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 if (lrg._is_vector) {
100 assert(ireg == Op_VecA, "scalable vector register");
101 }
102 n_regs = lrg.scalable_reg_slots();
103 }
104
105 return n_regs;
106 }
107
108 // Clear out partial bits; leave only bit pairs
109 void RegMask::clear_to_pairs() {
110 assert(valid_watermarks(), "sanity");
111 for (int i = _lwm; i <= _hwm; i++) {
112 int bits = _A[i];
113 bits &= ((bits & 0x55555555)<<1); // 1 hi-bit set for each pair
114 bits |= (bits>>1); // Smear 1 hi-bit into a pair
115 _A[i] = bits;
116 }
117 assert(is_aligned_pairs(), "mask is not aligned, adjacent pairs");
118 }
119
120 bool RegMask::is_misaligned_pair() const {
121 return Size() == 2 && !is_aligned_pairs();
122 }
123
124 bool RegMask::is_aligned_pairs() const {
125 // Assert that the register mask contains only bit pairs.
126 assert(valid_watermarks(), "sanity");
127 for (int i = _lwm; i <= _hwm; i++) {
128 int bits = _A[i];
129 while (bits) { // Check bits for pairing
130 int bit = bits & -bits; // Extract low bit
131 // Low bit is not odd means its mis-aligned.
132 if ((bit & 0x55555555) == 0) return false;
133 bits -= bit; // Remove bit from mask
134 // Check for aligned adjacent bit
135 if ((bits & (bit<<1)) == 0) return false;
136 bits -= (bit<<1); // Remove other halve of pair
137 }
138 }
139 return true;
140 }
141
142 // Return TRUE if the mask contains a single bit
143 bool RegMask::is_bound1() const {
144 if (is_AllStack()) return false;
145 return Size() == 1;
146 }
147
148 // Return TRUE if the mask contains an adjacent pair of bits and no other bits.
149 bool RegMask::is_bound_pair() const {
150 if (is_AllStack()) return false;
151 int bit = -1; // Set to hold the one bit allowed
152 assert(valid_watermarks(), "sanity");
153 for (int i = _lwm; i <= _hwm; i++) {
154 if (_A[i]) { // Found some bits
155 if (bit != -1) return false; // Already had bits, so fail
156 bit = _A[i] & -(_A[i]); // Extract 1 bit from mask
157 if ((bit << 1) != 0) { // Bit pair stays in same word?
158 if ((bit | (bit<<1)) != _A[i])
159 return false; // Require adjacent bit pair and no more bits
160 } else { // Else its a split-pair case
161 if(bit != _A[i]) return false; // Found many bits, so fail
162 i++; // Skip iteration forward
163 if (i > _hwm || _A[i] != 1)
164 return false; // Require 1 lo bit in next word
165 }
166 }
167 }
168 // True for both the empty mask and for a bit pair
169 return true;
170 }
171
172 // Test for a single adjacent set of ideal register's size.
173 bool RegMask::is_bound(uint ireg) const {
174 if (is_vector(ireg)) {
175 if (is_bound_set(num_registers(ireg)))
176 return true;
177 } else if (is_bound1() || is_bound_pair()) {
178 return true;
179 }
180 return false;
181 }
182 // Check that whether given reg number with size is valid
183 // for current regmask, where reg is the highest number.
184 bool RegMask::is_valid_reg(OptoReg::Name reg, const int size) const {
185 for (int i = 0; i < size; i++) {
186 if (!Member(reg - i)) {
187 return false;
188 }
189 }
190 return true;
191 }
192
193 // only indicies of power 2 are accessed, so index 3 is only filled in for storage.
194 static int low_bits[5] = { 0x55555555, 0x11111111, 0x01010101, 0x00000000, 0x00010001 };
195
196 // Find the lowest-numbered register set in the mask. Return the
197 // HIGHEST register number in the set, or BAD if no sets.
198 // Works also for size 1.
199 OptoReg::Name RegMask::find_first_set(LRG &lrg, const int size) const {
200 if (lrg._is_scalable && lrg._is_vector) {
201 // For scalable vector register, regmask is SlotsPerVecA bits aligned.
