runtime4/interp.c

/**************************************************************************/
/*                                                                        */
/*                                 OCaml                                  */
/*                                                                        */
/*             Xavier Leroy, projet Cristal, INRIA Rocquencourt           */
/*                                                                        */
/*   Copyright 1996 Institut National de Recherche en Informatique et     */
/*     en Automatique.                                                    */
/*                                                                        */
/*   All rights reserved.  This file is distributed under the terms of    */
/*   the GNU Lesser General Public License version 2.1, with the          */
/*   special exception on linking described in the file LICENSE.          */
/*                                                                        */
/**************************************************************************/

#define CAML_INTERNALS

/* The bytecode interpreter */
#include <stdio.h>
#include "caml/alloc.h"
#include "caml/backtrace.h"
#include "caml/callback.h"
#include "caml/debugger.h"
#include "caml/fail.h"
#include "caml/fix_code.h"
#include "caml/instrtrace.h"
#include "caml/instruct.h"
#include "caml/interp.h"
#include "caml/major_gc.h"
#include "caml/memory.h"
#include "caml/misc.h"
#include "caml/mlvalues.h"
#include "caml/prims.h"
#include "caml/signals.h"
#include "caml/stacks.h"
#include "caml/startup_aux.h"

/* Registers for the abstract machine:
        pc         the code pointer
        sp         the stack pointer (grows downward)
        accu       the accumulator
        env        heap-allocated environment
        Caml_state->trapsp pointer to the current trap frame
        extra_args number of extra arguments provided by the caller

sp is a local copy of the global variable Caml_state->extern_sp. */

/* Instruction decoding */

#ifdef THREADED_CODE
#  define Instruct(name) lbl_##name
#  if defined(ARCH_SIXTYFOUR) && !defined(ARCH_CODE32)
#    define Jumptbl_base &&lbl_ACC0
#  else
#    define Jumptbl_base 0
#    define jumptbl_base ((char *) 0)
#  endif
#  ifdef DEBUG
#    define Next goto next_instr
#  else
#    define Next goto *(void *)(jumptbl_base + *pc++)
#  endif
#else
#  define Instruct(name) case name
#  define Next break
#endif

/* GC interface */

#undef Alloc_small_origin
// Do call asynchronous callbacks from allocation functions
#define Alloc_small_origin CAML_FROM_CAML
#define Setup_for_gc \
  { sp -= 3; sp[0] = accu; sp[1] = env; sp[2] = (value)pc; \
    Caml_state->extern_sp = sp; }
#define Restore_after_gc \
  { sp = Caml_state->extern_sp; accu = sp[0]; env = sp[1]; sp += 3; }

/* We store [pc+1] in the stack so that, in case of an exception, the
   first backtrace slot points to the event following the C call
   instruction. */
#define Setup_for_c_call \
  { sp -= 2; sp[0] = env; sp[1] = (value)(pc + 1); Caml_state->extern_sp = sp; }
#define Restore_after_c_call \
  { sp = Caml_state->extern_sp; env = *sp; sp += 2; }

/* For VM threads purposes, an event frame must look like accu + a
   C_CALL frame + a RETURN 1 frame.
   TODO: now that VM threads are gone, we could get rid of that. But
   we need to make sure that this is not used elsewhere. */
#define Setup_for_event \
  { sp -= 6; \
    sp[0] = accu; /* accu */ \
    sp[1] = Val_unit; /* C_CALL frame: dummy environment */ \
    sp[2] = Val_unit; /* RETURN frame: dummy local 0 */ \
    sp[3] = (value) pc; /* RETURN frame: saved return address */ \
    sp[4] = env; /* RETURN frame: saved environment */ \
    sp[5] = Val_long(extra_args); /* RETURN frame: saved extra args */ \
    Caml_state->extern_sp = sp; }
#define Restore_after_event \
  { sp = Caml_state->extern_sp; accu = sp[0]; \
    pc = (code_t) sp[3]; env = sp[4]; extra_args = Long_val(sp[5]); \
    sp += 6; }

