[Bug c/59178] New: Stack corruption on register save/restore when using frame pointer on pdp-11

[Bug c/59178] New: Stack corruption on register save/restore when using frame pointer on pdp-11

[martin.alcock at praebius dot ca]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59178

            Bug ID: 59178
           Summary: Stack corruption on register save/restore when using
                    frame pointer on pdp-11
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: blocker
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: martin.alcock at praebius dot ca

Created attachment 31239
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31239&action=edit
simple C functions and their assembly prologues/epilogues

When targeting the pdp-11 and more than one register has to be saved in the
function pologue, different modes are used for the save and restore in the
epilogue that causes stack corruption. 

In the prologue, the registers are pushed onto the stack using a "-(sp)",
syntax, however when restored in the epilogue the "xx(fp)" syntax is used
instead, thus not correcting the stack pointer on the restore. R5 is used as
the frame pointer. This causes the code to go wild, as it returns to an address
that previously contained arbitrary register contents.

Attached is a file showing the C source from some small routines and the
assembly code for the prologue and epilogue.

[Bug target/59178] Stack corruption on register save/restore when using frame pointer on pdp-11

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59178

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
           Severity|blocker                     |normal

[Bug target/59178] Stack corruption on register save/restore when using frame pointer on pdp-11

[pkoning at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59178

pkoning at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from pkoning at gcc dot gnu.org ---
It works properly in the current version -- I see stack push in the prologue
and matching stack pop operations in the epilogue.

[Bug target/59178] Stack corruption on register save/restore when using frame pointer on pdp-11

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59178

Mikael Pettersson <mikpelinux at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikpelinux at gmail dot com

--- Comment #2 from Mikael Pettersson <mikpelinux at gmail dot com> ---
This was fixed for gcc-9.1.0, see PR59172.

[Bug target/59178] Stack corruption on register save/restore when using frame pointer on pdp-11

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59178

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |9.0