1 /*
2 * Copyright (c) 1997, 2020, 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/chaitin.hpp"
28 #include "opto/compile.hpp"
29 #include "opto/matcher.hpp"
30 #include "opto/node.hpp"
31 #include "opto/regmask.hpp"
32 #include "utilities/population_count.hpp"
33 #include "utilities/powerOfTwo.hpp"
34
35 #define RM_SIZE _RM_SIZE /* a constant private to the class RegMask */
36
37 //------------------------------dump-------------------------------------------
38
39 #ifndef PRODUCT
40 void OptoReg::dump(int r, outputStream *st) {
41 switch (r) {
42 case Special: st->print("r---"); break;
43 case Bad: st->print("rBAD"); break;
44 default:
45 if (r < _last_Mach_Reg) st->print("%s", Matcher::regName[r]);
46 else st->print("rS%d",r);
47 break;
48 }
49 }
50 #endif
51
52
53 //=============================================================================
54 const RegMask RegMask::Empty(
55 # define BODY(I) 0,
56 FORALL_BODY
57 # undef BODY
58 0
59 );
60
61 //=============================================================================
62 bool RegMask::is_vector(uint ireg) {
63 return (ireg == Op_VecA || ireg == Op_VecS || ireg == Op_VecD ||
64 ireg == Op_VecX || ireg == Op_VecY || ireg == Op_VecZ );
65 }
66
67 int RegMask::num_registers(uint ireg) {
68 switch(ireg) {
69 case Op_VecZ:
70 return SlotsPerVecZ;
71 case Op_VecY:
72 return SlotsPerVecY;
73 case Op_VecX:
74 return SlotsPerVecX;
75 case Op_VecD:
76 return SlotsPerVecD;
77 case Op_RegD:
78 case Op_RegL:
79 #ifdef _LP64
80 case Op_RegP:
81 #endif
82 return 2;
83 case Op_VecA:
84 assert(Matcher::supports_scalable_vector(), "does not support scalable vector");
85 return SlotsPerVecA;
86 }
87 // Op_VecS and the rest ideal registers.
88 return 1;
89 }
90
91 int RegMask::num_registers(uint ireg, LRG &lrg) {
92 int n_regs = num_registers(ireg);
93
94 // assigned is OptoReg which is selected by register allocator
95 OptoReg::Name assigned = lrg.reg();
96 assert(OptoReg::is_valid(assigned), "should be valid opto register");
97
98 if (lrg.is_scalable() && OptoReg::is_stack(assigned)) {
99 n_regs = lrg.scalable_reg_slots();
100 }
101 return n_regs;
102 }
103
104 // Clear out partial bits; leave only bit pairs
105 void RegMask::clear_to_pairs() {
106 assert(valid_watermarks(), "sanity");
107 for (int i = _lwm; i <= _hwm; i++) {
108 int bits = _A[i];
109 bits &= ((bits & 0x55555555)<<1); // 1 hi-bit set for each pair
110 bits |= (bits>>1); // Smear 1 hi-bit into a pair
111 _A[i] = bits;
112 }
113 assert(is_aligned_pairs(), "mask is not aligned, adjacent pairs");
114 }
115
116 bool RegMask::is_misaligned_pair() const {
117 return Size() == 2 && !is_aligned_pairs();
118 }
119
120 bool RegMask::is_aligned_pairs() const {
121 // Assert that the register mask contains only bit pairs.
122 assert(valid_watermarks(), "sanity");
123 for (int i = _lwm; i <= _hwm; i++) {
124 int bits = _A[i];
125 while (bits) { // Check bits for pairing
126 int bit = bits & -bits; // Extract low bit
127 // Low bit is not odd means its mis-aligned.
128 if ((bit & 0x55555555) == 0) return false;
129 bits -= bit; // Remove bit from mask
130 // Check for aligned adjacent bit
131 if ((bits & (bit<<1)) == 0) return false;
132 bits -= (bit<<1); // Remove other halve of pair
133 }
134 }
135 return true;
136 }
137
138 // Return TRUE if the mask contains a single bit
139 bool RegMask::is_bound1() const {
140 if (is_AllStack()) return false;
141 return Size() == 1;
142 }
143
144 // Return TRUE if the mask contains an adjacent pair of bits and no other bits.
145 bool RegMask::is_bound_pair() const {
146 if (is_AllStack()) return false;
147 int bit = -1; // Set to hold the one bit allowed
148 assert(valid_watermarks(), "sanity");
149 for (int i = _lwm; i <= _hwm; i++) {
150 if (_A[i]) { // Found some bits
151 if (bit != -1) return false; // Already had bits, so fail
152 bit = _A[i] & -(_A[i]); // Extract 1 bit from mask
153 if ((bit << 1) != 0) { // Bit pair stays in same word?
