extra comments in svp64
[soc.git] / src / soc / sv / trans / svp64.py
1 # SPDX-License-Identifier: LGPLv3+
2 # Copyright (C) 2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
3 # Funded by NLnet http://nlnet.nl
4
5 """SVP64 OpenPOWER v3.0B assembly translator
6
7 This class takes raw svp64 assembly mnemonics (aliases excluded) and
8 creates an EXT001-encoded "svp64 prefix" followed by a v3.0B opcode.
9
10 It is very simple and straightforward, the only weirdness being the
11 extraction of the register information and conversion to v3.0B numbering.
12
13 Encoding format of svp64: https://libre-soc.org/openpower/sv/svp64/
14 Bugtracker: https://bugs.libre-soc.org/show_bug.cgi?id=578
15 """
16
17 import os, sys
18 from collections import OrderedDict
19
20 from soc.decoder.pseudo.pagereader import ISA
21 from soc.decoder.power_enums import get_csv, find_wiki_dir
22
23
24 # identifies register by type
25 def is_CR_3bit(regname):
26 return regname in ['BF', 'BFA']
27
28 def is_CR_5bit(regname):
29 return regname in ['BA', 'BB', 'BC', 'BI', 'BT']
30
31 def is_GPR(regname):
32 return regname in ['RA', 'RB', 'RC', 'RS', 'RT']
33
34 def get_regtype(regname):
35 if is_CR_3bit(regname):
36 return "CR_3bit"
37 if is_CR_5bit(regname):
38 return "CR_5bit"
39 if is_GPR(regname):
40 return "GPR"
41
42 # decode GPR into sv extra
43 def get_extra_gpr(etype, regmode, field):
44 if regmode == 'scalar':
45 # cut into 2-bits 5-bits SS FFFFF
46 sv_extra = field >> 5
47 field = field & 0b11111
48 else:
49 # cut into 5-bits 2-bits FFFFF SS
50 sv_extra = field & 0b11
51 field = field >> 2
52 return sv_extra, field
53
54
55 # decode 3-bit CR into sv extra
56 def get_extra_cr_3bit(etype, regmode, field):
57 if regmode == 'scalar':
58 # cut into 2-bits 3-bits SS FFF
59 sv_extra = field >> 3
60 field = field & 0b111
61 else:
62 # cut into 3-bits 4-bits FFF SSSS but will cut 2 zeros off later
63 sv_extra = field & 0b1111
64 field = field >> 4
65 return sv_extra, field
66
67
68 # decodes SUBVL
69 def decode_subvl(encoding):
70 pmap = {'2': 0b01, '3': 0b10, '4': 0b11}
71 assert encoding in pmap, \
72 "encoding %s for SUBVL not recognised" % encoding
73 return pmap[encoding]
74
75
76 # decodes elwidth
77 def decode_elwidth(encoding):
78 pmap = {'8': 0b11, '16': 0b10, '32': 0b01}
79 assert encoding in pmap, \
80 "encoding %s for elwidth not recognised" % encoding
81 return pmap[encoding]
82
83
84 # decodes predicate register encoding
85 def decode_predicate(encoding):
86 pmap = { # integer
87 '1<<r3': (0, 0b001),
88 'r3' : (0, 0b010),
89 '~r3' : (0, 0b011),
90 'r10' : (0, 0b100),
91 '~r10' : (0, 0b101),
92 'r30' : (0, 0b110),
93 '~r30' : (0, 0b111),
94 # CR
95 'lt' : (1, 0b000),
96 'nl' : (1, 0b001), 'ge' : (1, 0b001), # same value
97 'gt' : (1, 0b010),
98 'ng' : (1, 0b011), 'le' : (1, 0b011), # same value
99 'eq' : (1, 0b100),
100 'ne' : (1, 0b101),
101 'so' : (1, 0b110), 'un' : (1, 0b110), # same value
102 'ns' : (1, 0b111), 'nu' : (1, 0b111), # same value
103 }
104 assert encoding in pmap, \
105 "encoding %s for predicate not recognised" % encoding
106 return pmap[encoding]
107
108
109 # decodes "Mode" in similar way to BO field (supposed to, anyway)
110 def decode_bo(encoding):
111 pmap = { # TODO: double-check that these are the same as Branch BO
112 'lt' : 0b000,
