[PATCH v2] Fix aarch64 ftrace JIT condition testcase

[Antoine Tremblay <antoine dot tremblay at ericsson dot com>]

This patch fixes the following failure:
FAIL: gdb.trace/trace-condition.exp: ftrace: -(21 << 1) == -42: check 10
frames were collected.

This was due to aarch64_emit_sub using the wrong order in its operands, so the
operation would end up being 42 - 0 rather than 0 - 42.

This patch also fixes the order of aarch64_emit_add for clarity.

The test case for emit_sub is fixed so that the proper order of
the operands is needed for the test to pass.

Tested on aarch64-native-extended-gdbserver.

Note: trace-condition.exp was broken a bit so I had to modify it to run
the test. A fix is coming for that in another patch.

gdb/gdbserver/ChangeLog:

	* linux-aarch64-low.c (aarch64_emit_add): Switch x1 and x0.
	(aarch64_emit_sub): Likewise.

gdb/testsuite/ChangeLog:

	* gdb.trace/trace-condition.exp (foreach): Fix emit_sub testcase.
---
 gdb/gdbserver/linux-aarch64-low.c           | 4 ++--
 gdb/testsuite/gdb.trace/trace-condition.exp | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
index 12fe2e6..d237bde 100644
--- a/gdb/gdbserver/linux-aarch64-low.c
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -2258,7 +2258,7 @@ aarch64_emit_add (void)
   uint32_t *p = buf;
 
   p += emit_pop (p, x1);
-  p += emit_add (p, x0, x0, register_operand (x1));
+  p += emit_add (p, x0, x1, register_operand (x0));
 
   emit_ops_insns (buf, p - buf);
 }
@@ -2272,7 +2272,7 @@ aarch64_emit_sub (void)
   uint32_t *p = buf;
 
   p += emit_pop (p, x1);
-  p += emit_sub (p, x0, x0, register_operand (x1));
+  p += emit_sub (p, x0, x1, register_operand (x0));
 
   emit_ops_insns (buf, p - buf);
 }
diff --git a/gdb/testsuite/gdb.trace/trace-condition.exp b/gdb/testsuite/gdb.trace/trace-condition.exp
index 2c47028..44fd720 100644
--- a/gdb/testsuite/gdb.trace/trace-condition.exp
+++ b/gdb/testsuite/gdb.trace/trace-condition.exp
@@ -138,7 +138,7 @@ foreach trace_command { "trace" "ftrace" } {
 
     # Test various operations to cover as many opcodes as possible.
     test_tracepoints $trace_command "21 + 21 == 42" 10
-    test_tracepoints $trace_command "21 - 21 == 0" 10
+    test_tracepoints $trace_command "42 - 21 == 21" 10
     test_tracepoints $trace_command "21 * 2 == 42" 10
     test_tracepoints $trace_command "21 << 1 == 42" 10
     test_tracepoints $trace_command "42 >> 1 == 21" 10
-- 
2.7.3