On Mon, Oct 07, 2019 at 05:17:56PM -0400, Jason Merrill wrote:
Ah, I see. And it occurs to me this situation fails condition #1 for
get_formal_tmp_var anyway. So I guess the predicate direction doesn't make
sense. Let's factor out the above pattern differently, then. Maybe a
preevaluate function that takes a predicate as an argument?
Ok, so this patch does, compared to the previous one:
1) shifts are now done in cp_build_binary_op with the cp_save_expr,
so no fold-const.c or cp-gimplify.c change is needed
2) the array ref x[y] -> *(x + y) where y has side-effects is now handled
as *(SAVE_EXPR<x>, SAVE_EXPR<x> + y) rather than
SAVE_EXPR<x>, *(SAVE_EXPR<x> + y) where the former is friendlier to
wrapping it in ADDR_EXPR etc.; nevertheless, I had to disable it for the
OpenMP reductions, I'll discuss in the language committee what to do if
anything in that case
3) I've added the new function in cp-gimplify.c and used it in the CALL_EXPR
case
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
If wanted, can commit the 3 unrelated changes separately.
And the call argument side-effects aren't handled yet.
2019-10-10 Jakub Jelinek <jakub@redhat.com>
PR c++/91987
cp/
* decl2.c (grok_array_decl): For -fstrong-eval-order, when array ref
operands have been swapped and at least one operand has side-effects,
revert the swapping before calling build_array_ref.
* typeck.c (cp_build_array_ref): For non-ARRAY_TYPE array ref with
side-effects on the index operand, if -fstrong-eval-order use
save_expr around the array operand.
(cp_build_binary_op): For shifts with side-effects in the second
operand, wrap first operand into SAVE_EXPR and evaluate it before
the shift.
* semantics.c (handle_omp_array_sections_1): Temporarily disable
flag_strong_eval_order during OMP_CLAUSE_REDUCTION array section
processing.
* cp-gimplify.c (gimplify_to_rvalue): New function.
(cp_gimplify_expr): Use it.
testsuite/
* g++.dg/cpp1z/eval-order6.C: New test.
* g++.dg/cpp1z/eval-order7.C: New test.
* g++.dg/cpp1z/eval-order8.C: New test.
* c-c++-common/gomp/pr91987.c: New test.
--- gcc/cp/decl2.c.jj 2019-10-09 10:27:12.704400889 +0200
+++ gcc/cp/decl2.c 2019-10-09 10:32:44.932416373 +0200
@@ -405,6 +405,7 @@ grok_array_decl (location_t loc, tree ar
else
{
tree p1, p2, i1, i2;
+ bool swapped = false;
/* Otherwise, create an ARRAY_REF for a pointer or array type.
It is a little-known fact that, if `a' is an array and `i' is
@@ -431,7 +432,7 @@ grok_array_decl (location_t loc, tree ar
if (p1 && i2)
array_expr = p1, index_exp = i2;
else if (i1 && p2)
- array_expr = p2, index_exp = i1;
+ swapped = true, array_expr = p2, index_exp = i1;
else
{
error_at (loc, "invalid types %<%T[%T]%> for array subscript",
@@ -447,7 +448,12 @@ grok_array_decl (location_t loc, tree ar
else
array_expr = mark_lvalue_use_nonread (array_expr);
index_exp = mark_rvalue_use (index_exp);
- expr = build_array_ref (input_location, array_expr, index_exp);
+ if (swapped
+ && flag_strong_eval_order == 2
+ && (TREE_SIDE_EFFECTS (array_expr) || TREE_SIDE_EFFECTS (index_exp)))
+ expr = build_array_ref (input_location, index_exp, array_expr);
+ else
+ expr = build_array_ref (input_location, array_expr, index_exp);
}
if (processing_template_decl && expr != error_mark_node)
{
--- gcc/cp/typeck.c.jj 2019-10-09 10:27:12.625402077 +0200
+++ gcc/cp/typeck.c 2019-10-09 11:21:09.058765959 +0200
@@ -3550,6 +3550,10 @@ cp_build_array_ref (location_t loc, tree
{
tree ar = cp_default_conversion (array, complain);
tree ind = cp_default_conversion (idx, complain);
+ tree first = NULL_TREE;
+
+ if (flag_strong_eval_order == 2 && TREE_SIDE_EFFECTS (ind))
+ ar = first = cp_save_expr (ar);
/* Put the integer in IND to simplify error checking. */
if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
@@ -3573,11 +3577,10 @@ cp_build_array_ref (location_t loc, tree
warn_array_subscript_with_type_char (loc, idx);
- ret = cp_build_indirect_ref (cp_build_binary_op (input_location,
- PLUS_EXPR, ar, ind,
- complain),
- RO_ARRAY_INDEXING,
- complain);
+ ret = cp_build_binary_op (input_location, PLUS_EXPR, ar, ind, complain);
+ if (first)
+ ret = build2_loc (loc, COMPOUND_EXPR, TREE_TYPE (ret), first, ret);
+ ret = cp_build_indirect_ref (ret, RO_ARRAY_INDEXING, complain);
protected_set_expr_location (ret, loc);
if (non_lvalue)
ret = non_lvalue_loc (loc, ret);
@@ -5555,6 +5558,17 @@ cp_build_binary_op (const op_location_t
if (build_type == NULL_TREE)
build_type = result_type;
+ if (doing_shift
+ && flag_strong_eval_order == 2
+ && TREE_SIDE_EFFECTS (op1)
+ && !processing_template_decl)
+ {
+ /* In C++17, in both op0 << op1 and op0 >> op1 op0 is sequenced before
+ op1, so if op1 has side-effects, use SAVE_EXPR around op0. */
+ op0 = cp_save_expr (op0);
+ instrument_expr = op0;
+ }
+
if (sanitize_flags_p ((SANITIZE_SHIFT
| SANITIZE_DIVIDE | SANITIZE_FLOAT_DIVIDE))
&& current_function_decl != NULL_TREE
@@ -5566,6 +5580,7 @@ cp_build_binary_op (const op_location_t
op1 = cp_save_expr (op1);
op0 = fold_non_dependent_expr (op0, complain);
op1 = fold_non_dependent_expr (op1, complain);
+ tree instrument_expr1 = NULL_TREE;
if (doing_div_or_mod
&& sanitize_flags_p (SANITIZE_DIVIDE | SANITIZE_FLOAT_DIVIDE))
{
@@ -5578,10 +5593,15 @@ cp_build_binary_op (const op_location_t
cop0 = cp_convert (orig_type, op0, complain);
if (TREE_TYPE (cop1) != orig_type)
cop1 = cp_convert (orig_type, op1, complain);
- instrument_expr = ubsan_instrument_division (location, cop0, cop1);
+ instrument_expr1 = ubsan_instrument_division (location, cop0, cop1);
}
else if (doing_shift && sanitize_flags_p (SANITIZE_SHIFT))
- instrument_expr = ubsan_instrument_shift (location, code, op0, op1);
+ instrument_expr1 = ubsan_instrument_shift (location, code, op0, op1);
+ if (instrument_expr != NULL)
+ instrument_expr = build2 (COMPOUND_EXPR, TREE_TYPE (instrument_expr1),
+ instrument_expr, instrument_expr1);
+ else
+ instrument_expr = instrument_expr1;