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1.1 root 1: /*
2: * Optimizations for Tiny Code Generator for QEMU
3: *
4: * Copyright (c) 2010 Samsung Electronics.
5: * Contributed by Kirill Batuzov <[email protected]>
6: *
7: * Permission is hereby granted, free of charge, to any person obtaining a copy
8: * of this software and associated documentation files (the "Software"), to deal
9: * in the Software without restriction, including without limitation the rights
10: * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11: * copies of the Software, and to permit persons to whom the Software is
12: * furnished to do so, subject to the following conditions:
13: *
14: * The above copyright notice and this permission notice shall be included in
15: * all copies or substantial portions of the Software.
16: *
17: * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18: * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19: * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20: * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21: * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22: * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23: * THE SOFTWARE.
24: */
25:
26: #include "config.h"
27:
28: #include <stdlib.h>
29: #include <stdio.h>
30:
31: #include "qemu-common.h"
32: #include "tcg-op.h"
33:
34: #define CASE_OP_32_64(x) \
35: glue(glue(case INDEX_op_, x), _i32): \
36: glue(glue(case INDEX_op_, x), _i64)
37:
38: typedef enum {
39: TCG_TEMP_UNDEF = 0,
40: TCG_TEMP_CONST,
41: TCG_TEMP_COPY,
42: TCG_TEMP_HAS_COPY,
43: TCG_TEMP_ANY
44: } tcg_temp_state;
45:
46: struct tcg_temp_info {
47: tcg_temp_state state;
48: uint16_t prev_copy;
49: uint16_t next_copy;
50: tcg_target_ulong val;
51: };
52:
53: static struct tcg_temp_info temps[TCG_MAX_TEMPS];
54:
55: /* Reset TEMP's state to TCG_TEMP_ANY. If TEMP was a representative of some
56: class of equivalent temp's, a new representative should be chosen in this
57: class. */
58: static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
59: {
60: int i;
61: TCGArg new_base = (TCGArg)-1;
62: if (temps[temp].state == TCG_TEMP_HAS_COPY) {
63: for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
64: if (i >= nb_globals) {
65: temps[i].state = TCG_TEMP_HAS_COPY;
66: new_base = i;
67: break;
68: }
69: }
70: for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
71: if (new_base == (TCGArg)-1) {
72: temps[i].state = TCG_TEMP_ANY;
73: } else {
74: temps[i].val = new_base;
75: }
76: }
77: temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
78: temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
79: } else if (temps[temp].state == TCG_TEMP_COPY) {
80: temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
81: temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
82: new_base = temps[temp].val;
83: }
84: temps[temp].state = TCG_TEMP_ANY;
85: if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) {
86: temps[new_base].state = TCG_TEMP_ANY;
87: }
88: }
89:
90: static int op_bits(TCGOpcode op)
91: {
92: const TCGOpDef *def = &tcg_op_defs[op];
93: return def->flags & TCG_OPF_64BIT ? 64 : 32;
94: }
95:
96: static TCGOpcode op_to_movi(TCGOpcode op)
97: {
98: switch (op_bits(op)) {
99: case 32:
100: return INDEX_op_movi_i32;
101: case 64:
102: return INDEX_op_movi_i64;
103: default:
104: fprintf(stderr, "op_to_movi: unexpected return value of "
105: "function op_bits.\n");
106: tcg_abort();
107: }
108: }
109:
110: static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args, TCGArg dst,
111: TCGArg src, int nb_temps, int nb_globals)
112: {
113: reset_temp(dst, nb_temps, nb_globals);
114: assert(temps[src].state != TCG_TEMP_COPY);
115: /* Don't try to copy if one of temps is a global or either one
116: is local and another is register */
117: if (src >= nb_globals && dst >= nb_globals &&
118: tcg_arg_is_local(s, src) == tcg_arg_is_local(s, dst)) {
