Re: [PATCH] xtensa: Prepare the transition from Reload to LRA

[Max Filippov <jcmvbkbc@gmail.com>]

Hi Suwa-san,

On Fri, Oct 14, 2022 at 4:19 AM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
> This patch provides the first step in the transition from Reload to LRA
> in Xtensa.
>
> gcc/ChangeLog:
>
>         * config/xtensa/xtensa-proto.h (xtensa_split1_is_finished_p):
>         New prototype.
>         * config/xtensa/xtensa.cc
>         (xtensa_split1_is_finished_p, xtensa_lra_p): New functions.
>         (TARGET_LRA_P): Replace the dummy hook with xtensa_lra_p.
>         (xt_true_regnum): Rework.
>         * gcc/config/xtensa/xtensa.h (CALL_REALLY_USED_REGISTERS):
>         Rename from CALL_USED_REGISTERS, and remove what correspond to
>         FIXED_REGISTERS.
>         * gcc/config/xtensa/constraints.md (Y):
>         Use !xtensa_split1_is_finished_p() instead of can_create_pseudo_p().
>         * gcc/config/xtensa/predicates.md (move_operand): Ditto.
>         * gcc/config/xtensa/xtensa.md:
>         Add new split pattern that puts out-of-constraint integer constants
>         into the constant pool.
>         * gcc/config/xtensa/xtensa.opt (-mlra): New target-specific option
>         for testing purpose.
> ---
>  gcc/config/xtensa/constraints.md  |  2 +-
>  gcc/config/xtensa/predicates.md   |  2 +-
>  gcc/config/xtensa/xtensa-protos.h |  1 +
>  gcc/config/xtensa/xtensa.cc       | 48 ++++++++++++++++++++++++-------
>  gcc/config/xtensa/xtensa.h        |  6 ++--
>  gcc/config/xtensa/xtensa.md       | 12 ++++++++
>  gcc/config/xtensa/xtensa.opt      |  4 +++
>  7 files changed, 60 insertions(+), 15 deletions(-)

Thank you for doing this, I couldn't find time to get back to it since 2020 ):

This change results in a few new regressions in the following tests
caused by ICE even when running without -mlra option:

+FAIL: gcc.c-torture/execute/pr92904.c   -O1  (internal compiler
error: in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -O2  (internal compiler
error: in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  (internal
compiler error: in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -O3 -g  (internal compiler
error: in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -Os  (internal compiler
error: in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  (internal compiler error:
in extract_insn, at recog.cc:2791)
+FAIL: gcc.c-torture/execute/pr92904.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  (internal compiler error: in extract_insn, at
recog.cc:2791)
+FAIL: g++.dg/torture/vshuf-v2si.C   -O3 -g  (internal compiler error:
in extract_insn, at recog.cc:2791)
+FAIL: g++.dg/torture/vshuf-v8qi.C   -O3 -g  (internal compiler error:
in extract_insn, at recog.cc:2791)

The backtraces look like this in all of them:

gcc/gcc/testsuite/gcc.c-torture/execute/pr92904.c:395:1: error:
unrecognizable insn:
(insn 10501 7 10502 2 (set (reg:SI 5913)
       (const_int 1431655765 [0x55555555]))
"gcc/gcc/testsuite/gcc.c-torture/execute/pr92904.c":239:9 -1
    (nil))
during RTL pass: subreg3
gcc/gcc/testsuite/gcc.c-torture/execute/pr92904.c:395:1: internal
compiler error: in extract_insn, at recog.cc:2791
0x6b17f7 _fatal_insn(char const*, rtx_def const*, char const*, int, char const*)
       gcc/gcc/rtl-error.cc:108
0x6b187a _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
       gcc/gcc/rtl-error.cc:116
0x6a2aa4 extract_insn(rtx_insn*)
       gcc/gcc/recog.cc:2791
0x179e94d decompose_multiword_subregs
       gcc/gcc/lower-subreg.cc:1678
0x179ebdd execute
       gcc/gcc/lower-subreg.cc:1820

There's also the following runtime failures, but only on
call0 configuration:

+FAIL: gcc.c-torture/execute/20010122-1.c   -O1  execution test
+FAIL: gcc.c-torture/execute/20010122-1.c   -O2  execution test
+FAIL: gcc.c-torture/execute/20010122-1.c   -O3 -g  execution test
+FAIL: gcc.c-torture/execute/20010122-1.c   -Os  execution test
+FAIL: gcc.c-torture/execute/20010122-1.c   -O2 -flto
-fno-use-linker-plugin -flto-partition=none  execution test

-- 
Thanks.
-- Max