[RFC][gdb/testsuite] Fix base address selection entry encoding in dw2-skip-prologue.S

[Tom de Vries <tdevries@suse.de>]

Hi,

A base address selection entry in a location list consist of two (constant or
relocated) address offsets.  The two offsets are the same size as an address
on the target machine.

The test-case gdb.dwarf2/dw2-skip-prologue.S encodes a base address selection
entry using .4byte, which is incorrect for 8-byte pointer size.  [ Which
triggers an assert in dwz, see PR dwz/24172. ]

Fix this by using PTRBYTE instead.

Tested on x86_64-linux.

Do we fix this type of errors in the testsuite?  AFAICT, the invalid dwarf is
not intentional.

Thanks,
- Tom

[gdb/testsuite] Fix base address selection entry encoding in dw2-skip-prologue.S

gdb/testsuite/ChangeLog:

2019-03-07  Tom de Vries  <tdevries@suse.de>

	* gdb.dwarf2/dw2-skip-prologue.S (.debug_loc): Fix base address
	selection entry encoding.

---
 gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S b/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S
index cef6e6df12..a55699fdc6 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S
+++ b/gdb/testsuite/gdb.dwarf2/dw2-skip-prologue.S
@@ -123,7 +123,7 @@
 	.section	.debug_loc
 loclist:
 	/* Reset the location list base address first.  */
-	.4byte		-1, 0
+	PTRBYTE		-1, 0
 
 	PTRBYTE		func_start, func_end
 	.2byte		2f-1f