Mercurial > hg > CbC > CbC_gcc
comparison gcc/ccmp.c @ 111:04ced10e8804
gcc 7
author | kono |
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date | Fri, 27 Oct 2017 22:46:09 +0900 |
parents | |
children | 84e7813d76e9 |
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1 /* Conditional compare related functions | |
2 Copyright (C) 2014-2017 Free Software Foundation, Inc. | |
3 | |
4 This file is part of GCC. | |
5 | |
6 GCC is free software; you can redistribute it and/or modify it under | |
7 the terms of the GNU General Public License as published by the Free | |
8 Software Foundation; either version 3, or (at your option) any later | |
9 version. | |
10 | |
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 for more details. | |
15 | |
16 You should have received a copy of the GNU General Public License | |
17 along with GCC; see the file COPYING3. If not see | |
18 <http://www.gnu.org/licenses/>. */ | |
19 | |
20 #include "config.h" | |
21 #include "system.h" | |
22 #include "coretypes.h" | |
23 #include "backend.h" | |
24 #include "target.h" | |
25 #include "rtl.h" | |
26 #include "tree.h" | |
27 #include "gimple.h" | |
28 #include "memmodel.h" | |
29 #include "tm_p.h" | |
30 #include "ssa.h" | |
31 #include "expmed.h" | |
32 #include "optabs.h" | |
33 #include "emit-rtl.h" | |
34 #include "stor-layout.h" | |
35 #include "tree-ssa-live.h" | |
36 #include "tree-outof-ssa.h" | |
37 #include "cfgexpand.h" | |
38 #include "ccmp.h" | |
39 #include "predict.h" | |
40 | |
41 /* Check whether T is a simple boolean variable or a SSA name | |
42 set by a comparison operator in the same basic block. */ | |
43 static bool | |
44 ccmp_tree_comparison_p (tree t, basic_block bb) | |
45 { | |
46 gimple *g = get_gimple_for_ssa_name (t); | |
47 tree_code tcode; | |
48 | |
49 /* If we have a boolean variable allow it and generate a compare | |
50 to zero reg when expanding. */ | |
51 if (!g) | |
52 return (TREE_CODE (TREE_TYPE (t)) == BOOLEAN_TYPE); | |
53 | |
54 /* Check to see if SSA name is set by a comparison operator in | |
55 the same basic block. */ | |
56 if (!is_gimple_assign (g)) | |
57 return false; | |
58 if (bb != gimple_bb (g)) | |
59 return false; | |
60 tcode = gimple_assign_rhs_code (g); | |
61 return TREE_CODE_CLASS (tcode) == tcc_comparison; | |
62 } | |
63 | |
64 /* The following functions expand conditional compare (CCMP) instructions. | |
65 Here is a short description about the over all algorithm: | |
66 * ccmp_candidate_p is used to identify the CCMP candidate | |
67 | |
68 * expand_ccmp_expr is the main entry, which calls expand_ccmp_expr_1 | |
69 to expand CCMP. | |
70 | |
71 * expand_ccmp_expr_1 uses a recursive algorithm to expand CCMP. | |
72 It calls two target hooks gen_ccmp_first and gen_ccmp_next to generate | |
73 CCMP instructions. | |
74 - gen_ccmp_first expands the first compare in CCMP. | |
75 - gen_ccmp_next expands the following compares. | |
76 | |
77 Both hooks return a comparison with the CC register that is equivalent | |
78 to the value of the gimple comparison. This is used by the next CCMP | |
79 and in the final conditional store. | |
80 | |
81 * We use cstorecc4 pattern to convert the CCmode intermediate to | |
82 the integer mode result that expand_normal is expecting. | |
83 | |
84 Since the operands of the later compares might clobber CC reg, we do not | |
85 emit the insns during expand. We keep the insn sequences in two seq | |
86 | |
87 * prep_seq, which includes all the insns to prepare the operands. | |
88 * gen_seq, which includes all the compare and conditional compares. | |
89 | |
90 If all checks OK in expand_ccmp_expr, it emits insns in prep_seq, then | |
91 insns in gen_seq. */ | |
92 | |
93 /* Check whether G is a potential conditional compare candidate. */ | |
94 static bool | |
95 ccmp_candidate_p (gimple *g) | |
96 { | |
97 tree rhs; | |
