[Bug target/91708] [10 regression][ARM] Bootstrap fails in gen_movsi, at config/arm/arm.md:5258

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91708

--- Comment #10 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
$ grep -A4 -r "insn 234 .*:SI 340" real.c.*|less

real.c.237r.subreg1:(insn 234 233 235 11 (set (reg:SI 340)
real.c.237r.subreg1-        (mem:SI (reg/v/f:SI 273 [ rD.73757 ]) [52 MEM
<unsigned int> [(struct real_valueD.28367 *)r_77(D)]+0 S4 A32]))
"../../gcc-trunk-1/gcc/real.c":5185:9 643 {*thumb2_movsi_vfp}
real.c.237r.subreg1-     (nil))
real.c.237r.subreg1-(insn 235 234 236 11 (set (reg:SI 339)
real.c.237r.subreg1-        (and:SI (reg:SI 340)
--
real.c.238r.dfinit:(insn 234 233 235 11 (set (reg:SI 340)
real.c.238r.dfinit-        (mem:SI (reg/v/f:SI 273 [ rD.73757 ]) [52 MEM
<unsigned int> [(struct real_valueD.28367 *)r_77(D)]+0 S4 A32]))
"../../gcc-trunk-1/gcc/real.c":5185:9 643 {*thumb2_movsi_vfp}
real.c.238r.dfinit-     (nil))
real.c.238r.dfinit-(insn 235 234 236 11 (set (reg:SI 339)
real.c.238r.dfinit-        (and:SI (reg:SI 340)
--
real.c.239r.cse1:(insn 234 233 235 11 (set (reg:SI 340)
real.c.239r.cse1-        (mem:SI (reg/v/f:SI 273 [ rD.73757 ]) [52 MEM
<unsigned int> [(struct real_valueD.28367 *)r_77(D)]+0 S4 A32]))
"../../gcc-trunk-1/gcc/real.c":5185:9 643 {*thumb2_movsi_vfp}
real.c.239r.cse1-     (nil))
real.c.239r.cse1-(insn 235 234 236 11 (set (reg:SI 339)
real.c.239r.cse1-        (and:SI (reg:SI 340)
--
real.c.239r.cse1:(insn 234 233 235 11 (set (reg:SI 340 [ MEM <unsigned int>
[(struct real_valueD.28367 *)r_77(D)] ])
real.c.239r.cse1-        (mem:SI (plus:SI (reg/v/f:SI 273 [ rD.73757 ])
real.c.239r.cse1-                (const_int 20 [0x14])) [0 MEM <charD.7[1:24]>
[(voidD.73 *)r_77(D)]+20 S4 A8])) "../../gcc-trunk-1/gcc/real.c":5185:9 643
{*thumb2_movsi_vfp}
real.c.239r.cse1-     (nil))
real.c.239r.cse1-(insn 235 234 236 11 (set (reg:SI 339)
--

so initially the mem-ref was:
[52 MEM <unsigned int> [(struct real_valueD.28367 *)r_77(D)]+0 S4 A32]

but it is replaced by:
[0 MEM <charD.7[1:24]> [(voidD.73 *)r_77(D)]+20 S4 A8]

this is bad, because the Alignment is worse, and the alias-set
is changed from 52 to 0, alias everything.