https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112415
--- Comment #44 from Manolis Tsamis <manolis.tsamis at vrull dot eu> ---
(In reply to John David Anglin from comment #39)
> In the f-m-o pass, the following three insns that set call clobbered
> registers r20-r22 are pulled from loop:
>
> (insn 186 183 190 29 (set (reg/f:SI 22 %r22 [478])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 388 [0x184]))) "../Python/compile.c":5964:9 120
> {addsi3}
> (nil))
> (insn 190 186 187 29 (set (reg/f:SI 21 %r21 [479])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 392 [0x188]))) "../Python/compile.c":5964:9 120
> {addsi3}
> (nil))
> (insn 194 191 195 29 (set (reg/f:SI 20 %r20 [480])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 396 [0x18c]))) "../Python/compile.c":5964:9 120
> {addsi3}
> (nil))
>
> They are used in the following insns before call to compiler_visit_expr1:
>
> (insn 242 238 258 32 (set (mem:SI (reg/f:SI 22 %r22 [478]) [4 MEM[(int
> *)prephit
> mp_37 + 388B]+0 S4 A32])
> (reg:SI 23 %r23 [orig:173 vect__102.2442 ] [173]))
> "../Python/compile.c"
> :5968:22 42 {*pa.md:2193}
> (expr_list:REG_DEAD (reg:SI 23 %r23 [orig:173 vect__102.2442 ] [173])
> (expr_list:REG_DEAD (reg/f:SI 22 %r22 [478])
> (nil))))
> (insn 258 242 246 32 (set (reg:SI 26 %r26)
> (reg/v/f:SI 5 %r5 [orig:198 c ] [198]))
> "../Python/compile.c":5969:15 42 {*pa.md:2193}
> (nil))
> (insn 246 258 250 32 (set (mem:SI (reg/f:SI 21 %r21 [479]) [4 MEM[(int
> *)prephitmp_37 + 392B]+0 S4 A32])
> (reg:SI 29 %r29 [orig:169 vect__102.2443 ] [169]))
> "../Python/compile.c":5968:22 42 {*pa.md:2193}
> (expr_list:REG_DEAD (reg:SI 29 %r29 [orig:169 vect__102.2443 ] [169])
> (expr_list:REG_DEAD (reg/f:SI 21 %r21 [479])
> (nil))))
> (insn 250 246 254 32 (set (mem:SI (reg/f:SI 20 %r20 [480]) [4 MEM[(int
> *)prephitmp_37 + 396B]+0 S4 A32])
> (reg:SI 31 %r31 [orig:145 vect__102.2444 ] [145]))
> "../Python/compile.c":5968:22 42 {*pa.md:2193}
> (expr_list:REG_DEAD (reg:SI 31 %r31 [orig:145 vect__102.2444 ] [145])
> (expr_list:REG_DEAD (reg/f:SI 20 %r20 [480])
> (nil))))
>
> After the call, we have:
>
> (insn 1241 269 273 30 (set (reg/f:SI 22 %r22 [478])
> (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]))
> "../Python/compile.c":5970:20 -1
> (nil))
> (insn 273 1241 1242 30 (set (mem:SI (plus:SI (reg/f:SI 22 %r22 [478])
> (const_int 388 [0x184])) [4 MEM[(int *)_107 + 388B]+0 S4
> A32])
> (reg:SI 14 %r14 [orig:167 vect_pretmp_36.2450 ] [167]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
> (insn 1242 273 277 30 (set (reg/f:SI 21 %r21 [479])
> (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]))
> "../Python/compile.c":5970:20 -1
> (nil))
> (insn 277 1242 1243 30 (set (mem:SI (plus:SI (reg/f:SI 21 %r21 [479])
> (const_int 392 [0x188])) [4 MEM[(int *)_107 + 392B]+0 S4
> A32])
> (reg:SI 13 %r13 [orig:156 vect_pretmp_36.2451 ] [156]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
> (insn 1243 277 281 30 (set (reg/f:SI 20 %r20 [480])
> (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127]))
> "../Python/compile.c":5970:20 -1
> (nil))
> (insn 281 1243 299 30 (set (mem:SI (plus:SI (reg/f:SI 20 %r20 [480])
> (const_int 396 [0x18c])) [4 MEM[(int *)_107 + 396B]+0 S4
> A32])
> (reg:SI 12 %r12 [orig:134 vect_pretmp_36.2452 ] [134]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
>
> We have lost the offsets that were added initially to r20, r21 and r22.
