(size);
 249   for (int i = 0; i < RM_SIZE; i++) {
 250     if (_A[i]) {                // Found some bits
 251       int bit = _A[i] & -_A[i]; // Extract low bit
 252       // Convert to bit number, return hi bit in pair
 253       return OptoReg::Name((i<<_LogWordBits)+find_lowest_bit(bit)+(size-1));
 254     }
 255   }
 256   return OptoReg::Bad;
 257 }
 258 
 259 //------------------------------clear_to_sets----------------------------------
 260 // Clear out partial bits; leave only aligned adjacent bit pairs
 261 void RegMask::clear_to_sets(const int size) {
 262   if (size == 1) return;
 263   assert(2 <= size && size <= 16, "update low bits table");
 264   assert(is_power_of_2(size), "sanity");
 265   int low_bits_mask = low_bits[size>>2];
 266   for (int i = 0; i < RM_SIZE; i++) {
 267     int bits = _A[i];
 268     int sets = (bits & low_bits_mask);
 269     for (int j = 1; j < size; j++) {
 270       sets = (bits & (sets<<1)); // filter bits which produce whole sets
 271     }
 272     sets |= (sets>>1);           // Smear 1 hi-bit into a set
 273     if (size > 2) {
 274       sets |= (sets>>2);         // Smear 2 hi-bits into a set
 275       if (size > 4) {
 276         sets |= (sets>>4);       // Smear 4 hi-bits into a set
 277         if (size > 8) {
 278           sets |= (sets>>8);     // Smear 8 hi-bits into a set
 279         }
 280       }
 281     }
 282     _A[i] = sets;
 283   }
 284   verify_sets(size);
 285 }
 286 
 287 //------------------------------smear_to_sets----------------------------------
 288 // Smear out partial bits to aligned adjacent bit sets
 289 void RegMask::smear_to_sets(const int size) {
 290   if (size == 1) return;
 291   assert(2 <= size && size <= 16, "update low bits table");
 292   assert(is_power_of_2(size), "sanity");
 293   int low_bits_mask = low_bits[size>>2];
 294   for (int i = 0; i < RM_SIZE; i++) {
 295     int bits = _A[i];
 296     int sets = 0;
 297     for (int j = 0; j < size; j++) {
 298       sets |= (bits & low_bits_mask);  // collect partial bits
 299       bits  = bits>>1;
 300     }
 301     sets |= (sets<<1);           // Smear 1 lo-bit  into a set
 302     if (size > 2) {
 303       sets |= (sets<<2);         // Smear 2 lo-bits into a set
 304       if (size > 4) {
 305         sets |= (sets<<4);       // Smear 4 lo-bits into a set
 306         if (size > 8) {
 307           sets |= (sets<<8);     // Smear 8 lo-bits into a set
 308         }
 309       }
 310     }
 311     _A[i] = sets;
 312   }
 313   verify_sets(size);
 314 }
 315 
 316 //------------------------------is_aligned_set--------------------------------
 317 bool RegMask::is_aligned_sets(const int size) const {
 318   if (size == 1) return true;
 319   assert(2 <= size && size <= 16, "update low bits table");
 320   assert(is_power_of_2(size), "sanity");
 321   int low_bits_mask = low_bits[size>>2];
 322   // Assert that the register mask contains only bit sets.
 323   for (int i = 0; i < RM_SIZE; i++) {
 324     int bits = _A[i];
 325     while (bits) {              // Check bits for pairing
 326       int bit = bits & -bits;   // Extract low bit
 327       // Low bit is not odd means its mis-aligned.
 328       if ((bit & low_bits_mask) == 0) return false;
 329       // Do extra work since (bit << size) may overflow.
 330       int hi_bit = bit << (size-1); // high bit
 331       int set = hi_bit + ((hi_bit-1) & ~(bit-1));
 332       // Check for aligned adjacent bits in this set
 333       if ((bits & set) != set) return false;
 334       bits -= set;  // Remove this set
 335     }
 336   }
 337   return true;
 338 }
 339 
 340 //------------------------------is_bound_set-----------------------------------
 341 // Return TRUE if the mask contains one adjacent set of bits and no other bits.
 342 // Works also for size 1.
 343 int RegMask::is_bound_set(const int size) const {
 344   if( is_AllStack() ) return false;
 345   assert(1 <= size && size <= 16, "update low bits table");
 346   int bit = -1;                 // Set to hold the one bit allowed
 347   for (int i = 0; i < RM_SIZE; i++) {
 348     if (_A[i] ) {               // Found some bits
 349       if (bit != -1)
 350        return false;            // Already had bits, so fail
 351       bit = _A[i] & -_A[i];     // Extract low bit from mask
 352       int hi_bit = bit << (size-1); // high bit
 353       if (hi_bit != 0) {        // Bit set stays in same word?
