[Bug middle-end/69854] New: [6 regression] ICE: tree check: expected class 'constant', have 'binary' (plus_expr) in generic_simplify_65, at generic-match.c:3110

[nsz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69854

            Bug ID: 69854
           Summary: [6 regression]  ICE: tree check: expected class
                    'constant', have 'binary' (plus_expr) in
                    generic_simplify_65, at generic-match.c:3110
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nsz at gcc dot gnu.org
  Target Milestone: ---

Created attachment 37725
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37725&action=edit
test case

gcc -frounding-math -Ofast -c t.c
t.c: In function 'acos':
t.c:62:1: internal compiler error: tree check: expected class 'constant', have
'binary' (plus_expr) in generic_simplify_65, at generic-match.c:3110
 }
 ^
0xda99d7 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        S/gcc/tree.c:9688
0x5b706c tree_class_check(tree_node*, tree_code_class, char const*, int, char
const*)
        S/gcc/tree.h:3129
0x5b706c generic_simplify_65
        B/gcc/generic-match.c:3110
0xf20cf5 generic_simplify_PLUS_EXPR
        B/gcc/generic-match.c:9662
0xf4213d generic_simplify(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        B/gcc/generic-match.c:25902
0x84b7be fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        S/gcc/fold-const.c:9235
0x856eaa fold_build2_stat_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        S/gcc/fold-const.c:12451
0xd3a29f find_tail_calls
        S/gcc/tree-tailcall.c:561
0xd39bff find_tail_calls
        S/gcc/tree-tailcall.c:442
0xd3ae51 tree_optimize_tail_calls_1
        S/gcc/tree-tailcall.c:982
Please submit a full bug report,
with preprocessed source if appropriate.

gcc version 6.0.0 20160217 (experimental) (GCC) 

i can reproduce it on arm, aarch64 and x86_64 with the attached test case.
(found while building acos.c in musl libc with CFLAGS+=-Ofast, the test case is
preprocessed and somewhat cleaned up, it's target independent)