/* Debugger interface */

#define Setup_for_debugger \
   { sp -= 4; \
     sp[0] = accu; sp[1] = (value)(pc - 1); \
     sp[2] = env; sp[3] = Val_long(extra_args); \
     Caml_state->extern_sp = sp; }
#define Restore_after_debugger \
   { CAMLassert(sp == Caml_state->extern_sp); \
     CAMLassert(sp[0] == accu); \
     CAMLassert(sp[2] == env); \
     sp += 4; }

#ifdef THREADED_CODE
#define Restart_curr_instr \
  goto *((void*)(jumptbl_base + caml_debugger_saved_instruction(pc - 1)))
#else
#define Restart_curr_instr \
  curr_instr = caml_debugger_saved_instruction(pc - 1); \
  goto dispatch_instr
#endif

#define Check_trap_barrier \
  if (Caml_state->trapsp >= Caml_state->trap_barrier) \
    caml_debugger(TRAP_BARRIER, Val_unit)

/* Register optimization.
   Some compilers underestimate the use of the local variables representing
   the abstract machine registers, and don't put them in hardware registers,
   which slows down the interpreter considerably.
   For GCC, I have hand-assigned hardware registers for several architectures.
*/

#if defined(__GNUC__) && !defined(DEBUG) && !defined(__INTEL_COMPILER) \
    && !defined(__llvm__)
#ifdef __mips__
#define PC_REG asm("$16")
#define SP_REG asm("$17")
#define ACCU_REG asm("$18")
#endif
#ifdef __sparc__
#define PC_REG asm("%l0")
#define SP_REG asm("%l1")
#define ACCU_REG asm("%l2")
#endif
#ifdef __alpha__
#ifdef __CRAY__
#define PC_REG asm("r9")
#define SP_REG asm("r10")
#define ACCU_REG asm("r11")
#define JUMPTBL_BASE_REG asm("r12")
#else
#define PC_REG asm("$9")
#define SP_REG asm("$10")
#define ACCU_REG asm("$11")
#define JUMPTBL_BASE_REG asm("$12")
#endif
#endif
#ifdef __i386__
#define PC_REG asm("%esi")
#define SP_REG asm("%edi")
#define ACCU_REG
#endif
#if defined(__ppc__) || defined(__ppc64__)
#define PC_REG asm("26")
#define SP_REG asm("27")
#define ACCU_REG asm("28")
#endif
#ifdef __hppa__
#define PC_REG asm("%r18")
#define SP_REG asm("%r17")
#define ACCU_REG asm("%r16")
#endif
#ifdef __mc68000__
#define PC_REG asm("a5")
#define SP_REG asm("a4")
#define ACCU_REG asm("d7")
#endif
/* PR#4953: these specific registers not available in Thumb mode */
#if defined (__arm__) && !defined(__thumb__)
#define PC_REG asm("r6")
#define SP_REG asm("r8")
#define ACCU_REG asm("r7")
#endif
#ifdef __ia64__
#define PC_REG asm("36")
#define SP_REG asm("37")
#define ACCU_REG asm("38")
#define JUMPTBL_BASE_REG asm("39")
#endif
#ifdef __x86_64__
#define PC_REG asm("%r15")
#define SP_REG asm("%r14")
#define ACCU_REG asm("%r13")
#endif
#ifdef __aarch64__
#define PC_REG asm("%x19")
#define SP_REG asm("%x20")
#define ACCU_REG asm("%x21")
#define JUMPTBL_BASE_REG asm("%x22")
#endif
#endif

