* src/vm/jit/trap.cpp: Finally switched s390 to the new trap decoding method.
[cacao.git] / src / vm / jit / s390 / md.c
index daf413b943058aaa0522161c3168ec17727dcc36..95eb600ed710b05877ca0c55e1bcdea704db0a2b 100644 (file)
@@ -1,9 +1,7 @@
-/* src/vm/jit/x86_64/md.c - machine dependent x86_64 Linux functions
+/* src/vm/jit/s390/md.c - machine dependent s390 Linux functions
 
-   Copyright (C) 1996-2005, 2006 R. Grafl, A. Krall, C. Kruegel,
-   C. Oates, R. Obermaisser, M. Platter, M. Probst, S. Ring,
-   E. Steiner, C. Thalinger, D. Thuernbeck, P. Tomsich, C. Ullrich,
-   J. Wenninger, Institut f. Computersprachen - TU Wien
+   Copyright (C) 2006, 2007, 2008, 2010
+   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO
 
    This file is part of CACAO.
 
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.
 
-   Contact: cacao@cacaojvm.org
-
-   Authors: Christian Thalinger
-
-   Changes: Edwin Steiner
-
-   $Id: md.c 8097 2007-06-17 14:50:16Z pm $
-
 */
 
+
 #define _GNU_SOURCE
 
 #include "config.h"
 
 #include <assert.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <ucontext.h>
 
 #include "vm/jit/s390/md-abi.h"
 
-#if defined(ENABLE_THREADS)
-# include "threads/threads-common.h"
-# include "threads/native/threads.h"
-#endif
+#include "threads/thread.hpp"
+
+#include "vm/exceptions.hpp"
+#include "vm/signallocal.hpp"
 
-#include "vm/exceptions.h"
-#include "vm/signallocal.h"
-#include "vm/jit/asmpart.h"
+#include "vm/jit/abi.h"
+#include "vm/jit/executionstate.h"
 #include "vm/jit/methodheader.h"
-#include "vm/jit/stacktrace.h"
+#include "vm/jit/methodtree.h"
+#include "vm/jit/stacktrace.hpp"
+#include "vm/jit/trap.hpp"
 
 #if !defined(NDEBUG) && defined(ENABLE_DISASSEMBLER)
-#include "vmcore/options.h" /* XXX debug */
-#include "vm/jit/disass.h" /* XXX debug */
+#include "vm/options.h" /* XXX debug */
 #endif
 
-#include "vm/jit/codegen-common.h"
+#include "vm/jit/codegen-common.hpp"
 #include "vm/jit/s390/codegen.h"
+#include "vm/jit/s390/md.h"
 
-#include <assert.h>
-#define OOPS() assert(0);
 
 /* prototypes *****************************************************************/
 
+u1 *exceptions_handle_exception(java_object_t *xptro, u1 *xpc, u1 *pv, u1 *sp);
+
 void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p);
 
 void md_dump_context(u1 *pc, mcontext_t *mc);
@@ -90,7 +83,7 @@ void md_dump_context(u1 *pc, mcontext_t *mc) {
        int i;
        u1 *pv;
        methodinfo *m;
-       
+
        union {
                u8 l;
                fpreg_t fr;
@@ -100,14 +93,15 @@ void md_dump_context(u1 *pc, mcontext_t *mc) {
 
        log_println("Program counter: 0x%08X", pc);
 
-       pv = codegen_get_pv_from_pc_nocheck(pc);
+       pv = methodtree_find_nocheck(pc);
+
        if (pv == NULL) {
                log_println("No java method found at location.");
        } else {
-               m = ((codeinfo *)(pv + CodeinfoPointer))->m;
+               m = (*(codeinfo **)(pv + CodeinfoPointer))->m;
                log_println(
                        "Java method: class %s, method %s, descriptor %s.",
-                       utf_bytes(m->class->name), utf_bytes(m->name), utf_bytes(m->descriptor)
+                       m->clazz->name->text, m->name->text, m->descriptor->text
                );
        }
 
