Hi!
My recent protected_set_expr_location changes work well when
that function is called unconditionally, but as the testcase shows, the C++
FE has a few spots that do:
if (!EXPR_HAS_LOCATION (stmt))
protected_set_expr_location (stmt, locus);
or similar. Now, if we have for -g0 stmt of some expression that can
have location and has != UNKNOWN_LOCATION, while -g instead has
a STATEMENT_LIST containing some DEBUG_BEGIN_STMTs + that expression with
that location, we don't call protected_set_expr_location in the -g0 case,
but do call it in the -g case, because on the STATEMENT_LIST
!EXPR_HAS_LOCATION.
The following patch introduces a helper function which digs up the single
expression of a STATEMENT_LIST and uses that expression in the
EXPR_HAS_LOCATION check (plus changes protected_set_expr_location to
also use that helper).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Or do we want a further wrapper, perhaps C++ FE only, that would do this
protected_set_expr_location_if_unset (stmt, locus)?
2020-04-02 Jakub Jelinek <ja...@redhat.com>
PR debug/94441
* tree-iterator.h (expr_single): Declare.
* tree-iterator.c (expr_single): New function.
* tree.c (protected_set_expr_location): Use it.
* parser.c (cp_parser_omp_for_loop): Use expr_single.
* cp-gimplify.c (genericize_if_stmt, genericize_cp_loop): Likewise.
* g++.dg/opt/pr94441.C: New test.
--- gcc/tree-iterator.h.jj 2020-01-12 11:54:38.497381967 +0100
+++ gcc/tree-iterator.h 2020-04-01 16:58:00.034347283 +0200
@@ -119,5 +119,6 @@ extern void append_to_statement_list (tr
extern void append_to_statement_list_force (tree, tree *);
extern tree expr_first (tree);
extern tree expr_last (tree);
+extern tree expr_single (tree);
#endif /* GCC_TREE_ITERATOR_H */
--- gcc/tree-iterator.c.jj 2020-01-12 11:54:38.497381967 +0100
+++ gcc/tree-iterator.c 2020-04-01 17:05:23.388920122 +0200
@@ -354,4 +354,45 @@ expr_last (tree expr)
return expr;
}
+/* If EXPR is a STATEMENT_LIST containing just DEBUG_BEGIN_STMTs and
+ a single other stmt, return that other stmt (recursively).
+ If it is a STATEMENT_LIST containing no non-DEBUG_BEGIN_STMTs or
+ multiple, return NULL_TREE.
+ Otherwise return EXPR. */
+
+tree
+expr_single (tree expr)
+{
+ if (expr == NULL_TREE)
+ return expr;
+
+ if (TREE_CODE (expr) == STATEMENT_LIST)
+ {
+ /* With -gstatement-frontiers we could have a STATEMENT_LIST with
+ DEBUG_BEGIN_STMT(s) and only a single other stmt, which with
+ -g wouldn't be present and we'd have that single other stmt
+ directly instead. */
+ struct tree_statement_list_node *n = STATEMENT_LIST_HEAD (expr);
+ if (!n)
+ return NULL_TREE;
+ while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT)
+ {
+ n = n->next;
+ if (!n)
+ return NULL_TREE;
+ }
+ expr = n->stmt;
+ do
+ {
+ n = n->next;
+ if (!n)
+ return expr_single (expr);
+ }
+ while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT);
+ return NULL_TREE;
+ }
+
+ return expr;
+}
+
#include "gt-tree-iterator.h"
--- gcc/tree.c.jj 2020-03-26 10:35:29.984667559 +0100
+++ gcc/tree.c 2020-04-01 16:59:01.689453490 +0200
@@ -5148,30 +5148,9 @@ protected_set_expr_location (tree t, loc
SET_EXPR_LOCATION (t, loc);
else if (t && TREE_CODE (t) == STATEMENT_LIST)
{
- /* With -gstatement-frontiers we could have a STATEMENT_LIST with
- DEBUG_BEGIN_STMT(s) and only a single other stmt, which with
- -g wouldn't be present and we'd have that single other stmt
- directly instead. */
- struct tree_statement_list_node *n = STATEMENT_LIST_HEAD (t);
- if (!n)
- return;
- while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT)
- {
- n = n->next;
- if (!n)
- return;
- }
- tree t2 = n->stmt;
- do
- {
- n = n->next;
- if (!n)
- {
- protected_set_expr_location (t2, loc);
- return;
- }
- }
- while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT);
+ t = expr_single (t);
+ if (t && CAN_HAVE_LOCATION_P (t))
+ SET_EXPR_LOCATION (t, loc);
}
}
--- gcc/cp/parser.c.jj 2020-03-29 11:14:41.087556278 +0200
+++ gcc/cp/parser.c 2020-04-01 17:03:00.730988186 +0200
@@ -39149,8 +39149,9 @@ cp_parser_omp_for_loop (cp_parser *parse
incr = cp_parser_omp_for_incr (parser, real_decl);
else
incr = cp_parser_expression (parser);
- if (!EXPR_HAS_LOCATION (incr))
- protected_set_expr_location (incr, input_location);
+ if (tree incrl = expr_single (incr))
+ if (!EXPR_HAS_LOCATION (incrl))
+ protected_set_expr_location (incrl, input_location);
}
parse_close_paren:
--- gcc/cp/cp-gimplify.c.jj 2020-03-29 11:14:41.057556738 +0200
+++ gcc/cp/cp-gimplify.c 2020-04-01 17:01:28.916319192 +0200
@@ -226,8 +226,9 @@ genericize_if_stmt (tree *stmt_p)
stmt = else_;
else
stmt = build3 (COND_EXPR, void_type_node, cond, then_, else_);
- if (!EXPR_HAS_LOCATION (stmt))
- protected_set_expr_location (stmt, locus);
+ if (tree stmtl = expr_single (stmt))
+ if (!EXPR_HAS_LOCATION (stmtl))
+ protected_set_expr_location (stmtl, locus);
*stmt_p = stmt;
}
@@ -248,8 +249,9 @@ genericize_cp_loop (tree *stmt_p, locati
tree stmt_list = NULL;
tree debug_begin = NULL;
- if (EXPR_LOCATION (incr) == UNKNOWN_LOCATION)
- protected_set_expr_location (incr, start_locus);
+ if (tree incrl = expr_single (incr))
+ if (!EXPR_HAS_LOCATION (incrl))
+ protected_set_expr_location (incrl, start_locus);
cp_walk_tree (&cond, cp_genericize_r, data, NULL);
cp_walk_tree (&incr, cp_genericize_r, data, NULL);
--- gcc/testsuite/g++.dg/opt/pr94441.C.jj 2020-04-01 17:13:43.014677438
+0200
+++ gcc/testsuite/g++.dg/opt/pr94441.C 2020-04-01 17:14:33.495946020 +0200
@@ -0,0 +1,16 @@
+// PR debug/94441
+// { dg-do compile }
+// { dg-options "-O3 -fno-forward-propagate --param=max-cse-insns=0
-flive-range-shrinkage -std=c++17 -fcompare-debug" }
+
+template <class,class> struct Same;
+template <class T> struct Same<T,T> {};
+
+auto f()
+{
+ if constexpr (sizeof(int)==3)
+ return 42;
+ else
+ return 42L;
+}
+
+Same<decltype(f()), long> s;
Jakub
