Hi!
As mentioned in the PR, since PR96690 r11-2834 we call rtl_for_decl_init
which can call expand_expr already during early_dwarf. The comment and PR
explains it that the intent is to ensure the referenced vars and functions
are properly mangled because free_lang_data doesn't cover everything, like
template parameters etc. It doesn't work well though, because expand_expr
can set DECL_RTLs e.g. on referenced vars and keep them there, and they can
be created e.g. with different MEM_ALIGN compared to what they would be
created with if they were emitted later.
So, the following patch stops calling rtl_for_decl_init and instead
for cases for which rtl_for_decl_init does anything at all walks the
initializer and ensures referenced vars or functions are mangled.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2022-02-08 Jakub Jelinek <ja...@redhat.com>
PR debug/104407
* dwarf2out.cc (mangle_referenced_decls): New function.
(tree_add_const_value_attribute): Don't call rtl_for_decl_init if
early_dwarf. Instead walk the initializer and try to mangle vars or
functions referenced from it.
* g++.dg/debug/dwarf2/pr104407.C: New test.
--- gcc/dwarf2out.cc.jj 2022-02-04 14:36:54.966605844 +0100
+++ gcc/dwarf2out.cc 2022-02-07 12:28:13.000520666 +0100
@@ -20881,6 +20881,19 @@ add_location_or_const_value_attribute (d
return tree_add_const_value_attribute_for_decl (die, decl);
}
+/* Mangle referenced decls. */
+static tree
+mangle_referenced_decls (tree *tp, int *walk_subtrees, void *)
+{
+ if (! EXPR_P (*tp) && ! CONSTANT_CLASS_P (*tp))
+ *walk_subtrees = 0;
+
+ if (VAR_OR_FUNCTION_DECL_P (*tp))
+ assign_assembler_name_if_needed (*tp);
+
+ return NULL_TREE;
+}
+
/* Attach a DW_AT_const_value attribute to DIE. The value of the
attribute is the const value T. */
@@ -20889,7 +20902,6 @@ tree_add_const_value_attribute (dw_die_r
{
tree init;
tree type = TREE_TYPE (t);
- rtx rtl;
if (!t || !TREE_TYPE (t) || TREE_TYPE (t) == error_mark_node)
return false;
@@ -20910,11 +20922,26 @@ tree_add_const_value_attribute (dw_die_r
return true;
}
}
- /* Generate the RTL even if early_dwarf to force mangling of all refered to
- symbols. */
- rtl = rtl_for_decl_init (init, type);
- if (rtl && !early_dwarf)
- return add_const_value_attribute (die, TYPE_MODE (type), rtl);
+ if (!early_dwarf)
+ {
+ rtx rtl = rtl_for_decl_init (init, type);
+ if (rtl && !early_dwarf)
+ return add_const_value_attribute (die, TYPE_MODE (type), rtl);
+ }
+ else
+ {
+ /* For early_dwarf force mangling of all referenced symbols. */
+ tree initializer = init;
+ STRIP_NOPS (initializer);
+ /* rtl_for_decl_init punts on other aggregates, and complex values. */
+ if (AGGREGATE_TYPE_P (type)
+ || (TREE_CODE (initializer) == VIEW_CONVERT_EXPR
+ && AGGREGATE_TYPE_P (TREE_TYPE (TREE_OPERAND (initializer, 0))))
+ || TREE_CODE (type) == COMPLEX_TYPE)
+ ;
+ else if (initializer_constant_valid_p (initializer, type))
+ walk_tree (&initializer, mangle_referenced_decls, NULL, NULL);
+ }
/* If the host and target are sane, try harder. */
if (CHAR_BIT == 8 && BITS_PER_UNIT == 8
&& initializer_constant_valid_p (init, type))
--- gcc/testsuite/g++.dg/debug/dwarf2/pr104407.C.jj 2022-02-07
10:45:51.945041031 +0100
+++ gcc/testsuite/g++.dg/debug/dwarf2/pr104407.C 2022-02-07
10:45:09.834635340 +0100
@@ -0,0 +1,12 @@
+// PR debug/104407
+// { dg-do compile { target c++17 } }
+// { dg-options "-O1 -fcompare-debug" }
+
+struct A { int i; long j; int k : 2; char l; } a;
+
+auto [ aa, bb, cc, dd ] = a;
+
+namespace N
+{
+ auto & [ m, n, o, ppp ] = a;
+}
Jakub
