[msp430] special case sym->SI moves

[DJ Delorie]

Symbols are normally PSImode, and the MSP430 has PSImode registers and
PSImode moves to reg/mem.  But sometimes gcc uses an SImode move
instead, if the result will later be used in SImode (as in getP() in
gcc/testsuite/gcc.dg/torture/pr65077.c).  Committed.

        * config/msp430/msp430.md (movsi_s): New.  Special case for
        storing a 20-bit symbol into a 32-bit register.
        * config/msp430/msp430.c (msp430_subreg): Add support for it.
        * config/msp430/predicates.md (msp430_symbol_operand): New.

Index: gcc/config/msp430/predicates.md
===================================================================
--- gcc/config/msp430/predicates.md     (revision 224143)
+++ gcc/config/msp430/predicates.md     (working copy)
@@ -79,6 +79,10 @@
 
 ; TRUE for constants which are bit positions for zero_extract
 (define_predicate "msp430_bitpos"
   (and (match_code "const_int")
        (match_test ("   INTVAL (op) >= 0
                     && INTVAL (op) <= 15 "))))
+
+(define_predicate "msp430_symbol_operand"
+  (match_code "symbol_ref")
+)
Index: gcc/config/msp430/msp430.md
===================================================================
--- gcc/config/msp430/msp430.md (revision 224143)
+++ gcc/config/msp430/msp430.md (working copy)
@@ -211,12 +211,25 @@
   [(set (match_operand:SI 0 "nonimmediate_operand")
        (match_operand:SI 1 "general_operand"))]
   ""
   ""
   )
 
+(define_insn_and_split "movsi_s"
+  [(set (match_operand:SI 0 "nonimmediate_operand" "=rm")
+       (subreg:SI (match_operand:PSI 1 "msp430_symbol_operand" "i") 0))]
+  ""
+  ""
+  "reload_completed"
+  [(set (match_operand:HI 2 "nonimmediate_operand")
+       (match_operand:HI 4 "general_operand"))
+   (set (match_operand:HI 3 "nonimmediate_operand")
+       (match_operand:HI 5 "general_operand"))]
+  "msp430_split_movsi (operands);"
+  )
+
 (define_insn_and_split "movsi_x"
   [(set (match_operand:SI 0 "nonimmediate_operand" "=rm")
        (match_operand:SI 1 "general_operand" "rmi"))]
   ""
   "#"
   "reload_completed"
Index: gcc/config/msp430/msp430.c
===================================================================
--- gcc/config/msp430/msp430.c  (revision 224143)
+++ gcc/config/msp430/msp430.c  (working copy)
@@ -2371,12 +2371,19 @@ msp430_subreg (machine_mode mode, rtx r,
        rv = gen_rtx_SUBREG (mode, ireg, byte);
       else
        rv = simplify_gen_subreg (mode, ireg, imode, byte);
     }
   else if (GET_CODE (r) == MEM)
     rv = adjust_address (r, mode, byte);
+  else if (GET_CODE (r) == SYMBOL_REF
+          && (byte == 0 || byte == 2)
+          && mode == HImode)
+    {
+      rv = gen_rtx_ZERO_EXTRACT (HImode, r, GEN_INT (16), GEN_INT (8*byte));
+      rv = gen_rtx_CONST (HImode, r);
+    }
   else
     rv = simplify_gen_subreg (mode, r, omode, byte);
 
   if (!rv)
     gcc_unreachable ();