113 'nl' : 0b001, 'ge' : 0b001, # same value
114 'gt' : 0b010,
115 'ng' : 0b011, 'le' : 0b011, # same value
116 'eq' : 0b100,
117 'ne' : 0b101,
118 'so' : 0b110, 'un' : 0b110, # same value
119 'ns' : 0b111, 'nu' : 0b111, # same value
120 }
121 assert encoding in pmap, \
122 "encoding %s for BO Mode not recognised" % encoding
123 return pmap[encoding]
124
125 # partial-decode fail-first mode
126 def decode_ffirst(encoding):
127 if encoding in ['RC1', '~RC1']:
128 return encoding
129 return decode_bo(encoding)
130
131
132 # gets SVP64 ReMap information
133 class SVP64RM:
134 def __init__(self):
135 self.instrs = {}
136 pth = find_wiki_dir()
137 for fname in os.listdir(pth):
138 if fname.startswith("RM"):
139 for entry in get_csv(fname):
140 self.instrs[entry['insn']] = entry
141
142
143 # decodes svp64 assembly listings and creates EXT001 svp64 prefixes
144 class SVP64:
145 def __init__(self, lst):
146 self.lst = lst
147 self.trans = self.translate(lst)
148
149 def __iter__(self):
150 for insn in self.trans:
151 yield insn
152
153 def translate(self, lst):
154 isa = ISA() # reads the v3.0B pseudo-code markdown files
155 svp64 = SVP64RM() # reads the svp64 Remap entries for registers
156 res = []
157 for insn in lst:
158 # find first space, to get opcode
159 ls = insn.split(' ')
160 opcode = ls[0]
161 # now find opcode fields
162 fields = ''.join(ls[1:]).split(',')
163 fields = list(map(str.strip, fields))
164 print ("opcode, fields", ls, opcode, fields)
165
166 # identify if is a svp64 mnemonic
167 if not opcode.startswith('sv.'):
168 res.append(insn) # unaltered
169 continue
170 opcode = opcode[3:] # strip leading "sv."
171
172 # start working on decoding the svp64 op: sv.basev30Bop/vec2/mode
173 opmodes = opcode.split("/") # split at "/"
174 v30b_op = opmodes.pop(0) # first is the v3.0B
175 # check instruction ends with dot
176 rc_mode = v30b_op.endswith('.')
177 if rc_mode:
178 v30b_op = v30b_op[:-1]
179
180 if v30b_op not in isa.instr:
181 raise Exception("opcode %s of '%s' not supported" % \
182 (v30b_op, insn))
183 if v30b_op not in svp64.instrs:
184 raise Exception("opcode %s of '%s' not an svp64 instruction" % \
185 (v30b_op, insn))
186 v30b_regs = isa.instr[v30b_op].regs[0] # get regs info "RT, RA, RB"
187 rm = svp64.instrs[v30b_op] # one row of the svp64 RM CSV
188 print ("v3.0B op", v30b_op, "Rc=1" if rc_mode else '')
189 print ("v3.0B regs", opcode, v30b_regs)
190 print (rm)
191
192 # right. the first thing to do is identify the ordering of
193 # the registers, by name. the EXTRA2/3 ordering is in
194 # rm['0']..rm['3'] but those fields contain the names RA, BB
195 # etc. we have to read the pseudocode to understand which
196 # reg is which in our instruction. sigh.
197
198 # first turn the svp64 rm into a "by name" dict, recording
199 # which position in the RM EXTRA it goes into
200 # also: record if the src or dest was a CR, for sanity-checking
201 # (elwidth overrides on CRs are banned)
202 dest_reg_cr, src_reg_cr = False, False
203 svp64_reg_byname = {}
204 for i in range(4):
205 rfield = rm[str(i)]
206 if not rfield or rfield == '0':
207 continue
208 print ("EXTRA field", i, rfield)
209 rfield = rfield.split(";") # s:RA;d:CR1 etc.
210 for r in rfield:
211 rtype = r[0]
212 # TODO: ignoring s/d makes it impossible to do
213 # LD/ST-with-update.
