Re: RV64 Zicond ICE (was Re: [committed][RISC-V]Don't reject constants in cmov condition)

[Jeff Law <jeffreyalaw@gmail.com>]

On 8/8/23 11:21, Vineet Gupta wrote:
> Hi Jeff,
> 
> On 8/7/23 13:36, Jeff Law wrote:
>>
>> This test is too aggressive.  Constants have VOIDmode, so we need to 
>> let the through this phase of conditional move support.
>>
>> Fixes several missed conditional moves with the trunk.
>>
>> Committed to the trunk,
> 
> As discussed this morning, this triggers an ICE when building glibc for 
> rv64_zicond
> 
> programs/ld-ctype.c:3977:1: error: unrecognizable insn:
>   3977 | }
>        | ^
> (insn 238 237 239 18 (set (reg:SI 727)
>          (if_then_else:SI (eq:SI (reg:SI 725)
>                  (const_int 0 [0]))
>              (const_int 0 [0])
>              (reg:SI 721))) -1
>       (nil))
> during RTL pass: vregs
> programs/ld-ctype.c:3977:1: internal compiler error: in extract_insn, at 
> recog.cc:2791
> 0x885de7 _fatal_insn(char const*, rtx_def const*, char const*, int, char 
> const*)     ../.././gcc/gcc/rtl-error.cc:108
> 0x885e09 _fatal_insn_not_found(rtx_def const*, char const*, int, char 
> const*)    ../.././gcc/gcc/rtl-error.cc:116
> 0x8846f9 extract_insn(rtx_insn*)    ../.././gcc/gcc/recog.cc:2791
> 0xcf77ae instantiate_virtual_regs_in_insn ../.././gcc/gcc/function.cc:1610
> 0xcf77ae instantiate_virtual_regs ../.././gcc/gcc/function.cc:1983
> 0xcf77ae execute    ../.././gcc/gcc/function.cc:2030
> 
> Here's the reduced reproducer.
> 
> a, c;
> long b;
> d() {
>    for (;;)
>      if (a & (b < 8 ?: 1 << b))
>        c = 1;
> }
> 
> I'll try to muster a fix :-)
:-)  That's even simpler than the one I just reduced.  But I can see the 
same basic structure in my reduced case.

I'll take it from here.  I mucked something up, so I feel I ought to fix it.

jeff