The compiled pattern is: The string to match is: "DESCRIPTION;LANGUAGE=..."

0x144aa80: EXECUTING on_failure_jump_smart 4 (to 0x144aa87).
  smart default => slow loop.

0x144aa80: EXECUTING on_failure_jump 4 (to 0x144aa87):

Thread 1 "emacs" hit Breakpoint 4, debug_spot (fail_stack_avail=0, 
    string1=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., 
    string2=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "...) at regex.c:846
846	  fail_stack_avail++;
Hardware watchpoint 5: -location string1[0]
(gdb) bt 5
#0  debug_spot (fail_stack_avail=0, 
    string1=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., 
    string2=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "...) at regex.c:846
#1  0x00000000005ee090 in re_match_2_internal (bufp=0xd6d650 <searchbufs+5072>, 
    string1=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., size1=0, 
    string2=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., size2=40918, pos=0, regs=0xd6deb0 <search_regs>, stop=40918)
    at regex.c:5844
#2  0x00000000005e9022 in re_search_2 (bufp=0xd6d650 <searchbufs+5072>, 
    str1=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., size1=0, 
    str2=0x1835980 "DESCRIPTION;LANGUAGE=en-US:Nn Nnnnn\\,\\n\\nNnnnnnnnn nnn nnn nnnnnn nn nnnnnn\n nnnnnnn nnnn nnnnnnnnn. N nnnn nnnnnnnnn nn nnn nnnnnnnn nnnnnnn nnn nn nn\n nn nn-nnnnnnn nn Nnnnnnn nn 99.99 NNNN\\n\\nNnnn "..., size2=40918, startpos=0, range=40918, regs=0xd6deb0 <search_regs>, 
    stop=40918) at regex.c:4470
#3  0x00000000005d6c06 in search_buffer (string=25301860, pos=1, pos_byte=1, lim=40891, 
    lim_byte=40919, n=1, RE=1, trt=20893029, inverse_trt=20483397, posix=false) at search.c:1265
#4  0x00000000005d63a1 in search_command (string=25301860, bound=0, noerror=44544, count=0, 
    direction=1, RE=1, posix=false) at search.c:1058
(More stack frames follow...)


(gdb) cont
[...]

PUSH_FAILURE_POINT:
  Before push, next avail: 5115
			size: 5120

  Push frame index: 5115
  Push string 0x1836013: ".nnn>\;\n> +NNNN <NNN..."
0:	/on_failure_jump to 7
3:	/anychar
4:	/jump to 0
7:	/stop_memory/1
9:	/jump to -8
12:	/succeed
13:	end of pattern.
  Push pattern 0x144aa8f: 
0x144aa92: EXECUTING anychar.
  Matched "46".

0x144aa93: EXECUTING jump -7 (to 0x144aa8f).

0x144aa8f: EXECUTING on_failure_jump 4 (to 0x144aa96):

PUSH_FAILURE_POINT:
  Before push, next avail: 5118
			size: 5120

Thread 1 "emacs" hit Hardware watchpoint 5: -location string1[0]

Old value = 68 'D'
New value = 0 '\000'
0x00007ffff0cc01a7 in __memset_sse2_unaligned_erms () from /usr/lib/libc.so.6

