1 """Power ISA Decoder second stage
3 based on Anton Blanchard microwatt decode2.vhdl
5 Note: OP_TRAP is used for exceptions and interrupts (micro-code style) by
6 over-riding the internal opcode when an exception is needed.
9 from nmigen
import Module
, Elaboratable
, Signal
, Mux
, Const
, Cat
, Repl
, Record
10 from nmigen
.cli
import rtlil
11 from soc
.regfile
.regfiles
import XERRegs
13 from nmutil
.picker
import PriorityPicker
14 from nmutil
.iocontrol
import RecordObject
15 from nmutil
.extend
import exts
17 from soc
.experiment
.mem_types
import LDSTException
19 from soc
.decoder
.power_regspec_map
import regspec_decode_read
20 from soc
.decoder
.power_regspec_map
import regspec_decode_write
21 from soc
.decoder
.power_decoder
import create_pdecode
22 from soc
.decoder
.power_enums
import (MicrOp
, CryIn
, Function
,
24 LdstLen
, In1Sel
, In2Sel
, In3Sel
,
25 OutSel
, SPR
, RC
, LDSTMode
,
27 from soc
.decoder
.decode2execute1
import (Decode2ToExecute1Type
, Data
,
29 from soc
.sv
.svp64
import SVP64Rec
30 from soc
.consts
import MSR
32 from soc
.regfile
.regfiles
import FastRegs
33 from soc
.consts
import TT
34 from soc
.config
.state
import CoreState
35 from soc
.regfile
.util
import spr_to_fast
38 def decode_spr_num(spr
):
39 return Cat(spr
[5:10], spr
[0:5])
42 def instr_is_priv(m
, op
, insn
):
43 """determines if the instruction is privileged or not
46 is_priv_insn
= Signal(reset_less
=True)
48 with m
.Case(MicrOp
.OP_ATTN
, MicrOp
.OP_MFMSR
, MicrOp
.OP_MTMSRD
,
49 MicrOp
.OP_MTMSR
, MicrOp
.OP_RFID
):
50 comb
+= is_priv_insn
.eq(1)
52 #with m.Case(MicrOp.OP_TLBIE) : comb += is_priv_insn.eq(1)
53 with m
.Case(MicrOp
.OP_MFSPR
, MicrOp
.OP_MTSPR
):
54 with m
.If(insn
[20]): # field XFX.spr[-1] i think
55 comb
+= is_priv_insn
.eq(1)
59 class SPRMap(Elaboratable
):
60 """SPRMap: maps POWER9 SPR numbers to internal enum values, fast and slow
64 self
.spr_i
= Signal(10, reset_less
=True)
65 self
.spr_o
= Data(SPR
, name
="spr_o")
66 self
.fast_o
= Data(3, name
="fast_o")
68 def elaborate(self
, platform
):
70 with m
.Switch(self
.spr_i
):
71 for i
, x
in enumerate(SPR
):
73 m
.d
.comb
+= self
.spr_o
.data
.eq(i
)
74 m
.d
.comb
+= self
.spr_o
.ok
.eq(1)
75 for x
, v
in spr_to_fast
.items():
77 m
.d
.comb
+= self
.fast_o
.data
.eq(v
)
78 m
.d
.comb
+= self
.fast_o
.ok
.eq(1)
82 class SVP64ExtraSpec(Elaboratable
):
83 """SVP64ExtraSpec - decodes SVP64 Extra specification.
85 selects the required EXTRA2/3 field.
87 see https://libre-soc.org/openpower/sv/svp64/
90 self
.extra
= Signal(10, reset_less
=True)
91 self
.etype
= Signal(SVEtype
, reset_less
=True) # 2 or 3 bits
92 self
.idx
= Signal(SVEXTRA
, reset_less
=True) # which part of extra
93 self
.spec
= Signal(3) # EXTRA spec for the register
95 def elaborate(self
, platform
):
100 # back in the LDSTRM-* and RM-* files generated by sv_analysis.py
101 # we marked every op with an Etype: EXTRA2 or EXTRA3, and also said
102 # which of the 4 (or 3 for EXTRA3) sub-fields of bits 10:18 contain
103 # the register-extension information. extract those now
104 with m
.Switch(self
.etype
):
105 # 2-bit index selection mode
106 with m
.Case(SVEtype
.EXTRA2
):
107 with m
.Switch(self
.idx
):
108 with m
.Case(SVEXTRA
.Idx0
): # 1st 2 bits
109 comb
+= spec
[1:3].eq(self
.extra
[0:2])
110 with m
.Case(SVEXTRA
.Idx1
): # 2nd 2 bits
111 comb
+= spec
[1:3].eq(self
.extra
[2:4])
112 with m
.Case(SVEXTRA
.Idx2
): # 3rd 2 bits
113 comb
+= spec
[1:3].eq(self
.extra
[4:6])
114 with m
.Case(SVEXTRA
.Idx3
): # 4th 2 bits
115 comb
+= spec
[1:3].eq(self
.extra
[6:8])
116 # 3-bit index selection mode
117 with m
.Case(SVEtype
.EXTRA3
):
118 with m
.Switch(self
.idx
):
119 with m
.Case(SVEXTRA
.Idx0
): # 1st 3 bits
120 comb
+= spec
.eq(self
.extra
[0:3])
121 with m
.Case(SVEXTRA
.Idx1
): # 2nd 3 bits
122 comb
+= spec
.eq(self
.extra
[3:6])
123 with m
.Case(SVEXTRA
.Idx2
): # 3rd 3 bits
124 comb
+= spec
.eq(self
.extra
[6:9])
125 # cannot fit more than 9 bits so there is no 4th thing
130 class SVP64RegExtra(SVP64ExtraSpec
):
131 """SVP64RegExtra - decodes SVP64 Extra fields to determine reg extension
133 incoming 5-bit GPR/FP is turned into a 7-bit and marked as scalar/vector
134 depending on info in one of the positions in the EXTRA field.
136 designed so that "no change" to the 5-bit register number occurs if
137 SV either does not apply or the relevant EXTRA2/3 field bits are zero.
139 see https://libre-soc.org/openpower/sv/svp64/
142 SVP64ExtraSpec
.__init
__(self
)
143 self
.reg_in
= Signal(5) # incoming reg number (5 bits, RA, RB)
144 self
.reg_out
= Signal(7) # extra-augmented output (7 bits)
145 self
.isvec
= Signal(1) # reg is marked as vector if true
147 def elaborate(self
, platform
):
148 m
= super().elaborate(platform
) # select required EXTRA2/3
151 # first get the spec. if not changed it's "scalar identity behaviour"
152 # which is zero which is ok.
155 # now decode it. bit 2 is "scalar/vector". note that spec could be zero
156 # from above, which (by design) has the effect of "no change", below.
158 # simple: isvec is top bit of spec
159 comb
+= self
.isvec
.eq(spec
[2])
161 # decode vector differently from scalar
162 with m
.If(self
.isvec
):
163 # Vector: shifted up, extra in LSBs (RA << 2) | spec[0:1]
164 comb
+= self
.reg_out
.eq(Cat(spec
[:2], self
.reg_in
))
166 # Scalar: not shifted up, extra in MSBs RA | (spec[0:1] << 5)
167 comb
+= self
.reg_out
.eq(Cat(self
.reg_in
, spec
[:2]))
172 class SVP64CRExtra(SVP64ExtraSpec
):
173 """SVP64CRExtra - decodes SVP64 Extra fields to determine CR extension
175 incoming 3-bit CR is turned into a 7-bit and marked as scalar/vector
176 depending on info in one of the positions in the EXTRA field.
178 yes, really, 128 CRs. INT is 128, FP is 128, therefore CRs are 128.
