libdw: Handle DW_OP_GNU_uninit in dwarf_getlocation

dwarf_getlocation would return an error when it saw a
DW_OP_GNU_uninit. Handle it by simply recognizing as a no argument
operation.

DW_OP_GNU_uninit is emitted by GCC as a marker to flag the location
expression as referring to an uninitialized value.

Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 2c1f61e..ddf14e5 100644 (file)
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,8 @@
+2023-02-10  Mark Wielaard  <mark@klomp.org>
+
+       * dwarf_getlocation.c (__libdw_intern_expression): Handle
+       DW_OP_GNU_uninit.
+
 2023-02-12  Mark Wielaard  <mark@klomp.org>
 
        * cfi.c (execute_cfi): Add cfi_asser before reading second lib128.

diff --git a/libdw/dwarf_getlocation.c b/libdw/dwarf_getlocation.c
index 4e8c047..66eab3e 100644 (file)
--- a/libdw/dwarf_getlocation.c
+++ b/libdw/dwarf_getlocation.c
@@ -396,6 +396,7 @@ __libdw_intern_expression (Dwarf *dbg, bool other_byte_order,
        case DW_OP_form_tls_address:
        case DW_OP_GNU_push_tls_address:
        case DW_OP_stack_value:
+       case DW_OP_GNU_uninit:
          /* No operand.  */
          break;
 

diff --git a/tests/ChangeLog b/tests/ChangeLog
index 89f1a99..eb3e111 100644 (file)
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,7 @@
+2023-02-10  Mark Wielaard  <mark@klomp.org>
+
+       * varlocs.c (print_expr): Handle DW_OP_GNU_uninit.
+
 2023-02-07  Mark Wielaard  <mark@klomp.org>
 
        * tests/funcretval.c (handle_function): Check for

diff --git a/tests/varlocs.c b/tests/varlocs.c
index d2c1376..8e563fd 100644 (file)
--- a/tests/varlocs.c
+++ b/tests/varlocs.c
@@ -251,6 +251,12 @@ print_expr (Dwarf_Attribute *attr, Dwarf_Op *expr, Dwarf_Addr addr, int depth)
       printf ("%s", opname);
       break;
 
+    case DW_OP_GNU_uninit:
+      /* No arguments. Special. It means the expression describes
+        an value which hasn't been initialized (yet).  */
+      printf ("%s", opname);
+      break;
+
     case DW_OP_call_frame_cfa:
       /* No arguments. Special. Pushes Call Frame Address as computed
         by CFI data (dwarf_cfi_addrframe will fetch that info (either from