Re: [PATCH 0/7] ira/lra: Support subreg coalesce

[Lehua Ding <lehua.ding@rivai.ai>]

Hi Dimitar,

Thanks for the tests.

> This patch set breaks the build for at least three embedded targets. See
> below.
> 
> For avr the GCC build fails with:
> /mnt/nvme/dinux/local-workspace/gcc/gcc/ira-lives.cc:149:39: error: call of overloaded ‘set_subreg_conflict_hard_regs(ira_allocno*&, int&)’ is ambiguous
>    149 |         set_subreg_conflict_hard_regs (OBJECT_ALLOCNO (obj), regno);

I think it's because `HARD_REG_SET` and `unsigned int` are of the same 
type on avr target(i.e. No more than 32 registers on avr target), so 
these two bellow function prototypes conflict, I'll adjust it.

static void
set_subreg_conflict_hard_regs (ira_allocno_t a, HARD_REG_SET regs)

static void
set_subreg_conflict_hard_regs (ira_allocno_t a, unsigned int regno)

> For arm-none-eabi the newlib build fails with:
> /mnt/nvme/dinux/local-workspace/newlib/newlib/libm/math/e_jn.c:279:1: internal compiler error: Floating point exception
>    279 | }
>        | ^
> 0x1176e0f crash_signal
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/toplev.cc:316
> 0xf6008d get_range_hard_regs(int, subreg_range const&)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:609
> 0xf6008d get_range_hard_regs(int, subreg_range const&)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:601
> 0xf60312 new_insn_reg
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:658
> 0xf6064d add_regs_to_insn_regno_info
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1623
> 0xf62909 lra_update_insn_regno_info(rtx_insn*)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1769
> 0xf62e46 lra_update_insn_regno_info(rtx_insn*)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1762
> 0xf62e46 lra_push_insn_1
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1919
> 0xf62f2d lra_push_insn(rtx_insn*)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1927
> 0xf62f2d push_insns
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1970
> 0xf63302 push_insns
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1966
> 0xf63302 lra(_IO_FILE*)
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:2511
> 0xf0e399 do_reload
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/ira.cc:5960
> 0xf0e399 execute
>          /mnt/nvme/dinux/local-workspace/gcc/gcc/ira.cc:6148
> 
> The divide by zero error above is interesting. I'm not sure why ira_reg_class_max_nregs[] yields 0 for the pseudo register 168 in the following rtx:
> (debug_insn 168 167 169 19 (var_location:SI encoding (reg/v:SI 168 [ encoding ])) -1
>       (nil))

I just cross compiled an arm-none-eabi compiler and didn't encounter 
this error, can you give me a little more config info about build? For 
example, flags_for_target, etc. Thanks again.

-- 
Best,
Lehua (RiVAI)
lehua.ding@rivai.ai