202 assert(is_aligned_sets(SlotsPerVecA), "mask is not aligned, adjacent sets");
203 } else {
204 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
205 }
206 assert(valid_watermarks(), "sanity");
207 for (int i = _lwm; i <= _hwm; i++) {
208 if (_A[i]) { // Found some bits
209 // Convert to bit number, return hi bit in pair
210 return OptoReg::Name((i<<_LogWordBits) + find_lowest_bit(_A[i]) + (size - 1));
211 }
212 }
213 return OptoReg::Bad;
214 }
215
216 // Clear out partial bits; leave only aligned adjacent bit pairs
217 void RegMask::clear_to_sets(const int size) {
218 if (size == 1) return;
219 assert(2 <= size && size <= 16, "update low bits table");
220 assert(is_power_of_2(size), "sanity");
221 assert(valid_watermarks(), "sanity");
222 int low_bits_mask = low_bits[size>>2];
223 for (int i = _lwm; i <= _hwm; i++) {
224 int bits = _A[i];
225 int sets = (bits & low_bits_mask);
226 for (int j = 1; j < size; j++) {
227 sets = (bits & (sets<<1)); // filter bits which produce whole sets
228 }
229 sets |= (sets>>1); // Smear 1 hi-bit into a set
230 if (size > 2) {
231 sets |= (sets>>2); // Smear 2 hi-bits into a set
232 if (size > 4) {
233 sets |= (sets>>4); // Smear 4 hi-bits into a set
234 if (size > 8) {
235 sets |= (sets>>8); // Smear 8 hi-bits into a set
236 }
237 }
238 }
239 _A[i] = sets;
240 }
241 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
242 }
243
244 // Smear out partial bits to aligned adjacent bit sets
245 void RegMask::smear_to_sets(const int size) {
246 if (size == 1) return;
247 assert(2 <= size && size <= 16, "update low bits table");
248 assert(is_power_of_2(size), "sanity");
249 assert(valid_watermarks(), "sanity");
250 int low_bits_mask = low_bits[size>>2];
251 for (int i = _lwm; i <= _hwm; i++) {
252 int bits = _A[i];
253 int sets = 0;
254 for (int j = 0; j < size; j++) {
255 sets |= (bits & low_bits_mask); // collect partial bits
256 bits = bits>>1;
257 }
258 sets |= (sets<<1); // Smear 1 lo-bit into a set
259 if (size > 2) {
260 sets |= (sets<<2); // Smear 2 lo-bits into a set
261 if (size > 4) {
262 sets |= (sets<<4); // Smear 4 lo-bits into a set
263 if (size > 8) {
264 sets |= (sets<<8); // Smear 8 lo-bits into a set
265 }
266 }
267 }
268 _A[i] = sets;
269 }
270 assert(is_aligned_sets(size), "mask is not aligned, adjacent sets");
271 }
272
273 // Assert that the register mask contains only bit sets.
274 bool RegMask::is_aligned_sets(const int size) const {
275 if (size == 1) return true;
276 assert(2 <= size && size <= 16, "update low bits table");
277 assert(is_power_of_2(size), "sanity");
278 int low_bits_mask = low_bits[size>>2];
279 assert(valid_watermarks(), "sanity");
280 for (int i = _lwm; i <= _hwm; i++) {
281 int bits = _A[i];
282 while (bits) { // Check bits for pairing
283 int bit = bits & -bits; // Extract low bit
284 // Low bit is not odd means its mis-aligned.
285 if ((bit & low_bits_mask) == 0) {
286 return false;
287 }
288 // Do extra work since (bit << size) may overflow.
289 int hi_bit = bit << (size-1); // high bit
290 int set = hi_bit + ((hi_bit-1) & ~(bit-1));
291 // Check for aligned adjacent bits in this set
292 if ((bits & set) != set) {
293 return false;
294 }
295 bits -= set; // Remove this set
296 }
297 }
298 return true;
299 }
300
301 // Return TRUE if the mask contains one adjacent set of bits and no other bits.
302 // Works also for size 1.
