1 /*
2  * Copyright (c) 1997, 2019, 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.
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19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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 #include "utilities/population_count.hpp"
32 #include "utilities/powerOfTwo.hpp"
33 
34 #define RM_SIZE _RM_SIZE /* a constant private to the class RegMask */
35 
36 //------------------------------dump-------------------------------------------
37 
38 #ifndef PRODUCT
dump(int r,outputStream * st)39 void OptoReg::dump(int r, outputStream *st) {
40   switch (r) {
41   case Special: st->print("r---"); break;
42   case Bad:     st->print("rBAD"); break;
43   default:
44     if (r < _last_Mach_Reg) st->print("%s", Matcher::regName[r]);
45     else st->print("rS%d",r);
46     break;
47   }
48 }
49 #endif
50 
51 
52 //=============================================================================
53 const RegMask RegMask::Empty(
54 # define BODY(I) 0,
55   FORALL_BODY
56 # undef BODY
57   0
58 );
59 
60 //=============================================================================
is_vector(uint ireg)61 bool RegMask::is_vector(uint ireg) {
62   return (ireg == Op_VecS || ireg == Op_VecD ||
63           ireg == Op_VecX || ireg == Op_VecY || ireg == Op_VecZ );
64 }
65 
num_registers(uint ireg)66 int RegMask::num_registers(uint ireg) {
67     switch(ireg) {
68       case Op_VecZ:
69         return 16;
70       case Op_VecY:
71         return 8;
72       case Op_VecX:
73         return 4;
74       case Op_VecD:
75       case Op_RegD:
76       case Op_RegL:
77 #ifdef _LP64
78       case Op_RegP:
79 #endif
80         return 2;
81     }
82     // Op_VecS and the rest ideal registers.
83     return 1;
84 }
85 
86 // Clear out partial bits; leave only bit pairs
clear_to_pairs()87 void RegMask::clear_to_pairs() {
88   assert(valid_watermarks(), "sanity");
89   for (int i = _lwm; i <= _hwm; i++) {
90     int bits = _A[i];
91     bits &= ((bits & 0x55555555)<<1); // 1 hi-bit set for each pair
92     bits |= (bits>>1);          // Smear 1 hi-bit into a pair
93     _A[i] = bits;
94   }
95   assert(is_aligned_pairs(), "mask is not aligned, adjacent pairs");
96 }
97 
is_misaligned_pair() const98 bool RegMask::is_misaligned_pair() const {
99   return Size() == 2 && !is_aligned_pairs();
100 }
101 
is_aligned_pairs() const102 bool RegMask::is_aligned_pairs() const {
103   // Assert that the register mask contains only bit pairs.
104   assert(valid_watermarks(), "sanity");
105   for (int i = _lwm; i <= _hwm; i++) {
106     int bits = _A[i];
107     while (bits) {              // Check bits for pairing
108       int bit = bits & -bits;   // Extract low bit
109       // Low bit is not odd means its mis-aligned.
110       if ((bit & 0x55555555) == 0) return false;
111       bits -= bit;              // Remove bit from mask
112       // Check for aligned adjacent bit
113       if ((bits & (bit<<1)) == 0) return false;
114       bits -= (bit<<1);         // Remove other halve of pair
115     }
116   }
117   return true;
118 }
119 
120 // Return TRUE if the mask contains a single bit
is_bound1() const121 bool RegMask::is_bound1() const {
122   if (is_AllStack()) return false;
123   return Size() == 1;
124 }
125 
126 // Return TRUE if the mask contains an adjacent pair of bits and no other bits.
is_bound_pair() const127 bool RegMask::is_bound_pair() const {
128   if (is_AllStack()) return false;
129   int bit = -1;                 // Set to hold the one bit allowed
130   assert(valid_watermarks(), "sanity");
131   for (int i = _lwm; i <= _hwm; i++) {
132     if (_A[i]) {                   // Found some bits
133       if (bit != -1) return false; // Already had bits, so fail
134       bit = _A[i] & -(_A[i]);      // Extract 1 bit from mask
135       if ((bit << 1) != 0) {       // Bit pair stays in same word?
136         if ((bit | (bit<<1)) != _A[i])
137           return false;            // Require adjacent bit pair and no more bits
138       } else {                     // Else its a split-pair case
139         if(bit != _A[i]) return false; // Found many bits, so fail
140         i++;                       // Skip iteration forward
141         if (i > _hwm || _A[i] != 1)
142           return false; // Require 1 lo bit in next word
143       }
144     }
145   }
146   // True for both the empty mask and for a bit pair
147   return true;
148 }
149 
150 // Test for a single adjacent set of ideal register's size.
is_bound(uint ireg) const151 bool RegMask::is_bound(uint ireg) const {
152   if (is_vector(ireg)) {
153     if (is_bound_set(num_registers(ireg)))
154       return true;
155   } else if (is_bound1() || is_bound_pair()) {
156     return true;
157   }
158   return false;
159 }
160 
161 // only indicies of power 2 are accessed, so index 3 is only filled in for storage.
