[Bug target/99596] New: arm: internal error in single_pred_edge

[Bug target/99596] New: arm: internal error in single_pred_edge

[arnd at linaro dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

            Bug ID: 99596
           Summary: arm: internal error in single_pred_edge
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: arnd at linaro dot org
  Target Milestone: ---

I ran into this internal compiler error while building the Linux kernel in
random configurations, made a reduced test case:

$ arm-linux-gnueabihf-gcc-11 -Os -mtune=xscale -c cfi_cmdset_0002.c 
during RTL pass: fwprop2
cfi_cmdset_0002.c: In function ‘i’:
cfi_cmdset_0002.c:16:1: internal compiler error: in single_pred_edge, at
basic-block.h:350
   16 | }
      | ^
0x7bf679 single_pred_edge
        ../../src/gcc/basic-block.h:350
0x7bf679 single_pred
        ../../src/gcc/basic-block.h:369
0x7bf679 rtl_ssa::function_info::create_degenerate_phi(rtl_ssa::ebb_info*,
rtl_ssa::set_info*)
        ../../src/gcc/rtl-ssa/blocks.cc:535
0x1860f6d rtl_ssa::function_info::finalize_new_accesses(rtl_ssa::insn_change&)
        ../../src/gcc/rtl-ssa/changes.cc:508
0x18617c3
rtl_ssa::function_info::change_insns(array_slice<rtl_ssa::insn_change*>)
        ../../src/gcc/rtl-ssa/changes.cc:659
0x1862078 rtl_ssa::function_info::change_insn(rtl_ssa::insn_change&)
        ../../src/gcc/rtl-ssa/changes.cc:717
0x172f1cd try_fwprop_subst_pattern
        ../../src/gcc/fwprop.c:552
0x172f1cd try_fwprop_subst
        ../../src/gcc/fwprop.c:625
0x172f73e forward_propagate_and_simplify
        ../../src/gcc/fwprop.c:823
0x172f73e forward_propagate_into
        ../../src/gcc/fwprop.c:883
0x172fb8a forward_propagate_into
        ../../src/gcc/fwprop.c:835
0x172fb8a fwprop_insn
        ../../src/gcc/fwprop.c:954
0x172fc49 fwprop
        ../../src/gcc/fwprop.c:992
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-11/README.Bugs> for instructions.


$ cat cfi_cmdset_0002.c
register int a asm("sp");
extern int b;
typedef struct {
  long c[16 * 8 / 32];
} d;
int e;
int f;
int g;
d h;
int j(int, int, int, d);
int i(void) {
  for (;;) {
    b &&j(e, f, g, h);
    j(e, f, g, h);
  }
}

$ arm-linux-gnueabihf-gcc-11 --version
arm-linux-gnueabihf-gcc-11 (Ubuntu 11-20210310-1ubuntu1) 11.0.1 20210310
(experimental) [master revision
8dc225d311e:2453ef06221:5987d8a79cda1069c774e5c302d5597310270026]

[Bug target/99596] [11 Regression] arm: internal error in single_pred_edge

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

Alex Coplan <acoplan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
             Target|                            |arm
                 CC|                            |acoplan at gcc dot gnu.org,
                   |                            |rsandifo at gcc dot gnu.org
           Keywords|                            |ice-on-valid-code
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
      Known to fail|                            |11.0
   Last reconfirmed|                            |2021-03-15
      Known to work|                            |10.2.1
            Summary|arm: internal error in      |[11 Regression] arm:
                   |single_pred_edge            |internal error in
                   |                            |single_pred_edge

--- Comment #1 from Alex Coplan <acoplan at gcc dot gnu.org> ---
Confirmed on trunk. GCC 10 doesn't ICE.

[Bug target/99596] [11 Regression] arm: internal error in single_pred_edge

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rsandifo at gcc dot gnu.org

--- Comment #2 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Mine.

[Bug rtl-optimization/99596] [11 Regression] arm: internal error in single_pred_edge

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug rtl-optimization/99596] [11 Regression] arm: internal error in single_pred_edge

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Richard, any progress?

[Bug rtl-optimization/99596] [11 Regression] arm: internal error in single_pred_edge

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:b4d6af55fe55c0eab87ab875bfd0346677e12236

commit r11-8213-gb4d6af55fe55c0eab87ab875bfd0346677e12236
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Fri Apr 16 12:38:01 2021 +0100

    rtlanal: Don't assume that calls write to a global SP [PR99596]

    This patch is a GCC 11 regression caused by the rtl-ssa code.
    Normally we treat calls as containing a potential set of a global
    register, but DF makes a sensible exception for the stack pointer:

          if (i == STACK_POINTER_REGNUM)
            /* The stack ptr is used (honorarily) by a CALL insn.  */
            df_ref_record (DF_REF_BASE, collection_rec, regno_reg_rtx[i],
                           NULL, bb, insn_info, DF_REF_REG_USE,
                           DF_REF_CALL_STACK_USAGE | flags);
          else if (global_regs[i])
            {
              /* Calls to const functions cannot access any global registers
and
                 calls to pure functions cannot set them.  All other calls may
                 reference any of the global registers, so they are recorded as
                 used. */

    The only DF definition of SP was therefore the one in the entry block.
    However, the rtlanal.c rtx_properties code (wrongly) assumed that calls
    also clobbered the global SP.  This led to multiple definitions of SP
    when we only expected one.

    This patch tightens the rtlanal.c handling of global registers
    to match the DF approach.

    gcc/
            PR rtl-optimization/99596
            * rtlanal.c (rtx_properties::try_to_add_insn): Don't add global
            register accesses for const calls.  Assume that pure functions
            can only read from global registers.  Ignore cases in which
            the stack pointer has been marked global.

    gcc/testsuite/
            PR rtl-optimization/99596
            * gcc.target/arm/pr99596.c: New test.

[Bug rtl-optimization/99596] [11 Regression] arm: internal error in single_pred_edge

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99596

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.