180 designed so that "no change" to the 3-bit CR register number occurs if
181 SV either does not apply or the relevant EXTRA2/3 field bits are zero.
183 see https://libre-soc.org/openpower/sv/svp64/appendix
186 SVP64ExtraSpec
.__init
__(self
)
187 self
.cr_in
= Signal(3) # incoming CR number (3 bits, BA[2:5], BFA)
188 self
.cr_out
= Signal(7) # extra-augmented CR output (7 bits)
189 self
.isvec
= Signal(1) # reg is marked as vector if true
191 def elaborate(self
, platform
):
192 m
= super().elaborate(platform
) # select required EXTRA2/3
195 # first get the spec. if not changed it's "scalar identity behaviour"
196 # which is zero which is ok.
199 # now decode it. bit 2 is "scalar/vector". note that spec could be zero
200 # from above, which (by design) has the effect of "no change", below.
202 # simple: isvec is top bit of spec
203 comb
+= self
.isvec
.eq(spec
[2])
205 # decode vector differently from scalar, insert bits 0 and 1 accordingly
206 with m
.If(self
.isvec
):
207 # Vector: shifted up, extra in LSBs (CR << 4) | (spec[0:1] << 2)
208 comb
+= self
.cr_out
.eq(Cat(Const(0, 2), spec
[:2], self
.cr_in
))
210 # Scalar: not shifted up, extra in MSBs CR | (spec[0:1] << 3)
211 comb
+= self
.cr_out
.eq(Cat(self
.cr_in
, spec
[:2]))
216 class DecodeA(Elaboratable
):
217 """DecodeA from instruction
219 decodes register RA, implicit and explicit CSRs
222 def __init__(self
, dec
):
224 self
.sv_rm
= SVP64Rec() # SVP64 RM field
225 self
.sel_in
= Signal(In1Sel
, reset_less
=True)
226 self
.insn_in
= Signal(32, reset_less
=True)
227 self
.reg_out
= Data(7, name
="reg_a")
228 self
.reg_isvec
= Signal(1, name
="reg_a_isvec") # TODO: in reg_out
229 self
.spr_out
= Data(SPR
, "spr_a")
230 self
.fast_out
= Data(3, "fast_a")
232 def elaborate(self
, platform
):
236 m
.submodules
.sprmap
= sprmap
= SPRMap()
237 m
.submodules
.svdec
= svdec
= SVP64RegExtra()
239 # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
240 reg
= Signal(5, reset_less
=True)
242 # select Register A field
243 ra
= Signal(5, reset_less
=True)
244 comb
+= ra
.eq(self
.dec
.RA
)
245 with m
.If((self
.sel_in
== In1Sel
.RA
) |
246 ((self
.sel_in
== In1Sel
.RA_OR_ZERO
) &
247 (ra
!= Const(0, 5)))):
249 comb
+= self
.reg_out
.ok
.eq(1)
251 # some Logic/ALU ops have RS as the 3rd arg, but no "RA".
252 # moved it to 1st position (in1_sel)... because
253 rs
= Signal(5, reset_less
=True)
254 comb
+= rs
.eq(self
.dec
.RS
)
255 with m
.If(self
.sel_in
== In1Sel
.RS
):
257 comb
+= self
.reg_out
.ok
.eq(1)
259 # now do the SVP64 munging. op.SV_Etype and op.sv_in1 comes from
260 # PowerDecoder which in turn comes from LDST-RM*.csv and RM-*.csv
261 # which in turn were auto-generated by sv_analysis.py
263 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
264 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
265 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
266 comb
+= svdec
.idx
.eq(op
.sv_in1
) # SVP64 reg #1 (matches in1_sel)
267 comb
+= svdec
.reg_in
.eq(reg
) # 5-bit (RA, RS)
269 # outputs: 7-bit reg number and whether it's vectorised
270 comb
+= self
.reg_out
.data
.eq(svdec
.reg_out
)
271 comb
+= self
.reg_isvec
.eq(svdec
.isvec
)
273 # decode Fast-SPR based on instruction type
274 with m
.Switch(op
.internal_op
):
276 # BC or BCREG: implicit register (CTR) NOTE: same in DecodeOut
277 with m
.Case(MicrOp
.OP_BC
):
278 with m
.If(~self
.dec
.BO
[2]): # 3.0B p38 BO2=0, use CTR reg
280 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
281 comb
+= self
.fast_out
.ok
.eq(1)
282 with m
.Case(MicrOp
.OP_BCREG
):
283 xo9
= self
.dec
.FormXL
.XO
[9] # 3.0B p38 top bit of XO
284 xo5
= self
.dec
.FormXL
.XO
[5] # 3.0B p38
285 with m
.If(xo9
& ~xo5
):
287 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
288 comb
+= self
.fast_out
.ok
.eq(1)
290 # MFSPR move from SPRs
291 with m
.Case(MicrOp
.OP_MFSPR
):
292 spr
= Signal(10, reset_less
=True)
293 comb
+= spr
.eq(decode_spr_num(self
.dec
.SPR
)) # from XFX
294 comb
+= sprmap
.spr_i
.eq(spr
)
295 comb
+= self
.spr_out
.eq(sprmap
.spr_o
)
296 comb
+= self
.fast_out
.eq(sprmap
.fast_o
)
301 class DecodeAImm(Elaboratable
):
302 """DecodeA immediate from instruction
304 decodes register RA, whether immediate-zero, implicit and
308 def __init__(self
, dec
):
310 self
.sel_in
= Signal(In1Sel
, reset_less
=True)
311 self
.immz_out
= Signal(reset_less
=True)
313 def elaborate(self
, platform
):
317 # zero immediate requested
318 ra
= Signal(5, reset_less
=True)
319 comb
+= ra
.eq(self
.dec
.RA
)
320 with m
.If((self
.sel_in
== In1Sel
.RA_OR_ZERO
) & (ra
== Const(0, 5))):
321 comb
+= self
.immz_out
.eq(1)
326 class DecodeB(Elaboratable
):
327 """DecodeB from instruction
329 decodes register RB, different forms of immediate (signed, unsigned),
330 and implicit SPRs. register B is basically "lane 2" into the CompUnits.
331 by industry-standard convention, "lane 2" is where fully-decoded
332 immediates are muxed in.
335 def __init__(self
, dec
):
337 self
.sv_rm
= SVP64Rec() # SVP64 RM field
338 self
.sel_in
= Signal(In2Sel
, reset_less
=True)
339 self
.insn_in
= Signal(32, reset_less
=True)
340 self
.reg_out
= Data(7, "reg_b")
341 self
.reg_isvec
= Signal(1, name
="reg_b_isvec") # TODO: in reg_out
342 self
.fast_out
= Data(3, "fast_b")
344 def elaborate(self
, platform
):
348 m
.submodules
.svdec
= svdec
= SVP64RegExtra()
350 # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
351 reg
= Signal(5, reset_less
=True)
353 # select Register B field
354 with m
.Switch(self
.sel_in
):
355 with m
.Case(In2Sel
.RB
):
356 comb
+= reg
.eq(self
.dec
.RB
)
357 comb
+= self
.reg_out
.ok
.eq(1)
358 with m
.Case(In2Sel
.RS
):
359 # for M-Form shiftrot
360 comb
+= reg
.eq(self
.dec
.RS
)
361 comb
+= self
.reg_out
.ok
.eq(1)
363 # now do the SVP64 munging. different from DecodeA only by sv_in2
365 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
366 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
367 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
368 comb
+= svdec
.idx
.eq(op
.sv_in2
) # SVP64 reg #2 (matches in2_sel)
369 comb
+= svdec
.reg_in
.eq(reg
) # 5-bit (RA, RS)
371 # outputs: 7-bit reg number and whether it's vectorised
372 comb
+= self
.reg_out
.data
.eq(svdec
.reg_out
)
373 comb
+= self
.reg_isvec
.eq(svdec
.isvec
)
375 # decode SPR2 based on instruction type
376 # BCREG implicitly uses LR or TAR for 2nd reg
377 # CTR however is already in fast_spr1 *not* 2.
