[gdb/testsuite] Fix DW_AT_decl_file in gdb.trace tests

When running gdb.trace/{entry-values.exp,unavailable-dwarf-piece.exp} with
board cc-with-dwz, we run into two failures related to the DW_AT_decl_file
attribute:
- The encoding DW_FOR_sdata is used for DW_AT_decl_file, while the attribute
  is required to have a an "unsigned integer constant" value.
- The DW_AT_decl_file attributes refer to a file with index one, while there's
  no such file.

Fix this by using DW_FOR_udata and the value 0, meaning "no file specified".

Tested on x86_64-linux with board native-gdbserver.

gdb/testsuite/ChangeLog:

2019-06-24  Tom de Vries  <tdevries@suse.de>

	* gdb.trace/entry-values.exp: Use DW_FORM_udata instead of
	DW_FOR_sdata for DW_AT_decl_file.  Use 0 for DW_AT_decl_file.
	* gdb.trace/unavailable-dwarf-piece.exp: Same.

3 files changed, 12 insertions, 6 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 4d48d2f..a8e4755 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,11 @@
 2019-06-24  Tom de Vries  <tdevries@suse.de>
 
+	* gdb.trace/entry-values.exp: Use DW_FORM_udata instead of
+	DW_FOR_sdata for DW_AT_decl_file.  Use 0 for DW_AT_decl_file.
+	* gdb.trace/unavailable-dwarf-piece.exp: Same.
+
+2019-06-24  Tom de Vries  <tdevries@suse.de>
+
 	* gdb.dwarf2/inlined_subroutine-inheritance.exp:
 
 2019-06-21  Tom de Vries  <tdevries@suse.de>
diff --git a/gdb/testsuite/gdb.trace/entry-values.exp b/gdb/testsuite/gdb.trace/entry-values.exp
index 13619ba..6637e5e 100644
--- a/gdb/testsuite/gdb.trace/entry-values.exp
+++ b/gdb/testsuite/gdb.trace/entry-values.exp
@@ -109,7 +109,7 @@ Dwarf::assemble $asm_file {
 	    }
 
 	    foo_label: subprogram {
-		{decl_file 1 sdata}
+		{decl_file 0 udata}
 		{MACRO_AT_func { foo ${srcdir}/${subdir}/${srcfile} }}
 	    } {
 		formal_parameter {
@@ -126,7 +126,7 @@ Dwarf::assemble $asm_file {
 
 	    subprogram {
 		{name bar}
-		{decl_file 1 sdata}
+		{decl_file 0 udata}
 		{low_pc $bar_start addr}
 		{high_pc "$bar_start + $bar_length" addr}
 		{GNU_all_call_sites 1 sdata}
diff --git a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
index c62e344..8717785 100644
--- a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
+++ b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
@@ -44,7 +44,7 @@ Dwarf::assemble $asm_file {
 	    struct_s_label: DW_TAG_structure_type {
 		{name s}
 		{byte_size 3 DW_FORM_sdata}
-		{decl_file 1 DW_FORM_sdata}
+		{decl_file 0 DW_FORM_udata}
 		{decl_line 1 DW_FORM_sdata}
 	    } {
 		DW_TAG_member {
@@ -73,7 +73,7 @@ Dwarf::assemble $asm_file {
 	    struct_t_label: DW_TAG_structure_type {
 		{name t}
 		{byte_size 3 DW_FORM_sdata}
-		{decl_file 1 DW_FORM_sdata}
+		{decl_file 0 DW_FORM_udata}
 		{decl_line 1 DW_FORM_sdata}
 	    } {
 		DW_TAG_member {
@@ -174,7 +174,7 @@ Dwarf::assemble $asm_file {
 
 	    DW_TAG_subprogram {
 		{name foo}
-		{decl_file 1 sdata}
+		{decl_file 0 udata}
 		{low_pc foo_start_lbl addr}
 		{high_pc foo_end_lbl addr}
 	    } {
@@ -219,7 +219,7 @@ Dwarf::assemble $asm_file {
 
 	    DW_TAG_subprogram {
 		{name bar}
-		{decl_file 1 sdata}
+		{decl_file 0 udata}
 		{low_pc bar_start_lbl addr}
 		{high_pc bar_end_lbl addr}
 	    } {