#ifdef DEBUG
static intnat caml_bcodcount;
#endif

/* The interpreter itself */

typedef value (*primitive_arity_1)(value);
typedef value (*primitive_arity_2)(value, value);
typedef value (*primitive_arity_3)(value, value, value);
typedef value (*primitive_arity_4)(value, value, value, value);
typedef value (*primitive_arity_5)(value, value, value, value, value);
typedef value (*primitive_arity_n)(value*, int);

value caml_interprete(code_t prog, asize_t prog_size)
{
#ifdef PC_REG
  register code_t pc PC_REG;
  register value * sp SP_REG;
  register value accu ACCU_REG;
#else
  register code_t pc;
  register value * sp;
  register value accu;
#endif
#if defined(THREADED_CODE) && defined(ARCH_SIXTYFOUR) && !defined(ARCH_CODE32)
#ifdef JUMPTBL_BASE_REG
  register char * jumptbl_base JUMPTBL_BASE_REG;
#else
  register char * jumptbl_base;
#endif
#endif
  value env;
  intnat extra_args;
  struct longjmp_buffer * initial_external_raise;
  struct longjmp_buffer * initial_external_raise_async;
  intnat initial_sp_offset;
  intnat initial_trapsp_offset;
  /* volatile ensures that initial_local_roots will keep correct values across
     longjmp.  The other "initial_..." variables don't need "volatile"
     because they aren't changed between the setjmp and any longjmp. */
  struct caml__roots_block * volatile initial_local_roots;
  struct longjmp_buffer raise_buf, raise_async_buf;
#ifndef THREADED_CODE
  opcode_t curr_instr;
#endif

#ifdef THREADED_CODE
  static void * jumptable[] = {
#    include "caml/jumptbl.h"
  };
#endif

  if (prog == NULL) {           /* Interpreter is initializing */
#ifdef THREADED_CODE
    caml_init_thread_code(jumptable, Jumptbl_base);
#endif
    return Val_unit;
  }

#if defined(THREADED_CODE) && defined(ARCH_SIXTYFOUR) && !defined(ARCH_CODE32)
  jumptbl_base = Jumptbl_base;
#endif
  initial_local_roots = Caml_state->local_roots;
  initial_sp_offset =
    (char *) Caml_state->stack_high - (char *) Caml_state->extern_sp;
  initial_external_raise = Caml_state->external_raise;
  initial_external_raise_async = Caml_state->external_raise_async;
  initial_trapsp_offset =
    (char *) Caml_state->stack_high - (char *) Caml_state->trapsp;

  caml_callback_depth++;

  if (sigsetjmp(raise_buf.buf, 0)) {
    Caml_state->local_roots = initial_local_roots;
    sp = Caml_state->extern_sp;
    accu = Caml_state->exn_bucket;

    Check_trap_barrier;
    if (Caml_state->backtrace_active) {
      /* pc has already been pushed on the stack when calling the C
         function that raised the exception. No need to push it again
         here. */
      caml_stash_backtrace(accu, sp, 0);
    }
    goto raise_notrace;
  }
  Caml_state->external_raise = &raise_buf;

  if (sigsetjmp(raise_async_buf.buf, 0)) {
    Caml_state->local_roots = initial_local_roots;
    sp = Caml_state->extern_sp;
    accu = Caml_state->exn_bucket;

    Check_trap_barrier;
    if (Caml_state->backtrace_active) {
      caml_stash_backtrace(accu, sp, 0);
    }

    /* Skip any exception handlers installed by this invocation of
       [caml_interprete].  This will cause the [raise_notrace] code below to
       return asynchronous exceptions to the caller, typically in
       [caml_callbackN_exn0].  When that function reraises such an exception
       then [Caml_state->trapsp] will correctly be pointing at the most
       recent prior trap. */
    Caml_state->trapsp = (value *) ((char *) Caml_state->stack_high
                                      - initial_trapsp_offset);

    goto raise_notrace;
  }
  Caml_state->external_raise_async = &raise_async_buf;

  sp = Caml_state->extern_sp;
  pc = prog;
  extra_args = 0;
  env = Atom(0);
  accu = Val_int(0);

