* src/vm/jit/i386/emit.c (emit_copy): Eliminate register move if one

of the variables resides in memory.

--HG--
branch : new_instruction_format

diff --git a/src/vm/jit/i386/emit.c b/src/vm/jit/i386/emit.c
index 6cac7fd36b10ee06107334c29dcb1dafd58c971c..0d2dcb9003ca68373e3ba7e54b100e6b90090f2c 100644 (file)
--- a/src/vm/jit/i386/emit.c
+++ b/src/vm/jit/i386/emit.c
@@ -28,7 +28,7 @@
 
    Changes:
 
-   $Id: emit.c 5352 2006-09-05 22:51:48Z christian $
+   $Id: emit.c 5395 2006-09-07 10:46:39Z twisti $
 
 */
 
@@ -420,9 +420,10 @@ void emit_store_dst(jitdata *jd, instruction *iptr, s4 d)
        emit_store(jd, iptr, dst, d);
 }
 
+
 /* emit_copy *******************************************************************
 
-   XXX
+   Generates a register/memory to register/memory copy.
 
 *******************************************************************************/
 
@@ -439,12 +440,27 @@ void emit_copy(jitdata *jd, instruction *iptr, stackptr src, stackptr dst)
 
        if ((src->regoff != dst->regoff) ||
                ((src->flags ^ dst->flags) & INMEMORY)) {
-               if (IS_LNG_TYPE(src->type))
-                       d = codegen_reg_of_var(rd, iptr->opc, dst, REG_ITMP12_PACKED);
-               else
-                       d = codegen_reg_of_var(rd, iptr->opc, dst, REG_ITMP1);
 
-               s1 = emit_load(jd, iptr, src, d);
+               /* If one of the variables resides in memory, we can eliminate
+                  the register move from/to the temporary register with the
+                  order of getting the destination register and the load. */
+
+               if (IS_INMEMORY(src->flags)) {
+                       if (IS_LNG_TYPE(src->type))
+                               d = codegen_reg_of_var(rd, iptr->opc, dst, REG_ITMP12_PACKED);
+                       else
+                               d = codegen_reg_of_var(rd, iptr->opc, dst, REG_ITMP1);
+
+                       s1 = emit_load(jd, iptr, src, d);
+               }
+               else {
+                       if (IS_LNG_TYPE(src->type))
+                               s1 = emit_load(jd, iptr, src, REG_ITMP12_PACKED);
+                       else
+                               s1 = emit_load(jd, iptr, src, REG_ITMP1);
+
+                       d = codegen_reg_of_var(rd, iptr->opc, dst, s1);
+               }
 
                if (s1 != d) {
                        if (IS_FLT_DBL_TYPE(src->type)) {