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0abb4049fb
This commit adds support for TYPE_CODE_FIXED_POINT types for
"finish" and "return" commands.
Consider the following Ada code...
type FP1_Type is delta 0.1 range -1.0 .. +1.0; -- Ordinary
function Call_FP1 (F : FP1_Type) return FP1_Type is
begin
FP1_Arg := F;
return FP1_Arg;
end Call_FP1;
... used as follow:
F1 : FP1_Type := 1.0;
F1 := Call_FP1 (F1);
"finish" currently behaves as follow:
| (gdb) finish
| [...]
| Value returned is $1 = 0
We expect the returned value to be "1".
Similarly, "return" makes the function return the wrong value:
| (gdb) return 1.0
| Make pck.call_fp1 return now? (y or n) y
| [...]
| 9 F1 := Call_FP1 (F1);
| (gdb) next
| (gdb) print f1
| $1 = 0.0625
(we expect it to print "1" instead).
This problem comes from the handling of integral return values
when the return value is actually fixed point type. Our type
here is actually a range of a fixed point type, but the same
principles should also apply to pure fixed-point types. For
the record, here is what the debugging info looks like:
<1><238>: Abbrev Number: 2 (DW_TAG_subrange_type)
<239> DW_AT_lower_bound : -16
<23a> DW_AT_upper_bound : 16
<23b> DW_AT_name : pck__fp1_type
<23f> DW_AT_type : <0x248>
<1><248>: Abbrev Number: 4 (DW_TAG_base_type)
<249> DW_AT_byte_size : 1
<24a> DW_AT_encoding : 13 (signed_fixed)
<24b> DW_AT_binary_scale: -4
<24c> DW_AT_name : pck__Tfp1_typeB
<250> DW_AT_artificial : 1
... where the scaling factor is 1/16.
Looking at the "finish" command, what happens is that riscv_arg_location
determines that our return value should be returned by parameter using
an integral convention (via builtin type long). And then,
riscv_return_value uses a cast to that builtin type long to
store the value of into a buffer with the right register size.
This doesn't work in our case, because the underlying value
returned by the function is unscaled, which means it is 16,
and thus the cast is like doing:
arg_val = (FP1_Type) 16
... In other words, it is trying to create an FP1_Type enty whose
value is 16. Applying the scaling factor, that's 256, and because
the size of FP1_Type is 1 byte, we overflow and thus it ends up
being zero.
The same happen with the "return" function, but the other way around.
The fix consists in handling fixed-point types separately from
integral types.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.