378 with m
.If(op
.internal_op
== MicrOp
.OP_BCREG
):
379 xo9
= self
.dec
.FormXL
.XO
[9] # 3.0B p38 top bit of XO
380 xo5
= self
.dec
.FormXL
.XO
[5] # 3.0B p38
382 comb
+= self
.fast_out
.data
.eq(FastRegs
.LR
)
383 comb
+= self
.fast_out
.ok
.eq(1)
385 comb
+= self
.fast_out
.data
.eq(FastRegs
.TAR
)
386 comb
+= self
.fast_out
.ok
.eq(1)
391 class DecodeBImm(Elaboratable
):
392 """DecodeB immediate from instruction
394 def __init__(self
, dec
):
396 self
.sel_in
= Signal(In2Sel
, reset_less
=True)
397 self
.imm_out
= Data(64, "imm_b")
399 def elaborate(self
, platform
):
403 # select Register B Immediate
404 with m
.Switch(self
.sel_in
):
405 with m
.Case(In2Sel
.CONST_UI
): # unsigned
406 comb
+= self
.imm_out
.data
.eq(self
.dec
.UI
)
407 comb
+= self
.imm_out
.ok
.eq(1)
408 with m
.Case(In2Sel
.CONST_SI
): # sign-extended 16-bit
409 si
= Signal(16, reset_less
=True)
410 comb
+= si
.eq(self
.dec
.SI
)
411 comb
+= self
.imm_out
.data
.eq(exts(si
, 16, 64))
412 comb
+= self
.imm_out
.ok
.eq(1)
413 with m
.Case(In2Sel
.CONST_SI_HI
): # sign-extended 16+16=32 bit
414 si_hi
= Signal(32, reset_less
=True)
415 comb
+= si_hi
.eq(self
.dec
.SI
<< 16)
416 comb
+= self
.imm_out
.data
.eq(exts(si_hi
, 32, 64))
417 comb
+= self
.imm_out
.ok
.eq(1)
418 with m
.Case(In2Sel
.CONST_UI_HI
): # unsigned
419 ui
= Signal(16, reset_less
=True)
420 comb
+= ui
.eq(self
.dec
.UI
)
421 comb
+= self
.imm_out
.data
.eq(ui
<< 16)
422 comb
+= self
.imm_out
.ok
.eq(1)
423 with m
.Case(In2Sel
.CONST_LI
): # sign-extend 24+2=26 bit
424 li
= Signal(26, reset_less
=True)
425 comb
+= li
.eq(self
.dec
.LI
<< 2)
426 comb
+= self
.imm_out
.data
.eq(exts(li
, 26, 64))
427 comb
+= self
.imm_out
.ok
.eq(1)
428 with m
.Case(In2Sel
.CONST_BD
): # sign-extend (14+2)=16 bit
429 bd
= Signal(16, reset_less
=True)
430 comb
+= bd
.eq(self
.dec
.BD
<< 2)
431 comb
+= self
.imm_out
.data
.eq(exts(bd
, 16, 64))
432 comb
+= self
.imm_out
.ok
.eq(1)
433 with m
.Case(In2Sel
.CONST_DS
): # sign-extended (14+2=16) bit
434 ds
= Signal(16, reset_less
=True)
435 comb
+= ds
.eq(self
.dec
.DS
<< 2)
436 comb
+= self
.imm_out
.data
.eq(exts(ds
, 16, 64))
437 comb
+= self
.imm_out
.ok
.eq(1)
438 with m
.Case(In2Sel
.CONST_M1
): # signed (-1)
439 comb
+= self
.imm_out
.data
.eq(~
Const(0, 64)) # all 1s
440 comb
+= self
.imm_out
.ok
.eq(1)
441 with m
.Case(In2Sel
.CONST_SH
): # unsigned - for shift
442 comb
+= self
.imm_out
.data
.eq(self
.dec
.sh
)
443 comb
+= self
.imm_out
.ok
.eq(1)
444 with m
.Case(In2Sel
.CONST_SH32
): # unsigned - for shift
445 comb
+= self
.imm_out
.data
.eq(self
.dec
.SH32
)
446 comb
+= self
.imm_out
.ok
.eq(1)
451 class DecodeC(Elaboratable
):
452 """DecodeC from instruction
454 decodes register RC. this is "lane 3" into some CompUnits (not many)
457 def __init__(self
, dec
):
459 self
.sv_rm
= SVP64Rec() # SVP64 RM field
460 self
.sel_in
= Signal(In3Sel
, reset_less
=True)
461 self
.insn_in
= Signal(32, reset_less
=True)
462 self
.reg_out
= Data(7, "reg_c")
463 self
.reg_isvec
= Signal(1, name
="reg_c_isvec") # TODO: in reg_out
465 def elaborate(self
, platform
):
469 m
.submodules
.svdec
= svdec
= SVP64RegExtra()
471 # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
472 reg
= Signal(5, reset_less
=True)
474 # select Register C field
475 with m
.Switch(self
.sel_in
):
476 with m
.Case(In3Sel
.RB
):
477 # for M-Form shiftrot
478 comb
+= reg
.eq(self
.dec
.RB
)
479 comb
+= self
.reg_out
.ok
.eq(1)
480 with m
.Case(In3Sel
.RS
):
481 comb
+= reg
.eq(self
.dec
.RS
)
482 comb
+= self
.reg_out
.ok
.eq(1)
484 # now do the SVP64 munging. different from DecodeA only by sv_in3
486 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
487 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
488 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
489 comb
+= svdec
.idx
.eq(op
.sv_in3
) # SVP64 reg #3 (matches in3_sel)
490 comb
+= svdec
.reg_in
.eq(reg
) # 5-bit (RA, RS)
492 # outputs: 7-bit reg number and whether it's vectorised
493 comb
+= self
.reg_out
.data
.eq(svdec
.reg_out
)
494 comb
+= self
.reg_isvec
.eq(svdec
.isvec
)
499 class DecodeOut(Elaboratable
):
500 """DecodeOut from instruction
502 decodes output register RA, RT or SPR
505 def __init__(self
, dec
):
507 self
.sv_rm
= SVP64Rec() # SVP64 RM field
508 self
.sel_in
= Signal(OutSel
, reset_less
=True)
509 self
.insn_in
= Signal(32, reset_less
=True)
510 self
.reg_out
= Data(7, "reg_o")
511 self
.reg_isvec
= Signal(1, name
="reg_o_isvec") # TODO: in reg_out
512 self
.spr_out
= Data(SPR
, "spr_o")
513 self
.fast_out
= Data(3, "fast_o")
515 def elaborate(self
, platform
):
518 m
.submodules
.sprmap
= sprmap
= SPRMap()
520 m
.submodules
.svdec
= svdec
= SVP64RegExtra()
522 # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
523 reg
= Signal(5, reset_less
=True)
525 # select Register out field
526 with m
.Switch(self
.sel_in
):
527 with m
.Case(OutSel
.RT
):
528 comb
+= reg
.eq(self
.dec
.RT
)
529 comb
+= self
.reg_out
.ok
.eq(1)
530 with m
.Case(OutSel
.RA
):
531 comb
+= reg
.eq(self
.dec
.RA
)
532 comb
+= self
.reg_out
.ok
.eq(1)
533 with m
.Case(OutSel
.SPR
):
534 spr
= Signal(10, reset_less
=True)
535 comb
+= spr
.eq(decode_spr_num(self
.dec
.SPR
)) # from XFX
536 # MFSPR move to SPRs - needs mapping
537 with m
.If(op
.internal_op
== MicrOp
.OP_MTSPR
):
538 comb
+= sprmap
.spr_i
.eq(spr
)
539 comb
+= self
.spr_out
.eq(sprmap
.spr_o
)
540 comb
+= self
.fast_out
.eq(sprmap
.fast_o
)
542 # now do the SVP64 munging. different from DecodeA only by sv_out
544 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
545 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
546 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
547 comb
+= svdec
.idx
.eq(op
.sv_out
) # SVP64 reg out1 (matches out_sel)
548 comb
+= svdec
.reg_in
.eq(reg
) # 5-bit (RA, RS)
550 # outputs: 7-bit reg number and whether it's vectorised
551 comb
+= self
.reg_out
.data
.eq(svdec
.reg_out
)
552 comb
+= self
.reg_isvec
.eq(svdec
.isvec
)
555 with m
.Switch(op
.internal_op
):
557 # BC or BCREG: implicit register (CTR) NOTE: same in DecodeA
558 with m
.Case(MicrOp
.OP_BC
, MicrOp
.OP_BCREG
):
559 with m
.If(~self
.dec
.BO
[2]): # 3.0B p38 BO2=0, use CTR reg
561 comb
+= self
.fast_out
.data
.eq(FastRegs
.CTR
)
562 comb
+= self
.fast_out
.ok
.eq(1)
564 # RFID 1st spr (fast)
565 with m
.Case(MicrOp
.OP_RFID
):
566 comb
+= self
.fast_out
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
567 comb
+= self
.fast_out
.ok
.eq(1)
572 class DecodeOut2(Elaboratable
):
573 """DecodeOut2 from instruction
575 decodes output registers (2nd one). note that RA is *implicit* below,
576 which now causes problems with SVP64
578 TODO: SVP64 is a little more complex, here. svp64 allows extending
579 by one more destination by having one more EXTRA field. RA-as-src
580 is not the same as RA-as-dest. limited in that it's the same first
581 5 bits (from the v3.0B opcode), but still kinda cool. mostly used
582 for operations that have src-as-dest: mostly this is LD/ST-with-update
583 but there are others.
