[PATCH 3/3] Use code cache in aarch64 prologue analyzer

[Yao Qi <qiyaoltc@gmail.com>]

This patch change aarch prologue analyzer using code cache, in order
to improve the performance of remote debugging.

gdb.perf/skip-prologue.exp (measured by wall-time) is improved when
the program is compiled without debug information.

			Original	Patched		Original	Patched
			without dbg	without dbg	with dbg	with dbg

/			11.1635239124	9.99472999573	9.65339517593	9.66648793221
-fstack-protector-all	11.2560930252	9.338118	9.63896489143	9.59474396706

gdb:

2016-12-06  Yao Qi  <yao.qi@linaro.org>

	* aarch64-tdep.c (instruction_reader::read): Call
	read_code_unsigned_integer instead of
	read_memory_unsigned_integer.
---
 gdb/aarch64-tdep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 590dcf6..0175630 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -213,7 +213,7 @@ class instruction_reader : public abstract_instruction_reader
  public:
   ULONGEST read (CORE_ADDR memaddr, int len, enum bfd_endian byte_order)
   {
-    return read_memory_unsigned_integer (memaddr, len, byte_order);
+    return read_code_unsigned_integer (memaddr, len, byte_order);
   }
 };
 
-- 
1.9.1