Patcher synchronization.

diff --git a/src/vm/jit/alpha/asmpart.S b/src/vm/jit/alpha/asmpart.S
index 08a592358b8a7cd114f3df7b4b09b5daf95710e1..7302ae8b83552076b263f1bee739ea1d66874050 100644 (file)
--- a/src/vm/jit/alpha/asmpart.S
+++ b/src/vm/jit/alpha/asmpart.S
@@ -30,7 +30,7 @@
    Changes: Joseph Wenninger
             Christian Thalinger
 
-   $Id: asmpart.S 2399 2005-04-27 12:53:03Z twisti $
+   $Id: asmpart.S 2431 2005-05-03 19:27:11Z twisti $
 
 */
 
@@ -1123,7 +1123,8 @@ ex_flt2:
    XXX
 
    Stack layout:
-        24   return address into JIT code (patch position)
+        32   return address into JIT code (patch position)
+     24   pointer to virtual java_objectheader
      16   machine code (which is patched back later)
       8   unresolved class/method/field reference
       0   patcher function pointer to call
@@ -1158,8 +1159,8 @@ asm_wrapper_patcher:
        ldq     ra,(12+27+2)*8(sp)    /* restore method return address (for leafs)*/
        ldq     pv,(12+27+3)*8(sp)    /* restore pv of calling java function      */
 
-       ldq     itmp3,(3+12+27+4)*8(sp)/* get return address (into JIT code)      */
-       lda     sp,(4+12+27+4)*8(sp)  /* remove stack frame                       */
+       ldq     itmp3,(4+12+27+4)*8(sp)/* get return address (into JIT code)      */
+       lda     sp,(5+12+27+4)*8(sp)  /* remove stack frame                       */
 
        beq     v0,L_asm_wrapper_patcher_exception
 

diff --git a/src/vm/jit/alpha/codegen.c b/src/vm/jit/alpha/codegen.c
index fb81c850bf37cb7d4a9e5ce985278b3953eb70bc..380db147593f1c8fbe6d31e8c2f53c6177902205 100644 (file)
--- a/src/vm/jit/alpha/codegen.c
+++ b/src/vm/jit/alpha/codegen.c
@@ -30,7 +30,7 @@
    Changes: Joseph Wenninger
             Christian Thalinger
 
-   $Id: codegen.c 2398 2005-04-27 12:46:40Z twisti $
+   $Id: codegen.c 2431 2005-05-03 19:27:11Z twisti $
 
 */
 
@@ -4119,13 +4119,28 @@ gen_method: {
 
                for (pref = cd->patchrefs; pref != NULL; pref = pref->next) {
                        /* check code segment size */
-                       MCODECHECK(9);
+
+                       MCODECHECK(13 + 4 + 1);
 
                        /* Get machine code which is patched back in later. The call is   */
                        /* 1 instruction word long.                                       */
+
                        xcodeptr = (s4 *) (cd->mcodebase + pref->branchpos);
                        mcode = *xcodeptr;
 
+#if defined(USE_THREADS) && defined(NATIVE_THREADS)
+                       /* create a virtual java_objectheader */
+
+                       /* align data structure to 8-byte */
+
+                       if (!((ptrint) mcodeptr & 0x7))
+                               M_NOP;
+
+                       *((ptrint *) mcodeptr++) = 0;                            /* vftbl */
+                       *((ptrint *) (mcodeptr + 2)) = (ptrint) get_dummyLR(); /* monitorPtr */
+                       mcodeptr += 4;
+#endif
+
                        /* patch in the call to call the following code (done at compile  */
                        /* time)                                                          */
 
@@ -4138,11 +4153,21 @@ gen_method: {
 
                        /* create stack frame */
 
-                       M_LSUB_IMM(REG_SP, 4 * 8, REG_SP);
+                       M_LSUB_IMM(REG_SP, 5 * 8, REG_SP);
 