586 def __init__(self
, dec
):
588 self
.sv_rm
= SVP64Rec() # SVP64 RM field
589 self
.sel_in
= Signal(OutSel
, reset_less
=True)
590 self
.lk
= Signal(reset_less
=True)
591 self
.insn_in
= Signal(32, reset_less
=True)
592 self
.reg_out
= Data(7, "reg_o2")
593 #self.reg_isvec = Signal(1, name="reg_o2_isvec") # TODO: in reg_out
594 self
.fast_out
= Data(3, "fast_o2")
596 def elaborate(self
, platform
):
600 #m.submodules.svdec = svdec = SVP64RegExtra()
602 # get the 5-bit reg data before svp64-munging it into 7-bit plus isvec
603 #reg = Signal(5, reset_less=True)
605 if hasattr(self
.dec
.op
, "upd"):
606 # update mode LD/ST uses read-reg A also as an output
607 with m
.If(self
.dec
.op
.upd
== LDSTMode
.update
):
608 comb
+= self
.reg_out
.data
.eq(self
.dec
.RA
)
609 comb
+= self
.reg_out
.ok
.eq(1)
611 # B, BC or BCREG: potential implicit register (LR) output
612 # these give bl, bcl, bclrl, etc.
613 with m
.Switch(op
.internal_op
):
615 # BC* implicit register (LR)
616 with m
.Case(MicrOp
.OP_BC
, MicrOp
.OP_B
, MicrOp
.OP_BCREG
):
617 with m
.If(self
.lk
): # "link" mode
618 comb
+= self
.fast_out
.data
.eq(FastRegs
.LR
) # constant: LR
619 comb
+= self
.fast_out
.ok
.eq(1)
621 # RFID 2nd spr (fast)
622 with m
.Case(MicrOp
.OP_RFID
):
623 comb
+= self
.fast_out
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
624 comb
+= self
.fast_out
.ok
.eq(1)
629 class DecodeRC(Elaboratable
):
630 """DecodeRc from instruction
632 decodes Record bit Rc
635 def __init__(self
, dec
):
637 self
.sel_in
= Signal(RC
, reset_less
=True)
638 self
.insn_in
= Signal(32, reset_less
=True)
639 self
.rc_out
= Data(1, "rc")
641 def elaborate(self
, platform
):
645 # select Record bit out field
646 with m
.Switch(self
.sel_in
):
648 comb
+= self
.rc_out
.data
.eq(self
.dec
.Rc
)
649 comb
+= self
.rc_out
.ok
.eq(1)
651 comb
+= self
.rc_out
.data
.eq(1)
652 comb
+= self
.rc_out
.ok
.eq(1)
653 with m
.Case(RC
.NONE
):
654 comb
+= self
.rc_out
.data
.eq(0)
655 comb
+= self
.rc_out
.ok
.eq(1)
660 class DecodeOE(Elaboratable
):
661 """DecodeOE from instruction
663 decodes OE field: uses RC decode detection which might not be good
665 -- For now, use "rc" in the decode table to decide whether oe exists.
666 -- This is not entirely correct architecturally: For mulhd and
667 -- mulhdu, the OE field is reserved. It remains to be seen what an
668 -- actual POWER9 does if we set it on those instructions, for now we
669 -- test that further down when assigning to the multiplier oe input.