214 r = r[2:] # ignore s: and d:
215 svp64_reg_byname[r] = i # this reg in EXTRA position 0-3
216 # check the regtype (if CR, record that)
217 regtype = get_regtype(r)
218 if regtype in ['CR_3bit', 'CR_5bit']:
219 if rtype == 'd':
220 dest_reg_cr = True
221 if rtype == 'd':
222 src_reg_cr = True
223
224 print ("EXTRA field index, by regname", svp64_reg_byname)
225
226 # okaaay now we identify the field value (opcode N,N,N) with
227 # the pseudo-code info (opcode RT, RA, RB)
228 assert len(fields) == len(v30b_regs), \
229 "length of fields %s must match insn `%s`" % \
230 (str(v30b_regs), insn)
231 opregfields = zip(fields, v30b_regs) # err that was easy
232
233 # now for each of those find its place in the EXTRA encoding
234 extras = OrderedDict()
235 for idx, (field, regname) in enumerate(opregfields):
236 extra = svp64_reg_byname.get(regname, None)
237 regtype = get_regtype(regname)
238 extras[extra] = (idx, field, regname, regtype)
239 print (" ", extra, extras[extra])
240
241 # great! got the extra fields in their associated positions:
242 # also we know the register type. now to create the EXTRA encodings
243 etype = rm['Etype'] # Extra type: EXTRA3/EXTRA2
244 ptype = rm['Ptype'] # Predication type: Twin / Single
245 extra_bits = 0
246 v30b_newfields = []
247 for extra_idx, (idx, field, regname, regtype) in extras.items():
248 # is it a field we don't alter/examine? if so just put it
249 # into newfields
250 if regtype is None:
251 v30b_newfields.append(field)
252
253 # first, decode the field number. "5.v" or "3.s" or "9"
254 field = field.split(".")
255 regmode = 'scalar' # default
256 if len(field) == 2:
257 if field[1] == 's':
258 regmode = 'scalar'
259 elif field[1] == 'v':
260 regmode = 'vector'
261 field = int(field[0]) # actual register number
262 print (" ", regmode, field, end=" ")
263
264 # XXX TODO: the following is a bit of a laborious repeated
265 # mess, which could (and should) easily be parameterised.
266
267 # encode SV-GPR field into extra, v3.0field
268 if regtype == 'GPR':
269 sv_extra, field = get_extra_gpr(etype, regmode, field)
270 # now sanity-check. EXTRA3 is ok, EXTRA2 has limits
271 # (and shrink to a single bit if ok)
272 if etype == 'EXTRA2':
273 if regmode == 'scalar':
274 # range is r0-r63 in increments of 1
275 assert (sv_extra >> 1) == 0, \
276 "scalar GPR %s cannot fit into EXTRA2 %s" % \
277 (regname, str(extras[extra_idx]))
278 # all good: encode as scalar
279 sv_extra = sv_extra & 0b01
280 else:
281 # range is r0-r127 in increments of 4
282 assert sv_extra & 0b01 == 0, \
283 "vector field %s cannot fit into EXTRA2 %s" % \
284 (regname, str(extras[extra_idx]))
285 # all good: encode as vector (bit 2 set)
286 sv_extra = 0b10 | (sv_extra >> 1)
287 elif regmode == 'vector':
288 # EXTRA3 vector bit needs marking
289 sv_extra |= 0b100
290
291 # encode SV-CR 3-bit field into extra, v3.0field
292 elif regtype == 'CR_3bit':
293 sv_extra, field = get_extra_cr_3bit(etype, regmode, field)
294 # now sanity-check (and shrink afterwards)
295 if etype == 'EXTRA2':
296 if regmode == 'scalar':
297 # range is CR0-CR15 in increments of 1
298 assert (sv_extra >> 1) == 0, \
299 "scalar CR %s cannot fit into EXTRA2 %s" % \
300 (regname, str(extras[extra_idx]))
301 # all good: encode as scalar
302 sv_extra = sv_extra & 0b01
303 else:
304 # range is CR0-CR127 in increments of 16
305 assert sv_extra & 0b111 == 0, \