119: assert(temps[src].state != TCG_TEMP_CONST);
120: if (temps[src].state != TCG_TEMP_HAS_COPY) {
121: temps[src].state = TCG_TEMP_HAS_COPY;
122: temps[src].next_copy = src;
123: temps[src].prev_copy = src;
124: }
125: temps[dst].state = TCG_TEMP_COPY;
126: temps[dst].val = src;
127: temps[dst].next_copy = temps[src].next_copy;
128: temps[dst].prev_copy = src;
129: temps[temps[dst].next_copy].prev_copy = dst;
130: temps[src].next_copy = dst;
131: }
132: gen_args[0] = dst;
133: gen_args[1] = src;
134: }
135:
136: static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val,
137: int nb_temps, int nb_globals)
138: {
139: reset_temp(dst, nb_temps, nb_globals);
140: temps[dst].state = TCG_TEMP_CONST;
141: temps[dst].val = val;
142: gen_args[0] = dst;
143: gen_args[1] = val;
144: }
145:
146: static TCGOpcode op_to_mov(TCGOpcode op)
147: {
148: switch (op_bits(op)) {
149: case 32:
150: return INDEX_op_mov_i32;
151: case 64:
152: return INDEX_op_mov_i64;
153: default:
154: fprintf(stderr, "op_to_mov: unexpected return value of "
155: "function op_bits.\n");
156: tcg_abort();
157: }
158: }
159:
160: static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)
161: {
162: switch (op) {
163: CASE_OP_32_64(add):
164: return x + y;
165:
166: CASE_OP_32_64(sub):
167: return x - y;
168:
169: CASE_OP_32_64(mul):
170: return x * y;
171:
172: CASE_OP_32_64(and):
173: return x & y;
174:
175: CASE_OP_32_64(or):
176: return x | y;
177:
178: CASE_OP_32_64(xor):
179: return x ^ y;
180:
181: case INDEX_op_shl_i32:
182: return (uint32_t)x << (uint32_t)y;
183:
184: case INDEX_op_shl_i64:
185: return (uint64_t)x << (uint64_t)y;
186:
187: case INDEX_op_shr_i32:
188: return (uint32_t)x >> (uint32_t)y;
189:
190: case INDEX_op_shr_i64:
191: return (uint64_t)x >> (uint64_t)y;
192:
193: case INDEX_op_sar_i32:
194: return (int32_t)x >> (int32_t)y;
195:
196: case INDEX_op_sar_i64:
197: return (int64_t)x >> (int64_t)y;
198:
199: case INDEX_op_rotr_i32:
200: x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);
201: return x;
202:
203: case INDEX_op_rotr_i64:
204: x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);
205: return x;
206:
207: case INDEX_op_rotl_i32:
208: x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));
209: return x;
210:
211: case INDEX_op_rotl_i64:
212: x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));
213: return x;
214:
215: CASE_OP_32_64(not):
216: return ~x;
217:
218: CASE_OP_32_64(neg):
219: return -x;
220:
221: CASE_OP_32_64(andc):
222: return x & ~y;
223:
224: CASE_OP_32_64(orc):
225: return x | ~y;
226:
227: CASE_OP_32_64(eqv):
228: return ~(x ^ y);
229:
230: CASE_OP_32_64(nand):
231: return ~(x & y);
232:
233: CASE_OP_32_64(nor):
234: return ~(x | y);
235:
236: CASE_OP_32_64(ext8s):
237: return (int8_t)x;
238:
239: CASE_OP_32_64(ext16s):
240: return (int16_t)x;
241:
242: CASE_OP_32_64(ext8u):
243: return (uint8_t)x;
244:
245: CASE_OP_32_64(ext16u):
246: return (uint16_t)x;
247:
248: case INDEX_op_ext32s_i64:
249: return (int32_t)x;
250:
251: case INDEX_op_ext32u_i64:
252: return (uint32_t)x;
253:
254: default:
255: fprintf(stderr,
256: "Unrecognized operation %d in do_constant_folding.\n", op);
257: tcg_abort();
258: }
259: }
260:
261: static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)
262: {
263: TCGArg res = do_constant_folding_2(op, x, y);
264: if (op_bits(op) == 32) {
265: res &= 0xffffffff;
266: }
267: return res;
268: }
269:
270: /* Propagate constants and copies, fold constant expressions. */
271: static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
272: TCGArg *args, TCGOpDef *tcg_op_defs)
273: {
274: int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;
275: TCGOpcode op;
276: const TCGOpDef *def;
277: TCGArg *gen_args;
278: TCGArg tmp;
279: /* Array VALS has an element for each temp.
280: If this temp holds a constant then its value is kept in VALS' element.