672 def __init__(self
, dec
):
674 self
.sel_in
= Signal(RC
, reset_less
=True)
675 self
.insn_in
= Signal(32, reset_less
=True)
676 self
.oe_out
= Data(1, "oe")
678 def elaborate(self
, platform
):
683 with m
.Switch(op
.internal_op
):
685 # mulhw, mulhwu, mulhd, mulhdu - these *ignore* OE
687 # XXX ARGH! ignoring OE causes incompatibility with microwatt
688 # http://lists.libre-soc.org/pipermail/libre-soc-dev/2020-August/000302.html
689 with m
.Case(MicrOp
.OP_MUL_H64
, MicrOp
.OP_MUL_H32
,
690 MicrOp
.OP_EXTS
, MicrOp
.OP_CNTZ
,
691 MicrOp
.OP_SHL
, MicrOp
.OP_SHR
, MicrOp
.OP_RLC
,
692 MicrOp
.OP_LOAD
, MicrOp
.OP_STORE
,
693 MicrOp
.OP_RLCL
, MicrOp
.OP_RLCR
,
697 # all other ops decode OE field
699 # select OE bit out field
700 with m
.Switch(self
.sel_in
):
702 comb
+= self
.oe_out
.data
.eq(self
.dec
.OE
)
703 comb
+= self
.oe_out
.ok
.eq(1)
708 class DecodeCRIn(Elaboratable
):
709 """Decodes input CR from instruction
711 CR indices - insn fields - (not the data *in* the CR) require only 3
712 bits because they refer to CR0-CR7
715 def __init__(self
, dec
):
717 self
.sv_rm
= SVP64Rec() # SVP64 RM field
718 self
.sel_in
= Signal(CRInSel
, reset_less
=True)
719 self
.insn_in
= Signal(32, reset_less
=True)
720 self
.cr_bitfield
= Data(7, "cr_bitfield")
721 self
.cr_bitfield_b
= Data(7, "cr_bitfield_b")
722 self
.cr_bitfield_o
= Data(7, "cr_bitfield_o")
723 self
.cr_isvec
= Signal(1, name
="cr_isvec")
724 self
.cr_b_isvec
= Signal(1, name
="cr_b_isvec")
725 self
.cr_o_isvec
= Signal(1, name
="cr_o_isvec")
726 self
.whole_reg
= Data(8, "cr_fxm")
728 def elaborate(self
, platform
):
732 m
.submodules
.svdec
= svdec
= SVP64CRExtra()
733 m
.submodules
.svdec_b
= svdec_b
= SVP64CRExtra()
734 m
.submodules
.svdec_o
= svdec_o
= SVP64CRExtra()
735 m
.submodules
.ppick
= ppick
= PriorityPicker(8, reverse_i
=True,
738 # get the 3-bit reg data before svp64-munging it into 7-bit plus isvec
739 cr_bf
= Signal(3, reset_less
=True)
740 cr_bf_b
= Signal(3, reset_less
=True)
741 cr_bf_o
= Signal(3, reset_less
=True)
743 # index selection slightly different due to shared CR field sigh
744 cr_a_idx
= Signal(SVEXTRA
)
745 cr_b_idx
= Signal(SVEXTRA
)
747 # zero-initialisation
748 comb
+= self
.cr_bitfield
.ok
.eq(0)
749 comb
+= self
.cr_bitfield_b
.ok
.eq(0)
750 comb
+= self
.cr_bitfield_o
.ok
.eq(0)
751 comb
+= self
.whole_reg
.ok
.eq(0)
753 # these change slighly, when decoding BA/BB. really should have
754 # their own separate CSV column: sv_cr_in1 and sv_cr_in2, but hey
755 comb
+= cr_a_idx
.eq(op
.sv_cr_in
)
756 comb
+= cr_b_idx
.eq(SVEXTRA
.NONE
)
757 with m
.If(op
.sv_cr_in
== SVEXTRA
.Idx_1_2
.value
):
758 comb
+= cr_a_idx
.eq(SVEXTRA
.Idx1
)
759 comb
+= cr_b_idx
.eq(SVEXTRA
.Idx2
)
761 # select the relevant CR bitfields
762 with m
.Switch(self
.sel_in
):
763 with m
.Case(CRInSel
.NONE
):
764 pass # No bitfield activated
765 with m
.Case(CRInSel
.CR0
):
766 comb
+= cr_bf
.eq(0) # CR0 (MSB0 numbering)
767 comb
+= self
.cr_bitfield
.ok
.eq(1)
768 with m
.Case(CRInSel
.BI
):
769 comb
+= cr_bf
.eq(self
.dec
.BI
[2:5])
770 comb
+= self
.cr_bitfield
.ok
.eq(1)
771 with m
.Case(CRInSel
.BFA
):
772 comb
+= cr_bf
.eq(self
.dec
.FormX
.BFA
)
773 comb
+= self
.cr_bitfield
.ok
.eq(1)
774 with m
.Case(CRInSel
.BA_BB
):
775 comb
+= cr_bf
.eq(self
.dec
.BA
[2:5])
776 comb
+= self
.cr_bitfield
.ok
.eq(1)
777 comb
+= cr_bf_b
.eq(self
.dec
.BB
[2:5])
778 comb
+= self
.cr_bitfield_b
.ok
.eq(1)
779 comb
+= cr_bf_o
.eq(self
.dec
.BT
[2:5])
780 comb
+= self
.cr_bitfield_o
.ok
.eq(1)
781 with m
.Case(CRInSel
.BC
):
782 comb
+= cr_bf
.eq(self
.dec
.BC
[2:5])
783 comb
+= self
.cr_bitfield
.ok
.eq(1)
784 with m
.Case(CRInSel
.WHOLE_REG
):
785 comb
+= self
.whole_reg
.ok
.eq(1)
786 move_one
= Signal(reset_less
=True)
787 comb
+= move_one
.eq(self
.insn_in
[20]) # MSB0 bit 11
788 with m
.If((op
.internal_op
== MicrOp
.OP_MFCR
) & move_one
):
789 # must one-hot the FXM field
790 comb
+= ppick
.i
.eq(self
.dec
.FXM
)
791 comb
+= self
.whole_reg
.data
.eq(ppick
.o
)
793 # otherwise use all of it
794 comb
+= self
.whole_reg
.data
.eq(0xff)
796 # now do the SVP64 munging.
797 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
799 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
800 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
801 comb
+= svdec
.cr_in
.eq(cr_bf
) # 3-bit (CR0/BC/BFA)
803 comb
+= svdec_b
.extra
.eq(extra
) # EXTRA field of SVP64 RM
804 comb
+= svdec_b
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
805 comb
+= svdec_b
.cr_in
.eq(cr_bf_b
) # 3-bit (BB[2:5])
807 comb
+= svdec_o
.extra
.eq(extra
) # EXTRA field of SVP64 RM
808 comb
+= svdec_o
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
809 comb
+= svdec_o
.cr_in
.eq(cr_bf_o
) # 3-bit (BT[2:5])
811 # indices are slightly different, BA/BB mess sorted above
812 comb
+= svdec
.idx
.eq(cr_a_idx
) # SVP64 CR in A
813 comb
+= svdec_b
.idx
.eq(cr_b_idx
) # SVP64 CR in B
814 comb
+= svdec_o
.idx
.eq(op
.sv_cr_out
) # SVP64 CR out
816 # outputs: 7-bit reg number and whether it's vectorised
817 comb
+= self
.cr_bitfield
.data
.eq(svdec
.cr_out
)
818 comb
+= self
.cr_isvec
.eq(svdec
.isvec
)
819 comb
+= self
.cr_bitfield_b
.data
.eq(svdec_b
.cr_out
)
820 comb
+= self
.cr_b_isvec
.eq(svdec_b
.isvec
)
821 comb
+= self
.cr_bitfield_o
.data
.eq(svdec_o
.cr_out
)
822 comb
+= self
.cr_o_isvec
.eq(svdec_o
.isvec
)
827 class DecodeCROut(Elaboratable
):
828 """Decodes input CR from instruction
830 CR indices - insn fields - (not the data *in* the CR) require only 3
831 bits because they refer to CR0-CR7
834 def __init__(self
, dec
):
836 self
.sv_rm
= SVP64Rec() # SVP64 RM field
837 self
.rc_in
= Signal(reset_less
=True)
838 self
.sel_in
= Signal(CROutSel
, reset_less
=True)
839 self
.insn_in
= Signal(32, reset_less
=True)
840 self
.cr_bitfield
= Data(7, "cr_bitfield")
841 self
.cr_isvec
= Signal(1, name
="cr_isvec")
842 self
.whole_reg
= Data(8, "cr_fxm")
844 def elaborate(self
, platform
):
848 m
.submodules
.svdec
= svdec
= SVP64CRExtra()
849 m
.submodules
.ppick
= ppick
= PriorityPicker(8, reverse_i
=True,
852 # get the 3-bit reg data before svp64-munging it into 7-bit plus isvec
853 cr_bf
= Signal(3, reset_less
=True)
855 comb
+= self
.cr_bitfield
.ok
.eq(0)
856 comb
+= self
.whole_reg
.ok
.eq(0)
858 with m
.Switch(self
.sel_in
):
859 with m
.Case(CROutSel
.NONE
):
860 pass # No bitfield activated
861 with m
.Case(CROutSel
.CR0
):
862 comb
+= cr_bf
.eq(0) # CR0 (MSB0 numbering)
863 comb
+= self
.cr_bitfield
.ok
.eq(self
.rc_in
) # only when RC=1
864 with m
.Case(CROutSel
.BF
):
865 comb
+= cr_bf
.eq(self
.dec
.FormX
.BF
)
866 comb
+= self
.cr_bitfield
.ok
.eq(1)
867 with m
.Case(CROutSel
.BT
):
868 comb
+= cr_bf
.eq(self
.dec
.FormXL
.BT
[2:5])
869 comb
+= self
.cr_bitfield
.ok
.eq(1)
870 with m
.Case(CROutSel
.WHOLE_REG
):
871 comb
+= self
.whole_reg
.ok
.eq(1)
872 move_one
= Signal(reset_less
=True)
873 comb
+= move_one
.eq(self
.insn_in
[20])
874 with m
.If((op
.internal_op
== MicrOp
.OP_MTCRF
)):
876 # must one-hot the FXM field
877 comb
+= ppick
.i
.eq(self
.dec
.FXM
)
878 with m
.If(ppick
.en_o
):
879 comb
+= self
.whole_reg
.data
.eq(ppick
.o
)
881 comb
+= self
.whole_reg
.data
.eq(0b00000001) # CR7
883 comb
+= self
.whole_reg
.data
.eq(self
.dec
.FXM
)
885 # otherwise use all of it
886 comb
+= self
.whole_reg
.data
.eq(0xff)
888 # now do the SVP64 munging.