306 "vector CR %s cannot fit into EXTRA2 %s" % \
307 (regname, str(extras[extra_idx]))
308 # all good: encode as vector (bit 2 set)
309 sv_extra = 0b10 | (sv_extra >> 3)
310 else:
311 if regmode == 'scalar':
312 # range is CR0-CR31 in increments of 1
313 assert (sv_extra >> 2) == 0, \
314 "scalar CR %s cannot fit into EXTRA2 %s" % \
315 (regname, str(extras[extra_idx]))
316 # all good: encode as scalar
317 sv_extra = sv_extra & 0b11
318 else:
319 # range is CR0-CR127 in increments of 8
320 assert sv_extra & 0b11 == 0, \
321 "vector CR %s cannot fit into EXTRA2 %s" % \
322 (regname, str(extras[extra_idx]))
323 # all good: encode as vector (bit 3 set)
324 sv_extra = 0b100 | (sv_extra >> 2)
325
326 # encode SV-CR 5-bit field into extra, v3.0field
327 # *sigh* this is the same as 3-bit except the 2 LSBs are
328 # passed through
329 elif regtype == 'CR_5bit':
330 cr_subfield = field & 0b11
331 field = field >> 2 # strip bottom 2 bits
332 sv_extra, field = get_extra_cr_3bit(etype, regmode, field)
333 # now sanity-check (and shrink afterwards)
334 if etype == 'EXTRA2':
335 if regmode == 'scalar':
336 # range is CR0-CR15 in increments of 1
337 assert (sv_extra >> 1) == 0, \
338 "scalar CR %s cannot fit into EXTRA2 %s" % \
339 (regname, str(extras[extra_idx]))
340 # all good: encode as scalar
341 sv_extra = sv_extra & 0b01
342 else:
343 # range is CR0-CR127 in increments of 16
344 assert sv_extra & 0b111 == 0, \
345 "vector CR %s cannot fit into EXTRA2 %s" % \
346 (regname, str(extras[extra_idx]))
347 # all good: encode as vector (bit 2 set)
348 sv_extra = 0b10 | (sv_extra >> 3)
349 else:
350 if regmode == 'scalar':
351 # range is CR0-CR31 in increments of 1
352 assert (sv_extra >> 2) == 0, \
353 "scalar CR %s cannot fit into EXTRA2 %s" % \
354 (regname, str(extras[extra_idx]))
355 # all good: encode as scalar
356 sv_extra = sv_extra & 0b11
357 else:
358 # range is CR0-CR127 in increments of 8
359 assert sv_extra & 0b11 == 0, \
360 "vector CR %s cannot fit into EXTRA2 %s" % \
361 (regname, str(extras[extra_idx]))
362 # all good: encode as vector (bit 3 set)
363 sv_extra = 0b100 | (sv_extra >> 2)
364
365 # reconstruct the actual 5-bit CR field
366 field = (field << 2) | cr_subfield
367
368 # capture the extra field info
369 print ("=>", "%5s" % bin(sv_extra), field)
370 extras[extra_idx] = sv_extra
371
372 # append altered field value to v3.0b
373 v30b_newfields.append(str(field))
374
375 print ("new v3.0B fields", v30b_op, v30b_newfields)
376 print ("extras", extras)
377
378 # rright. now we have all the info. start creating SVP64 RM
379 svp64_rm = 0b0
380
381 # begin with EXTRA fields
382 for idx, sv_extra in extras.items():
383 if idx is None: continue
384 # start at bit 10, work up 2/3 times EXTRA idx
385 offs = 2 if etype == 'EXTRA2' else 3 # 2 or 3 bits
386 svp64_rm |= sv_extra << (10+idx*offs)
387
388 # parts of svp64_rm
389 mmode = 0 # bit 0
390 pmask = 0 # bits 1-3
391 destwid = 0 # bits 4-5
392 srcwid = 0 # bits 6-7
393 subvl = 0 # bits 8-9
394 smask = 0 # bits 16-18 but only for twin-predication
395 mode = 0 # bits 19-23
396
397 has_pmask = False
398 has_smask = False
399
400 saturation = None
401 src_zero = 0
402 dst_zero = 0
403 sv_mode = None
404
405 mapreduce = False
406 mapreduce_crm = False
407 mapreduce_svm = False
408
409 predresult = False
410 failfirst = False
411
412 # ok let's start identifying opcode augmentation fields