@@ -129,117 +123,36 @@ void md_dump_context(u1 *pc, mcontext_t *mc) {
                log_println("\tf%d\t0x%016llX\t(double)%e\t(float)%f", i, freg.l, freg.fr.d, freg.fr.f);
        }
 
-#if defined(ENABLE_THREADS)
        log_println("Dumping the current stacktrace:");
-       threads_print_stacktrace();
-#endif
-
+       stacktrace_print_current();
 }
 
-/* md_signal_handler_sigsegv ***************************************************
-
-   NullPointerException signal handler for hardware null pointer
-   check.
-
-*******************************************************************************/
-
+/**
+ * NullPointerException signal handler for hardware null pointer check.
+ */
 void md_signal_handler_sigsegv(int sig, siginfo_t *siginfo, void *_p)
 {
-       ucontext_t        *_uc;
-       mcontext_t        *_mc;
-       u1                *pv;
-       u1                *sp;
-       u1                *ra;
-       u1                *xpc;
-       s4                 type;
-       ptrint             val;
-       java_objectheader *e;
-       s4                 base;
-       s4                 is_null;
-
-       _uc = (ucontext_t *) _p;
-       _mc = &_uc->uc_mcontext;
-
-       xpc = (u1 *)_mc->psw.addr;
-
-       /* Check opcodes and verify it is a null pointer exception */
-
-       switch (xpc[0]) {
-               case 0x58: /* L */
-               case 0x50: /* ST */
-                       base = (xpc[2] >> 4) & 0xF;
-                       if (base == 0) {
-                               is_null = 1;
-                       } else if (_mc->gregs[base] == 0) {
-                               is_null = 1;
-                       } else {
-                               is_null = 0;
-                       }
-                       break;
-       }
+       ucontext_t* _uc = (ucontext_t *) _p;
+       mcontext_t* _mc = &_uc->uc_mcontext;
 
-       if (! is_null) {
-#if !defined(NDEBUG)
-               md_dump_context(xpc, _mc);
-#endif
-               vm_abort("%s: segmentation fault at %p, aborting.", __FUNCTION__, xpc);
-       }
+       void* xpc = (u1 *) _mc->psw.addr;
 
-       pv = (u1 *)_mc->gregs[REG_PV] - N_PV_OFFSET;
-       sp = (u1 *)_mc->gregs[REG_SP];
-       ra = xpc;
-       type = EXCEPTION_HARDWARE_NULLPOINTER;
-       val = 0;
-
-       e = exceptions_new_hardware_exception(pv, sp, ra, xpc, type, val);
-
-       _mc->gregs[REG_ITMP2_XPC] = (ptrint) xpc;
-       _mc->gregs[REG_ITMP1_XPTR] = (ptrint) e;
-       _mc->psw.addr = (ptrint) asm_handle_exception;
+       // Handle the trap.
+       trap_handle(TRAP_SIGSEGV, xpc, _p);
 }
 
-void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p) {
-       ucontext_t        *_uc;
-       mcontext_t        *_mc;
-       u1                *xpc;
-       u1                *ra;
-       u1                *pv;
-       u1                *sp;
-       s4                 type;
-       ptrint             val;
-       java_objectheader *e;
-       s4                 reg;
-
-       _uc = (ucontext_t *) _p;
-       _mc = &_uc->uc_mcontext;
-       xpc = ra = siginfo->si_addr;
-
-       /* Our trap instruction has the format: { 0x02, one_byte_of_data }. */
-
-       if ((siginfo->si_code == ILL_ILLOPC) && (xpc[0] == 0x02)) {
-
-               /* bits 7-4 contain a register holding a value */
-               reg = (xpc[1] >> 4) & 0xF;
-
-               /* bits 3-0 designate the exception type */
-               type = xpc[1] & 0xF;  
-
-               pv = (u1 *)_mc->gregs[REG_PV] - N_PV_OFFSET;
-               sp = (u1 *)_mc->gregs[REG_SP];
-               val = (ptrint)_mc->gregs[reg];
-
-               e = exceptions_new_hardware_exception(pv, sp, ra, xpc, type, val);
+/**
+  * Illegal Instruction signal handler for hardware exception checks.
+  */
+void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p)
+{
+       ucontext_t* _uc = (ucontext_t *) _p;
+       mcontext_t* _mc = &_uc->uc_mcontext;
 