889 extra
= self
.sv_rm
.extra
# SVP64 extra bits 10:18
890 comb
+= svdec
.extra
.eq(extra
) # EXTRA field of SVP64 RM
891 comb
+= svdec
.etype
.eq(op
.SV_Etype
) # EXTRA2/3 for this insn
892 comb
+= svdec
.cr_in
.eq(cr_bf
) # 3-bit (CR0/BC/BFA)
893 comb
+= svdec
.idx
.eq(op
.sv_cr_out
) # SVP64 CR out
895 # outputs: 7-bit reg number and whether it's vectorised
896 comb
+= self
.cr_bitfield
.data
.eq(svdec
.cr_out
)
897 comb
+= self
.cr_isvec
.eq(svdec
.isvec
)
901 # dictionary of Input Record field names that, if they exist,
902 # will need a corresponding CSV Decoder file column (actually, PowerOp)
903 # to be decoded (this includes the single bit names)
904 record_names
= {'insn_type': 'internal_op',
905 'fn_unit': 'function_unit',
909 'imm_data': 'in2_sel',
910 'invert_in': 'inv_a',
911 'invert_out': 'inv_out',
914 'output_carry': 'cry_out',
915 'input_carry': 'cry_in',
916 'is_32bit': 'is_32b',
919 'data_len': 'ldst_len',
920 'byte_reverse': 'br',
921 'sign_extend': 'sgn_ext',
926 class PowerDecodeSubset(Elaboratable
):
927 """PowerDecodeSubset: dynamic subset decoder
929 only fields actually requested are copied over. hence, "subset" (duh).
931 def __init__(self
, dec
, opkls
=None, fn_name
=None, final
=False, state
=None):
933 self
.sv_rm
= SVP64Rec(name
="dec_svp64") # SVP64 RM field
936 self
.fn_name
= fn_name
938 opkls
= Decode2ToOperand
939 self
.do
= opkls(fn_name
)
940 col_subset
= self
.get_col_subset(self
.do
)
942 # only needed for "main" PowerDecode2
944 self
.e
= Decode2ToExecute1Type(name
=self
.fn_name
, do
=self
.do
)
946 # create decoder if one not already given
948 dec
= create_pdecode(name
=fn_name
, col_subset
=col_subset
,
949 row_subset
=self
.rowsubsetfn
)
952 # state information needed by the Decoder
954 state
= CoreState("dec2")
957 def get_col_subset(self
, do
):
958 subset
= {'sv_cr_in', 'sv_cr_out', 'SV_Etype',
959 'cr_in', 'cr_out', 'rc_sel'} # needed, non-optional
960 for k
, v
in record_names
.items():
963 print ("get_col_subset", self
.fn_name
, do
.fields
, subset
)
966 def rowsubsetfn(self
, opcode
, row
):
967 return row
['unit'] == self
.fn_name
970 return self
.dec
.ports() + self
.e
.ports() + self
.sv_rm
.ports()
972 def needs_field(self
, field
, op_field
):
977 return hasattr(do
, field
) and self
.op_get(op_field
) is not None
979 def do_copy(self
, field
, val
, final
=False):
980 if final
or self
.final
:
984 if hasattr(do
, field
) and val
is not None:
985 return getattr(do
, field
).eq(val
)
988 def op_get(self
, op_field
):
989 return getattr(self
.dec
.op
, op_field
, None)
991 def elaborate(self
, platform
):
995 op
, do
= self
.dec
.op
, self
.do
996 msr
, cia
= state
.msr
, state
.pc
998 # fill in for a normal instruction (not an exception)
999 # copy over if non-exception, non-privileged etc. is detected
1001 if self
.fn_name
is None:
1004 name
= self
.fn_name
+ "tmp"
1005 self
.e_tmp
= Decode2ToExecute1Type(name
=name
, opkls
=self
.opkls
)
1007 # set up submodule decoders
1008 m
.submodules
.dec
= self
.dec
1009 m
.submodules
.dec_rc
= dec_rc
= DecodeRC(self
.dec
)
1010 m
.submodules
.dec_oe
= dec_oe
= DecodeOE(self
.dec
)
1011 m
.submodules
.dec_cr_in
= self
.dec_cr_in
= DecodeCRIn(self
.dec
)
1012 m
.submodules
.dec_cr_out
= self
.dec_cr_out
= DecodeCROut(self
.dec
)
1014 # copy instruction through...
1016 dec_rc
.insn_in
, dec_oe
.insn_in
,
1017 self
.dec_cr_in
.insn_in
, self
.dec_cr_out
.insn_in
]:
1018 comb
+= i
.eq(self
.dec
.opcode_in
)
1020 # ...and subdecoders' input fields
1021 comb
+= dec_rc
.sel_in
.eq(op
.rc_sel
)
1022 comb
+= dec_oe
.sel_in
.eq(op
.rc_sel
) # XXX should be OE sel
1023 comb
+= self
.dec_cr_in
.sel_in
.eq(op
.cr_in
)
1024 comb
+= self
.dec_cr_in
.sv_rm
.eq(self
.sv_rm
)
1025 comb
+= self
.dec_cr_out
.sv_rm
.eq(self
.sv_rm
)
1026 comb
+= self
.dec_cr_out
.sel_in
.eq(op
.cr_out
)
1027 comb
+= self
.dec_cr_out
.rc_in
.eq(dec_rc
.rc_out
.data
)
1030 comb
+= self
.do_copy("msr", msr
)
1031 comb
+= self
.do_copy("cia", cia
)
1033 # set up instruction type
1034 # no op: defaults to OP_ILLEGAL
1035 comb
+= self
.do_copy("insn_type", self
.op_get("internal_op"))
1037 # function unit for decoded instruction: requires minor redirect
1039 fn
= self
.op_get("function_unit")
1040 spr
= Signal(10, reset_less
=True)
1041 comb
+= spr
.eq(decode_spr_num(self
.dec
.SPR
)) # from XFX
1043 # for first test only forward SPRs 18 and 19 to MMU, when
1044 # operation is MTSPR or MFSPR. TODO: add other MMU SPRs
1045 with m
.If(((self
.dec
.op
.internal_op
== MicrOp
.OP_MTSPR
) |
1046 (self
.dec
.op
.internal_op
== MicrOp
.OP_MFSPR
)) &
1047 ((spr
== SPR
.DSISR
) |
(spr
== SPR
.DAR
))):
1048 comb
+= self
.do_copy("fn_unit", Function
.MMU
)
1050 comb
+= self
.do_copy("fn_unit",fn
)
1053 if self
.needs_field("zero_a", "in1_sel"):
1054 m
.submodules
.dec_ai
= dec_ai
= DecodeAImm(self
.dec
)
1055 comb
+= dec_ai
.sel_in
.eq(op
.in1_sel
)
1056 comb
+= self
.do_copy("zero_a", dec_ai
.immz_out
) # RA==0 detected
1057 if self
.needs_field("imm_data", "in2_sel"):
1058 m
.submodules
.dec_bi
= dec_bi
= DecodeBImm(self
.dec
)
1059 comb
+= dec_bi
.sel_in
.eq(op
.in2_sel
)
1060 comb
+= self
.do_copy("imm_data", dec_bi
.imm_out
) # imm in RB
1063 comb
+= self
.do_copy("rc", dec_rc
.rc_out
)
1064 comb
+= self
.do_copy("oe", dec_oe
.oe_out
)
1067 comb
+= self
.do_copy("read_cr_whole", self
.dec_cr_in
.whole_reg
)
1068 comb
+= self
.do_copy("write_cr_whole", self
.dec_cr_out
.whole_reg
)
1069 comb
+= self
.do_copy("write_cr0", self
.dec_cr_out
.cr_bitfield
.ok
)
1071 comb
+= self
.do_copy("input_cr", self
.op_get("cr_in")) # CR in
1072 comb
+= self
.do_copy("output_cr", self
.op_get("cr_out")) # CR out
1074 # decoded/selected instruction flags
1075 comb
+= self
.do_copy("data_len", self
.op_get("ldst_len"))
1076 comb
+= self
.do_copy("invert_in", self
.op_get("inv_a"))
1077 comb
