On Thu, Dec 09, 2021 at 05:32:02PM +0000, Hafiz Abid Qadeer wrote:
> Commit 13b6c7639cf assumed that registers in a span will be in a certain
> order. But that assumption is not true at least for the big endian targets.
> Currently amdgcn is probably only target where CFA is split into multiple
> registers so build_span_loc is only gets called for it. However, the
> dwf_cfa_reg function where this ICE was seen can be called for any
> architecture from the comparison dwf_cfa_reg (src) == cur_cfa->reg in
> dwarf2out_frame_debug_expr. So dwf_cfa_reg should not assume certain
> order of registers.
>
> I was tempted to modify the assert to handle big-endian cases but that will
> still be error prone and may fail on some other targets.
Do you have a preprocessed testcase on which the ICE triggers on ARM EB?
I think I'd like to see what we were emitting in debug info for it before
r12-5833 and what we emit with this assert removed after it.
I assumed it wouldn't affect anything but GCN during the review.
Seems the arm span hook for EB will swap pairs in the list:
for (i = 0; i < nregs; i += 2)
if (TARGET_BIG_END)
{
parts[i] = gen_rtx_REG (SImode, regno + i + 1);
parts[i + 1] = gen_rtx_REG (SImode, regno + i);
}
BTW, I wonder about those
dw_stack_pointer_regnum = dwf_cfa_reg (gen_rtx_REG (Pmode,
STACK_POINTER_REGNUM));
and
dw_frame_pointer_regnum
= dwf_cfa_reg (gen_rtx_REG (Pmode, HARD_FRAME_POINTER_REGNUM));
Can't those use
dw_stack_pointer_regnum = dwf_cfa_reg (stack_pointer_rtx);
and
dw_frame_pointer_regnum = dwf_cfa_reg (hard_frame_pointer_rtx);
?
> gcc/ChangeLog:
>
> PR debug/103619
> * dwarf2cfi.c (dwf_cfa_reg): Remove gcc_assert.
> ---
> gcc/dwarf2cfi.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/gcc/dwarf2cfi.c b/gcc/dwarf2cfi.c
> index 9dd1dfe71b7..55ae172eda2 100644
> --- a/gcc/dwarf2cfi.c
> +++ b/gcc/dwarf2cfi.c
> @@ -1136,7 +1136,6 @@ dwf_cfa_reg (rtx reg)
> gcc_assert (GET_MODE_SIZE (GET_MODE (XVECEXP (span, 0, i)))
> .to_constant () == result.span_width);
> gcc_assert (REG_P (XVECEXP (span, 0, i)));
> - gcc_assert (dwf_regno (XVECEXP (span, 0, i)) == result.reg + i);
> }
> }
> }
Jakub