281: If this temp is a copy of other ones then this equivalence class'
282: representative is kept in VALS' element.
283: If this temp is neither copy nor constant then corresponding VALS'
284: element is unused. */
285:
286: nb_temps = s->nb_temps;
287: nb_globals = s->nb_globals;
288: memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
289:
290: nb_ops = tcg_opc_ptr - gen_opc_buf;
291: gen_args = args;
292: for (op_index = 0; op_index < nb_ops; op_index++) {
293: op = gen_opc_buf[op_index];
294: def = &tcg_op_defs[op];
295: /* Do copy propagation */
296: if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
297: assert(op != INDEX_op_call);
298: for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
299: if (temps[args[i]].state == TCG_TEMP_COPY) {
300: args[i] = temps[args[i]].val;
301: }
302: }
303: }
304:
305: /* For commutative operations make constant second argument */
306: switch (op) {
307: CASE_OP_32_64(add):
308: CASE_OP_32_64(mul):
309: CASE_OP_32_64(and):
310: CASE_OP_32_64(or):
311: CASE_OP_32_64(xor):
312: CASE_OP_32_64(eqv):
313: CASE_OP_32_64(nand):
314: CASE_OP_32_64(nor):
315: if (temps[args[1]].state == TCG_TEMP_CONST) {
316: tmp = args[1];
317: args[1] = args[2];
318: args[2] = tmp;
319: }
320: break;
321: default:
322: break;
323: }
324:
325: /* Simplify expression if possible. */
326: switch (op) {
327: CASE_OP_32_64(add):
328: CASE_OP_32_64(sub):
329: CASE_OP_32_64(shl):
330: CASE_OP_32_64(shr):
331: CASE_OP_32_64(sar):
332: CASE_OP_32_64(rotl):
333: CASE_OP_32_64(rotr):
334: if (temps[args[1]].state == TCG_TEMP_CONST) {
335: /* Proceed with possible constant folding. */
336: break;
337: }
338: if (temps[args[2]].state == TCG_TEMP_CONST
339: && temps[args[2]].val == 0) {
340: if ((temps[args[0]].state == TCG_TEMP_COPY
341: && temps[args[0]].val == args[1])
342: || args[0] == args[1]) {
343: args += 3;
344: gen_opc_buf[op_index] = INDEX_op_nop;
345: } else {
346: gen_opc_buf[op_index] = op_to_mov(op);
347: tcg_opt_gen_mov(s, gen_args, args[0], args[1],
348: nb_temps, nb_globals);
349: gen_args += 2;
350: args += 3;
351: }
352: continue;
353: }
354: break;
355: CASE_OP_32_64(mul):
356: if ((temps[args[2]].state == TCG_TEMP_CONST
357: && temps[args[2]].val == 0)) {
358: gen_opc_buf[op_index] = op_to_movi(op);
359: tcg_opt_gen_movi(gen_args, args[0], 0, nb_temps, nb_globals);
360: args += 3;
361: gen_args += 2;
362: continue;
363: }
364: break;
365: CASE_OP_32_64(or):
366: CASE_OP_32_64(and):
367: if (args[1] == args[2]) {
368: if (args[1] == args[0]) {
369: args += 3;
370: gen_opc_buf[op_index] = INDEX_op_nop;
371: } else {
372: gen_opc_buf[op_index] = op_to_mov(op);
373: tcg_opt_gen_mov(s, gen_args, args[0], args[1], nb_temps,
374: nb_globals);
375: gen_args += 2;
376: args += 3;
377: }
378: continue;
379: }
380: break;
381: default:
382: break;
383: }
384:
385: /* Propagate constants through copy operations and do constant
386: folding. Constants will be substituted to arguments by register
387: allocator where needed and possible. Also detect copies. */
388: switch (op) {
389: CASE_OP_32_64(mov):
390: if ((temps[args[1]].state == TCG_TEMP_COPY
391: && temps[args[1]].val == args[0])
392: || args[0] == args[1]) {
393: args += 2;
394: gen_opc_buf[op_index] = INDEX_op_nop;
395: break;
396: }
397: if (temps[args[1]].state != TCG_TEMP_CONST) {
398: tcg_opt_gen_mov(s, gen_args, args[0], args[1],
399: nb_temps, nb_globals);
400: gen_args += 2;
