> Presumably the rx back-end and more precisely TARGET_FRAME_POINTER_REQUIRED,
> which needs to return true if cfun->calls_alloca.
The rx back-end doesn't define TARGET_FRAME_POINTER_REQUIRED, as the
documentation says the compiler handles target-independent reasons why
there needs to be a frame pointer. But, the default
TARGET_FRAME_POINTER_REQUIRED just returns false - shouldn't it, by
default, check for calls_alloca ?
Also, I added that hook and set it to return true always, and it
didn't fix the bug. There is a frame pointer (there was before, too),
but there's also a stack adjustment after the pseudo-alloca which the
dwarf2 stuff doesn't know about. The last stack adjustment it sees is
the rx backend's adjustment to allocate the frame:
_medium_frame:
pushm r6-r12
add #-4, r0, r6 ; marked frame-related (fp = sp - 4)
mov.L r6, r0 ; marked frame-related (sp = fp)
. . . ; stack checking code goes here
add #0xffffc000, r0 ; not marked frame-related
00000000 <_medium_frame>:
0: 6e 6c pushm r6-r12
2: 71 06 fc add #-4, r0, r6
5: ef 60 mov.l r6, r0
7:
2e: 72 00 00 c0 add #0xffffc000, r0, r0
00000014 00000030 00000000 FDE cie=00000000 pc=00000000..00000043
DW_CFA_advance_loc4: 2 to 00000002
DW_CFA_def_cfa_offset: 32
DW_CFA_offset: r12 at cfa-8
. . .
DW_CFA_offset: r6 at cfa-32
DW_CFA_advance_loc4: 3 to 00000005
DW_CFA_def_cfa: r6 ofs 36
DW_CFA_advance_loc4: 2 to 00000007
DW_CFA_def_cfa_register: r0
( that's it for debug info )
Perhaps the stack-check code should set FRAME_RELATED on any stack
adjustment insn?