+= self
.do_copy("invert_out", self
.op_get("inv_out"))
1078 comb
+= self
.do_copy("input_carry", self
.op_get("cry_in"))
1079 comb
+= self
.do_copy("output_carry", self
.op_get("cry_out"))
1080 comb
+= self
.do_copy("is_32bit", self
.op_get("is_32b"))
1081 comb
+= self
.do_copy("is_signed", self
.op_get("sgn"))
1082 lk
= self
.op_get("lk")
1085 comb
+= self
.do_copy("lk", self
.dec
.LK
) # XXX TODO: accessor
1087 comb
+= self
.do_copy("byte_reverse", self
.op_get("br"))
1088 comb
+= self
.do_copy("sign_extend", self
.op_get("sgn_ext"))
1089 comb
+= self
.do_copy("ldst_mode", self
.op_get("upd")) # LD/ST mode
1094 class PowerDecode2(PowerDecodeSubset
):
1095 """PowerDecode2: the main instruction decoder.
1097 whilst PowerDecode is responsible for decoding the actual opcode, this
1098 module encapsulates further specialist, sparse information and
1099 expansion of fields that is inconvenient to have in the CSV files.
1100 for example: the encoding of the immediates, which are detected
1101 and expanded out to their full value from an annotated (enum)
1104 implicit register usage is also set up, here. for example: OP_BC
1105 requires implicitly reading CTR, OP_RFID requires implicitly writing
1108 in addition, PowerDecoder2 is responsible for detecting whether
1109 instructions are illegal (or privileged) or not, and instead of
1110 just leaving at that, *replacing* the instruction to execute with
1111 a suitable alternative (trap).
1113 LDSTExceptions are done the cycle _after_ they're detected (after
1114 they come out of LDSTCompUnit). basically despite the instruction
1115 being decoded, the results of the decode are completely ignored
1116 and "exception.happened" used to set the "actual" instruction to
1117 "OP_TRAP". the LDSTException data structure gets filled in,
1118 in the CompTrapOpSubset and that's what it fills in SRR.
1120 to make this work, TestIssuer must notice "exception.happened"
1121 after the (failed) LD/ST and copies the LDSTException info from
1122 the output, into here (PowerDecoder2). without incrementing PC.
1125 def __init__(self
, dec
, opkls
=None, fn_name
=None, final
=False, state
=None):
1126 super().__init
__(dec
, opkls
, fn_name
, final
, state
)
1127 self
.exc
= LDSTException("dec2_exc")
1129 def get_col_subset(self
, opkls
):
1130 subset
= super().get_col_subset(opkls
)
1131 subset
.add("asmcode")
1132 subset
.add("in1_sel")
1133 subset
.add("in2_sel")
1134 subset
.add("in3_sel")
1135 subset
.add("out_sel")
1136 subset
.add("sv_in1")
1137 subset
.add("sv_in2")
1138 subset
.add("sv_in3")
1139 subset
.add("sv_out")
1140 subset
.add("sv_cr_in")
1141 subset
.add("sv_cr_out")
1142 subset
.add("SV_Etype")
1143 subset
.add("SV_Ptype")
1145 subset
.add("internal_op")
1149 def elaborate(self
, platform
):
1150 m
= super().elaborate(platform
)
1153 e_out
, op
, do_out
= self
.e
, self
.dec
.op
, self
.e
.do
1154 dec_spr
, msr
, cia
, ext_irq
= state
.dec
, state
.msr
, state
.pc
, state
.eint
1158 # fill in for a normal instruction (not an exception)
1159 # copy over if non-exception, non-privileged etc. is detected
1161 # set up submodule decoders
1162 m
.submodules
.dec_a
= dec_a
= DecodeA(self
.dec
)
1163 m
.submodules
.dec_b
= dec_b
= DecodeB(self
.dec
)
1164 m
.submodules
.dec_c
= dec_c
= DecodeC(self
.dec
)
1165 m
.submodules
.dec_o
= dec_o
= DecodeOut(self
.dec
)
1166 m
.submodules
.dec_o2
= dec_o2
= DecodeOut2(self
.dec
)
1168 # copy instruction through...
1169 for i
in [do
.insn
, dec_a
.insn_in
, dec_b
.insn_in
,
1170 dec_c
.insn_in
, dec_o
.insn_in
, dec_o2
.insn_in
]:
1171 comb
+= i
.eq(self
.dec
.opcode_in
)
1174 for i
in [dec_a
.insn_in
, dec_b
.insn_in
,
1175 dec_c
.insn_in
, dec_o
.insn_in
, dec_o2
.insn_in
]:
1176 comb
+= i
.eq(self
.sv_rm
)
1178 # ...and subdecoders' input fields
1179 comb
+= dec_a
.sel_in
.eq(op
.in1_sel
)
1180 comb
+= dec_b
.sel_in
.eq(op
.in2_sel
)
1181 comb
+= dec_c
.sel_in
.eq(op
.in3_sel
)
1182 comb
+= dec_o
.sel_in
.eq(op
.out_sel
)
1183 comb
+= dec_o2
.sel_in
.eq(op
.out_sel
)
1184 if hasattr(do
, "lk"):
1185 comb
+= dec_o2
.lk
.eq(do
.lk
)
1187 # registers a, b, c and out and out2 (LD/ST EA)
1188 for to_reg
, fromreg
in (
1189 (e
.read_reg1
, dec_a
.reg_out
),
1190 (e
.read_reg2
, dec_b
.reg_out
),
1191 (e
.read_reg3
, dec_c
.reg_out
),
1192 (e
.write_reg
, dec_o
.reg_out
),
1193 (e
.write_ea
, dec_o2
.reg_out
)):
1194 comb
+= to_reg
.data
.eq(fromreg
.data
)
1195 comb
+= to_reg
.ok
.eq(fromreg
.ok
)
1198 comb
+= e
.read_spr1
.eq(dec_a
.spr_out
)
1199 comb
+= e
.write_spr
.eq(dec_o
.spr_out
)
1202 comb
+= e
.read_fast1
.eq(dec_a
.fast_out
)
1203 comb
+= e
.read_fast2
.eq(dec_b
.fast_out
)
1204 comb
+= e
.write_fast1
.eq(dec_o
.fast_out
)
1205 comb
+= e
.write_fast2
.eq(dec_o2
.fast_out
)
1207 # condition registers (CR)
1208 for to_reg
, fromreg
in (
1209 (e
.read_cr1
, self
.dec_cr_in
.cr_bitfield
),
1210 (e
.read_cr2
, self
.dec_cr_in
.cr_bitfield_b
),
1211 (e
.read_cr3
, self
.dec_cr_in
.cr_bitfield_o
),
1212 (e
.write_cr
, self
.dec_cr_out
.cr_bitfield
)):
1213 comb
+= to_reg
.data
.eq(fromreg
.data
)
1214 comb
+= to_reg
.ok
.eq(fromreg
.ok
)
1216 # sigh this is exactly the sort of thing for which the
1217 # decoder is designed to not need. MTSPR, MFSPR and others need
1218 # access to the XER bits. however setting e.oe is not appropriate
1219 with m
.If(op
.internal_op
== MicrOp
.OP_MFSPR
):
1220 comb
+= e
.xer_in
.eq(0b111) # SO, CA, OV
1221 with m
.If(op
.internal_op
== MicrOp
.OP_CMP
):
1222 comb
+= e
.xer_in
.eq(1<<XERRegs
.SO
) # SO
1223 with m
.If(op
.internal_op
== MicrOp
.OP_MTSPR
):
1224 comb
+= e
.xer_out
.eq(1)
1226 # set the trapaddr to 0x700 for a td/tw/tdi/twi operation
1227 with m
.If(op
.internal_op
== MicrOp
.OP_TRAP
):
1228 # *DO NOT* call self.trap here. that would reset absolutely
1229 # everything including destroying read of RA and RB.