162 static int low_bits[5] = { 0x55555555, 0x11111111, 0x01010101, 0x00000000, 0x00010001 };
163 
164 // Find the lowest-numbered register set in the mask.  Return the
165 // HIGHEST register number in the set, or BAD if no sets.
166 // Works also for size 1.
find_first_set(const int size) const167 OptoReg::Name RegMask::find_first_set(const int size) const {
168   assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
169   assert(valid_watermarks(), "sanity");
170   for (int i = _lwm; i <= _hwm; i++) {
171     if (_A[i]) {                // Found some bits
172       // Convert to bit number, return hi bit in pair
173       return OptoReg::Name((i<<_LogWordBits) + find_lowest_bit(_A[i]) + (size - 1));
174     }
175   }
176   return OptoReg::Bad;
177 }
178 
179 // Clear out partial bits; leave only aligned adjacent bit pairs
clear_to_sets(const int size)180 void RegMask::clear_to_sets(const int size) {
181   if (size == 1) return;
182   assert(2 <= size && size <= 16, "update low bits table");
183   assert(is_power_of_2(size), "sanity");
184   assert(valid_watermarks(), "sanity");
185   int low_bits_mask = low_bits[size>>2];
186   for (int i = _lwm; i <= _hwm; i++) {
187     int bits = _A[i];
188     int sets = (bits & low_bits_mask);
189     for (int j = 1; j < size; j++) {
190       sets = (bits & (sets<<1)); // filter bits which produce whole sets
191     }
192     sets |= (sets>>1);           // Smear 1 hi-bit into a set
193     if (size > 2) {
194       sets |= (sets>>2);         // Smear 2 hi-bits into a set
195       if (size > 4) {
196         sets |= (sets>>4);       // Smear 4 hi-bits into a set
197         if (size > 8) {
198           sets |= (sets>>8);     // Smear 8 hi-bits into a set
199         }
200       }
201     }
202     _A[i] = sets;
203   }
204   assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
205 }
206 
207 // Smear out partial bits to aligned adjacent bit sets
smear_to_sets(const int size)208 void RegMask::smear_to_sets(const int size) {
209   if (size == 1) return;
210   assert(2 <= size && size <= 16, "update low bits table");
211   assert(is_power_of_2(size), "sanity");
212   assert(valid_watermarks(), "sanity");
213   int low_bits_mask = low_bits[size>>2];
214   for (int i = _lwm; i <= _hwm; i++) {
215     int bits = _A[i];
216     int sets = 0;
217     for (int j = 0; j < size; j++) {
218       sets |= (bits & low_bits_mask);  // collect partial bits
219       bits  = bits>>1;
220     }
221     sets |= (sets<<1);           // Smear 1 lo-bit  into a set
222     if (size > 2) {
223       sets |= (sets<<2);         // Smear 2 lo-bits into a set
224       if (size > 4) {
225         sets |= (sets<<4);       // Smear 4 lo-bits into a set
226         if (size > 8) {
227           sets |= (sets<<8);     // Smear 8 lo-bits into a set
228         }
229       }
230     }
231     _A[i] = sets;
232   }
233   assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
234 }
235 
236 // Assert that the register mask contains only bit sets.
is_aligned_sets(const int size) const237 bool RegMask::is_aligned_sets(const int size) const {
238   if (size == 1) return true;
239   assert(2 <= size && size <= 16, "update low bits table");
240   assert(is_power_of_2(size), "sanity");
241   int low_bits_mask = low_bits[size>>2];
242   assert(valid_watermarks(), "sanity");
243   for (int i = _lwm; i <= _hwm; i++) {
244     int bits = _A[i];
245     while (bits) {              // Check bits for pairing
246       int bit = bits & -bits;   // Extract low bit
247       // Low bit is not odd means its mis-aligned.
248       if ((bit & low_bits_mask) == 0) return false;
249       // Do extra work since (bit << size) may overflow.
250       int hi_bit = bit << (size-1); // high bit
251       int set = hi_bit + ((hi_bit-1) & ~(bit-1));
252       // Check for aligned adjacent bits in this set
253       if ((bits & set) != set) return false;
254       bits -= set;  // Remove this set
255     }
256   }
257   return true;
258 }
259 
260 // Return TRUE if the mask contains one adjacent set of bits and no other bits.
