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Tom de Vries 4cf88725da [gdb/symtab] Fix infinite recursion in dwarf2_cu::get_builder()
With the test-case attached in PR26327, gdb aborts:
...
$ gdb -q -batch 447.dealII -ex "b main"
Aborted (core dumped)
...
when running out of stack due to infinite recursion:
...
 #8  0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x35e4b40)
     at src/gdb/dwarf2/read.c:700
 #9  0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x22ee2c0)
     at src/gdb/dwarf2/read.c:700
 #10 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x35e4b40)
     at src/gdb/dwarf2/read.c:700
 #11 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x22ee2c0)
     at src/gdb/dwarf2/read.c:700
...

We're recursing in this code in dwarf2_cu::get_builder():
...
     /* Otherwise, search ancestors for a valid builder.  */
     if (ancestor != nullptr)
       return ancestor->get_builder ();
...
due to the fact that the ancestor chain is a cycle.

Higher up in the call stack, we find some code that is responsible for
triggering this, in new_symbol:
...
       case DW_TAG_formal_parameter:
         {
           /* If we are inside a function, mark this as an argument.  If
              not, we might be looking at an argument to an inlined function
              when we do not have enough information to show inlined frames;
              pretend it's a local variable in that case so that the user can
              still see it.  */
           struct context_stack *curr
             = cu->get_builder ()->get_current_context_stack ();
           if (curr != nullptr && curr->name != nullptr)
             SYMBOL_IS_ARGUMENT (sym) = 1;
...

This is code that was added to support pre-4.1 gcc, to be able to show
arguments of inlined functions as locals, in the absense of sufficiently
correct debug information.

Removing this code (that is, doing SYMBOL_IS_ARGUMENT (sym) = 1
unconditially), fixes the crash.  The ancestor variable also seems to have
been added specifically to deal with fallout from this code, so remove that as
well.

Tested on x86_64-linux:
- openSUSE Leap 15.2 with gcc 7.5.0, and
- openSUSE Tumbleweed with gcc 10.3.0.

gdb/ChangeLog:

2021-05-07  Tom de Vries  <tdevries@suse.de>

	PR symtab/26327
	* dwarf2/read.c (struct dwarf2_cu): Remove ancestor.
	(dwarf2_cu::get_builder): Remove ancestor-related code.
	(new_symbol): Remove code supporting pre-4.1 gcc that show arguments
	of inlined functions as locals.
	(follow_die_offset, follow_die_sig_1): Remove setting of ancestor.

gdb/doc/ChangeLog:

2021-05-07  Tom de Vries  <tdevries@suse.de>

	PR symtab/26327
	* gdb.texinfo (Inline Functions): Update.
2021-05-07 12:13:05 +02:00
bfd x86-64/ELF: clear src_mask for all reloc types 2021-05-07 12:05:12 +02:00
binutils dwarf: Don't omit second operand of '?' operator 2021-05-07 16:54:00 +09:30
config
contrib
cpu or1k: Implement relocation R_OR1K_GOT_AHI16 for gotha() 2021-05-06 20:51:24 +09:00
elfcpp
etc
gas x86-64/ELF: clear src_mask for all reloc types 2021-05-07 12:05:12 +02:00
gdb [gdb/symtab] Fix infinite recursion in dwarf2_cu::get_builder() 2021-05-07 12:13:05 +02:00
gdbserver gdbserver/server: make some functions void 2021-05-06 15:15:38 +02:00
gdbsupport Use rvalue reference in thread_pool::post_task 2021-04-30 10:04:56 -06:00
gnulib gnulib: import gendocs 2021-05-04 13:50:33 -04:00
gold
gprof
include or1k: Implement relocation R_OR1K_GOT_AHI16 for gotha() 2021-05-06 20:51:24 +09:00
intl
ld x86-64/ELF: clear src_mask for all reloc types 2021-05-07 12:05:12 +02:00
libctf libctf, ld: fix test results for upstream GCC 2021-05-06 09:31:31 +01:00
libdecnumber
libiberty
opcodes or1k: Implement relocation R_OR1K_GOT_AHI16 for gotha() 2021-05-06 20:51:24 +09:00
readline
sim sim: m32c: clean up various warnings 2021-05-07 00:36:26 -04:00
texinfo
zlib
.cvsignore
.gitattributes
.gitignore
ar-lib
ChangeLog Replace AC_PROG_CC with AC_PROG_CC_C99 in top level configure file. 2021-05-04 13:40:34 +01:00
compile
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configure Replace AC_PROG_CC with AC_PROG_CC_C99 in top level configure file. 2021-05-04 13:40:34 +01:00
configure.ac Replace AC_PROG_CC with AC_PROG_CC_C99 in top level configure file. 2021-05-04 13:40:34 +01:00
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