1230 comb
+= self
.do_copy("trapaddr", 0x70) # strip first nibble
1232 ####################
1233 # ok so the instruction's been decoded, blah blah, however
1234 # now we need to determine if it's actually going to go ahead...
1235 # *or* if in fact it's a privileged operation, whether there's
1236 # an external interrupt, etc. etc. this is a simple priority
1237 # if-elif-elif sequence. decrement takes highest priority,
1238 # EINT next highest, privileged operation third.
1240 # check if instruction is privileged
1241 is_priv_insn
= instr_is_priv(m
, op
.internal_op
, e
.do
.insn
)
1243 # different IRQ conditions
1244 ext_irq_ok
= Signal()
1245 dec_irq_ok
= Signal()
1250 comb
+= ext_irq_ok
.eq(ext_irq
& msr
[MSR
.EE
]) # v3.0B p944 (MSR.EE)
1251 comb
+= dec_irq_ok
.eq(dec_spr
[63] & msr
[MSR
.EE
]) # 6.5.11 p1076
1252 comb
+= priv_ok
.eq(is_priv_insn
& msr
[MSR
.PR
])
1253 comb
+= illeg_ok
.eq(op
.internal_op
== MicrOp
.OP_ILLEGAL
)
1255 # LD/ST exceptions. TestIssuer copies the exception info at us
1256 # after a failed LD/ST.
1257 with m
.If(exc
.happened
):
1258 with m
.If(exc
.alignment
):
1259 self
.trap(m
, TT
.PRIV
, 0x600)
1260 with m
.Elif(exc
.instr_fault
):
1261 with m
.If(exc
.segment_fault
):
1262 self
.trap(m
, TT
.PRIV
, 0x480)
1264 # pass exception info to trap to create SRR1
1265 self
.trap(m
, TT
.MEMEXC
, 0x400, exc
)
1267 with m
.If(exc
.segment_fault
):
1268 self
.trap(m
, TT
.PRIV
, 0x380)
1270 self
.trap(m
, TT
.PRIV
, 0x300)
1272 # decrement counter (v3.0B p1099): TODO 32-bit version (MSR.LPCR)
1273 with m
.Elif(dec_irq_ok
):
1274 self
.trap(m
, TT
.DEC
, 0x900) # v3.0B 6.5 p1065
1276 # external interrupt? only if MSR.EE set
1277 with m
.Elif(ext_irq_ok
):
1278 self
.trap(m
, TT
.EINT
, 0x500)
1280 # privileged instruction trap
1281 with m
.Elif(priv_ok
):
1282 self
.trap(m
, TT
.PRIV
, 0x700)
1284 # illegal instruction must redirect to trap. this is done by
1285 # *overwriting* the decoded instruction and starting again.
1286 # (note: the same goes for interrupts and for privileged operations,
1287 # just with different trapaddr and traptype)
1288 with m
.Elif(illeg_ok
):
1289 # illegal instruction trap
1290 self
.trap(m
, TT
.ILLEG
, 0x700)
1292 # no exception, just copy things to the output
1296 ####################
1297 # follow-up after trap/irq to set up SRR0/1
1299 # trap: (note e.insn_type so this includes OP_ILLEGAL) set up fast regs
1300 # Note: OP_SC could actually be modified to just be a trap
1301 with m
.If((do_out
.insn_type
== MicrOp
.OP_TRAP
) |
1302 (do_out
.insn_type
== MicrOp
.OP_SC
)):
1303 # TRAP write fast1 = SRR0
1304 comb
+= e_out
.write_fast1
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
1305 comb
+= e_out
.write_fast1
.ok
.eq(1)
1306 # TRAP write fast2 = SRR1
1307 comb
+= e_out
.write_fast2
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
1308 comb
+= e_out
.write_fast2
.ok
.eq(1)
1310 # RFID: needs to read SRR0/1
1311 with m
.If(do_out
.insn_type
== MicrOp
.OP_RFID
):
1312 # TRAP read fast1 = SRR0
1313 comb
+= e_out
.read_fast1
.data
.eq(FastRegs
.SRR0
) # constant: SRR0
1314 comb
+= e_out
.read_fast1
.ok
.eq(1)
1315 # TRAP read fast2 = SRR1
1316 comb
+= e_out
.read_fast2
.data
.eq(FastRegs
.SRR1
) # constant: SRR1
1317 comb
+= e_out
.read_fast2
.ok
.eq(1)
1319 # annoying simulator bug
1320 if hasattr(e_out
, "asmcode") and hasattr(self
.dec
.op
, "asmcode"):
1321 comb
+= e_out
.asmcode
.eq(self
.dec
.op
.asmcode
)
1325 def trap(self
, m
, traptype
, trapaddr
, exc
=None):
1326 """trap: this basically "rewrites" the decoded instruction as a trap
1329 op
, e
= self
.dec
.op
, self
.e
1330 comb
+= e
.eq(0) # reset eeeeeverything
1333 comb
+= self
.do_copy("insn", self
.dec
.opcode_in
, True)
1334 comb
+= self
.do_copy("insn_type", MicrOp
.OP_TRAP
, True)
1335 comb
+= self
.do_copy("fn_unit", Function
.TRAP
, True)
1336 comb
+= self
.do_copy("trapaddr", trapaddr
>> 4, True) # bottom 4 bits
1337 comb
+= self
.do_copy("traptype", traptype
, True) # request type
1338 comb
+= self
.do_copy("ldst_exc", exc
, True) # request type
1339 comb
+= self
.do_copy("msr", self
.state
.msr
, True) # copy of MSR "state"
1340 comb
+= self
.do_copy("cia", self
.state
.pc
, True) # copy of PC "state"
1343 def get_rdflags(e
, cu
):
1345 for idx
in range(cu
.n_src
):
1346 regfile
, regname
, _
= cu
.get_in_spec(idx
)
1347 rdflag
, read
= regspec_decode_read(e
, regfile
, regname
)
1349 print("rdflags", rdl
)
1353 if __name__
== '__main__':
1354 pdecode
= create_pdecode()
1355 dec2
= PowerDecode2(pdecode
)
1356 vl
= rtlil
.convert(dec2
, ports
=dec2
.ports() + pdecode
.ports())
1357 with
open("dec2.il", "w") as f
: