(movdf): Don't have reload choose alternative of loading a constant

into a GPR.

From-SVN: r6001

gcc/config/rs6000/rs6000.md

@@ -3059,8 +3059,14 @@
   operands[4] = operand_subword (operands[0], 1, 0, DFmode);
   operands[5] = operand_subword (operands[1], 1, 0, DFmode); }")
 
-(define_insn ""
-  [(set (match_operand:DF 0 "nonimmediate_operand" "=!r,r,o,r,f,f,m")
+;; Don't have reload use general registers to load a constant.  First,
+;; it might not work if the output operand has is the equivalent of
+;; a non-offsettable memref, but also it is less efficient than loading
+;; the constant into an FP register, since it will probably be used there.
+;; The "??" is a kludge until we can figure out a more reasonable way
+;; of handling these non-offsettable values.
+(define_insn ""
+  [(set (match_operand:DF 0 "nonimmediate_operand" "=!r,??r,o,!r,f,f,m")
 	(match_operand:DF 1 "input_operand" "r,o,r,G,f,m,f"))]
   "register_operand (operands[0], DFmode)
    || register_operand (operands[1], DFmode)"