Re: [PATCH V2] RTL_SSA: Relax PHI_MODE in phi_setup

[Richard Sandiford <richard.sandiford@arm.com>]

juzhe.zhong@rivai.ai writes:
> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
>
> Hi, Richard.
>
> RISC-V port needs to add a bunch VLS modes (V16QI,V32QI,V64QI,...etc)
> There are sharing same REG_CLASS with VLA modes (VNx16QI,VNx32QI,...etc)
>
> When I am adding those VLS modes, the RTL_SSA initialization in VSETVL PASS (inserted after RA) ICE:
> rvv.c:13:1: internal compiler error: in partial_subreg_p, at rtl.h:3186
>    13 | }
>       | ^
> 0xf7a5b1 partial_subreg_p(machine_mode, machine_mode)
>         ../../../riscv-gcc/gcc/rtl.h:3186
> 0x1407616 wider_subreg_mode(machine_mode, machine_mode)
>         ../../../riscv-gcc/gcc/rtl.h:3252
> 0x2a2c6ff rtl_ssa::combine_modes(machine_mode, machine_mode)
>         ../../../riscv-gcc/gcc/rtl-ssa/internals.inl:677
> 0x2a2b9a4 rtl_ssa::function_info::simplify_phi_setup(rtl_ssa::phi_info*, rtl_ssa::set_info**, bitmap_head*)
>         ../../../riscv-gcc/gcc/rtl-ssa/functions.cc:146
> 0x2a2c142 rtl_ssa::function_info::simplify_phis()
>         ../../../riscv-gcc/gcc/rtl-ssa/functions.cc:258
> 0x2a2b3f0 rtl_ssa::function_info::function_info(function*)
>         ../../../riscv-gcc/gcc/rtl-ssa/functions.cc:51
> 0x1cebab9 pass_vsetvl::init()
>         ../../../riscv-gcc/gcc/config/riscv/riscv-vsetvl.cc:4578
> 0x1cec150 pass_vsetvl::execute(function*)
>         ../../../riscv-gcc/gcc/config/riscv/riscv-vsetvl.cc:4716
>
> The reason is that we have V32QImode (size = [32,0]) which is the mode set as regno_reg_rtx[97]
> When the PHI input def comes from ENTRY BLOCK (index =0), the def->mode () = V32QImode.
> But the phi_mode = VNx2QI for example (I use VLA modes intrinsic write the codes).
> Then combine_modes report ICE.
>
> gcc/ChangeLog:
>
>         * rtl-ssa/internals.inl: Fix when mode1 and mode2 are not ordred.

OK if it passes testing.

Thanks,
Richard

> ---
>  gcc/rtl-ssa/internals.inl | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/gcc/rtl-ssa/internals.inl b/gcc/rtl-ssa/internals.inl
> index 0a61811289d..e49297c12b3 100644
> --- a/gcc/rtl-ssa/internals.inl
> +++ b/gcc/rtl-ssa/internals.inl
> @@ -673,6 +673,9 @@ combine_modes (machine_mode mode1, machine_mode mode2)
>    if (mode2 == E_BLKmode)
>      return mode1;
>  
> +  if (!ordered_p (GET_MODE_SIZE (mode1), GET_MODE_SIZE (mode2)))
> +    return BLKmode;
> +
>    return wider_subreg_mode (mode1, mode2);
>  }