#ifdef THREADED_CODE
#ifdef DEBUG
 next_instr:
  if (caml_icount-- == 0) caml_stop_here ();
  CAMLassert(sp >= Caml_state->stack_low);
  CAMLassert(sp <= Caml_state->stack_high);
#endif
  goto *(void *)(jumptbl_base + *pc++); /* Jump to the first instruction */
#else
  while(1) {
#ifdef DEBUG
    caml_bcodcount++;
    if (caml_icount-- == 0) caml_stop_here ();
    if (caml_trace_level>1) printf("\n##%" ARCH_INTNAT_PRINTF_FORMAT "d\n",
                                   caml_bcodcount);
    if (caml_trace_level>0) caml_disasm_instr(pc);
    if (caml_trace_level>1) {
      printf("env=");
      caml_trace_value_file(env,prog,prog_size,stdout);
      putchar('\n');
      caml_trace_accu_sp_file(accu,sp,prog,prog_size,stdout);
      fflush(stdout);
    };
    CAMLassert(sp >= Caml_state->stack_low);
    CAMLassert(sp <= Caml_state->stack_high);
#endif
    curr_instr = *pc++;

  dispatch_instr:
    switch(curr_instr) {
#endif

/* Basic stack operations */

    Instruct(ACC0):
      accu = sp[0]; Next;
    Instruct(ACC1):
      accu = sp[1]; Next;
    Instruct(ACC2):
      accu = sp[2]; Next;
    Instruct(ACC3):
      accu = sp[3]; Next;
    Instruct(ACC4):
      accu = sp[4]; Next;
    Instruct(ACC5):
      accu = sp[5]; Next;
    Instruct(ACC6):
      accu = sp[6]; Next;
    Instruct(ACC7):
      accu = sp[7]; Next;

    Instruct(PUSH): Instruct(PUSHACC0):
      *--sp = accu; Next;
    Instruct(PUSHACC1):
      *--sp = accu; accu = sp[1]; Next;
    Instruct(PUSHACC2):
      *--sp = accu; accu = sp[2]; Next;
    Instruct(PUSHACC3):
      *--sp = accu; accu = sp[3]; Next;
    Instruct(PUSHACC4):
      *--sp = accu; accu = sp[4]; Next;
    Instruct(PUSHACC5):
      *--sp = accu; accu = sp[5]; Next;
    Instruct(PUSHACC6):
      *--sp = accu; accu = sp[6]; Next;
    Instruct(PUSHACC7):
      *--sp = accu; accu = sp[7]; Next;

    Instruct(PUSHACC):
      *--sp = accu;
      /* Fallthrough */
    Instruct(ACC):
      accu = sp[*pc++];
      Next;

    Instruct(POP):
      sp += *pc++;
      Next;
    Instruct(ASSIGN):
      sp[*pc++] = accu;
      accu = Val_unit;
      Next;

/* Access in heap-allocated environment */

    Instruct(ENVACC1):
      accu = Field(env, 1); Next;
    Instruct(ENVACC2):
      accu = Field(env, 2); Next;
    Instruct(ENVACC3):
      accu = Field(env, 3); Next;
    Instruct(ENVACC4):
      accu = Field(env, 4); Next;

    Instruct(PUSHENVACC1):
      *--sp = accu; accu = Field(env, 1); Next;
    Instruct(PUSHENVACC2):
      *--sp = accu; accu = Field(env, 2); Next;
    Instruct(PUSHENVACC3):
      *--sp = accu; accu = Field(env, 3); Next;
    Instruct(PUSHENVACC4):
      *--sp = accu; accu = Field(env, 4); Next;

    Instruct(PUSHENVACC):
      *--sp = accu;
      /* Fallthrough */
    Instruct(ENVACC):
      accu = Field(env, *pc++);
      Next;

