[arm-gnu] ICE segfault in 2009q3 (G++ Lite, GNU/Linux EABI)

[Chris Winter <elwintro@xxxxxxxxx>]

Hi guys,

I've encountered an ICE segfault when cross-compiling an application
for ARM using 2009q3 (G++ Lite, GNU/Linux EABI). It's happening during
one of the tree SSA passes, specifically during the conditional copy
propagation pass wherein a NULL pointer is getting dereferenced.

Here are the main compiler switches I'm using:

-march=armv7-a -mtune=cortex-a8 -mfpu=neon -mfloat-abi=softfp -O2
-fno-omit-frame-pointer -mapcs-frame -fno-exceptions -Wall
-fno-strict-aliasing -funsigned-char

Now, I know you folks frown heavily upon rebuilding CodeSourcery tool
chains from scratch, and thus cannot offer support to those mavericks
who do their own rebuilds. However, I've been able to get a backtrace
from cc1 when the ICE occurs, but I know basically nothing about the
tree SSA code in gcc so I was hoping someone could have a look at the
backtrace and at least throw me a bone since I'm willing to help
figure out the root cause, and even the dogs eat the crumbs that fall
from their masters' table.

Just to be clear, the ICE occurs even with the official release of
2009q3, both the Linux and Windows versions, so it's definitely a real
problem and not just an artifact of a dodgy unauthorized rebuild.
Since the segfault happens in the tree optimizer, I am able to compile
with -O0 just fine.

I'm trying to distill a test case that will reproduce the issue
reliably, but, as I said, I would appreciate any pointers based on the
attached backtrace.

Thanks.

--
Chris

(gdb) run -march=armv7-a -mtune=cortex-a8 -mfpu=neon -mfloat-abi=softfp -O2 -fno-omit-frame-pointer -mapcs-frame -fno-exceptions -Wall -fno-strict-aliasing -funsigned-char src_file.i

Starting program: /home/winterc/projects/build-tools/poky.2009q3/build/tmp/cross/armv7a/libexec/gcc/arm-linux-gnueabi/4.4.1/cc1 -march=armv7-a -mtune=cortex-a8 -mfpu=neon -mfloat-abi=softfp -O2 -fno-omit-frame-pointer -mapcs-frame -fno-exceptions -Wall -fno-strict-aliasing -funsigned-char src_file.i
 __strcspn_c1 __strcspn_c2 __strcspn_c3 __strspn_c1 __strspn_c2 __strspn_c3 __strpbrk_c2 __strpbrk_c3 __strtok_r_1c __strsep_1c __strsep_2c __strsep_3c gnu_dev_major gnu_dev_minor gnu_dev_makedev pthread_equal vprintf getchar fgetc_unlocked getc_unlocked getchar_unlocked putchar fputc_unlocked putc_unlocked putchar_unlocked getline feof_unlocked ferror_unlocked {GC 5329k -> 4411k} [ .... ]
Analyzing compilation unit
 {GC 10931k -> 9472k}Performing interprocedural optimizations
 <visibility> <early_local_cleanups> <summary generate> <cp> <inline> <static-var> <pure-const>Assembling functions:
 [ ... ]
Program received signal SIGSEGV, Segmentation fault.
0x086a2555 in next_readonly_imm_use (imm=0xbfcea1c4)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-flow-inline.h:423
423       imm->iter_node.next = old->next->next;
(gdb) bt full
#0  0x086a2555 in next_readonly_imm_use (imm=0xbfcea1c4)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-flow-inline.h:423
        old = (use_operand_p) 0xb7d08de0
        __FUNCTION__ = "next_readonly_imm_use"
#1  0x086a21c5 in add_ssa_edge (var=0xb7d58b98, is_varying=0 '\0')
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-ssa-propagate.c:262
        iter = {imm_use = 0xb7d08de0, end_p = 0xb7d58bc0, iter_node = {prev = 0x20e, next = 0x0, loc = {stmt = 0xb7127000, ssa_name = 0xb7127000}, use = 0xbfcea1e8}, 
  next_imm_name = 0x86a22ae}
        use_p = (use_operand_p) 0xb7d08de0
        __FUNCTION__ = "add_ssa_edge"
#2  0x086a27b8 in simulate_stmt (stmt=0xb7d578e8)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-ssa-propagate.c:353
        val = SSA_PROP_INTERESTING
        taken_edge = (edge) 0x0
        output_name = (tree) 0xb7d58b98
#3  0x086a2e24 in simulate_block (block=0xb7d57924)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-ssa-propagate.c:449
        stmt = (gimple) 0xb7d578e8
        normal_edge_count = 149532472
        e = (edge) 0x8b608f0
        normal_edge = (edge) 0xb7ba26b4
        ei = {index = 148782160, container = 0x27}
        j = {ptr = 0xb7d54b94, seq = 0xb7d54b88, bb = 0xb7d57924}
        gsi = {ptr = 0x0, seq = 0x0, bb = 0x0}
#4  0x086a53df in ssa_propagate (visit_stmt=0x8623a6f <copy_prop_visit_stmt>, visit_phi=0x8623bfd <copy_prop_visit_phi_node>)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-ssa-propagate.c:811
        dest_block = (basic_block) 0xb7d57924
#5  0x08624875 in execute_copy_prop ()
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-ssa-copy.c:1147
No locals.
#6  0x08447182 in execute_one_pass (pass=0x8de7270)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/passes.c:1279
        initializing_dump = 1 '\001'
        todo_after = 0
        __FUNCTION__ = "execute_one_pass"
#7  0x084473b8 in execute_pass_list (pass=0x8de7270)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/passes.c:1328
        __FUNCTION__ = "execute_pass_list"
#8  0x084473d4 in execute_pass_list (pass=0x8d23680)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/passes.c:1329
        __FUNCTION__ = "execute_pass_list"
#9  0x085aa590 in tree_rest_of_compilation (fndecl=0xb71e5880)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/tree-optimize.c:420
        saved_loc = 9466028
        node = (struct cgraph_node *) 0xb7034900
        __FUNCTION__ = "tree_rest_of_compilation"
#10 0x087e1bd7 in cgraph_expand_function (node=0xb7034900)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/cgraphunit.c:1047
        decl = (tree) 0xb71e5880
        __FUNCTION__ = "cgraph_expand_function"
#11 0x087e1d8b in cgraph_expand_all_functions ()
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/cgraphunit.c:1106
        node = (struct cgraph_node *) 0xb7034900
        order = (struct cgraph_node **) 0x8e637a8
        order_pos = 83
        new_order_pos = 41
        i = 22
        __FUNCTION__ = "cgraph_expand_all_functions"
#12 0x087e2311 in cgraph_optimize () at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/cgraphunit.c:1311
No locals.
#13 0x080750b1 in c_write_global_declarations ()
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/c-decl.c:8118
        t = (tree) 0x0
        __FUNCTION__ = "c_write_global_declarations"
#14 0x08531086 in compile_file () at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/toplev.c:981
No locals.
#15 0x08532c21 in do_compile () at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/toplev.c:2197
No locals.
#16 0x08532c83 in toplev_main (argc=14, argv=0xbfcea604)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/toplev.c:2229
No locals.
#17 0x0811c89a in main (argc=-1211069056, argv=0xb7d578e8)
    at /home/winterc/projects/build-tools/poky.2009q3/build/tmp/work/armv7a-linux-gnueabi/gcc-cross-4.4.1+csl-arm-2009q3-67-r0/gcc-4.4/gcc/main.c:35
No locals.
(gdb)