[Bug tree-optimization/96579] New: [8/9/10/11 Regression] ICE in gimple check: expected gimple_assign(error_mark), have gimple_nop() in gimple_assign_rhs1, at gimple.h:2605 since r7-950-g8a85cee26eabf5cf

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96579

            Bug ID: 96579
           Summary: [8/9/10/11 Regression] ICE in gimple check: expected
                    gimple_assign(error_mark), have gimple_nop() in
                    gimple_assign_rhs1, at gimple.h:2605 since
                    r7-950-g8a85cee26eabf5cf
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---

I see the following ICE:

$ gcc /home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/pr96370.c
-fno-tree-forwprop -funsafe-math-optimizations -fno-tree-vrp -O3
during GIMPLE pass: reassoc
/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/pr96370.c: In function ‘a’:
/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/pr96370.c:5:6: internal
compiler error: gimple check: expected gimple_assign(error_mark), have
gimple_nop() in gimple_assign_rhs1, at gimple.h:2605
    5 | void a(_Decimal128 b)
      |      ^
0x674ecc gimple_check_failed(gimple const*, char const*, int, char const*,
gimple_code, tree_code)
        /home/marxin/Programming/gcc/gcc/gimple.c:1256
0x714c21 GIMPLE_CHECK2<gassign*>
        /home/marxin/Programming/gcc/gcc/gimple.h:93
0x714c61 GIMPLE_CHECK2<const gassign*>
        /home/marxin/Programming/gcc/gcc/gimple.h:2603
0x714c61 gimple_assign_rhs1
        /home/marxin/Programming/gcc/gcc/gimple.h:2605
0x71535d gimple_assign_rhs1
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:5042
0x71535d rewrite_expr_tree
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:4987
0xf35ee5 rewrite_expr_tree
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:5075
0xf442cc reassociate_bb
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:6548
0xf43e28 reassociate_bb
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:6597
0xf4627e do_reassoc
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:6709
0xf4627e execute_reassoc
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:6796
0xf4627e execute
        /home/marxin/Programming/gcc/gcc/tree-ssa-reassoc.c:6835
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