On Fri, 04 Mar 2016 17:15:26 +0100, Neven Sajko wrote:
> But in p `print *m` just gets me {a11, ..., a1n}.

I think it is a bug in GCC.  I haven't found it in GCC Bugzilla.
I haven't filed it anywhere yet.  All these compilers fail the same way:
	gcc-5.3.1-2.fc23.x86_64
	gcc-6.0.0-0.13.fc25.x86_64
	gcc (GCC) 6.0.0 20160213 (experimental)
	clang-3.7.0-4.fc23.x86_64
	clang-3.8.0-0.3.fc25.x86_64

The .s diff is for: gcc -o matrix.s matrix.c -Wall -g -S -dA


Jan


The array variable:
(gdb) s
f (n=1) at matrix2.c:22
(gdb) ptype m
type = int [17][17]
(gdb) p m
$1 = {{-134241616, 32767, -134252848, 32767, -140382932, 32767, 2224, 0, -134252032, 32767, -136422399, 32767, 2224, 0, -140329216,
    32767, -134252112}, {32767, -134252032, 32767, -11384, 32767, -11388, 32767, 1, 0, -136460380, 32767, -140329216, 32767,
[...]
    -10400, 32767, -134225592, 32767, 0, 0, 1, 0, 4195965, 0, 4195328, 0, 0, 0, 4195888}}

The bug with the parameter:
(gdb) s
p (m=0x7fffffffd2a0, n=1) at matrix2.c:9
(gdb) ptype m
type = int (*)[17]
(gdb) p m
$2 = (int (*)[17]) 0x7fffffffd2a0
(gdb) p *m
$3 = {-134241616, 32767, -134252848, 32767, -140382932, 32767, 2224, 0, -134252032, 32767, -136422399, 32767, 2224, 0, -140329216,
  32767, -134252112}

Workaroundable by:
(gdb) p *(int[17][17] *)m
$4 = {{-134241616, 32767, -134252848, 32767, -140382932, 32767, 2224, 0, -134252032, 32767, -136422399, 32767, 2224, 0, -140329216,
    32767, -134252112}, {32767, -134252032, 32767, -11384, 32767, -11388, 32767, 1, 0, -136460380, 32767, -140329216, 32767,
[...]
    -10400, 32767, -134225592, 32767, 0, 0, 1, 0, 4195965, 0, 4195328, 0, 0, 0, 4195888}}

After fixed DWARF without the workaround:
(gdb) s
p (m=0x7fffffffd2a0, n=1) at matrix2.c:9
(gdb) ptype m
type = int (*)[17][17]
(gdb) p m
$1 = (int (*)[17][17]) 0x7fffffffd2a0
(gdb) p *m
$2 = {{-134241616, 32767, -134252848, 32767, -140382932, 32767, 2224, 0, -134252032, 32767, -136422399, 32767, 2224, 0, -140329216,
    32767, -134252112}, {32767, -134252032, 32767, -11384, 32767, -11388, 32767, 1, 0, -136460380, 32767, -140329216, 32767,
[...]
    -10400, 32767, -134225592, 32767, 0, 0, 1, 0, 4195965, 0, 4195328, 0, 0, 0, 4195888}}