98 tree lhs, op0, op1; | |
99 gimple *gs0, *gs1; | |
100 tree_code tcode; | |
101 basic_block bb; | |
102 | |
103 if (!g) | |
104 return false; | |
105 | |
106 rhs = gimple_assign_rhs_to_tree (g); | |
107 tcode = TREE_CODE (rhs); | |
108 if (tcode != BIT_AND_EXPR && tcode != BIT_IOR_EXPR) | |
109 return false; | |
110 | |
111 lhs = gimple_assign_lhs (g); | |
112 op0 = TREE_OPERAND (rhs, 0); | |
113 op1 = TREE_OPERAND (rhs, 1); | |
114 bb = gimple_bb (g); | |
115 | |
116 if ((TREE_CODE (op0) != SSA_NAME) || (TREE_CODE (op1) != SSA_NAME) | |
117 || !has_single_use (lhs)) | |
118 return false; | |
119 | |
120 gs0 = get_gimple_for_ssa_name (op0); /* gs0 may be NULL */ | |
121 gs1 = get_gimple_for_ssa_name (op1); /* gs1 may be NULL */ | |
122 | |
123 if (ccmp_tree_comparison_p (op0, bb) && ccmp_tree_comparison_p (op1, bb)) | |
124 return true; | |
125 if (ccmp_tree_comparison_p (op0, bb) && ccmp_candidate_p (gs1)) | |
126 return true; | |
127 if (ccmp_tree_comparison_p (op1, bb) && ccmp_candidate_p (gs0)) | |
128 return true; | |
129 /* We skip ccmp_candidate_p (gs1) && ccmp_candidate_p (gs0) since | |
130 there is no way to set and maintain the CC flag on both sides of | |
131 the logical operator at the same time. */ | |
132 return false; | |
133 } | |
134 | |
135 /* Extract the comparison we want to do from the tree. */ | |
136 void | |
137 get_compare_parts (tree t, int *up, rtx_code *rcode, | |
138 tree *rhs1, tree *rhs2) | |
139 { | |
140 tree_code code; | |
141 gimple *g = get_gimple_for_ssa_name (t); | |
142 if (g) | |
143 { | |
144 *up = TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (g))); | |
145 code = gimple_assign_rhs_code (g); | |
146 *rcode = get_rtx_code (code, *up); | |
147 *rhs1 = gimple_assign_rhs1 (g); | |
148 *rhs2 = gimple_assign_rhs2 (g); | |
149 } | |
150 else | |
151 { | |
152 /* If g is not a comparison operator create a compare to zero. */ | |
153 *up = 1; | |
154 *rcode = NE; | |
155 *rhs1 = t; | |
156 *rhs2 = build_zero_cst (TREE_TYPE (t)); | |
157 } | |
158 } | |
159 | |
160 /* PREV is a comparison with the CC register which represents the | |
161 result of the previous CMP or CCMP. The function expands the | |
162 next compare based on G which is ANDed/ORed with the previous | |
163 compare depending on CODE. | |
164 PREP_SEQ returns all insns to prepare opearands for compare. | |
165 GEN_SEQ returns all compare insns. */ | |
166 static rtx | |
167 expand_ccmp_next (tree op, tree_code code, rtx prev, | |
168 rtx_insn **prep_seq, rtx_insn **gen_seq) | |
169 { | |
170 rtx_code rcode; | |
171 int unsignedp; | |
172 tree rhs1, rhs2; | |
173 | |
174 get_compare_parts(op, &unsignedp, &rcode, &rhs1, &rhs2); | |
175 return targetm.gen_ccmp_next (prep_seq, gen_seq, prev, rcode, | |
176 rhs1, rhs2, get_rtx_code (code, 0)); | |
177 } | |
178 | |
179 /* Expand conditional compare gimple G. A typical CCMP sequence is like: | |
180 | |
181 CC0 = CMP (a, b); | |
182 CC1 = CCMP (NE (CC0, 0), CMP (e, f)); | |
183 ... | |
184 CCn = CCMP (NE (CCn-1, 0), CMP (...)); | |
185 | |
186 hook gen_ccmp_first is used to expand the first compare. | |
187 hook gen_ccmp_next is used to expand the following CCMP. | |
188 PREP_SEQ returns all insns to prepare opearand. | |
189 GEN_SEQ returns all compare insns. */ | |
190 static rtx | |
191 expand_ccmp_expr_1 (gimple *g, rtx_insn **prep_seq, rtx_insn **gen_seq) | |
192 { | |
193 tree exp = gimple_assign_rhs_to_tree (g); | |
194 tree_code code = TREE_CODE (exp); | |
195 basic_block bb = gimple_bb (g); | |
196 | |
197 tree op0 = TREE_OPERAND (exp, 0); | |
198 tree op1 = TREE_OPERAND (exp, 1); | |
199 gimple *gs0 = get_gimple_for_ssa_name (op0); | |
200 gimple *gs1 = get_gimple_for_ssa_name (op1); | |
201 rtx tmp; | |
202 | |
203 gcc_assert (code == BIT_AND_EXPR || code == BIT_IOR_EXPR); | |
204 | |
205 if (ccmp_tree_comparison_p (op0, bb)) | |
206 { | |
207 if (ccmp_tree_comparison_p (op1, bb)) | |
