[RS6000] power8 unaligned fp load/store

According to the POWER8 Processor User’s Manual and some
experimentation on power8 hardware, unaligned fp load/store on power8
does not invoke the alignment interrupt.

	* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Make scalar
	float access depend on TARGET_EFFICIENT_UNALIGNED_VSX.
	* config/rs6000/rs6000.opt (-mefficient-unaligned-vsx): Renamed
	from -mefficient-unaligned-vector.  Note that this affects fp too.

From-SVN: r239013

gcc/ChangeLog

 2016-08-03  Alan Modra  <amodra@gmail.com>
 
+	* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Make scalar
+	float access depend on TARGET_EFFICIENT_UNALIGNED_VSX.
+	* config/rs6000/rs6000.opt (-mefficient-unaligned-vsx): Renamed
+	from -mefficient-unaligned-vector.  Note that this affects fp too.
+
+2016-08-03  Alan Modra  <amodra@gmail.com>
+
 	* config/rs6000/rs6000.c (rs6000_rtx_costs): Make unaligned mem
 	cost more.
 

gcc/config/rs6000/rs6000.h

@@ -990,10 +990,10 @@ enum data_align { align_abi, align_opt, align_both };
    aligned to 4 or 8 bytes.  */
 #define SLOW_UNALIGNED_ACCESS(MODE, ALIGN)				\
   (STRICT_ALIGNMENT							\
-   || (SCALAR_FLOAT_MODE_NOT_VECTOR_P (MODE) && (ALIGN) < 32)		\
-   || (!TARGET_EFFICIENT_UNALIGNED_VSX                                  \
-       && ((VECTOR_MODE_P (MODE) || FLOAT128_VECTOR_P (MODE))		\
-	   && (((int)(ALIGN)) < VECTOR_ALIGN (MODE)))))
+   || (!TARGET_EFFICIENT_UNALIGNED_VSX					\
+       && ((SCALAR_FLOAT_MODE_NOT_VECTOR_P (MODE) && (ALIGN) < 32)	\
+	   || ((VECTOR_MODE_P (MODE) || FLOAT128_VECTOR_P (MODE))	\
+	       && (int) (ALIGN) < VECTOR_ALIGN (MODE)))))
 
 
 /* Standard register usage.  */

gcc/config/rs6000/rs6000.opt

@@ -211,9 +211,9 @@ mallow-movmisalign
 Target Undocumented Var(TARGET_ALLOW_MOVMISALIGN) Init(-1) Save
 ; Allow the movmisalign in DF/DI vectors
 
-mefficient-unaligned-vector
+mefficient-unaligned-vsx
 Target Undocumented Report Mask(EFFICIENT_UNALIGNED_VSX) Var(rs6000_isa_flags)
-; Consider unaligned VSX accesses to be efficient
+; Consider unaligned VSX vector and fp accesses to be efficient
 
 mallow-df-permute
 Target Undocumented Var(TARGET_ALLOW_DF_PERMUTE) Save