(gdb) bt 13
#0  0x00007ffff0cc01a7 in __memset_sse2_unaligned_erms () from /usr/lib/libc.so.6
#1  0x00000000006d27f5 in r_alloc_sbrk (size=290816) at ralloc.c:848
#2  0x00000000006ced96 in get_contiguous_space (size=290816, position=0x1833000) at gmalloc.c:476
#3  0x00000000006cf92a in _malloc_internal_nolock (size=163840) at gmalloc.c:844
#4  0x00000000006cfe9d in _malloc_internal (size=163840) at gmalloc.c:927
#5  0x00000000006cff1a in gmalloc (size=163840) at gmalloc.c:951
#6  0x00000000006d14e4 in malloc (size=163840) at gmalloc.c:1827
#7  0x00000000005f3e6b in lmalloc (size=163840) at alloc.c:1414
#8  0x00000000005f3356 in xmalloc (size=163840) at alloc.c:821
#9  0x00000000005f38e4 in record_xmalloc (size=163840) at alloc.c:1038
#10 0x00000000005ee233 in re_match_2_internal (bufp=0xd6d650 <searchbufs+5072>, string1=0x1835980 "", 
    size1=0, string2=0x1835980 "", size2=40918, pos=0, regs=0xd6deb0 <search_regs>, stop=40918)
    at regex.c:5844
#11 0x00000000005e9022 in re_search_2 (bufp=0xd6d650 <searchbufs+5072>, str1=0x1835980 "", size1=0, 
    str2=0x1835980 "", size2=40918, startpos=0, range=40918, regs=0xd6deb0 <search_regs>, stop=40918)
    at regex.c:4470
#12 0x00000000005d6c06 in search_buffer (string=25301860, pos=1, pos_byte=1, lim=40891, 
    lim_byte=40919, n=1, RE=1, trt=20893029, inverse_trt=20483397, posix=false) at search.c:1265
(More stack frames follow...)

Continuing.

Thread 1 "emacs" hit Hardware watchpoint 5: -location string1[0]

Old value = 0 '\000'
New value = -34 '\336'
0x00007ffff0d67b64 in __memcpy_ssse3 () from /usr/lib/libc.so.6

(gdb) cont
Continuing.

  Doubled stack; size now: 20480
	 slots available: 15362

  Push frame index: 5118
  Push string 0x1836014: "ª$..."

[...]

PUSH_FAILURE_POINT:
  Before push, next avail: 5130
			size: 20480

  Push frame index: 5130
  Push string 0x1836018: "ª$\..."
0:	/on_failure_jump to 7
3:	/anychar
4:	/jump to 0
7:	/stop_memory/1
9:	/jump to -8
12:	/succeed
13:	end of pattern.
  Push pattern 0x144aa8f: 
0x144aa92: EXECUTING anychar.

character.h:696: Emacs fatal error: assertion failed: CHAR_VALID_P (ch)

Thread 1 "emacs" hit Breakpoint 1, terminate_due_to_signal (sig=6, backtrace_limit=2147483647)
    at emacs.c:354
354	  signal (sig, SIG_DFL);

(gdb) bt 7
#0  terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:354
#1  0x00000000005fdb9b in die (msg=0x725888 "CHAR_VALID_P (ch)", file=0x72587c "character.h", 
    line=696) at alloc.c:7224
#2  0x000000000056c000 in char_table_translate (obj=20893029, ch=4195178) at character.h:696
#3  0x00000000005eb8db in re_match_2_internal (bufp=0xd6d650 <searchbufs+5072>, 
    string1=0x1835980 "\336[\203\001", size1=0, string2=0x1835980 "\336[\203\001", size2=40918, 
    pos=0, regs=0xd6deb0 <search_regs>, stop=40918) at regex.c:5454
#4  0x00000000005e9022 in re_search_2 (bufp=0xd6d650 <searchbufs+5072>, 
    str1=0x1835980 "\336[\203\001", size1=0, str2=0x1835980 "\336[\203\001", size2=40918, startpos=0, 
    range=40918, regs=0xd6deb0 <search_regs>, stop=40918) at regex.c:4470
#5  0x00000000005d6c06 in search_buffer (string=25301860, pos=1, pos_byte=1, lim=40891, 
    lim_byte=40919, n=1, RE=1, trt=20893029, inverse_trt=20483397, posix=false) at search.c:1265
#6  0x00000000005d63a1 in search_command (string=25301860, bound=0, noerror=44544, count=0, 
    direction=1, RE=1, posix=false) at search.c:1058
(More stack frames follow...)