                        /* move return address onto stack */
 
+                       M_AST(REG_ITMP3, REG_SP, 4 * 8);
+
+                       /* move pointer to java_objectheader onto stack */
+
+#if defined(USE_THREADS) && defined(NATIVE_THREADS)
+                       M_BSR(REG_ITMP3, 0);
+                       M_LSUB_IMM(REG_ITMP3, 3 * 4 + 2 * 8, REG_ITMP3);
                        M_AST(REG_ITMP3, REG_SP, 3 * 8);
+#else
+                       M_AST(REG_ZERO, REG_SP, 3 * 8);
+#endif
 
                        /* move machine code onto stack */
 
@@ -4581,9 +4606,23 @@ u1 *createnativestub(functionptr f, methodinfo *m)
                if (pref) {
                        /* Get machine code which is patched back in later. The call is   */
                        /* 1 instruction word long.                                       */
+
                        xcodeptr = (s4 *) (cd->mcodebase + pref->branchpos);
                        *(cs-11) = (u4) *xcodeptr;
 
+#if defined(USE_THREADS) && defined(NATIVE_THREADS)
+                       /* create a virtual java_objectheader */
+
+                       /* align data structure to 8-byte */
+
+                       if (!((ptrint) mcodeptr & 0x7))
+                               M_NOP;
+
+                       *((ptrint *) mcodeptr++) = 0;                            /* vftbl */
+                       *((ptrint *) (mcodeptr + 2)) = (ptrint) get_dummyLR(); /* monitorPtr */
+                       mcodeptr += 4;
+#endif
+
                        /* patch in the call to call the following code (done at compile  */
                        /* time)                                                          */
 
@@ -4596,11 +4635,21 @@ u1 *createnativestub(functionptr f, methodinfo *m)
 
                        /* create stack frame                                             */
 
-                       M_LSUB_IMM(REG_SP, 4 * 8, REG_SP);
+                       M_LSUB_IMM(REG_SP, 5 * 8, REG_SP);
 
                        /* move return address onto stack */
 
+                       M_AST(REG_ITMP3, REG_SP, 4 * 8);
+
+                       /* move pointer to java_objectheader onto stack */
+
+#if defined(USE_THREADS) && defined(NATIVE_THREADS)
+                       M_BSR(REG_ITMP3, 0);
+                       M_LSUB_IMM(REG_ITMP3, 3 * 4 + 2 * 8, REG_ITMP3);
                        M_AST(REG_ITMP3, REG_SP, 3 * 8);
+#else
+                       M_AST(REG_ZERO, REG_SP, 3 * 8);
+#endif
 
                        /* move machine code onto stack                                   */
 

diff --git a/src/vm/jit/alpha/patcher.c b/src/vm/jit/alpha/patcher.c
index f46fcfb87013fdfdd32a86e4d80dc849cb8166f5..3c6f8b4a09c7c1270ecac4fc4480e8b84be1fc7e 100644 (file)
--- a/src/vm/jit/alpha/patcher.c
+++ b/src/vm/jit/alpha/patcher.c
@@ -28,7 +28,7 @@
 
    Changes:
 
-   $Id: patcher.c 2396 2005-04-27 12:44:31Z twisti $
+   $Id: patcher.c 2431 2005-05-03 19:27:11Z twisti $
 
 */
 
@@ -55,24 +55,40 @@
 
 bool patcher_get_putstatic(u1 *sp)
 {
-       u1               *ra;
-       u4                mcode;
-       unresolved_field *uf;
-       u1               *pv;
-       fieldinfo        *fi;
-       s2                offset;
+       u1                *ra;
+       java_objectheader *o;
+       u4                 mcode;
+       unresolved_field  *uf;
+       u1                *pv;
+       fieldinfo         *fi;
+       s2                 offset;
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)               *((ptrint *) (sp + 2 * 8));
-       mcode =                      *((u4 *)     (sp + 1 * 8));
-       uf    = (unresolved_field *) *((ptrint *) (sp + 0 * 8));
-       pv    = (u1 *)               *((ptrint *) (sp - 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
+       mcode =                       *((u4 *)     (sp + 1 * 8));
+       uf    = (unresolved_field *)  *((ptrint *) (sp + 0 * 8));
+       pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -106,6 +122,16 @@ bool patcher_get_putstatic(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -121,21 +147,37 @@ bool patcher_get_putstatic(u1 *sp)
 