>
> Previous ce3 pass had:
>
> (insn 272 269 273 30 (set (reg/f:SI 22 %r22 [478])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 388 [0x184]))) "../Python/compile.c":5970:20 120
> {addsi3}
> (nil))
> (insn 273 272 276 30 (set (mem:SI (reg/f:SI 22 %r22 [478]) [4 MEM[(int
> *)_107 + 388B]+0 S4 A32])
> (reg:SI 14 %r14 [orig:167 vect_pretmp_36.2450 ] [167]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
> (insn 276 273 277 30 (set (reg/f:SI 21 %r21 [479])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 392 [0x188]))) "../Python/compile.c":5970:20 120
> {addsi3}
> (nil))
> (insn 277 276 280 30 (set (mem:SI (reg/f:SI 21 %r21 [479]) [4 MEM[(int
> *)_107 + 392B]+0 S4 A32])
> (reg:SI 13 %r13 [orig:156 vect_pretmp_36.2451 ] [156]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
> (insn 280 277 281 30 (set (reg/f:SI 20 %r20 [480])
> (plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
> (const_int 396 [0x18c]))) "../Python/compile.c":5970:20 120
> {addsi3}
> (nil))
> (insn 281 280 284 30 (set (mem:SI (reg/f:SI 20 %r20 [480]) [4 MEM[(int
> *)_107 + 396B]+0 S4 A32])
> (reg:SI 12 %r12 [orig:134 vect_pretmp_36.2452 ] [134]))
> "../Python/compile.c":5970:20 42 {*pa.md:2193}
> (nil))
>
> So, this is a f-m-o bug.
Hi Dave,
I don't see an f-m-o bug here. The offsets aren't lost, they're just moved in
the corresponding memory loads/stores. If you look the stores in ce3 they
don't have offsets whereas after f-m-o they have. E.g. in ce3: (insn 273 272
276 30 (set (mem:SI (reg/f:SI 22 %r22 [478]) ...) but in f-m-o it is (insn 273
1241 1242 30 (set (mem:SI (plus:SI (reg/f:SI 22 %r22 [478]) (const_int 388
[0x184]) ...).
This is the way that f-m-o works. It can also be seen in the f-m-o dumps, where
offsets changes to memory ops are reported as 'Memory offset changed' and
instructions which got their offset propagated (like insns 272, 276, 280) are
reported as 'Instruction folded':
Memory offset changed from 0 to 388 for instruction:
(insn 273 272 276 30 (set (mem:SI (reg/f:SI 22 %r22 [478]) [4 MEM[(int *)_107 +
388B]+0 S4 A32])
(reg:SI 14 %r14 [orig:167 vect_pretmp_36.2450 ] [167]))
"../Python/compile.c":5970:20 42 {*pa.md:2193}
(nil))
deferring rescan insn with uid = 273.
Memory offset changed from 0 to 392 for instruction:
(insn 277 276 280 30 (set (mem:SI (reg/f:SI 21 %r21 [479]) [4 MEM[(int *)_107 +
392B]+0 S4 A32])
(reg:SI 13 %r13 [orig:156 vect_pretmp_36.2451 ] [156]))
"../Python/compile.c":5970:20 42 {*pa.md:2193}
(nil))
deferring rescan insn with uid = 277.
Memory offset changed from 0 to 396 for instruction:
(insn 281 280 284 30 (set (mem:SI (reg/f:SI 20 %r20 [480]) [4 MEM[(int *)_107 +
396B]+0 S4 A32])
(reg:SI 12 %r12 [orig:134 vect_pretmp_36.2452 ] [134]))
"../Python/compile.c":5970:20 42 {*pa.md:2193}
(nil))
deferring rescan insn with uid = 281.
Memory offset changed from 0 to 400 for instruction:
(insn 285 301 286 30 (set (mem:SI (reg/f:SI 19 %r19 [481]) [4 MEM[(int *)_107 +
400B]+0 S4 A32])
(reg:SI 11 %r11 [orig:133 vect_pretmp_36.2453 ] [133]))
"../Python/compile.c":5970:20 42 {*pa.md:2193}
(nil))
deferring rescan insn with uid = 285.
Instruction folded:(insn 272 269 273 30 (set (reg/f:SI 22 %r22 [478])
(plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
(const_int 388 [0x184]))) "../Python/compile.c":5970:20 120
{addsi3}
(nil))
deferring rescan insn with uid = 1241.
deferring rescan insn with uid = 1241.
deferring deletion of insn with uid = 272.
Instruction folded:(insn 276 273 277 30 (set (reg/f:SI 21 %r21 [479])
(plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
(const_int 392 [0x188]))) "../Python/compile.c":5970:20 120
{addsi3}
(nil))
deferring rescan insn with uid = 1242.
deferring rescan insn with uid = 1242.
deferring deletion of insn with uid = 276.
Instruction folded:(insn 280 277 281 30 (set (reg/f:SI 20 %r20 [480])
(plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
(const_int 396 [0x18c]))) "../Python/compile.c":5970:20 120
{addsi3}
(nil))
deferring rescan insn with uid = 1243.
deferring rescan insn with uid = 1243.
deferring deletion of insn with uid = 280.
Instruction folded:(insn 284 281 299 30 (set (reg/f:SI 19 %r19 [481])
(plus:SI (reg/f:SI 19 %r19 [orig:127 prephitmp_37 ] [127])
(const_int 400 [0x190]))) "../Python/compile.c":5970:20 120
{addsi3}
(nil))
If I'm missing something that makes this illegal please explain it to me.
Thanks,
Manolis