-               _mc->gregs[REG_ITMP1_XPTR] = (ptrint)e;
-               _mc->gregs[REG_ITMP2_XPC] = (ptrint)xpc;
-               _mc->psw.addr = (ptrint) asm_handle_exception;
+       void* xpc = siginfo->si_addr;
 
-       } else {
-#if !defined(NDEBUG)
-               md_dump_context(xpc, _mc);
-#endif
-               vm_abort("%s: illegal instruction at %p, aborting.", __FUNCTION__, xpc);
-       }
+       // Handle the trap.
+       trap_handle(TRAP_SIGILL, xpc, _p);
 }
 
 /* md_signal_handler_sigfpe ****************************************************
@@ -251,73 +164,37 @@ void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p) {
 
 void md_signal_handler_sigfpe(int sig, siginfo_t *siginfo, void *_p)
 {
-       ucontext_t         *_uc;
-       mcontext_t         *_mc;
-       u1                 *pv;
-       u1                 *sp;
-       u1                 *ra;
-       u1                 *xpc;
-       u1                 *pc;
-       s4                  r1, r2;
-       s4                  type;
-       ptrint              val;
-       java_objectheader  *e;
-
-       _uc = (ucontext_t *) _p;
-       _mc = &_uc->uc_mcontext;
+       ucontext_t* _uc = (ucontext_t *) _p;
+       mcontext_t* _mc = &_uc->uc_mcontext;
 
-       /* Instruction that raised signal */
-       xpc = siginfo->si_addr;
+       void* xpc = siginfo->si_addr;
 
-       /* Check opcodes */
+       if (N_RR_GET_OPC(xpc) == OPC_DR) { /* DR */
 
-       if (xpc[0] == 0x1D) { /* DR */
-
-               r1 = (xpc[1] >> 4) & 0xF;
-               r2 = xpc[1] & 0xF;
+               int r1 = N_RR_GET_REG1(xpc);
+               int r2 = N_RR_GET_REG2(xpc);
 
                if (
                        (_mc->gregs[r1] == 0xFFFFFFFF) &&
                        (_mc->gregs[r1 + 1] == 0x80000000) && 
                        (_mc->gregs[r2] == 0xFFFFFFFF)
                ) {
-                       /* handle special case */
+                       /* handle special case 0x80000000 / 0xFFFFFFFF that fails on hardware */
                        /* next instruction */
-                       pc = (u1 *)_mc->psw.addr;
-                       /* reminder */
+                       u1 *pc = (u1 *)_mc->psw.addr;
+                       /* remainder */
                        _mc->gregs[r1] = 0;
                        /* quotient */
                        _mc->gregs[r1 + 1] = 0x80000000;
                        /* continue at next instruction */
                        _mc->psw.addr = (ptrint) pc;
 
-                       return;
-               } else if (_mc->gregs[r2] == 0) {
-                       /* division by 0 */
-
-                       pv = (u1 *)_mc->gregs[REG_PV] - N_PV_OFFSET;
-                       sp = (u1 *)_mc->gregs[REG_SP];
-                       ra = xpc;
-
-                       type = EXCEPTION_HARDWARE_ARITHMETIC;
-                       val = 0;
-
-                       e = exceptions_new_hardware_exception(pv, sp, ra, xpc, type, val);
-
-                       _mc->gregs[REG_ITMP1_XPTR] = (ptrint)e;
-                       _mc->gregs[REG_ITMP2_XPC] = (ptrint)xpc;
-                       _mc->psw.addr = (ptrint) asm_handle_exception;
-
                        return;
                }
        }
 