 bool patcher_get_putfield(u1 *sp)
 {
-       u1               *ra;
-       u8                mcode;
-       unresolved_field *uf;
-       u1               *pv;
-       fieldinfo        *fi;
+       u1                *ra;
+       java_objectheader *o;
+       u8                 mcode;
+       unresolved_field  *uf;
+       u1                *pv;
+       fieldinfo         *fi;
 
-       ra    = (u1 *)               *((ptrint *) (sp + 2 * 8));
-       mcode =                      *((u4 *)     (sp + 1 * 8));
-       uf    = (unresolved_field *) *((ptrint *) (sp + 0 * 8));
-       pv    = (u1 *)               *((ptrint *) (sp - 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
+       mcode =                       *((u4 *)     (sp + 1 * 8));
+       uf    = (unresolved_field *)  *((ptrint *) (sp + 0 * 8));
+       pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -159,6 +201,16 @@ bool patcher_get_putfield(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -177,6 +229,7 @@ bool patcher_get_putfield(u1 *sp)
 bool patcher_builtin_new(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -185,7 +238,8 @@ bool patcher_builtin_new(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -193,7 +247,21 @@ bool patcher_builtin_new(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - (4 + 4);
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the classinfo */
 
@@ -229,6 +297,16 @@ bool patcher_builtin_new(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -247,6 +325,7 @@ bool patcher_builtin_new(u1 *sp)
 bool patcher_builtin_newarray(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -255,7 +334,8 @@ bool patcher_builtin_newarray(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -263,7 +343,21 @@ bool patcher_builtin_newarray(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - (4 + 4);
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the classinfo */
 
@@ -299,6 +393,16 @@ bool patcher_builtin_newarray(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -319,6 +423,7 @@ bool patcher_builtin_newarray(u1 *sp)
 bool patcher_builtin_multianewarray(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -327,7 +432,8 @@ bool patcher_builtin_multianewarray(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -335,7 +441,21 @@ bool patcher_builtin_multianewarray(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the classinfo */
 
@@ -363,6 +483,16 @@ bool patcher_builtin_multianewarray(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -381,6 +511,7 @@ bool patcher_builtin_multianewarray(u1 *sp)
 bool patcher_builtin_checkarraycast(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -389,7 +520,8 @@ bool patcher_builtin_checkarraycast(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -397,7 +529,21 @@ bool patcher_builtin_checkarraycast(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - (2 * 4);
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the classinfo */
 
@@ -433,6 +579,16 @@ bool patcher_builtin_checkarraycast(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -451,6 +607,7 @@ bool patcher_builtin_checkarraycast(u1 *sp)
 bool patcher_builtin_arrayinstanceof(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -459,7 +616,8 @@ bool patcher_builtin_arrayinstanceof(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -467,7 +625,21 @@ bool patcher_builtin_arrayinstanceof(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - (4 + 4);
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the classinfo */
 
