[Bug compile/18202] New: [compile] cv-qualified self-references crash

[Bug compile/18202] New: [compile] cv-qualified self-references crash

[jan.kratochvil at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18202

            Bug ID: 18202
           Summary: [compile] cv-qualified self-references crash
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: compile
          Assignee: unassigned at sourceware dot org
          Reporter: jan.kratochvil at redhat dot com

Created attachment 8225
  --> https://sourceware.org/bugzilla/attachment.cgi?id=8225&action=edit
reproducer for GDB

gdb/testsuite/gdb.compile/compile.c
struct struct_type {
-  struct struct_type *selffield;
+  volatile struct struct_type *selffield;

->
compile code struct_object.selffield = &struct_object
gdb command line:1:1: internal compiler error: Segmentation fault

This is because selffield has !COMPLETE_TYPE_P as at that time struct
struct_type is not yet complete and the cv-qualifier creates a copy (not
reference) of the type inside GCC.

I guess cv-qualified self-references will need to create opaque type inside
GCC.

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[Bug compile/18202] [compile] cv-qualified self-references crash

[jan.kratochvil at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18202

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat dot com

--- Comment #1 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
Simplified/standalone reproducer:

cat >1.c <<EOH
// b tree.c:build_qualified_type
// p TYPE_SIZE (type)
volatile struct sv { volatile struct sv *p; } sv; // CRASH: compile code sv.p =
&sv;
volatile struct s { int i; } s, *sp; // OK: compile code sp = &s;
int main(void) { return 0; }
EOH
gcc -o 1 1.c -Wall -g; gdb ./1 -ex start -ex 'compile code sv.p = &sv'

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[Bug compile/18202] [compile] cv-qualified self-references crash

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18202

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jan Kratochvil <jkratoch@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3a9558c494e9b461f752ce26382701d4446f0958

commit 3a9558c494e9b461f752ce26382701d4446f0958
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Sat May 16 14:20:45 2015 +0200

    compile: Use -Wall, not -w

    For a reason unknown to me GDB was using -w instead of -Wall for 'compile
code'.
    The problem is later patch for 'compile printf' really needs some warnings
to
    be able to catch for example missing format string parameters:
        (gdb) compile printf "%d\n"
    GCC does not seem to be able to cancel -w (there is nothing like -no-w).

    Besides that I think even 'compile code' can benefit from -Wall.

    That #ifndef change in print_one_macro() is needed otherwise we get
    macro-redefinition warnings for the GCC built-in macros (as -w is no
    longer in effect).  For example, without the #ifndef/#endif one gets:

        compile -r -- void _gdb_expr(){int i = 5;}^M
        /tmp/gdbobj-xpU1yB/out4.c:4:0: warning: "__FILE__" redefined
[-Wbuiltin-macro-redefined]^M
        /tmp/gdbobj-xpU1yB/out4.c:5:0: warning: "__LINE__" redefined^M
        ...

    It makes more sense to pick the inferior's version of the macros, hence
    #ifndef instead of #undef.

    That new testsuite XFAIL is there as if one changes the struct definition
to be
    compliant with cv-qualifiers (to prevent the warnings):
    struct struct_type {
    -  struct struct_type *selffield;
    +  volatile struct struct_type *selffield;
    only then GCC/GDB will hit the crash, described in that GDB PR 18202.


    gdb/ChangeLog
    2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

        * compile/compile-c-support.c (print_one_macro): Use #ifndef.
        (generate_register_struct): Use __gdb_uintptr for TYPE_CODE_PTR.
        (c_compute_program): Call generate_register_struct after typedefs.
        * compile/compile-loc2c.c (push, pushf_register_address)
        (pushf_register): Cast to GCC_UINTPTR.
        (do_compile_dwarf_expr_to_c): Use unused attribute.  Add space after
        type.  Use GCC_UINTPTR instead of void *.  Remove excessive cast.
        (compile_dwarf_expr_to_c): Use GCC_UINTPTR instead of void *.
        * compile/compile.c (_initialize_compile): Enable warnings for
        COMPILE_ARGS.

    gdb/testsuite/ChangeLog
    2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

        * gdb.compile/compile-ops.exp: Cast param to void.
        * gdb.compile/compile.exp: Complete type for _gdb_expr.
        (compile code struct_object.selffield = &struct_object): Add xfail.

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[Bug compile/18202] [compile] cv-qualified self-references crash

[jan.kratochvil at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18202

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |7.10

--- Comment #3 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
This has been primarily fixed in GCC.

But some commit was done also for GDB-7.10:
  https://sourceware.org/ml/gdb-patches/2015-07/msg00204.html

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