-       /* Could not handle signal */
-
-#if !defined(NDEBUG)
-       md_dump_context(xpc, _mc);
-#endif
-       vm_abort("%s: floating point exception at %p, aborting.", __FUNCTION__, xpc);
+       // Handle the trap.
+       trap_handle(TRAP_SIGFPE, xpc, _p);
 }
 
 
@@ -350,77 +227,75 @@ void md_signal_handler_sigusr2(int sig, siginfo_t *siginfo, void *_p)
 #endif
 
 
-#if defined(ENABLE_THREADS)
-void md_critical_section_restart(ucontext_t *_uc)
+/**
+ * Read the given context into an executionstate.
+ *
+ * @param es      execution state
+ * @param context machine context
+ */
+void md_executionstate_read(executionstate_t* es, void* context)
 {
+       ucontext_t *_uc;
        mcontext_t *_mc;
-       u1         *pc;
-       void       *npc;
+       int         i;
 
+       _uc = (ucontext_t *) context;
        _mc = &_uc->uc_mcontext;
 
-       pc = (u1 *)_mc->psw.addr;
-
-       npc = critical_find_restart_point(pc);
-
-       if (npc != NULL) {
-               log_println("%s: pc=%p, npc=%p", __FUNCTION__, pc, npc);
-               _mc->psw.addr = (ptrint) npc;
-       }
-}
-#endif
-
-
-/* md_codegen_patch_branch *****************************************************
-
-   Back-patches a branch instruction.
-
-*******************************************************************************/
-
-void md_codegen_patch_branch(codegendata *cd, s4 branchmpc, s4 targetmpc)
-{
-
-       s4 *mcodeptr;
-       s4  disp;                           /* branch displacement                */
-
-       /* calculate the patch position */
-
-       mcodeptr = (s4 *) (cd->mcodebase + branchmpc);
-
-       /* Calculate the branch displacement. */
+       /* read special registers */
+       es->pc = (u1 *) _mc->psw.addr;
+       es->sp = (u1 *) _mc->gregs[REG_SP];
+       es->pv = (u1 *) _mc->gregs[REG_PV] - N_PV_OFFSET;
+       es->ra = (u1 *) _mc->gregs[REG_RA];
 
-       disp = targetmpc - branchmpc;
-       disp += 4; /* size of branch */
-       disp /= 2; /* specified in halfwords */
+       /* read integer registers */
+       for (i = 0; i < INT_REG_CNT; i++)
+               es->intregs[i] = _mc->gregs[i];
 
-       ASSERT_VALID_BRANCH(disp);      
+       /* read float registers */
+       /* Do not use the assignment operator '=', as the type of
+        * the _mc->sc_fpregs[i] can cause invalid conversions. */
 
-       /* patch the branch instruction before the mcodeptr */
-
-       mcodeptr[-1] |= (disp & 0xFFFF);
+       assert(sizeof(_mc->fpregs.fprs) == sizeof(es->fltregs));
+       os_memcpy(&es->fltregs, &_mc->fpregs.fprs, sizeof(_mc->fpregs.fprs));
 }
 
 
-/* md_stacktrace_get_returnaddress *********************************************
-
-   Returns the return address of the current stackframe, specified by
-   the passed stack pointer and the stack frame size.
+/**
+ * Write the given executionstate back to the context.
+ *
+ * @param es      execution state
+ * @param context machine context
+ */
+void md_executionstate_write(executionstate_t* es, void* context)
+{
+       ucontext_t *_uc;
+       mcontext_t *_mc;
+       int         i;
 
-*******************************************************************************/
+       _uc = (ucontext_t *) context;
+       _mc = &_uc->uc_mcontext;
 
-u1 *md_stacktrace_get_returnaddress(u1 *sp, u4 framesize)
-{
-       u1 *ra;
+       /* write integer registers */
+       for (i = 0; i < INT_REG_CNT; i++)
+               _mc->gregs[i] = es->intregs[i];
 