303 int RegMask::is_bound_set(const int size) const {
304 if (is_AllStack()) return false;
305 assert(1 <= size && size <= 16, "update low bits table");
306 assert(valid_watermarks(), "sanity");
307 int bit = -1; // Set to hold the one bit allowed
308 for (int i = _lwm; i <= _hwm; i++) {
309 if (_A[i] ) { // Found some bits
310 if (bit != -1)
311 return false; // Already had bits, so fail
312 bit = _A[i] & -_A[i]; // Extract low bit from mask
313 int hi_bit = bit << (size-1); // high bit
314 if (hi_bit != 0) { // Bit set stays in same word?
315 int set = hi_bit + ((hi_bit-1) & ~(bit-1));
316 if (set != _A[i])
317 return false; // Require adjacent bit set and no more bits
318 } else { // Else its a split-set case
319 if (((-1) & ~(bit-1)) != _A[i])
320 return false; // Found many bits, so fail
321 i++; // Skip iteration forward and check high part
322 // The lower (32-size) bits should be 0 since it is split case.
323 int clear_bit_size = 32-size;
324 int shift_back_size = 32-clear_bit_size;
325 int set = bit>>clear_bit_size;
326 set = set & -set; // Remove sign extension.
327 set = (((set << size) - 1) >> shift_back_size);
328 if (i > _hwm || _A[i] != set)
329 return false; // Require expected low bits in next word
330 }
331 }
332 }
333 // True for both the empty mask and for a bit set
334 return true;
335 }
336
337 // UP means register only, Register plus stack, or stack only is DOWN
338 bool RegMask::is_UP() const {
339 // Quick common case check for DOWN (any stack slot is legal)
340 if (is_AllStack())
341 return false;
342 // Slower check for any stack bits set (also DOWN)
343 if (overlap(Matcher::STACK_ONLY_mask))
344 return false;
345 // Not DOWN, so must be UP
346 return true;
347 }
348
349 // Compute size of register mask in bits
350 uint RegMask::Size() const {
351 uint sum = 0;
352 assert(valid_watermarks(), "sanity");
353 for (int i = _lwm; i <= _hwm; i++) {
354 sum += population_count((unsigned)_A[i]);
355 }
356 return sum;
357 }
358
359 #ifndef PRODUCT
360 void RegMask::dump(outputStream *st) const {
361 st->print("[");
362 RegMask rm = *this; // Structure copy into local temp
363
364 OptoReg::Name start = rm.find_first_elem(); // Get a register
365 if (OptoReg::is_valid(start)) { // Check for empty mask
366 rm.Remove(start); // Yank from mask
367 OptoReg::dump(start, st); // Print register
368 OptoReg::Name last = start;
369
370 // Now I have printed an initial register.
371 // Print adjacent registers as "rX-rZ" instead of "rX,rY,rZ".
372 // Begin looping over the remaining registers.
373 while (1) { //
374 OptoReg::Name reg = rm.find_first_elem(); // Get a register
375 if (!OptoReg::is_valid(reg))
376 break; // Empty mask, end loop
377 rm.Remove(reg); // Yank from mask
378
379 if (last+1 == reg) { // See if they are adjacent
380 // Adjacent registers just collect into long runs, no printing.
381 last = reg;
382 } else { // Ending some kind of run
383 if (start == last) { // 1-register run; no special printing
384 } else if (start+1 == last) {
385 st->print(","); // 2-register run; print as "rX,rY"
386 OptoReg::dump(last, st);
387 } else { // Multi-register run; print as "rX-rZ"
388 st->print("-");
389 OptoReg::dump(last, st);
390 }
391 st->print(","); // Seperate start of new run
392 start = last = reg; // Start a new register run
393 OptoReg::dump(start, st); // Print register
394 } // End of if ending a register run or not
395 } // End of while regmask not empty
396
397 if (start == last) { // 1-register run; no special printing
398 } else if (start+1 == last) {
399 st->print(","); // 2-register run; print as "rX,rY"
400 OptoReg::dump(last, st);
401 } else { // Multi-register run; print as "rX-rZ"
402 st->print("-");
403 OptoReg::dump(last, st);
404 }
405 if (rm.is_AllStack()) st->print("...");
406 }
407 st->print("]");
408 }
409 #endif