 354         int set = hi_bit + ((hi_bit-1) & ~(bit-1));
 355         if (set != _A[i])
 356           return false;         // Require adjacent bit set and no more bits
 357       } else {                  // Else its a split-set case
 358         if (((-1) & ~(bit-1)) != _A[i])
 359           return false;         // Found many bits, so fail
 360         i++;                    // Skip iteration forward and check high part
 361         // The lower (32-size) bits should be 0 since it is split case.
 362         int clear_bit_size = 32-size;
 363         int shift_back_size = 32-clear_bit_size;
 364         int set = bit>>clear_bit_size;
 365         set = set & -set; // Remove sign extension.
 366         set = (((set << size) - 1) >> shift_back_size);
 367         if (i >= RM_SIZE || _A[i] != set)
 368           return false; // Require expected low bits in next word
 369       }
 370     }
 371   }
 372   // True for both the empty mask and for a bit set
 373   return true;
 374 }
 375 
 376 //------------------------------is_UP------------------------------------------
 377 // UP means register only, Register plus stack, or stack only is DOWN
 378 bool RegMask::is_UP() const {
 379   // Quick common case check for DOWN (any stack slot is legal)
 380   if( is_AllStack() )
 381     return false;
 382   // Slower check for any stack bits set (also DOWN)
 383   if( overlap(Matcher::STACK_ONLY_mask) )
 384     return false;
 385   // Not DOWN, so must be UP
 386   return true;
 387 }
 388 
 389 //------------------------------Size-------------------------------------------
 390 // Compute size of register mask in bits
 391 uint RegMask::Size() const {
 392   extern uint8_t bitsInByte[256];
 393   uint sum = 0;
 394   for( int i = 0; i < RM_SIZE; i++ )
 395     sum +=
 396       bitsInByte[(_A[i]>>24) & 0xff] +
 397       bitsInByte[(_A[i]>>16) & 0xff] +
 398       bitsInByte[(_A[i]>> 8) & 0xff] +
 399       bitsInByte[ _A[i]      & 0xff];
 400   return sum;
 401 }
 402 
 403 #ifndef PRODUCT
 404 //------------------------------print------------------------------------------
 405 void RegMask::dump(outputStream *st) const {
 406   st->print("[");
 407   RegMask rm = *this;           // Structure copy into local temp
 408 
 409   OptoReg::Name start = rm.find_first_elem(); // Get a register
 410   if (OptoReg::is_valid(start)) { // Check for empty mask
 411     rm.Remove(start);           // Yank from mask
 412     OptoReg::dump(start, st);   // Print register
 413     OptoReg::Name last = start;
 414 
 415     // Now I have printed an initial register.
 416     // Print adjacent registers as "rX-rZ" instead of "rX,rY,rZ".
 417     // Begin looping over the remaining registers.
 418     while (1) {                 //
 419       OptoReg::Name reg = rm.find_first_elem(); // Get a register
 420       if (!OptoReg::is_valid(reg))
 421         break;                  // Empty mask, end loop
 422       rm.Remove(reg);           // Yank from mask
 423 
 424       if (last+1 == reg) {      // See if they are adjacent
 425         // Adjacent registers just collect into long runs, no printing.
 426         last = reg;
 427       } else {                  // Ending some kind of run
 428         if (start == last) {    // 1-register run; no special printing
 429         } else if (start+1 == last) {
 430           st->print(",");       // 2-register run; print as "rX,rY"
 431           OptoReg::dump(last, st);
 432         } else {                // Multi-register run; print as "rX-rZ"
 433           st->print("-");
 434           OptoReg::dump(last, st);
 435         }
 436         st->print(",");         // Seperate start of new run
 437         start = last = reg;     // Start a new register run
 438         OptoReg::dump(start, st); // Print register
 439       } // End of if ending a register run or not
 440     } // End of while regmask not empty
 441 
 442     if (start == last) {        // 1-register run; no special printing
 443     } else if (start+1 == last) {
 444       st->print(",");           // 2-register run; print as "rX,rY"
 445       OptoReg::dump(last, st);
 446     } else {                    // Multi-register run; print as "rX-rZ"
 447       st->print("-");
 448       OptoReg::dump(last, st);
 449     }
 450     if (rm.is_AllStack()) st->print("...");
 451   }
 452   st->print("]");
 453 }
 454 #endif