arm.h (CANNOT_CHANGE_MODE_CLASS): Restrict FPA_REGS case to VFPv1.

gcc/
	* config/arm/arm.h (CANNOT_CHANGE_MODE_CLASS): Restrict FPA_REGS
	case to VFPv1.

From-SVN: r171520

gcc/ChangeLog

+2011-03-25  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	* config/arm/arm.h (CANNOT_CHANGE_MODE_CLASS): Restrict FPA_REGS
+	case to VFPv1.
+
 2011-03-25  Nathan Froyd  <froydnj@codesourcery.com>
 
 	* fold-const.c (expr_location_or): New function.

gcc/config/arm/arm.h

@@ -1167,12 +1167,12 @@ enum reg_class
 }
 
 /* FPA registers can't do subreg as all values are reformatted to internal
-   precision.  VFP registers may only be accessed in the mode they
-   were set.  */
+   precision.  In VFPv1, VFP registers could only be accessed in the mode
+   they were set, so subregs would be invalid there too.  However, we don't
+   support VFPv1 at the moment, and the restriction was lifted in VFPv2.  */
 #define CANNOT_CHANGE_MODE_CLASS(FROM, TO, CLASS)		\
   (GET_MODE_SIZE (FROM) != GET_MODE_SIZE (TO)			\
    ? reg_classes_intersect_p (FPA_REGS, (CLASS))		\
-     || reg_classes_intersect_p (VFP_REGS, (CLASS))	\
    : 0)
 
 /* The class value for index registers, and the one for base regs.  */