On 22/06/17 16:01, Jeff Law wrote:
> This fixes a bug discovered when we were evaluating the current state of
> -fstack-check. It ought to be able to go forward independent of the
> rest of the -fstack-check work.
>
> The aarch64 specific code does not correctly handle large frames and
> will generate RTL with unrecognizable insns for such cases. This is
> clearly visible if -fstack-check is enabled by default or if it were to
> be added to the torture flags in the testsuite.
>
> I've tested this by bootstrapping and regression testing an aarch64
> compiler with -fstack-check on by default and hacks to force all
> allocations/probing of more than PROBE_INTERVAL bytes to go through this
> path. It fixes a slew of testsuite failures (~80 for C and a few for
> Fortran and C++).
>
>
> One example is c-torture/compile/20031023-1.c which has a local frame of
> 0x10000000000 bytes.
>
> OK for the trunk?
>
OK. But as Jakub says, a test would be nice.
R.
> Jeff
>
>
>
>
>
> P
>
>
> * config/aarch64/aarch64.c (aarch64_emit_probe_stack_range): Handle
> frame sizes that do not satisfy aarch64_uimm12_shift.
>
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 04417dc..4f89457 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -2722,11 +2722,19 @@ aarch64_emit_probe_stack_range (HOST_WIDE_INT first,
> HOST_WIDE_INT size)
> plus_constant (Pmode, stack_pointer_rtx, -first));
>
> /* LAST_ADDR = SP + FIRST + ROUNDED_SIZE. */
> - emit_set_insn (reg2,
> - plus_constant (Pmode, stack_pointer_rtx,
> - -(first + rounded_size)));
> -
> -
> + HOST_WIDE_INT adjustment = - (first + rounded_size);
> + if (! aarch64_uimm12_shift (adjustment))
> + {
> + aarch64_internal_mov_immediate (reg2, GEN_INT (adjustment),
> + true, Pmode);
> + emit_set_insn (reg2, gen_rtx_PLUS (Pmode, stack_pointer_rtx, reg2));
> + }
> + else
> + {
> + emit_set_insn (reg2,
> + plus_constant (Pmode, stack_pointer_rtx, adjustment));
> + }
> +
> /* Step 3: the loop
>
> do
>
