[rfa] Fix Python lazy strings on Cell

[rfa] Fix Python lazy strings on Cell

[Ulrich Weigand]

Hello,

with current GDB the following test cases fail when built as SPU code and
executed via the combined Cell/B.E. debugger:
FAIL: gdb.python/py-prettyprint.exp: print estring
FAIL: gdb.python/py-prettyprint.exp: print estring

The reason is that in the Cell debugger we get internal 64-bit CORE_ADDR
values with the high bit set.  When such addresses are used as part of
a Python "lazy string" object, and then accesses via the "address"
attribute, they get converted via PyLong_FromUnsignedLongLong
(in stpy_get_address) to Python values larger than 2^63.

However, the routine gdbpy_extract_lazy_string then extracts a CORE_ADDR
from such Python values using PyLong_AsLongLong, i.e. as signed values.
This causes an OverflowError, as values larger than 2^63 cannot be
represented.

It seems to be that gdbpy_extract_lazy_string should likewise extract
address values as unsigned, using PyLong_AsUnsignedLongLong, to make
sure to get the same CORE_ADDR value back.

The patch below implements this change, fixing the above test cases.
Tested on Cell/B.E. (PPU and SPU).

OK for mainline and branch?

Bye,
Ulrich


ChangeLog:

	* python/py-lazy-string.c (gdbpy_extract_lazy_string): Extract
	address as UnsignedLongLong, not LongLong.

Index: gdb/python/py-lazy-string.c
===================================================================
RCS file: /cvs/src/src/gdb/python/py-lazy-string.c,v
retrieving revision 1.1
diff -u -p -r1.1 py-lazy-string.c
--- gdb/python/py-lazy-string.c	14 Jan 2010 08:03:37 -0000	1.1
+++ gdb/python/py-lazy-string.c	4 Mar 2010 18:43:14 -0000
@@ -187,7 +187,7 @@ gdbpy_extract_lazy_string (PyObject *str
     goto error;
 
   *length = PyLong_AsLong (py_len);
-  addr = PyLong_AsLongLong (py_addr);
+  addr = PyLong_AsUnsignedLongLong (py_addr);
 
   /* If the user supplies Py_None an encoding, set encoding to NULL.
      This will trigger the resulting LA_PRINT_CALL to automatically
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com

Re: [rfa] Fix Python lazy strings on Cell

[Tom Tromey]

>>>>> "Ulrich" == Ulrich Weigand <uweigand@de.ibm.com> writes:

Ulrich> It seems to be that gdbpy_extract_lazy_string should likewise extract
Ulrich> address values as unsigned, using PyLong_AsUnsignedLongLong, to make
Ulrich> sure to get the same CORE_ADDR value back.

This looks good to me, thanks.

Tom

Re: [rfa] Fix Python lazy strings on Cell

[Ulrich Weigand]

Tom Tromey wrote:
> >>>>> "Ulrich" == Ulrich Weigand <uweigand@de.ibm.com> writes:
> 
> Ulrich> It seems to be that gdbpy_extract_lazy_string should likewise extract
> Ulrich> address values as unsigned, using PyLong_AsUnsignedLongLong, to make
> Ulrich> sure to get the same CORE_ADDR value back.
> 
> This looks good to me, thanks.

OK, I've checked this in to head and 7.1 branch.

Thanks,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com