@@ -503,6 +675,16 @@ bool patcher_builtin_arrayinstanceof(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -520,6 +702,7 @@ bool patcher_builtin_arrayinstanceof(u1 *sp)
 bool patcher_invokestatic_special(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        unresolved_method *um;
        u1                *pv;
@@ -528,7 +711,8 @@ bool patcher_invokestatic_special(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        um    = (unresolved_method *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -536,7 +720,21 @@ bool patcher_invokestatic_special(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -564,6 +762,16 @@ bool patcher_invokestatic_special(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -582,20 +790,36 @@ bool patcher_invokestatic_special(u1 *sp)
 bool patcher_invokevirtual(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        unresolved_method *um;
        methodinfo        *m;
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        um    = (unresolved_method *) *((ptrint *) (sp + 0 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -620,6 +844,16 @@ bool patcher_invokevirtual(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -639,20 +873,36 @@ bool patcher_invokevirtual(u1 *sp)
 bool patcher_invokeinterface(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        unresolved_method *um;
        methodinfo        *m;
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        um    = (unresolved_method *) *((ptrint *) (sp + 0 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -682,6 +932,16 @@ bool patcher_invokeinterface(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -697,6 +957,7 @@ bool patcher_invokeinterface(u1 *sp)
 bool patcher_checkcast_instanceof_flags(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -705,7 +966,8 @@ bool patcher_checkcast_instanceof_flags(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -713,7 +975,21 @@ bool patcher_checkcast_instanceof_flags(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -741,6 +1017,16 @@ bool patcher_checkcast_instanceof_flags(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -761,20 +1047,36 @@ bool patcher_checkcast_instanceof_flags(u1 *sp)
 bool patcher_checkcast_instanceof_interface(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        classinfo         *c;
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -801,6 +1103,16 @@ bool patcher_checkcast_instanceof_interface(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -818,6 +1130,7 @@ bool patcher_checkcast_instanceof_interface(u1 *sp)
 bool patcher_checkcast_instanceof_class(u1 *sp)
 {
        u1                *ra;
+       java_objectheader *o;
        u4                 mcode;
        constant_classref *cr;
        u1                *pv;
@@ -826,7 +1139,8 @@ bool patcher_checkcast_instanceof_class(u1 *sp)
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)                *((ptrint *) (sp + 2 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
        mcode =                       *((u4 *)     (sp + 1 * 8));
        cr    = (constant_classref *) *((ptrint *) (sp + 0 * 8));
        pv    = (u1 *)                *((ptrint *) (sp - 2 * 8));
@@ -834,7 +1148,21 @@ bool patcher_checkcast_instanceof_class(u1 *sp)
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* get the fieldinfo */
 
@@ -862,6 +1190,16 @@ bool patcher_checkcast_instanceof_class(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }
 
@@ -874,20 +1212,36 @@ bool patcher_checkcast_instanceof_class(u1 *sp)
 
 bool patcher_clinit(u1 *sp)
 {
-       u1        *ra;
-       u4         mcode;
-       classinfo *c;
+       u1                *ra;
+       java_objectheader *o;
+       u4                 mcode;
+       classinfo         *c;
 
        /* get stuff from the stack */
 
-       ra    = (u1 *)        *((ptrint *) (sp + 2 * 8));
-       mcode =               *((u4 *)     (sp + 1 * 8));
-       c     = (classinfo *) *((ptrint *) (sp + 0 * 8));
+       ra    = (u1 *)                *((ptrint *) (sp + 3 * 8));
+       o     = (java_objectheader *) *((ptrint *) (sp + 2 * 8));
+       mcode =                       *((u4 *)     (sp + 1 * 8));
+       c     = (classinfo *)         *((ptrint *) (sp + 0 * 8));
 
        /* calculate and set the new return address */
 
        ra = ra - 4;
-       *((ptrint *) (sp + 2 * 8)) = (ptrint) ra;
+       *((ptrint *) (sp + 3 * 8)) = (ptrint) ra;
+
+#if defined(USE_THREADS)
+       /* enter a monitor on the patching position */
+
+       builtin_monitorenter(o);
+
+       /* check if the position has already been patched */
+
+       if (o->vftbl) {
+               builtin_monitorexit(o);
+
+               return true;
+       }
+#endif
 
        /* check if the class is initialized */
 
@@ -903,6 +1257,16 @@ bool patcher_clinit(u1 *sp)
 
        asm_sync_instruction_cache();
 
+#if defined(USE_THREADS)
+       /* this position has been patched */
+
+       o->vftbl = (vftbl_t *) 1;
+
+       /* leave the monitor on the patching position */
+
+       builtin_monitorexit(o);
+#endif
+
        return true;
 }