413 for encmode in opmodes:
414 # predicate mask (dest)
415 if encmode.startswith("m="):
416 pme = encmode
417 pmmode, pmask = decode_predicate(encmode[2:])
418 mmode = pmmode
419 has_pmask = True
420 # predicate mask (src, twin-pred)
421 elif encmode.startswith("sm="):
422 sme = encmode
423 smmode, smask = decode_predicate(encmode[3:])
424 mmode = smmode
425 has_smask = True
426 # vec2/3/4
427 elif encmode.startswith("vec"):
428 subvl = decode_subvl(encmode[3:])
429 # elwidth
430 elif encmode.startswith("ew="):
431 destwid = decode_elwidth(encmode[3:])
432 elif encmode.startswith("sw="):
433 srcwid = decode_elwidth(encmode[3:])
434 # saturation
435 elif encmode == 'sats':
436 assert sv_mode is None
437 saturation = 1
438 sv_mode = 0b10
439 elif encmode == 'satu':
440 assert sv_mode is None
441 sv_mode = 0b10
442 saturation = 0
443 # predicate zeroing
444 elif encmode == 'sz':
445 src_zero = 1
446 elif encmode == 'dz':
447 dst_zero = 1
448 # failfirst
449 elif encmode.startswith("ff="):
450 assert sv_mode is None
451 sv_mode = 0b01
452 failfirst = decode_ffirst(encmode[3:])
453 # predicate-result, interestingly same as fail-first
454 elif encmode.startswith("pr="):
455 assert sv_mode is None
456 sv_mode = 0b11
457 predresult = decode_ffirst(encmode[3:])
458 # map-reduce mode
459 elif encmode == 'mr':
460 assert sv_mode is None
461 sv_mode = 0b00
462 mapreduce = True
463 elif encmode == 'crm': # CR on map-reduce
464 assert sv_mode is None
465 sv_mode = 0b00
466 mapreduce_crm = True
467 elif encmode == 'svm': # sub-vector mode
468 mapreduce_svm = True
469
470 # sanity-check that 2Pred mask is same mode
471 if has_pmask and has_smask:
472 assert smmode == pmmode, \
473 "predicate masks %s and %s must be same reg type" % \
474 (pme, sme)
475
476 # sanity-check that twin-predication mask only specified in 2P mode
477 if ptype == '1P':
478 assert has_smask == False, \
479 "source-mask can only be specified on Twin-predicate ops"
480
481 # construct the mode field, doing sanity-checking along the way
482
483 if mapreduce_svm:
484 assert sv_mode == 0b00, "sub-vector mode in mapreduce only"
485 assert subvl != 0, "sub-vector mode not possible on SUBVL=1"
486
487 if src_zero:
488 assert has_smask, "src zeroing requires a source predicate"
489 if dst_zero:
490 assert has_pmask, "dest zeroing requires a dest predicate"
491
492 # "normal" mode
493 if sv_mode is None:
494 mode |= (src_zero << 3) | (dst_zero << 4) # predicate zeroing
495 sv_mode = 0b00
496
497 # "mapreduce" modes
498 elif sv_mode == 0b00:
499 mode |= (0b1<<2) # sets mapreduce
500 assert dst_zero == 0, "dest-zero not allowed in mapreduce mode"
501 if mapreduce_crm:
502 mode |= (0b1<<4) # sets CRM mode
503 assert rc_mode, "CRM only allowed when Rc=1"
504 # bit of weird encoding to jam zero-pred or SVM mode in.
505 # SVM mode can be enabled only when SUBVL=2/3/4 (vec2/3/4)
506 if subvl == 0:
507 mode |= (src_zero << 3) # predicate src-zeroing
508 elif mapreduce_svm:
509 mode |= (1 << 3) # SVM mode
510
511 # "failfirst" modes
512 elif sv_mode == 0b01:
513 assert dst_zero == 0, "dest-zero not allowed in failfirst mode"
514 if failfirst == 'RC1':
515 mode |= (0b1<<4) # sets RC1 mode
516 mode |= (src_zero << 3) # predicate src-zeroing
517 assert rc_mode==False, "ffirst RC1 only possible when Rc=0"
518 elif failfirst == '~RC1':
519 mode |= (0b1<<4) # sets RC1 mode...
