[Bug middle-end/70239] New: [6 Regression] ICE in ggc_set_mark

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70239

            Bug ID: 70239
           Summary: [6 Regression] ICE in ggc_set_mark
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

Created attachment 37969
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37969&action=edit
Testcase

At least gcc-6.0.0-alpha20160306 and gcc-6.0.0-alpha20160313 snapshots
terminate w/ SIGSEGV when compiling the attached artificial test case at -O2 or
-Os:

% x86_64-pc-linux-gnu-gcc-6.0.0-alpha20160313 -c -Os -w lh3spsvf.c 
lh3spsvf.c: In function 'd5':
lh3spsvf.c:7:1: internal compiler error: Segmentation fault
 d5(void)
 ^~

Thread 2.1 "cc1" received signal SIGSEGV, Segmentation fault.
[Switching to process 543]
0x00000000006da3b3 in ggc_set_mark(void const*) ()
(gdb) where
#0  0x00000000006da3b3 in ggc_set_mark(void const*) ()
#1  0x00000000005e0f54 in gt_ggc_mx_lang_tree_node(void*) ()
#2  0x0000000000901bff in gt_ggc_mx_gimple(void*) ()
#3  0x000000000090183a in gt_ggc_mx_basic_block_def(void*) ()
#4  0x000000000090189a in gt_ggc_mx_control_flow_graph(void*) ()
#5  0x00000000009027cc in gt_ggc_mx_function(void*) ()
#6  0x00000000005e106d in gt_ggc_mx_lang_tree_node(void*) ()
#7  0x00000000005e1620 in gt_ggc_mx_lang_tree_node(void*) ()
#8  0x00000000005e15e8 in gt_ggc_mx_lang_tree_node(void*) ()
#9  0x00000000005e0bde in gt_ggc_mx_lang_tree_node(void*) ()
#10 0x00000000005e10f3 in gt_ggc_mx_lang_tree_node(void*) ()
#11 0x00000000005e0ac2 in gt_ggc_mx_lang_tree_node(void*) ()
#12 0x00000000005e1612 in gt_ggc_mx_lang_tree_node(void*) ()
#13 0x00000000005e1567 in gt_ggc_mx_lang_tree_node(void*) ()
#14 0x00000000005e0fa0 in gt_ggc_mx_lang_tree_node(void*) ()
#15 0x0000000000a5e3e3 in gt_ggc_mx_hash_table_libfunc_decl_hasher_(void*) ()
#16 0x0000000000899e69 in ggc_mark_root_tab(ggc_root_tab const*) ()
#17 0x000000000089a0bd in ggc_mark_roots() ()
#18 0x00000000006dae19 in ggc_collect() ()
#19 0x0000000000a74e92 in execute_one_pass(opt_pass*) ()
#20 0x0000000000a752a8 in execute_pass_list_1(opt_pass*) ()
#21 0x0000000000a752ba in execute_pass_list_1(opt_pass*) ()
#22 0x0000000000a75305 in execute_pass_list(function*, opt_pass*) ()
#23 0x000000000075b724 in cgraph_node::expand() ()
#24 0x000000000075d057 in symbol_table::compile() [clone .part.49] ()
#25 0x000000000075f4c3 in symbol_table::finalize_compilation_unit() ()
#26 0x0000000000b3f55a in compile_file() ()
#27 0x00000000005c8eaf in toplev::main(int, char**) ()
#28 0x00000000005cb0c7 in main ()

I failed to reduce the test case in any significant way any more.