Built a bleeding-edge arm-gcc toolchain. It works fine but when I tried newlib built with -flto I got a crash in lto1.

$ arm-none-eabi-g++ -o main.elf -Wl,--relax -mthumb -mcpu=cortex-m4 -O3

during IPA pass: icf
In function '__retarget_lock_acquire_recursive':
lto1: internal compiler error: Segmentation fault

#0  __strchr_avx2 () at ../sysdeps/x86_64/multiarch/strchr-avx2.S:57
#1  0x00000000014de71a in strchr (__c=43, __s=0x0) at /usr/include/string.h:220
#2  arm_parse_cpu_option_name (list=0x1ab3400 <all_cores>, optname=optname@entry=0x18704ba "-mcpu", target=0x0, complain=complain@entry=true)
    at gcc-10-20190512/gcc/common/config/arm/arm-common.c:349
#3  0x0000000000f8545d in arm_configure_build_target (target=0x1e7b500 <arm_active_target>, opts=0x7fffff3e2a00, opts_set=0x1e81100 <global_options_set>,
    warn_compatible=<optimized out>) at gcc-10-20190512/gcc/config/arm/arm.c:3147
#4  0x0000000000fa5b68 in arm_set_current_function (fndecl=<optimized out>) at gcc-10-20190512/gcc/tree.h:3186
#5  0x000000000097da22 in invoke_set_current_function_hook (fndecl=0x7fffff402400)
    at gcc-10-20190512/gcc/function.c:4629
#6  0x0000000000984a48 in invoke_set_current_function_hook (fndecl=0x7fffff402400)
    at gcc-10-20190512/gcc/function.c:4788
#7  allocate_struct_function (fndecl=0x7fffff402400, abstract_p=<optimized out>) at gcc-10-20190512/gcc/function.c:4742
#8  0x0000000000afc5ed in input_function (ib_cfg=0x7ffffffed9c0, ib=0x7ffffffed9a0, data_in=0x1f8c510, fn_decl=0x7fffff402400)
    at gcc-10-20190512/gcc/lto-streamer-in.c:1066
#9  lto_read_body_or_constructor (file_data=0x7fffff3ec960, data=<optimized out>, node=<optimized out>, section_type=LTO_section_function_body)
    at gcc-10-20190512/gcc/lto-streamer-in.c:1296
#10 0x000000000083d38b in cgraph_node::get_untransformed_body (this=0x7fffff418708)
    at gcc-10-20190512/gcc/cgraph.c:3570
#11 0x000000000144762f in ipa_icf::sem_function::init (this=0x1f61230) at gcc-10-20190512/gcc/cgraph.h:2008
#12 0x0000000001441d12 in ipa_icf::sem_item_optimizer::parse_nonsingleton_classes (this=this@entry=0x1eca870)
    at gcc-10-20190512/gcc/ipa-icf.c:2776
#13 0x000000000144d730 in ipa_icf::sem_item_optimizer::execute (this=0x1eca870) at gcc-10-20190512/gcc/ipa-icf.c:2577
#14 0x000000000144e9b7 in ipa_icf::ipa_icf_driver () at gcc-10-20190512/gcc/ipa-icf.c:3698
#15 ipa_icf::pass_ipa_icf::execute (this=<optimized out>) at gcc-10-20190512/gcc/ipa-icf.c:3745
#16 0x0000000000b777ea in execute_one_pass (pass=0x1ec0940) at gcc-10-20190512/gcc/passes.c:2473
#17 0x0000000000b78517 in execute_ipa_pass_list (pass=0x1ec0940) at gcc-10-20190512/gcc/passes.c:2913
#18 0x00000000007ab461 in do_whole_program_analysis () at gcc-10-20190512/gcc/context.h:48
#19 lto_main () at gcc-10-20190512/gcc/lto/lto.c:628
#20 0x0000000000c472af in compile_file () at gcc-10-20190512/gcc/toplev.c:456
#21 0x000000000077b1e6 in do_compile () at gcc-10-20190512/gcc/toplev.c:2205
#22 toplev::main (this=this@entry=0x7ffffffedd86, argc=<optimized out>, argc@entry=24, argv=<optimized out>, argv@entry=0x7ffffffede88)
    at gcc-10-20190512/gcc/toplev.c:2340
#23 0x000000000077d9dc in main (argc=24, argv=0x7ffffffede88) at gcc-10-20190512/gcc/main.c:39

I'm not sure how to reduce this.