520 mode |= (src_zero << 3) # predicate src-zeroing
521 mode |= (0b1<<2) # ... with inversion
522 assert rc_mode==False, "ffirst RC1 only possible when Rc=0"
523 else:
524 assert src_zero == 0, "src-zero not allowed in ffirst BO"
525 assert rc_mode, "ffirst BO only possible when Rc=1"
526 mode |= (failfirst << 2) # set BO
527
528 # "saturation" modes
529 elif sv_mode == 0b10:
530 mode |= (src_zero << 3) | (dst_zero << 4) # predicate zeroing
531 mode |= (saturation<<2) # sets signed/unsigned saturation
532
533 # "predicate-result" modes. err... code-duplication from ffirst
534 elif sv_mode == 0b11:
535 assert dst_zero == 0, "dest-zero not allowed in predresult mode"
536 if predresult == 'RC1':
537 mode |= (0b1<<4) # sets RC1 mode
538 mode |= (src_zero << 3) # predicate src-zeroing
539 assert rc_mode==False, "pr-mode RC1 only possible when Rc=0"
540 elif predresult == '~RC1':
541 mode |= (0b1<<4) # sets RC1 mode...
542 mode |= (src_zero << 3) # predicate src-zeroing
543 mode |= (0b1<<2) # ... with inversion
544 assert rc_mode==False, "pr-mode RC1 only possible when Rc=0"
545 else:
546 assert src_zero == 0, "src-zero not allowed in pr-mode BO"
547 assert rc_mode, "pr-mode BO only possible when Rc=1"
548 mode |= (predresult << 2) # set BO
549
550 # whewww.... modes all done :)
551 # now put into svp64_rm
552 mode |= sv_mode
553 svp64_rm |= (mode << 19) # mode: bits 19-23
554
555 # put in predicate masks into svp64_rm
556 if ptype == '2P':
557 svp64_rm |= (smask << 16) # source pred: bits 16-18
558 svp64_rm |= (mmode) # mask mode: bit 0
559 svp64_rm |= (pmask << 1) # 1-pred: bits 1-3
560
561 # and subvl
562 svp64_rm += (subvl << 8) # subvl: bits 8-9
563
564 # put in elwidths
565 svp64_rm += (srcwid << 6) # srcwid: bits 6-7
566 svp64_rm += (destwid << 4) # destwid: bits 4-5
567
568 # nice debug printout. (and now for something completely different)
569 # https://youtu.be/u0WOIwlXE9g?t=146
570 print ("svp64_rm", hex(svp64_rm), bin(svp64_rm))
571 print (" mmode 0 :", bin(mmode))
572 print (" pmask 1-3 :", bin(pmask))
573 print (" dstwid 4-5 :", bin(destwid))
574 print (" srcwid 6-7 :", bin(srcwid))
575 print (" subvl 8-9 :", bin(subvl))
576 print (" mode 19-23:", bin(mode))
577 offs = 2 if etype == 'EXTRA2' else 3 # 2 or 3 bits
578 for idx, sv_extra in extras.items():
579 if idx is None: continue
580 start = (10+idx*offs)
581 end = start + offs-1
582 print (" extra%d %2d-%2d:" % (idx, start, end),
583 bin(sv_extra))
584 if ptype == '2P':
585 print (" smask 16-17:", bin(smask))
586 print ()
587
588 return res
589
590 if __name__ == '__main__':
591 isa = SVP64(['slw 3, 1, 4',
592 'extsw 5, 3',
593 'sv.extsw 5, 3',
594 'sv.cmpi 5, 1, 3, 2',
595 'sv.setb 5, 31',
596 'sv.isel 64.v, 3, 2, 65.v',
597 'sv.setb/m=r3/sm=1<<r3 5, 31',
598 'sv.setb/vec2 5, 31',
599 'sv.setb/sw=8/ew=16 5, 31',
600 'sv.extsw./ff=eq 5, 31',
601 'sv.extsw./satu/sz/dz/sm=r3/m=r3 5, 31',
602 'sv.extsw./pr=eq 5.v, 31',
603 ])
604 csvs = SVP64RM()