[ARC] Enable unaligned access.

Use munaligned-access to control if we can have unaligned accesses.  For ARC
HS family unaligned access is always on.

2018-01-08  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc-c.def (__ARC_UNALIGNED__): New define.
	* config/arc/arc.h (STRICT_ALIGNMENT): Control this macro using
	munaligned-access.

From-SVN: r256333

gcc/ChangeLog

+2018-01-08  Claudiu Zissulescu  <claziss@synopsys.com>
+
+	* config/arc/arc-c.def (__ARC_UNALIGNED__): New define.
+	* config/arc/arc.h (STRICT_ALIGNMENT): Control this macro using
+	munaligned-access.
+
 2018-01-08  Sebastian Huber  <sebastian.huber@embedded-brains.de>
 
 	PR target/83681

gcc/config/arc/arc-c.def

@@ -28,6 +28,7 @@ ARC_C_DEF ("__ARC_NORM__",	TARGET_NORM)
 ARC_C_DEF ("__ARC_MUL64__",	TARGET_MUL64_SET)
 ARC_C_DEF ("__ARC_MUL32BY16__", TARGET_MULMAC_32BY16_SET)
 ARC_C_DEF ("__ARC_SIMD__",	TARGET_SIMD_SET)
+ARC_C_DEF ("__ARC_UNALIGNED__", !STRICT_ALIGNMENT)
 
 ARC_C_DEF ("__ARC_BARREL_SHIFTER__", TARGET_BARREL_SHIFTER)
 

gcc/config/arc/arc.h

@@ -288,7 +288,7 @@ if (GET_MODE_CLASS (MODE) == MODE_INT		\
 /* On the ARC the lower address bits are masked to 0 as necessary.  The chip
    won't croak when given an unaligned address, but the insn will still fail
    to produce the correct result.  */
-#define STRICT_ALIGNMENT 1
+#define STRICT_ALIGNMENT (!unaligned_access && !TARGET_HS)
 
 /* Layout of source language data types.  */