On Fri, May 14, 2021 at 11:19 AM guojiufu via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On 2021-05-14 15:39, guojiufu via Gcc-patches wrote:
> > On 2021-05-14 15:15, Richard Biener wrote:
> >> On May 14, 2021 4:52:56 AM GMT+02:00, Jiufu Guo
> >> <guoji...@linux.ibm.com> wrote:
> >>> As discussed in the PR, Richard mentioned the method to
> >>> figure out which VAR was not set TREE_ADDRESSABLE, and
> >>> then cause this failure. It is address_expression which
> >>> build addr_expr (build_fold_addr_expr_loc), but not set
> >>> TREE_ADDRESSABLE.
> >>>
> >>> I drafted this patch with reference the comments from Richard
> >>> in this PR, while I'm not quite sure if more thing need to do.
> >>> So, please have review, thanks!
> >>>
> >>> Bootstrap and regtest pass on ppc64le. Is this ok for trunk?
> >>
> >> I suggest to use mark_addresssable unless we're sure expr is always an
> >> entity where TREE_ADDRESSABLE has the desired meaning.
>
> Thanks, Richard!
> You point out the root concern, I'm not sure ;)
>
> With looking at code "mark_addresssable" and code around
> tree-ssa.c:1013,
> VAR_P, PARM_DECL, and RESULT_DECL are checked before accessing
> TREE_ADDRESSABLE.
> So, just wondering if these entities need to be marked as
> TREE_ADDRESSABLE?
>
> diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
> index 5d9dbb5d068..85d324a92cc 100644
> --- a/gcc/go/go-gcc.cc
> +++ b/gcc/go/go-gcc.cc
> @@ -1680,6 +1680,11 @@ Gcc_backend::address_expression(Bexpression*
> bexpr, Location location)
> if (expr == error_mark_node)
> return this->error_expression();
>
> + if ((VAR_P(expr)
> + || TREE_CODE(expr) == PARM_DECL
> + || TREE_CODE(expr) == RESULT_DECL)
> + TREE_ADDRESSABLE (expr) = 1;
> +
The root concern is that mark_addressable does
while (handled_component_p (x))
x = TREE_OPERAND (x, 0);
and I do not know the constraints on 'expr' as passed to
Gcc_backend::address_expression.
I think we need input from Ian here. Most FEs have their own *_mark_addressable
function where they also emit diagnostics (guess this is handled in
the actual Go frontend).
Since Gcc_backend does lowering to GENERIC using a middle-end is probably OK.
> tree ret = build_fold_addr_expr_loc(location.gcc_location(), expr);
> return this->make_expression(ret);
> }
>
>
> Or call mark_addressable, and update mark_addressable to avoid NULL
> pointer ICE:
> The below patch also pass bootstrap-debug.
>
> diff --git a/gcc/gimple-expr.c b/gcc/gimple-expr.c
> index b8c732b632a..f682841391b 100644
> --- a/gcc/gimple-expr.c
> +++ b/gcc/gimple-expr.c
> @@ -915,6 +915,7 @@ mark_addressable (tree x)
> if (TREE_CODE (x) == VAR_DECL
> && !DECL_EXTERNAL (x)
> && !TREE_STATIC (x)
> + && cfun != NULL
I'd be OK with this hunk of course.
> && cfun->gimple_df != NULL
> && cfun->gimple_df->decls_to_pointers != NULL)
> {
> diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
> index 5d9dbb5d068..fe9dfaf8579 100644
> --- a/gcc/go/go-gcc.cc
> +++ b/gcc/go/go-gcc.cc
> @@ -1680,6 +1680,7 @@ Gcc_backend::address_expression(Bexpression*
> bexpr, Location location)
> if (expr == error_mark_node)
> return this->error_expression();
>
> + mark_addressable(expr);
> tree ret = build_fold_addr_expr_loc(location.gcc_location(), expr);
> return this->make_expression(ret);
> }
>
>
> >
> > I notice you mentioned "mark_addresssable" in PR.
> > And I had tried yesterday, it cause new ICEs at gimple-expr.c:918
> > below line:
> >
> > && cfun->gimple_df != NULL
> >
> >
> >
> >>
> >> Richard.
> >>
> >>> Jiufu Guo.
> >>>
> >>> 2021-05-14 Richard Biener <rguent...@suse.de>
> >>> Jiufu Guo <guoji...@linux.ibm.com>
> >>>
> >>> PR go/100537
> >>> * go-gcc.cc
> >>> (Gcc_backend::address_expression): Set TREE_ADDRESSABLE.
> >>>
> >>> ---
> >>> gcc/go/go-gcc.cc | 1 +
> >>> 1 file changed, 1 insertion(+)
> >>>
> >>> diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
> >>> index 5d9dbb5d068..8ed20a3b479 100644
> >>> --- a/gcc/go/go-gcc.cc
> >>> +++ b/gcc/go/go-gcc.cc
> >>> @@ -1680,6 +1680,7 @@ Gcc_backend::address_expression(Bexpression*
> >>> bexpr, Location location)
> >>> if (expr == error_mark_node)
> >>> return this->error_expression();
> >>>
> >>> + TREE_ADDRESSABLE (expr) = 1;
> >>> tree ret = build_fold_addr_expr_loc(location.gcc_location(), expr);
> >>> return this->make_expression(ret);
> >>> }
