[PATCH] gdb.trace: Fix unavailable-dwarf-piece.exp on big endian targets

["Marcin Kościelnicki" <koriakin@0x04.net>]

The test constructs fake DWARF info for a C structure involving bitfields.
DWARF bitfields are always counted from LSB, while the order in which
bitfields are allocated in a C struct depends on the target endianness -
thus the generated DWARF marks different bitfields as unavailable when
target is big endian.  Accordingly, we need different expected outputs.

Tested on s390 and s390x, no regression on x86_64.

gdb/testsuite/ChangeLog:

	* gdb.trace/unavailable-dwarf-piece.exp: Fix bitfield handling on big
	endian targets.
---
Not sure if that's the kosher way to get target endianness.  I looked for
an endian function in the test library, but didn't find one.

 gdb/testsuite/ChangeLog                             |  5 +++++
 gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp | 19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 8f7dc6d..8ee2efa 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-01-23  Marcin Kościelnicki  <koriakin@0x04.net>
+
+	* gdb.trace/unavailable-dwarf-piece.exp: Fix bitfield handling on big
+	endian targets.
+
 2016-01-22  Jan Kratochvil  <jan.kratochvil@redhat.com>
 	    Pedro Alves  <palves@redhat.com>
 
diff --git a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
index 60820dd..e511915 100644
--- a/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
+++ b/gdb/testsuite/gdb.trace/unavailable-dwarf-piece.exp
@@ -325,10 +325,23 @@ with_test_prefix "tracing bar" {
     gdb_test "continue" "Continuing\\.\[ \r\n\]+Breakpoint.*"
     gdb_test_no_output "tstop"
 
+    gdb_test_multiple "show endian" "show endian" {
+	-re ".* (big|little) endian.*$gdb_prompt $" {
+	    set endian $expect_out(1,string)
+	    pass "endianness: $endian"
+	}
+    }
+
     gdb_test "tfind 0" "Found trace frame 0, tracepoint .*"
-    gdb_test "p/d x" "\\\$${decimal} = {a = 0, b = <unavailable>, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = 0, j = 0}"
-    gdb_test "p/d y" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = <unavailable>, f = 0, g = 0, h = 0, i = 0, j = 0}"
-    gdb_test "p/d z" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = <unavailable>, j = 0}"
+    if { $endian == "little" } {
+        gdb_test "p/d x" "\\\$${decimal} = {a = 0, b = <unavailable>, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = 0, j = 0}"
+        gdb_test "p/d y" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = <unavailable>, f = 0, g = 0, h = 0, i = 0, j = 0}"
+        gdb_test "p/d z" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = <unavailable>, j = 0}"
+    } else {
+        gdb_test "p/d x" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = <unavailable>, j = 0}"
+        gdb_test "p/d y" "\\\$${decimal} = {a = 0, b = 0, c = 0, d = 0, e = 0, f = <unavailable>, g = 0, h = 0, i = 0, j = 0}"
+        gdb_test "p/d z" "\\\$${decimal} = {a = 0, b = <unavailable>, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, i = 0, j = 0}"
+    }
 
     gdb_test "tfind none" "No longer looking at any trace frame.*"
 }
-- 
2.7.0