154 if ((bit | (bit<<1)) != _A[i])
155 return false; // Require adjacent bit pair and no more bits
156 } else { // Else its a split-pair case
157 if(bit != _A[i]) return false; // Found many bits, so fail
158 i++; // Skip iteration forward
159 if (i > _hwm || _A[i] != 1)
160 return false; // Require 1 lo bit in next word
161 }
162 }
163 }
164 // True for both the empty mask and for a bit pair
165 return true;
166 }
167
168 // Test for a single adjacent set of ideal register's size.
169 bool RegMask::is_bound(uint ireg) const {
170 if (is_vector(ireg)) {
171 if (is_bound_set(num_registers(ireg)))
172 return true;
173 } else if (is_bound1() || is_bound_pair()) {
174 return true;
175 }
176 return false;
177 }
178 // Check that whether given reg number with size is valid
179 // for current regmask, where reg is the highest number.
180 bool RegMask::is_valid_reg(OptoReg::Name reg, const int size) const {
181 for (int i = 0; i < size; i++) {
182 if (!Member(reg - i)) {
183 return false;
184 }
185 }
186 return true;
187 }
188
189 // only indicies of power 2 are accessed, so index 3 is only filled in for storage.
190 static int low_bits[5] = { 0x55555555, 0x11111111, 0x01010101, 0x00000000, 0x00010001 };
191
192 // Find the lowest-numbered register set in the mask. Return the
193 // HIGHEST register number in the set, or BAD if no sets.
194 // Works also for size 1.
195 OptoReg::Name RegMask::find_first_set(LRG &lrg, const int size) const {
196 if (lrg.is_scalable()) {
197 // For scalable vector register, regmask is SlotsPerVecA bits aligned.
198 assert(is_aligned_sets(SlotsPerVecA), "mask is not aligned, adjacent sets");
199 } else {
200 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
201 }
202 assert(valid_watermarks(), "sanity");
203 for (int i = _lwm; i <= _hwm; i++) {
204 if (_A[i]) { // Found some bits
205 // Convert to bit number, return hi bit in pair
206 return OptoReg::Name((i<<_LogWordBits) + find_lowest_bit(_A[i]) + (size - 1));
207 }
208 }
209 return OptoReg::Bad;
210 }
211
212 // Clear out partial bits; leave only aligned adjacent bit pairs
213 void RegMask::clear_to_sets(const int size) {
214 if (size == 1) return;
215 assert(2 <= size && size <= 16, "update low bits table");
216 assert(is_power_of_2(size), "sanity");
217 assert(valid_watermarks(), "sanity");
218 int low_bits_mask = low_bits[size>>2];
219 for (int i = _lwm; i <= _hwm; i++) {
220 int bits = _A[i];
221 int sets = (bits & low_bits_mask);
222 for (int j = 1; j < size; j++) {
223 sets = (bits & (sets<<1)); // filter bits which produce whole sets
224 }
225 sets |= (sets>>1); // Smear 1 hi-bit into a set
226 if (size > 2) {
227 sets |= (sets>>2); // Smear 2 hi-bits into a set
228 if (size > 4) {
229 sets |= (sets>>4); // Smear 4 hi-bits into a set
230 if (size > 8) {
231 sets |= (sets>>8); // Smear 8 hi-bits into a set
232 }
233 }
234 }
235 _A[i] = sets;
236 }
237 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
238 }
239
240 // Smear out partial bits to aligned adjacent bit sets
241 void RegMask::smear_to_sets(const int size) {
242 if (size == 1) return;
243 assert(2 <= size && size <= 16, "update low bits table");
244 assert(is_power_of_2(size), "sanity");
245 assert(valid_watermarks(), "sanity");
246 int low_bits_mask = low_bits[size>>2];
247 for (int i = _lwm; i <= _hwm; i++) {
248 int bits = _A[i];
249 int sets = 0;
250 for (int j = 0; j < size; j++) {
251 sets |= (bits & low_bits_mask); // collect partial bits
252 bits = bits>>1;
253 }
254 sets |= (sets<<1); // Smear 1 lo-bit into a set
255 if (size > 2) {
256 sets |= (sets<<2); // Smear 2 lo-bits into a set
257 if (size > 4) {
258 sets |= (sets<<4); // Smear 4 lo-bits into a set
259 if (size > 8) {
260 sets |= (sets<<8); // Smear 8 lo-bits into a set
261 }
262 }
263 }
264 _A[i] = sets;
265 }
266 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
267 }
268
269 // Assert that the register mask contains only bit sets.
270 bool RegMask::is_aligned_sets(const int size) const {
271 if (size == 1) return true;
272 assert(2 <= size && size <= 16, "update low bits table");
273 assert(is_power_of_2(size), "sanity");
274 int low_bits_mask = low_bits[size>>2];
275 assert(valid_watermarks(), "sanity");
276 for (int i = _lwm; i <= _hwm; i++) {
277 int bits = _A[i];
278 while (bits) { // Check bits for pairing
279 int bit = bits & -bits; // Extract low bit
280 // Low bit is not odd means its mis-aligned.
