patch to mips16 truncdi{h,q}i2

[Gavin Koch <gavin at cygnus dot com>]

For the 4100 -mips16, the following bit of code causes gcc
to recur in convert_move until it runs out of stack; similar
code useing a long and a char will also cause this.  The
following patch defines a mips16 version of of truncdihi2
and truncdiqi2.

OK to push?

                                   -gavin...


./cc1 yy.c -quiet -mips16 -O0 -o yy.s

long l;
short i;

void x()
{
i = l;
}


	* mips.md (trucndihi2,truncdiqi2): Change these to support 
	mips16.

Index: mips.md
===================================================================
RCS file: /cvs/cvsfiles/devo/gcc/config/mips/mips.md,v
retrieving revision 1.95
diff -c -3 -p -r1.95 mips.md
*** mips.md	1998/01/23 07:20:09	1.95
--- mips.md	1998/02/09 21:00:03
*************** move\\t%0,%z4\\n\\
*** 3301,3320 ****
  (define_insn "truncdihi2"
    [(set (match_operand:HI 0 "register_operand" "=d")
  	(truncate:HI (match_operand:DI 1 "se_register_operand" "d")))]
!   "TARGET_64BIT && !TARGET_MIPS16"
!   "andi\\t%0,%1,0xffff"
    [(set_attr "type"	"darith")
     (set_attr "mode"	"HI")
!    (set_attr "length"	"1")])
! 
  (define_insn "truncdiqi2"
    [(set (match_operand:QI 0 "register_operand" "=d")
  	(truncate:QI (match_operand:DI 1 "se_register_operand" "d")))]
!   "TARGET_64BIT && !TARGET_MIPS16"
!   "andi\\t%0,%1,0x00ff"
    [(set_attr "type"	"darith")
     (set_attr "mode"	"QI")
!    (set_attr "length"	"1")])
  
  ;; Combiner patterns to optimize shift/truncate combinations.
  (define_insn ""
--- 3301,3333 ----
  (define_insn "truncdihi2"
    [(set (match_operand:HI 0 "register_operand" "=d")
  	(truncate:HI (match_operand:DI 1 "se_register_operand" "d")))]
!   "TARGET_64BIT"
!   "*
! {
!   if (TARGET_MIPS16)
!     return \"dsll\\t%0,%1,48\;dsra\\t%0,48\";
!   return \"andi\\t%0,%1,0xffff\";
! }"
    [(set_attr "type"	"darith")
     (set_attr "mode"	"HI")
!    (set (attr "length")	(if_then_else (eq (symbol_ref "mips16") (const_int 0))
! 				      (const_int 1)
! 				      (const_int 4)))])
  (define_insn "truncdiqi2"
    [(set (match_operand:QI 0 "register_operand" "=d")
  	(truncate:QI (match_operand:DI 1 "se_register_operand" "d")))]
!   "TARGET_64BIT"
!   "*
! {
!   if (TARGET_MIPS16)
!     return \"dsll\\t%0,%1,56\;dsra\\t%0,56\";
!   return \"andi\\t%0,%1,0x00ff\"; 
! }"
    [(set_attr "type"	"darith")
     (set_attr "mode"	"QI")
!    (set (attr "length")	(if_then_else (eq (symbol_ref "mips16") (const_int 0))
! 				      (const_int 1)
! 				      (const_int 4)))])
  
  ;; Combiner patterns to optimize shift/truncate combinations.
  (define_insn ""