208 { | |
209 int unsignedp0, unsignedp1; | |
210 rtx_code rcode0, rcode1; | |
211 tree logical_op0_rhs1, logical_op0_rhs2; | |
212 tree logical_op1_rhs1, logical_op1_rhs2; | |
213 int speed_p = optimize_insn_for_speed_p (); | |
214 | |
215 rtx tmp2 = NULL_RTX, ret = NULL_RTX, ret2 = NULL_RTX; | |
216 unsigned cost1 = MAX_COST; | |
217 unsigned cost2 = MAX_COST; | |
218 | |
219 get_compare_parts (op0, &unsignedp0, &rcode0, | |
220 &logical_op0_rhs1, &logical_op0_rhs2); | |
221 | |
222 get_compare_parts (op1, &unsignedp1, &rcode1, | |
223 &logical_op1_rhs1, &logical_op1_rhs2); | |
224 | |
225 rtx_insn *prep_seq_1, *gen_seq_1; | |
226 tmp = targetm.gen_ccmp_first (&prep_seq_1, &gen_seq_1, rcode0, | |
227 logical_op0_rhs1, logical_op0_rhs2); | |
228 if (tmp != NULL) | |
229 { | |
230 ret = expand_ccmp_next (op1, code, tmp, &prep_seq_1, &gen_seq_1); | |
231 cost1 = seq_cost (prep_seq_1, speed_p); | |
232 cost1 += seq_cost (gen_seq_1, speed_p); | |
233 } | |
234 | |
235 /* FIXME: Temporary workaround for PR69619. | |
236 Avoid exponential compile time due to expanding gs0 and gs1 twice. | |
237 If gs0 and gs1 are complex, the cost will be high, so avoid | |
238 reevaluation if above an arbitrary threshold. */ | |
239 rtx_insn *prep_seq_2, *gen_seq_2; | |
240 if (tmp == NULL || cost1 < COSTS_N_INSNS (25)) | |
241 tmp2 = targetm.gen_ccmp_first (&prep_seq_2, &gen_seq_2, rcode1, | |
242 logical_op1_rhs1, logical_op1_rhs2); | |
243 if (!tmp && !tmp2) | |
244 return NULL_RTX; | |
245 if (tmp2 != NULL) | |
246 { | |
247 ret2 = expand_ccmp_next (op0, code, tmp2, &prep_seq_2, | |
248 &gen_seq_2); | |
249 cost2 = seq_cost (prep_seq_2, speed_p); | |
250 cost2 += seq_cost (gen_seq_2, speed_p); | |
251 } | |
252 if (cost2 < cost1) | |
253 { | |
254 *prep_seq = prep_seq_2; | |
255 *gen_seq = gen_seq_2; | |
256 return ret2; | |
257 } | |
258 *prep_seq = prep_seq_1; | |
259 *gen_seq = gen_seq_1; | |
260 return ret; | |
261 } | |
262 else | |
263 { | |
264 tmp = expand_ccmp_expr_1 (gs1, prep_seq, gen_seq); | |
265 if (!tmp) | |
266 return NULL_RTX; | |
267 return expand_ccmp_next (op0, code, tmp, prep_seq, gen_seq); | |
268 } | |
269 } | |
270 else | |
271 { | |
272 gcc_assert (gimple_assign_rhs_code (gs0) == BIT_AND_EXPR | |
273 || gimple_assign_rhs_code (gs0) == BIT_IOR_EXPR); | |
274 gcc_assert (ccmp_tree_comparison_p (op1, bb)); | |
275 tmp = expand_ccmp_expr_1 (gs0, prep_seq, gen_seq); | |
276 if (!tmp) | |
277 return NULL_RTX; | |
278 return expand_ccmp_next (op1, code, tmp, prep_seq, gen_seq); | |
279 } | |
280 | |
281 return NULL_RTX; | |
282 } | |
283 | |
284 /* Main entry to expand conditional compare statement G. | |
285 Return NULL_RTX if G is not a legal candidate or expand fail. | |
286 Otherwise return the target. */ | |
287 rtx | |
288 expand_ccmp_expr (gimple *g, machine_mode mode) | |
289 { | |
290 rtx_insn *last; | |
291 rtx tmp; | |
292 | |
293 if (!ccmp_candidate_p (g)) | |
294 return NULL_RTX; | |
295 | |
296 last = get_last_insn (); | |
297 | |
298 rtx_insn *prep_seq = NULL, *gen_seq = NULL; | |
299 tmp = expand_ccmp_expr_1 (g, &prep_seq, &gen_seq); | |
300 | |
301 if (tmp) | |
302 { | |
303 insn_code icode; | |
304 machine_mode cc_mode = CCmode; | |
305 rtx_code cmp_code = GET_CODE (tmp); | |
306 | |
307 #ifdef SELECT_CC_MODE | |
308 cc_mode = SELECT_CC_MODE (cmp_code, XEXP (tmp, 0), const0_rtx); | |
309 #endif | |
310 icode = optab_handler (cstore_optab, cc_mode); | |
311 if (icode != CODE_FOR_nothing) | |
312 { | |
313 rtx target = gen_reg_rtx (mode); | |
314 | |
315 emit_insn (prep_seq); | |
316 emit_insn (gen_seq); | |
317 | |
318 tmp = emit_cstore (target, icode, cmp_code, cc_mode, cc_mode, | |
319 0, XEXP (tmp, 0), const0_rtx, 1, mode); | |
320 if (tmp) | |
321 return tmp; | |
322 } | |
323 } | |
324 /* Clean up. */ | |
325 delete_insns_since (last); | |
326 return NULL_RTX; | |
327 } |