[Bug lto/62034] New: ICE for big statically initialized arrays compiled with LTO

enkovich.gnu at gmail dot com gcc-bugzilla@gcc.gnu.org
Wed Aug 6 11:02:00 GMT 2014


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62034

            Bug ID: 62034
           Summary: ICE for big statically initialized arrays compiled
                    with LTO
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: enkovich.gnu at gmail dot com

Created attachment 33259
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33259&action=edit
Reproducer

I get ICE when try to compile tests with big amount of statically initialized
data.

gcc --version
gcc (GCC) 4.10.0 20140806 (experimental)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

gcc -flto test.c
gcc: internal compiler error: Segmentation fault (program lto1)
0x405c80 execute
        ../../gcc-ref/gcc/gcc.c:2900
0x409fe9 do_spec_1
        ../../gcc-ref/gcc/gcc.c:4704
0x40d475 process_brace_body
        ../../gcc-ref/gcc/gcc.c:5987
0x40d2b1 handle_braces
        ../../gcc-ref/gcc/gcc.c:5901
0x40bf9d do_spec_1
        ../../gcc-ref/gcc/gcc.c:5358
0x40d475 process_brace_body
        ../../gcc-ref/gcc/gcc.c:5987
0x40d2b1 handle_braces
        ../../gcc-ref/gcc/gcc.c:5901
0x40bf9d do_spec_1
        ../../gcc-ref/gcc/gcc.c:5358
0x40c38c do_spec_1
        ../../gcc-ref/gcc/gcc.c:5473
0x40d475 process_brace_body
        ../../gcc-ref/gcc/gcc.c:5987
0x40d2b1 handle_braces
        ../../gcc-ref/gcc/gcc.c:5901
0x40bf9d do_spec_1
        ../../gcc-ref/gcc/gcc.c:5358
0x409664 do_spec_2
        ../../gcc-ref/gcc/gcc.c:4405
0x409582 do_spec(char const*)
        ../../gcc-ref/gcc/gcc.c:4372
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
lto-wrapper: fatal error: gcc-ref-build/bin/gcc returned 4 exit status
compilation terminated.
/usr/bin/ld: lto-wrapper failed
collect2: error: ld returned 1 exit status

Debugger shows that problem appears when lto_input_tree tries to dig through a
bunch of SCC entries in input stream.  Each SCC entry cause two new functions
(lto_input_tree and lto_input_tree_1) in the call stack.  With many consequent
SCC entries stack may grow too much (in my case compiler segfaulted with ~600
000 entries in the call stack).

Attached test has a statically initialized array with a million elements. 
Bigger data set may be required to break the compiler if you use increased
stack size.

Problem appeared after this commit:
https://gcc.gnu.org/ml/gcc-cvs/2014-07/msg00291.html

Following patch removing recursion helps me to compile my tests:

diff --git a/gcc/lto-streamer-in.c b/gcc/lto-streamer-in.c
index 698f926..25657da 100644
--- a/gcc/lto-streamer-in.c
+++ b/gcc/lto-streamer-in.c
@@ -1345,7 +1345,16 @@ lto_input_tree_1 (struct lto_input_block *ib, struct
data_in *data_in,
 tree
 lto_input_tree (struct lto_input_block *ib, struct data_in *data_in)
 {
-  return lto_input_tree_1 (ib, data_in, streamer_read_record_start (ib), 0);
+  enum LTO_tags tag;
+
+  /* Skip SCC entries.  */
+  while ((tag = streamer_read_record_start (ib)) == LTO_tree_scc)
+    {
+      unsigned len, entry_len;
+      lto_input_scc (ib, data_in, &len, &entry_len);
+    }
+
+  return lto_input_tree_1 (ib, data_in, tag, 0);
 }

Did not fully test this patch yet.



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