-       /* on S390 the return address is located on the top of the stackframe */
+       /* write float registers */
+       /* Do not use the assignment operator '=', as the type of
+        * the _mc->sc_fpregs[i] can cause invalid conversions. */
 
-       ra = *((u1 **) (sp + framesize - SIZEOF_VOID_P));
+       assert(sizeof(_mc->fpregs.fprs) == sizeof(es->fltregs));
+       os_memcpy(&_mc->fpregs.fprs, &es->fltregs, sizeof(_mc->fpregs.fprs));
 
-       return ra;
+       /* write special registers */
+       _mc->psw.addr      = (ptrint) es->pc;
+       _mc->gregs[REG_SP] = (ptrint) es->sp;
+       _mc->gregs[REG_PV] = (ptrint) es->pv + N_PV_OFFSET;
+       _mc->gregs[REG_RA] = (ptrint) es->ra;
 }
 
 
-/* md_get_method_patch_address *************************************************
+/* md_jit_method_patch_address *************************************************
 
    Gets the patch address of the currently compiled method. The offset
    is extracted from the load instruction(s) before the jump and added
@@ -451,36 +326,36 @@ last 2 instructions the same as in invokevirtual
 
 *******************************************************************************/
 
-u1 *md_get_method_patch_address(u1 *ra, stackframeinfo *sfi, u1 *mptr)
+void *md_jit_method_patch_address(void* pv, void *ra, void *mptr)
 {
-       u1  base, index;
-       s4  offset;
-       u1 *pa;                             /* patch address                      */
+       uint8_t *pc;
+       uint8_t  base, index;
+       int32_t  offset;
+       void    *pa;                        /* patch address                      */
 
        /* go back to the load before the call instruction */
 
-       ra = ra - 2 /* sizeof bcr */ - 4 /* sizeof l */;
+       pc = ((uint8_t *) ra) - SZ_BCR - SZ_L;
 
        /* get the base register of the load */
 
-       base = ra[2] >> 4;
-       index = ra[1] & 0xF;
+       base  = N_RX_GET_BASE(pc);
+       index = N_RX_GET_INDEX(pc);
 
        /* check for the different calls */
 
        switch (base) {
-               case 0xd:
+               case REG_PV:
                        /* INVOKESTATIC/SPECIAL */
 
-               
                        switch (index) {
-                               case 0x0:
+                               case R0:
                                        /* the offset is in the load instruction */
-                                       offset = ((*(u2 *)(ra + 2)) & 0xFFF) + N_PV_OFFSET;
+                                       offset = N_RX_GET_DISP(pc) + N_PV_OFFSET;
                                        break;
-                               case 0x1:
+                               case REG_ITMP1:
                                        /* the offset is in the immediate load before the load */
-                                       offset = *((s2 *) (ra - 2));
+                                       offset = N_RI_GET_IMM(pc - SZ_L);
                                        break;
                                default:
                                        assert(0);
@@ -488,23 +363,28 @@ u1 *md_get_method_patch_address(u1 *ra, stackframeinfo *sfi, u1 *mptr)
 
                        /* add the offset to the procedure vector */
 
-                       pa = sfi->pv + offset;
-
+                       pa = ((uint8_t *) pv) + offset;
                        break;
 
-               case 0xc:
+               case REG_METHODPTR:
                        /* mptr relative */
                        /* INVOKEVIRTUAL/INTERFACE */
 
-                       offset = *((u2 *)(ra + 2)) & 0xFFF;
+                       offset = N_RX_GET_DISP(pc);
+
+                       /* return NULL if no mptr was specified (used for replacement) */
+
+                       if (mptr == NULL)
+                               return NULL;
 
                        /* add offset to method pointer */
                        
-                       pa = mptr + offset;
+                       pa = (uint8_t *)mptr + offset;
                        break;
+
                default:
                        /* catch any problems */
-                       assert(0); 
+                       vm_abort("md_jit_method_patch_address");
                        break;
        }
 
