On Wed, 11 Aug 2021, Eric Botcazou wrote:
> > So I'm leaning towards leaving build3 alone and fixing up frontends
> > as issues pop up.
>
> FWIW fine with me.
OK, so I pushed the original change (reposted below).
Bootstrapped / tested on x86_64-unknown-linux-gnu.
Richard.
>From e5a23d54d189f3d160c82f770683288a15c3645e Mon Sep 17 00:00:00 2001
From: Richard Biener <rguent...@suse.de>
Date: Mon, 9 Aug 2021 13:12:08 +0200
Subject: [PATCH] Adjust volatile handling of the operand scanner
To: gcc-patches@gcc.gnu.org
The GIMPLE SSA operand scanner handles COMPONENT_REFs that are
not marked TREE_THIS_VOLATILE but have a TREE_THIS_VOLATILE
FIELD_DECL as volatile. That's inconsistent in how TREE_THIS_VOLATILE
testing on GENERIC refs works which requires operand zero of
component references to mirror TREE_THIS_VOLATILE to the ref
so that testing TREE_THIS_VOLATILE on the outermost reference
is enough to determine the volatileness.
The following patch thus removes FIELD_DECL scanning from
the GIMPLE SSA operand scanner, possibly leaving fewer stmts
marked as gimple_has_volatile_ops.
It shows we miss at least one case in the fortran frontend, though
there's a suspicious amount of COMPONENT_REF creation compared
to little setting of TREE_THIS_VOLATILE. This fixes the FAIL
of gfortran.dg/volatile11.f90 that would otherwise occur.
Visually inspecting fortran/ reveals a bunch of likely to fix
cases but I don't know the constraints of 'volatile' uses in
the fortran language to assess whether some of these are not
necessary.
2021-08-09 Richard Biener <rguent...@suse.de>
gcc/
* tree-ssa-operands.c (operands_scanner::get_expr_operands):
Do not look at COMPONENT_REF FIELD_DECLs TREE_THIS_VOLATILE
to determine has_volatile_ops.
gcc/fortran/
* trans-common.c (create_common): Set TREE_THIS_VOLATILE on the
COMPONENT_REF if the field is volatile.
---
gcc/fortran/trans-common.c | 9 +++++----
gcc/tree-ssa-operands.c | 7 +------
2 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/gcc/fortran/trans-common.c b/gcc/fortran/trans-common.c
index a11cf4c839e..7bcf18dc475 100644
--- a/gcc/fortran/trans-common.c
+++ b/gcc/fortran/trans-common.c
@@ -759,10 +759,11 @@ create_common (gfc_common_head *com, segment_info *head,
bool saw_equiv)
else
gfc_add_decl_to_function (var_decl);
- SET_DECL_VALUE_EXPR (var_decl,
- fold_build3_loc (input_location, COMPONENT_REF,
- TREE_TYPE (s->field),
- decl, s->field, NULL_TREE));
+ tree comp = build3_loc (input_location, COMPONENT_REF,
+ TREE_TYPE (s->field), decl, s->field, NULL_TREE);
+ if (TREE_THIS_VOLATILE (s->field))
+ TREE_THIS_VOLATILE (comp) = 1;
+ SET_DECL_VALUE_EXPR (var_decl, comp);
DECL_HAS_VALUE_EXPR_P (var_decl) = 1;
GFC_DECL_COMMON_OR_EQUIV (var_decl) = 1;
diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index c15575416dd..ebf7eea3b04 100644
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -834,12 +834,7 @@ operands_scanner::get_expr_operands (tree *expr_p, int
flags)
get_expr_operands (&TREE_OPERAND (expr, 0), flags);
if (code == COMPONENT_REF)
- {
- if (!(flags & opf_no_vops)
- && TREE_THIS_VOLATILE (TREE_OPERAND (expr, 1)))
- gimple_set_has_volatile_ops (stmt, true);
- get_expr_operands (&TREE_OPERAND (expr, 2), uflags);
- }
+ get_expr_operands (&TREE_OPERAND (expr, 2), uflags);
else if (code == ARRAY_REF || code == ARRAY_RANGE_REF)
{
get_expr_operands (&TREE_OPERAND (expr, 1), uflags);
--
2.31.1
