Re: Why doesn't this pattern match?

[Andrew Pinski <pinskia@gmail.com>]

On Thu, Jan 6, 2022 at 8:13 PM Andras Tantos <andras@tantosonline.com> wrote:
>
> Hello!
>
> My name is Andras Tantos and I just joined this list, so if I'm asking
> something off-topic or not following the rules of the community, please
> let me know.
>
> What I'm working on is to port GCC (and Binutils) to a new CPU ISA, I
> call 'brew'. During developing for this target, I got the following
> error:

How are the following constraints defined:
W,A,B

Does one include the pc register?
Otherwise you have a mismatch between the predicate
brew_general_mov_src_operand (which accepts the pc register) and the
constraint which does not.

Thanks,
Andrew Pinski


>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> first.c: In function ‘test_call’:
> first.c:61:52: error: insn does not satisfy its constraints:
>    61 | int test_call(int a, int b) { return test_qm(a,b); }
>       |                                                    ^
> (insn 25 8 9 (set (reg:SI 6 $r6)
>         (reg:SI 0 $pc)) "first.c":61:38 17 {*movsi}
>      (nil))
> during RTL pass: final
> first.c:61:52: internal compiler error: in final_scan_insn_1, at
> final.c:2811
> 0x6c4c23 _fatal_insn(char const*, rtx_def const*, char const*, int,
> char const*)
>         ../../brew-gcc/gcc/rtl-error.c:108
> 0x6c4c4f _fatal_insn_not_found(rtx_def const*, char const*, int, char
> const*)
>         ../../brew-gcc/gcc/rtl-error.c:118
> 0x643585 final_scan_insn_1
>         ../../brew-gcc/gcc/final.c:2811
> 0xb1ef3f final_scan_insn(rtx_insn*, _IO_FILE*, int, int, int*)
>         ../../brew-gcc/gcc/final.c:2940
> 0xb1f207 final_1
>         ../../brew-gcc/gcc/final.c:1997
> 0xb1fbe6 rest_of_handle_final
>         ../../brew-gcc/gcc/final.c:4285
> 0xb1fbe6 execute
>         ../../brew-gcc/gcc/final.c:4363
> Please submit a full bug report,
> with preprocessed source if appropriate.
> Please include the complete backtrace with any bug report.
> See <https://gcc.gnu.org/bugs/> for instructions.
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> Clearly, the compiler couldn't find a rule that works for this register
> move. The relevant section of the .md file is:
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> (define_expand "movsi"
>    [(set (match_operand:SI 0 "general_operand" "")
>          (match_operand:SI 1 "general_operand" ""))]
>    ""
>   "
> {
>   /* If this is a store, force the value into a register.  */
>   if (! (reload_in_progress || reload_completed))
>   {
>     if (MEM_P (operands[0]))
>     {
>       operands[1] = force_reg (SImode, operands[1]);
>       if (MEM_P (XEXP (operands[0], 0)))
>         operands[0] = gen_rtx_MEM (SImode, force_reg (SImode, XEXP
> (operands[0], 0)));
>     }
>     else
>       if (MEM_P (operands[1])
>           && MEM_P (XEXP (operands[1], 0)))
>         operands[1] = gen_rtx_MEM (SImode, force_reg (SImode, XEXP
> (operands[1], 0)));
>   }
> }")
>
> (define_insn "*movsi"
>   [(set (match_operand:SI 0
> "nonimmediate_operand"        "=r,r,r,W,A,B,r,r,r")
>         (match_operand:SI 1 "brew_general_mov_src_operand"
> "O,r,i,r,r,r,W,A,B"))]
>   "register_operand (operands[0], SImode)
>    || register_operand (operands[1], SImode)"
>   "@
>    %0 <- %0 - %0
>    %0 <- %1
>    %0 <- %1
>    mem[%0] <- %1
>    mem[%0] <- %1
>    mem[%0] <- %1
>    %0 <- mem[%1]
>    %0 <- mem[%1]
>    %0 <- mem[%1]"
> )
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> As you can imagine, I'm fairly new to GCC development, so I must be
> making some rookie mistake here, but I would have thought that the
> second alternative in the "*movsi" rule above would match the pattern.
>
> brew_general_mov_src_operand is defined as follows:
>
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> (define_predicate "brew_general_mov_src_operand"
>   (match_code "mem,const_int,reg,subreg,symbol_ref,label_ref,const")
> {
>   /* Any (MEM LABEL_REF) is OK.  That is a pc-relative load.  */
>   if (MEM_P (op) && GET_CODE (XEXP (op, 0)) == LABEL_REF)
>     return 1;
>
>   if (MEM_P (op)
>       && GET_CODE (XEXP (op, 0)) == PLUS
>       && GET_CODE (XEXP (XEXP (op, 0), 0)) == REG
>       && GET_CODE (XEXP (XEXP (op, 0), 1)) == CONST_INT
>   )
>     return 1;
>   /* Any register is good too */
>   if (REG_P(op))
>     return 1;
>   /* PC as source is also acceptable */
>   if (op == pc_rtx)
>     return 1;
>   return general_operand (op, mode);
> })
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>
> Thanks for all the help,
> Andras
>
>