@@ -512,101 +392,196 @@ u1 *md_get_method_patch_address(u1 *ra, stackframeinfo *sfi, u1 *mptr)
 }
 
 
-/* md_codegen_get_pv_from_pc ***************************************************
+/**
+ * Decode the trap instruction at the given PC.
+ *
+ * @param trp information about trap to be filled
+ * @param sig signal number
+ * @param xpc exception PC
+ * @param es execution state of the machine
+ * @return true if trap was decoded successfully, false otherwise.
+ */
+bool md_trap_decode(trapinfo_t* trp, int sig, void* xpc, executionstate_t* es)
+{
+       switch (sig) {
+       case TRAP_SIGILL:
+               if (N_RR_GET_OPC(xpc) == OPC_ILL) {
+                       int32_t reg = N_ILL_GET_REG(xpc);
+                       trp->type  = N_ILL_GET_TYPE(xpc);
+                       trp->value = es->intregs[reg];
+                       return true;
+               }
+               return false;
 
-   On this architecture just a wrapper function to
-   codegen_get_pv_from_pc.
+       case TRAP_SIGSEGV:
+       {
+               int is_null;
+               int32_t base;
+               switch (N_RX_GET_OPC(xpc)) {
+                       case OPC_L:
+                       case OPC_ST:
+                       case OPC_CL: /* array size check on NULL array */
+                               base = N_RX_GET_BASE(xpc);
+                               if (base == 0) {
+                                       is_null = 1;
+                               } else if (es->intregs[base] == 0) {
+                                       is_null = 1;
+                               } else {
+                                       is_null = 0;
+                               }
+                               break;
+                       default:
+                               is_null = 0;
+                               break;
+               }
 
-*******************************************************************************/
+               // Check for implicit NullPointerException.
+               if (is_null) {
+                       trp->type  = TRAP_NullPointerException;
+                       trp->value = 0;
+                       return true;
+               }
 
-u1 *md_codegen_get_pv_from_pc(u1 *ra)
-{
-       u1 *pv;
+               return false;
+       }
 
-       /* Get the start address of the function which contains this
-       address from the method table. */
+       case TRAP_SIGFPE:
+       {
+               if (N_RR_GET_OPC(xpc) == OPC_DR) {
+                       int r2 = N_RR_GET_REG2(xpc);
+                       if (es->intregs[r2] == 0) {
+                               trp->type = TRAP_ArithmeticException;
+                               trp->value = 0;
+                               return true;
+                       }
+               }
 
-       pv = codegen_get_pv_from_pc(ra);
+               return false;
+       }
 
-       return pv;
+       default:
+               return false;
+       }
 }
 
 
-/* md_cacheflush ***************************************************************
 
-   Calls the system's function to flush the instruction and data
-   cache.
+/* md_patch_replacement_point **************************************************
 
-*******************************************************************************/
+   Patch the given replacement point.
 
-void md_cacheflush(u1 *addr, s4 nbytes)
+*******************************************************************************/
+#if defined(ENABLE_REPLACEMENT)
+void md_patch_replacement_point(u1 *pc, u1 *savedmcode, bool revert)
 {
-       /* do nothing */
+       assert(0);
 }
+#endif
 
+void md_handle_exception(int32_t *regs, int64_t *fregs, int32_t *out) {
+
+       uint8_t *xptr;
+       uint8_t *xpc;
+       uint8_t *sp;
+       uint8_t *pv;
+       uint8_t *ra;
+       uint8_t *handler;
+       int32_t framesize;
+       int32_t intsave;
+       int32_t fltsave;
+       int64_t *savearea;
+       int i;
+       int reg;
+       int loops = 0;
 
-/* md_icacheflush **************************************************************
+       /* get registers */
 
-   Calls the system's function to flush the instruction cache.
+       xptr = *(uint8_t **)(regs + REG_ITMP1_XPTR);
+       xpc = *(uint8_t **)(regs + REG_ITMP2_XPC);
+       sp = *(uint8_t **)(regs + REG_SP);
 
