[C++ PATCH] Partial fix for further -fstrong-eval-order issues (PR c++/91987, take 2)
Jakub Jelinek
jakub@redhat.com
Thu Oct 10 08:35:00 GMT 2019
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;
}
result = build2_loc (location, resultcode, build_type, op0, op1);
--- gcc/cp/semantics.c.jj 2019-09-27 22:13:18.336903781 +0200
+++ gcc/cp/semantics.c 2019-10-09 12:25:46.852235717 +0200
@@ -5017,6 +5017,15 @@ handle_omp_array_sections_1 (tree c, tre
TREE_PURPOSE (t) = lb;
low_bound = lb;
}
+ /* Temporarily disable -fstrong-eval-order for array reductions.
+ The SAVE_EXPR and COMPOUND_EXPR added if low_bound has side-effects
+ is something the middle-end can't cope with and more importantly,
+ it needs to be the actual base variable that is privatized, not some
+ temporary assigned previous value of it. That, together with OpenMP
+ saying how many times the side-effects are evaluated is unspecified,
+ makes int *a, *b; ... reduction(+:a[a = b, 3:10]) really unspecified. */
+ warning_sentinel s (flag_strong_eval_order,
+ OMP_CLAUSE_CODE (c) == OMP_CLAUSE_REDUCTION);
ret = grok_array_decl (OMP_CLAUSE_LOCATION (c), ret, low_bound, false);
return ret;
}
--- gcc/cp/cp-gimplify.c.jj 2019-10-09 10:27:12.654401641 +0200
+++ gcc/cp/cp-gimplify.c 2019-10-09 10:32:44.930416402 +0200
@@ -638,6 +638,22 @@ lvalue_has_side_effects (tree e)
return TREE_SIDE_EFFECTS (e);
}
+/* Gimplify *EXPR_P as rvalue into an expression that can't be modified
+ by expressions with side-effects in other operands. */
+
+static enum gimplify_status
+gimplify_to_rvalue (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
+ bool (*gimple_test_f) (tree))
+{
+ enum gimplify_status t
+ = gimplify_expr (expr_p, pre_p, post_p, gimple_test_f, fb_rvalue);
+ if (t == GS_ERROR)
+ return GS_ERROR;
+ else if (is_gimple_variable (*expr_p) && TREE_CODE (*expr_p) != SSA_NAME)
+ *expr_p = get_initialized_tmp_var (*expr_p, pre_p, NULL);
+ return t;
+}
+
/* Do C++-specific gimplification. Args are as for gimplify_expr. */
int
@@ -823,15 +839,10 @@ cp_gimplify_expr (tree *expr_p, gimple_s
&& cp_get_callee_fndecl_nofold (*expr_p) == NULL_TREE)
{
enum gimplify_status t
- = gimplify_expr (&CALL_EXPR_FN (*expr_p), pre_p, NULL,
- is_gimple_call_addr, fb_rvalue);
+ = gimplify_to_rvalue (&CALL_EXPR_FN (*expr_p), pre_p, NULL,
+ is_gimple_call_addr);
if (t == GS_ERROR)
ret = GS_ERROR;
- else if (is_gimple_variable (CALL_EXPR_FN (*expr_p))
- && TREE_CODE (CALL_EXPR_FN (*expr_p)) != SSA_NAME)
- CALL_EXPR_FN (*expr_p)
- = get_initialized_tmp_var (CALL_EXPR_FN (*expr_p), pre_p,
- NULL);
}
if (!CALL_EXPR_FN (*expr_p))
/* Internal function call. */;
--- gcc/testsuite/g++.dg/cpp1z/eval-order6.C.jj 2019-10-09 10:32:44.935416328 +0200
+++ gcc/testsuite/g++.dg/cpp1z/eval-order6.C 2019-10-09 10:32:44.935416328 +0200
@@ -0,0 +1,20 @@
+// PR c++/91987
+// { dg-do run }
+// { dg-options "-fstrong-eval-order" }
+
+int
+foo ()
+{
+ int x = 5;
+ int r = x << (x = 3, 2);
+ if (x != 3)
+ __builtin_abort ();
+ return r;
+}
+
+int
+main ()
+{
+ if (foo () != (5 << 2))
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/cpp1z/eval-order7.C.jj 2019-10-09 10:32:44.934416343 +0200
+++ gcc/testsuite/g++.dg/cpp1z/eval-order7.C 2019-10-09 10:32:44.934416343 +0200
@@ -0,0 +1,23 @@
+// PR c++/91987
+// { dg-do run }
+// { dg-options "-fstrong-eval-order" }
+
+int a[4] = { 1, 2, 3, 4 };
+int b[4] = { 5, 6, 7, 8 };
+
+int
+foo ()
+{
+ int *x = a;
+ int r = x[(x = b, 3)];
+ if (x != b)
+ __builtin_abort ();
+ return r;
+}
+
+int
+main ()
+{
+ if (foo () != 4)
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/cpp1z/eval-order8.C.jj 2019-10-09 10:32:44.935416328 +0200
+++ gcc/testsuite/g++.dg/cpp1z/eval-order8.C 2019-10-09 10:32:44.935416328 +0200
@@ -0,0 +1,20 @@
+// PR c++/91987
+// { dg-do run }
+// { dg-options "-fstrong-eval-order" }
+
+int a[4] = { 1, 2, 3, 4 };
+int b;
+
+int
+main ()
+{
+ int *x = a;
+ b = 1;
+ int r = (b = 4, x)[(b *= 2, 3)];
+ if (b != 8 || r != 4)
+ __builtin_abort ();
+ b = 1;
+ r = (b = 3, 2)[(b *= 2, x)];
+ if (b != 6 || r != 3)
+ __builtin_abort ();
+}
--- gcc/testsuite/c-c++-common/gomp/pr91987.c.jj 2019-10-09 12:42:40.059990464 +0200
+++ gcc/testsuite/c-c++-common/gomp/pr91987.c 2019-10-09 12:42:51.330820905 +0200
@@ -0,0 +1,26 @@
+/* PR c++/91987 */
+
+int bar (void);
+void baz (int *);
+#pragma omp declare target to (baz)
+
+void
+foo (int *a, int (*b)[10][10])
+{
+ #pragma omp target map(a[bar ()])
+ baz (a);
+ #pragma omp target map(a[bar ():1])
+ baz (a);
+ #pragma omp target map(a[10:bar ()])
+ baz (a);
+ #pragma omp task depend(inout:a[10:bar ()])
+ baz (a);
+ #pragma omp task depend(inout:a[10:bar ()])
+ baz (a);
+ #pragma omp parallel reduction(+:a[bar ():2])
+ baz (a);
+ #pragma omp parallel reduction(+:a[2:bar ()])
+ baz (a);
+ #pragma omp parallel reduction(+:b[bar ():2][bar ():10][bar ():10])
+ baz (a);
+}
Jakub
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