401: args += 2;
402: break;
403: }
404: /* Source argument is constant. Rewrite the operation and
405: let movi case handle it. */
406: op = op_to_movi(op);
407: gen_opc_buf[op_index] = op;
408: args[1] = temps[args[1]].val;
409: /* fallthrough */
410: CASE_OP_32_64(movi):
411: tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals);
412: gen_args += 2;
413: args += 2;
414: break;
415: CASE_OP_32_64(not):
416: CASE_OP_32_64(neg):
417: CASE_OP_32_64(ext8s):
418: CASE_OP_32_64(ext8u):
419: CASE_OP_32_64(ext16s):
420: CASE_OP_32_64(ext16u):
421: case INDEX_op_ext32s_i64:
422: case INDEX_op_ext32u_i64:
423: if (temps[args[1]].state == TCG_TEMP_CONST) {
424: gen_opc_buf[op_index] = op_to_movi(op);
425: tmp = do_constant_folding(op, temps[args[1]].val, 0);
426: tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
427: gen_args += 2;
428: args += 2;
429: break;
430: } else {
431: reset_temp(args[0], nb_temps, nb_globals);
432: gen_args[0] = args[0];
433: gen_args[1] = args[1];
434: gen_args += 2;
435: args += 2;
436: break;
437: }
438: CASE_OP_32_64(add):
439: CASE_OP_32_64(sub):
440: CASE_OP_32_64(mul):
441: CASE_OP_32_64(or):
442: CASE_OP_32_64(and):
443: CASE_OP_32_64(xor):
444: CASE_OP_32_64(shl):
445: CASE_OP_32_64(shr):
446: CASE_OP_32_64(sar):
447: CASE_OP_32_64(rotl):
448: CASE_OP_32_64(rotr):
449: CASE_OP_32_64(andc):
450: CASE_OP_32_64(orc):
451: CASE_OP_32_64(eqv):
452: CASE_OP_32_64(nand):
453: CASE_OP_32_64(nor):
454: if (temps[args[1]].state == TCG_TEMP_CONST
455: && temps[args[2]].state == TCG_TEMP_CONST) {
456: gen_opc_buf[op_index] = op_to_movi(op);
457: tmp = do_constant_folding(op, temps[args[1]].val,
458: temps[args[2]].val);
459: tcg_opt_gen_movi(gen_args, args[0], tmp, nb_temps, nb_globals);
460: gen_args += 2;
461: args += 3;
462: break;
463: } else {
464: reset_temp(args[0], nb_temps, nb_globals);
465: gen_args[0] = args[0];
466: gen_args[1] = args[1];
467: gen_args[2] = args[2];
468: gen_args += 3;
469: args += 3;
470: break;
471: }
472: case INDEX_op_call:
473: nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
474: if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
475: for (i = 0; i < nb_globals; i++) {
476: reset_temp(i, nb_temps, nb_globals);
477: }
478: }
479: for (i = 0; i < (args[0] >> 16); i++) {
480: reset_temp(args[i + 1], nb_temps, nb_globals);
481: }
482: i = nb_call_args + 3;
483: while (i) {
484: *gen_args = *args;
485: args++;
486: gen_args++;
487: i--;
488: }
489: break;
490: case INDEX_op_set_label:
491: case INDEX_op_jmp:
492: case INDEX_op_br:
493: CASE_OP_32_64(brcond):
494: memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
495: for (i = 0; i < def->nb_args; i++) {
496: *gen_args = *args;
497: args++;
498: gen_args++;
499: }
500: break;
501: default:
502: /* Default case: we do know nothing about operation so no
503: propagation is done. We only trash output args. */
504: for (i = 0; i < def->nb_oargs; i++) {
505: reset_temp(args[i], nb_temps, nb_globals);
506: }
507: for (i = 0; i < def->nb_args; i++) {
508: gen_args[i] = args[i];
509: }
510: args += def->nb_args;
511: gen_args += def->nb_args;
512: break;
513: }
514: }
515:
516: return gen_args;
517: }
518:
519: TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,
520: TCGArg *args, TCGOpDef *tcg_op_defs)
521: {
522: TCGArg *res;
523: res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);
524: return res;
525: }
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