[Bug target/105856] New: ice in emit_move_insn, at expr.cc:4011

[Bug target/105856] New: ice in emit_move_insn, at expr.cc:4011

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

            Bug ID: 105856
           Summary: ice in emit_move_insn, at expr.cc:4011
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

This C code:

#pragma pack(1)
struct {
  unsigned f0;
} static g_251 = {6};
void g_329_3() { func_19(g_251); }

when compiled with -O2 on a arm-32 compiler natively or cross, does this:

during RTL pass: expand
bug819.c: In function ‘g_329_3’:
bug819.c:5:18: internal compiler error: in emit_move_insn, at expr.cc:4011
    5 | void g_329_3() { func_19(g_251); }
      |                  ^~~~~~~~~~~~~~
0x67dcba emit_move_insn(rtx_def*, rtx_def*)
        /home/dcb/gcc/trunk.git/gcc/expr.cc:4011
0xa2940d load_register_parameters
        /home/dcb/gcc/trunk.git/gcc/calls.cc:2192
0xa2c59b expand_call(tree_node*, rtx_def*, int)
        /home/dcb/gcc/trunk.git/gcc/calls.cc:3593
0xba77d0 expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier,
 rtx_def**, bool)
        /home/dcb/gcc/trunk.git/gcc/expr.cc:11621

The bug appears sometime in the week before git hash aec868578d851576.

[Bug target/105856] ice in emit_move_insn, at expr.cc:4011

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> ---
The bug first appears sometime after git hash de57440858591a88.

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[roger at nextmovesoftware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

Roger Sayle <roger at nextmovesoftware dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ice in emit_move_insn, at   |[13 Regression] ice in
                   |expr.cc:4011                |emit_move_insn, at
                   |                            |expr.cc:4011
           Assignee|unassigned at gcc dot gnu.org      |roger at nextmovesoftware dot com
                 CC|                            |roger at nextmovesoftware dot com
           Priority|P3                          |P1
            Version|12.0                        |13.0
             Status|UNCONFIRMED                 |ASSIGNED
           Keywords|                            |ice-on-valid-code
   Target Milestone|---                         |13.0
   Last reconfirmed|                            |2022-06-05
             Target|                            |arm*
     Ever confirmed|0                           |1

--- Comment #2 from Roger Sayle <roger at nextmovesoftware dot com> ---
Mine.  Sorry for the breakage.  I've a fix that avoids the ICE on ARM, and
allows GCC to generate the following code for this testcase:
g_329_3:
        mov     r0, #6
        b       func_19
[i.e. the same code as without the #pragma pack(1)].
This is a big improvement on GCC v12 which generates
(both with and without #pragma pack(1)):

g_329_3:
  movw r3, #:lower16:.LANCHOR0
  movt r3, #:upper16:.LANCHOR0
  ldr r0, [r3]
  b func_19

I'm bootstrapping and regression testing on x86_64 now.

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[roger at nextmovesoftware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #3 from Roger Sayle <roger at nextmovesoftware dot com> ---
Patch proposed:
https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596242.html

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #4 from David Binderman <dcb314 at hotmail dot com> ---
Roger makes an interesting comment about test case coverage in the C and C++
testsuite.

There are about 45,000 C test cases and about 19,000 C++ test cases.
This gives pretty good coverage in practice, with only occasional problems 
failing to be found.

The much stronger test of compiling an entire Linux distribution on x86_64, 
which I do most weeks, generates about 340,000 object modules, so it is a far
bigger
and more comprehensive testcase.

It would be an obvious extension to compile a Linux distribution on
a different architecture. Maybe ARM or PowerPC or another primary gcc target ?

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>:

https://gcc.gnu.org/g:c00e1e3aa5ae62a991d105d309061d12f6a8764f

commit r13-1004-gc00e1e3aa5ae62a991d105d309061d12f6a8764f
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Tue Jun 7 10:09:49 2022 +0100

    PR middle-end/105853: Call store_constructor directly from calls.cc.