-*******************************************************************************/
 
-void md_icacheflush(u1 *addr, s4 nbytes)
-{
-       /* do nothing */
-}
+       /* initialize number of calle saved int regs to restore to 0 */
+       out[0] = 0;
 
+       /* initialize number of calle saved flt regs to restore to 0 */
+       out[1] = 0;
 
-/* md_dcacheflush **************************************************************
+       do {
 
-   Calls the system's function to flush the data cache.
+               ++loops;
 
-*******************************************************************************/
+               pv = methodtree_find(xpc);
 
-void md_dcacheflush(u1 *addr, s4 nbytes)
-{
-       /* do nothing */
-}
+               handler = exceptions_handle_exception((java_object_t *)xptr, xpc, pv, sp);
 
+               if (handler == NULL) {
 
-/* md_patch_replacement_point **************************************************
+                       /* exception was not handled
+                        * get values of calee saved registers and remove stack frame 
+                        */
 
-   Patch the given replacement point.
+                       /* read stuff from data segment */
 
-*******************************************************************************/
-#if 0
-void md_patch_replacement_point(rplpoint *rp)
-{
-    u8 mcode;
+                       framesize = *(int32_t *)(pv + FrameSize);
 
-       /* XXX this is probably unsafe! */
+                       intsave = *(int32_t *)(pv + IntSave);
+                       if (intsave > out[0]) {
+                               out[0] = intsave;
+                       }
 
-       /* save the current machine code */
-       mcode = *(u8*)rp->pc;
+                       fltsave = *(int32_t *)(pv + FltSave);
+                       if (fltsave > out[1]) {
+                               out[1] = fltsave;
+                       }
 
-       /* write spinning instruction */
-       *(u2*)(rp->pc) = 0xebfe;
+                       /* pointer to register save area */
 
-       /* write 5th byte */
-       rp->pc[4] = (rp->mcode >> 32);
+                       savearea = (int64_t *)(sp + framesize - 8);
 
-       /* write first word */
-    *(u4*)(rp->pc) = (u4) rp->mcode;
+                       /* return address */
 
-       /* store saved mcode */
-       rp->mcode = mcode;
-       
-#if !defined(NDEBUG) && defined(ENABLE_DISASSEMBLER)
-       {
-               u1* u1ptr = rp->pc;
-               DISASSINSTR(u1ptr);
-               fflush(stdout);
-       }
-#endif
-                       
-    /* XXX if required asm_cacheflush(rp->pc,8); */
+                       ra = *(uint8_t **)(sp + framesize - 8);
+
+                       /* restore saved registers */
+
+                       for (i = 0; i < intsave; ++i) {
+                               --savearea;
+                               reg = abi_registers_integer_saved[INT_SAV_CNT - 1 - i];
+                               regs[reg] = *(int32_t *)(savearea);
+                       }
+
+                       for (i = 0; i < fltsave; ++i) {
+                               --savearea;
+                               reg = abi_registers_float_saved[FLT_SAV_CNT - 1 - i];
+                               fregs[reg] = *savearea;
+                       }
+
+                       /* remove stack frame */
+
+                       sp += framesize;
+
+                       /* new xpc is call before return address */
+
+                       xpc = ra - 2;
+
+               } else {
+                       xpc = handler;
+               }
+       } while (handler == NULL);
+
+       /* write new values for registers */
+
+       *(uint8_t **)(regs + REG_ITMP1_XPTR) = xptr;
+       *(uint8_t **)(regs + REG_ITMP2_XPC) = xpc;
+       *(uint8_t **)(regs + REG_SP) = sp;
+       *(uint8_t **)(regs + REG_PV) = pv - 0XFFC;
+
+       /* maybe leaf flag */
+
+       out[2] = (loops == 1);
 }
-#endif
+
 /*
  * These are local overrides for various environment variables in Emacs.
  * Please do not remove this and leave it at the end of the file, where