imcc codegen - reuse temp register

* a user opcode <op> Nx, Iy, Iy created two temps for the I registers
  now reuse the temporary Nz (1 less ins and 1 less temp)


git-svn-id: https://svn.parrot.org/parrot/trunk@11670 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

compilers/imcc/parser_util.c

@@ -872,7 +872,12 @@ try_find_op(Parrot_Interp interpreter, IMC_Unit * unit, char *name,
     }
     if (n == 3 && r[0]->set == 'N') {
         if (r[1]->set == 'I') {
+            SymReg *r1 = r[1];
             changed |= change_op(interpreter, unit, r, 1, emit);
+            /* op Nx, Iy, Iy: reuse generated temp Nz */
+            if (r[2]->set == 'I' && r[2]->type != VTADDRESS &&
+                    r[2] == r1)
+                r[2] = r[1];
         }
         if (r[2]->set == 'I' && r[2]->type != VTADDRESS) {
             changed |= change_op(interpreter, unit, r, 2, emit);