    This patch fixes both ICE regressions PR middle-end/105853 and
    PR target/105856 caused by my recent patch to expand small const structs
    as immediate constants.  That patch updated code generation in three
    places: two in expr.cc that call store_constructor directly, and the
    third in calls.cc's load_register_parameters that expands its CONSTRUCTOR
    via expand_expr, as store_constructor is local/static to expr.cc, and
    the "public" API, should usually simply forward the constructor to the
    appropriate store_constructor function.

    Alas, despite the clean regression testing on multiple targets, the above
    ICEs show that expand_expr isn't a suitable proxy for store_constructor,
    and things that (I'd assumed) shouldn't affect how/whether a struct is
    placed in a register [such as whether the struct is considered packed/
    aligned or not] actually interfere with the optimization that is being
    attempted.

    The (proposed) solution is to export store_constructor (and it's helper
    function int_expr_size) from expr.cc, by removing their static qualifier
    and prototyping both functions in expr.h, so they can be called directly
    from load_register_parameters in calls.cc.  This cures both ICEs, but
    almost as importantly improves code generation over GCC 12.

    For PR 105853, GCC 12 generates:

    compose_nd_na_ipv6_src:
            movzx eax, WORD PTR eth_addr_zero[rip+2]
            movzx edx, WORD PTR eth_addr_zero[rip]
            movzx edi, WORD PTR eth_addr_zero[rip+4]
            sal rax, 16
            or rax, rdx
            sal rdi, 32
            or rdi, rax
            xor eax, eax
            jmp packet_set_nd
    eth_addr_zero:  .zero 6

    where now (with this fix) GCC 13 generates:
    compose_nd_na_ipv6_src:
            xorl    %edi, %edi
            xorl    %eax, %eax
            jmp     packet_set_nd

    Likewise, for PR 105856 on ARM, we'd previously generate:
    g_329_3:
            movw r3, #:lower16:.LANCHOR0
            movt r3, #:upper16:.LANCHOR0
            ldr r0, [r3]
            b func_19

    but with this optimization we now generate:
    g_329_3:
            mov     r0, #6
            b       func_19

    2022-06-07  Roger Sayle  <roger@nextmovesoftware.com>

    gcc/ChangeLog
            PR middle-end/105853
            PR target/105856
            * calls.cc (load_register_parameters): Call store_constructor
            and int_expr_size directly instead of expanding via expand_expr.
            * expr.cc (static void store_constructor): Don't prototype here.
            (static HOST_WIDE_INT int_expr_size): Likewise.
            (store_constructor): No longer static.
            (int_expr_size): Likewise, no longer static.
            * expr.h (store_constructor): Prototype here.
            (int_expr_size): Prototype here.

    gcc/testsuite/ChangeLog
            PR middle-end/105853
            PR target/105856
            * gcc.dg/pr105853.c: New test case.
            * gcc.dg/pr105856.c: New test case.

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[roger at nextmovesoftware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #6 from Roger Sayle <roger at nextmovesoftware dot com> ---
Hi David. Thanks again for all your help (building Linux distributions is a
helpful/vital service to the GCC community).  Can you confirm that this problem
is now fixed on ARM?

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

--- Comment #7 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Roger Sayle from comment #6)
> Hi David. Thanks again for all your help (building Linux distributions is a
> helpful/vital service to the GCC community).  

Thanks. Good to know I am doing something useful.
820 bugs in 10+ years.

>Can you confirm that this problem is now fixed on ARM?

I just confirmed that today's gcc compiler (git hash 2fc6e3d55f6080da)
has it fixed.

Much thanks for your fast work on this bug report.
Found & fixed in four days.

[Bug target/105856] [13 Regression] ice in emit_move_insn, at expr.cc:4011

[roger at nextmovesoftware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105856

Roger Sayle <roger at nextmovesoftware dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #8 from Roger Sayle <roger at nextmovesoftware dot com> ---
Thanks David.