Hi,
In GNAT, we materialize renamings that cannot be described in standard
DWARF as synthetic variables that describe how to fetch the renamed
object. Look for "___XR" in gcc/ada/exp_dbug.ads for more details about
this convention.
In order to have a location for these variables in the debug info (GDB
requires it not to discard the variable) but also to avoid allocating
runtime space for them, we make these variable hold a DECL_VALUE_EXPR
tree. However, since GCC 7, the DWARF back-end no longer generates a
DW_AT_location attribute for those. This patch is an attempt to restore
this attribute.
Bootstrapped and reg-tested on x86_64-linux. Also, I have a ~150 bytes
increase in the size of cc1, cc1plus and gnat1 (each of these is ~200MB
large). Ok to commit? Thank you in advance!
gcc/
* dwarf2out.c (dwarf2out_late_global_decl): Add locations for
symbols that hold a DECL_VALUE_EXPR.
gcc/testsuite/
* debug12.adb, debug12.ads: New testcase.
---
gcc/dwarf2out.c | 5 +++--
gcc/testsuite/gnat.dg/debug12.adb | 9 +++++++++
gcc/testsuite/gnat.dg/debug12.ads | 8 ++++++++
3 files changed, 20 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gnat.dg/debug12.adb
create mode 100644 gcc/testsuite/gnat.dg/debug12.ads
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 5ff45eb4efd..013c902bc89 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -25526,9 +25526,10 @@ dwarf2out_late_global_decl (tree decl)
{
/* We get called via the symtab code invoking late_global_decl
for symbols that are optimized out. Do not add locations
- for those. */
+ for those, except if they have a DECL_VALUE_EXPR, in which case
+ they are relevant for debuggers. */
varpool_node *node = varpool_node::get (decl);
- if (! node || ! node->definition)
+ if ((! node || ! node->definition) && ! DECL_HAS_VALUE_EXPR_P (decl))
tree_add_const_value_attribute_for_decl (die, decl);
else
add_location_or_const_value_attribute (die, decl, false);
diff --git a/gcc/testsuite/gnat.dg/debug12.adb
b/gcc/testsuite/gnat.dg/debug12.adb
new file mode 100644
index 00000000000..07175968703
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/debug12.adb
@@ -0,0 +1,9 @@
+-- { dg-options "-cargs -gdwarf-4 -fdebug-types-section -dA -margs" }
+-- { dg-final { scan-assembler-times "DW_AT_location" 4 } }
+
+package body Debug12 is
+ function Get_A2 return Boolean is
+ begin
+ return A2;
+ end Get_A2;
+end Debug12;
diff --git a/gcc/testsuite/gnat.dg/debug12.ads
b/gcc/testsuite/gnat.dg/debug12.ads
new file mode 100644
index 00000000000..dbc5896cc73
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/debug12.ads
@@ -0,0 +1,8 @@
+package Debug12 is
+ type Bit_Array is array (Positive range <>) of Boolean
+ with Pack;
+ A : Bit_Array := (1 .. 10 => False);
+ A2 : Boolean renames A (2);
+
+ function Get_A2 return Boolean;
+end Debug12;
--
2.13.0
