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

[Dimitar Dimitrov <dimitar@dinux.eu>]

On Wed, Nov 08, 2023 at 11:47:33AM +0800, Lehua Ding wrote:
> Hi,
> 
> These patchs try to support subreg coalesce feature in
> register allocation passes (ira and lra).

Hi Lehua,

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);


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


For pru-elf the GCC build fails with:
/mnt/nvme/dinux/local-workspace/gcc/libgcc/unwind-dw2-fde.c: In function 'linear_search_fdes':
/mnt/nvme/dinux/local-workspace/gcc/libgcc/unwind-dw2-fde.c:1035:1: internal compiler error: Floating point exception
 1035 | }
      | ^
0x1694f2e crash_signal
        /mnt/nvme/dinux/local-workspace/gcc/gcc/toplev.cc:316
0x1313178 get_range_hard_regs(int, subreg_range const&)
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:609
0x131343a new_insn_reg
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:658
0x13174f0 add_regs_to_insn_regno_info
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1608
0x1318479 lra_update_insn_regno_info(rtx_insn*)
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1769
0x13196ab lra_push_insn_1
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1919
0x13196de lra_push_insn(rtx_insn*)
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1927
0x13197da push_insns
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:1970
0x131b6dc lra(_IO_FILE*)
        /mnt/nvme/dinux/local-workspace/gcc/gcc/lra.cc:2511
0x129f237 do_reload
        /mnt/nvme/dinux/local-workspace/gcc/gcc/ira.cc:5960
0x129f6c6 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))

Regards,
Dimitar