281 if ((bit & low_bits_mask) == 0) {
282 return false;
283 }
284 // Do extra work since (bit << size) may overflow.
285 int hi_bit = bit << (size-1); // high bit
286 int set = hi_bit + ((hi_bit-1) & ~(bit-1));
287 // Check for aligned adjacent bits in this set
288 if ((bits & set) != set) {
289 return false;
290 }
291 bits -= set; // Remove this set
292 }
293 }
294 return true;
295 }
296
297 // Return TRUE if the mask contains one adjacent set of bits and no other bits.
298 // Works also for size 1.
299 int RegMask::is_bound_set(const int size) const {
300 if (is_AllStack()) return false;
301 assert(1 <= size && size <= 16, "update low bits table");
302 assert(valid_watermarks(), "sanity");
303 int bit = -1; // Set to hold the one bit allowed
304 for (int i = _lwm; i <= _hwm; i++) {
305 if (_A[i] ) { // Found some bits
306 if (bit != -1)
307 return false; // Already had bits, so fail
308 bit = _A[i] & -_A[i]; // Extract low bit from mask
309 int hi_bit = bit << (size-1); // high bit
310 if (hi_bit != 0) { // Bit set stays in same word?
311 int set = hi_bit + ((hi_bit-1) & ~(bit-1));
312 if (set != _A[i])
313 return false; // Require adjacent bit set and no more bits
314 } else { // Else its a split-set case
315 if (((-1) & ~(bit-1)) != _A[i])
316 return false; // Found many bits, so fail
317 i++; // Skip iteration forward and check high part
318 // The lower (32-size) bits should be 0 since it is split case.
319 int clear_bit_size = 32-size;
320 int shift_back_size = 32-clear_bit_size;
321 int set = bit>>clear_bit_size;
322 set = set & -set; // Remove sign extension.
323 set = (((set << size) - 1) >> shift_back_size);
324 if (i > _hwm || _A[i] != set)
325 return false; // Require expected low bits in next word
326 }
327 }
328 }
329 // True for both the empty mask and for a bit set
330 return true;
331 }
332
333 // UP means register only, Register plus stack, or stack only is DOWN
334 bool RegMask::is_UP() const {
335 // Quick common case check for DOWN (any stack slot is legal)
336 if (is_AllStack())
337 return false;
338 // Slower check for any stack bits set (also DOWN)
339 if (overlap(Matcher::STACK_ONLY_mask))
340 return false;
341 // Not DOWN, so must be UP
342 return true;
343 }
344
345 // Compute size of register mask in bits
346 uint RegMask::Size() const {
347 uint sum = 0;
348 assert(valid_watermarks(), "sanity");
349 for (int i = _lwm; i <= _hwm; i++) {
350 sum += population_count((unsigned)_A[i]);
351 }
352 return sum;
353 }
354
355 #ifndef PRODUCT
356 void RegMask::dump(outputStream *st) const {
357 st->print("[");
358 RegMask rm = *this; // Structure copy into local temp
359
360 OptoReg::Name start = rm.find_first_elem(); // Get a register
361 if (OptoReg::is_valid(start)) { // Check for empty mask
362 rm.Remove(start); // Yank from mask
363 OptoReg::dump(start, st); // Print register
364 OptoReg::Name last = start;
365
366 // Now I have printed an initial register.
367 // Print adjacent registers as "rX-rZ" instead of "rX,rY,rZ".
368 // Begin looping over the remaining registers.
369 while (1) { //
370 OptoReg::Name reg = rm.find_first_elem(); // Get a register
371 if (!OptoReg::is_valid(reg))
372 break; // Empty mask, end loop
373 rm.Remove(reg); // Yank from mask
374
375 if (last+1 == reg) { // See if they are adjacent
376 // Adjacent registers just collect into long runs, no printing.
377 last = reg;
378 } else { // Ending some kind of run
379 if (start == last) { // 1-register run; no special printing
380 } else if (start+1 == last) {
381 st->print(","); // 2-register run; print as "rX,rY"
382 OptoReg::dump(last, st);
383 } else { // Multi-register run; print as "rX-rZ"
384 st->print("-");
385 OptoReg::dump(last, st);
386 }
387 st->print(","); // Seperate start of new run
388 start = last = reg; // Start a new register run
389 OptoReg::dump(start, st); // Print register
390 } // End of if ending a register run or not
391 } // End of while regmask not empty
392
393 if (start == last) { // 1-register run; no special printing
394 } else if (start+1 == last) {
395 st->print(","); // 2-register run; print as "rX,rY"
396 OptoReg::dump(last, st);
397 } else { // Multi-register run; print as "rX-rZ"
398 st->print("-");
399 OptoReg::dump(last, st);
400 }
401 if (rm.is_AllStack()) st->print("...");
402 }
403 st->print("]");
404 }
405 #endif