261 // Works also for size 1.
is_bound_set(const int size) const262 int RegMask::is_bound_set(const int size) const {
263   if (is_AllStack()) return false;
264   assert(1 <= size && size <= 16, "update low bits table");
265   assert(valid_watermarks(), "sanity");
266   int bit = -1;                 // Set to hold the one bit allowed
267   for (int i = _lwm; i <= _hwm; i++) {
268     if (_A[i] ) {               // Found some bits
269       if (bit != -1)
270        return false;            // Already had bits, so fail
271       bit = _A[i] & -_A[i];     // Extract low bit from mask
272       int hi_bit = bit << (size-1); // high bit
273       if (hi_bit != 0) {        // Bit set stays in same word?
274         int set = hi_bit + ((hi_bit-1) & ~(bit-1));
275         if (set != _A[i])
276           return false;         // Require adjacent bit set and no more bits
277       } else {                  // Else its a split-set case
278         if (((-1) & ~(bit-1)) != _A[i])
279           return false;         // Found many bits, so fail
280         i++;                    // Skip iteration forward and check high part
281         // The lower (32-size) bits should be 0 since it is split case.
282         int clear_bit_size = 32-size;
283         int shift_back_size = 32-clear_bit_size;
284         int set = bit>>clear_bit_size;
285         set = set & -set; // Remove sign extension.
286         set = (((set << size) - 1) >> shift_back_size);
287         if (i > _hwm || _A[i] != set)
288           return false; // Require expected low bits in next word
289       }
290     }
291   }
292   // True for both the empty mask and for a bit set
293   return true;
294 }
295 
296 // UP means register only, Register plus stack, or stack only is DOWN
is_UP() const297 bool RegMask::is_UP() const {
298   // Quick common case check for DOWN (any stack slot is legal)
299   if (is_AllStack())
300     return false;
301   // Slower check for any stack bits set (also DOWN)
302   if (overlap(Matcher::STACK_ONLY_mask))
303     return false;
304   // Not DOWN, so must be UP
305   return true;
306 }
307 
308 // Compute size of register mask in bits
Size() const309 uint RegMask::Size() const {
310   uint sum = 0;
311   assert(valid_watermarks(), "sanity");
312   for (int i = _lwm; i <= _hwm; i++) {
313     sum += population_count((unsigned)_A[i]);
314   }
315   return sum;
316 }
317 
318 #ifndef PRODUCT
dump(outputStream * st) const319 void RegMask::dump(outputStream *st) const {
320   st->print("[");
321   RegMask rm = *this;           // Structure copy into local temp
322 
323   OptoReg::Name start = rm.find_first_elem(); // Get a register
324   if (OptoReg::is_valid(start)) { // Check for empty mask
325     rm.Remove(start);           // Yank from mask
326     OptoReg::dump(start, st);   // Print register
327     OptoReg::Name last = start;
328 
329     // Now I have printed an initial register.
330     // Print adjacent registers as "rX-rZ" instead of "rX,rY,rZ".
331     // Begin looping over the remaining registers.
332     while (1) {                 //
333       OptoReg::Name reg = rm.find_first_elem(); // Get a register
334       if (!OptoReg::is_valid(reg))
335         break;                  // Empty mask, end loop
336       rm.Remove(reg);           // Yank from mask
337 
338       if (last+1 == reg) {      // See if they are adjacent
339         // Adjacent registers just collect into long runs, no printing.
340         last = reg;
341       } else {                  // Ending some kind of run
342         if (start == last) {    // 1-register run; no special printing
343         } else if (start+1 == last) {
344           st->print(",");       // 2-register run; print as "rX,rY"
345           OptoReg::dump(last, st);
346         } else {                // Multi-register run; print as "rX-rZ"
347           st->print("-");
348           OptoReg::dump(last, st);
349         }
350         st->print(",");         // Seperate start of new run
351         start = last = reg;     // Start a new register run
352         OptoReg::dump(start, st); // Print register
353       } // End of if ending a register run or not
354     } // End of while regmask not empty
355 
356     if (start == last) {        // 1-register run; no special printing
357     } else if (start+1 == last) {
358       st->print(",");           // 2-register run; print as "rX,rY"
359       OptoReg::dump(last, st);
360     } else {                    // Multi-register run; print as "rX-rZ"
361       st->print("-");
362       OptoReg::dump(last, st);
363     }
364     if (rm.is_AllStack()) st->print("...");
365   }
366   st->print("]");
367 }
368 #endif
369