/* Function application */

    Instruct(PUSH_RETADDR): {
      sp -= 3;
      sp[0] = (value) (pc + *pc);
      sp[1] = env;
      sp[2] = Val_long(extra_args);
      pc++;
      Next;
    }
    Instruct(APPLY): {
      extra_args = *pc - 1;
      pc = Code_val(accu);
      env = accu;
      goto check_stacks;
    }
    Instruct(APPLY1): {
      value arg1 = sp[0];
      sp -= 3;
      sp[0] = arg1;
      sp[1] = (value)pc;
      sp[2] = env;
      sp[3] = Val_long(extra_args);
      pc = Code_val(accu);
      env = accu;
      extra_args = 0;
      goto check_stacks;
    }
    Instruct(APPLY2): {
      value arg1 = sp[0];
      value arg2 = sp[1];
      sp -= 3;
      sp[0] = arg1;
      sp[1] = arg2;
      sp[2] = (value)pc;
      sp[3] = env;
      sp[4] = Val_long(extra_args);
      pc = Code_val(accu);
      env = accu;
      extra_args = 1;
      goto check_stacks;
    }
    Instruct(APPLY3): {
      value arg1 = sp[0];
      value arg2 = sp[1];
      value arg3 = sp[2];
      sp -= 3;
      sp[0] = arg1;
      sp[1] = arg2;
      sp[2] = arg3;
      sp[3] = (value)pc;
      sp[4] = env;
      sp[5] = Val_long(extra_args);
      pc = Code_val(accu);
      env = accu;
      extra_args = 2;
      goto check_stacks;
    }

    Instruct(APPTERM): {
      int nargs = *pc++;
      int slotsize = *pc;
      value * newsp;
      int i;
      /* Slide the nargs bottom words of the current frame to the top
         of the frame, and discard the remainder of the frame */
      newsp = sp + slotsize - nargs;
      for (i = nargs - 1; i >= 0; i--) newsp[i] = sp[i];
      sp = newsp;
      pc = Code_val(accu);
      env = accu;
      extra_args += nargs - 1;
      goto check_stacks;
    }
    Instruct(APPTERM1): {
      value arg1 = sp[0];
      sp = sp + *pc - 1;
      sp[0] = arg1;
      pc = Code_val(accu);
      env = accu;
      goto check_stacks;
    }
    Instruct(APPTERM2): {
      value arg1 = sp[0];
      value arg2 = sp[1];
      sp = sp + *pc - 2;
      sp[0] = arg1;
      sp[1] = arg2;
      pc = Code_val(accu);
      env = accu;
      extra_args += 1;
      goto check_stacks;
    }
    Instruct(APPTERM3): {
      value arg1 = sp[0];
      value arg2 = sp[1];
      value arg3 = sp[2];
      sp = sp + *pc - 3;
      sp[0] = arg1;
      sp[1] = arg2;
      sp[2] = arg3;
      pc = Code_val(accu);
      env = accu;
      extra_args += 2;
      goto check_stacks;
    }

    Instruct(RETURN): {
      sp += *pc++;
      if (extra_args > 0) {
        extra_args--;
        pc = Code_val(accu);
        env = accu;
      } else {
        pc = (code_t)(sp[0]);
        env = sp[1];
        extra_args = Long_val(sp[2]);
        sp += 3;
      }
      Next;
    }

    Instruct(RESTART): {
      int num_args = Wosize_val(env) - 3;
      int i;
      sp -= num_args;
      for (i = 0; i < num_args; i++) sp[i] = Field(env, i + 3);
      env = Field(env, 2);
      extra_args += num_args;
      Next;
    }

    Instruct(GRAB): {
      int required = *pc++;
      if (extra_args >= required) {
        extra_args -= required;
      } else {
        mlsize_t num_args, i;
        num_args = 1 + extra_args; /* arg1 + extra args */
        Alloc_small(accu, num_args + 3, Closure_tag);
        Field(accu, 2) = env;
        for (i = 0; i < num_args; i++) Field(accu, i + 3) = sp[i];
        Code_val(accu) = pc - 3; /* Point to the preceding RESTART instr. */
        Closinfo_val(accu) = Make_closinfo(0, 2, 1);
        sp += num_args;
        pc = (code_t)(sp[0]);
        env = sp[1];
        extra_args = Long_val(sp[2]);
        sp += 3;
      }
      Next;
    }

    Instruct(CLOSURE): {
      int nvars = *pc++;
      int i;
      if (nvars > 0) *--sp = accu;
      if (nvars <= Max_young_wosize - 2) {
        /* nvars + 2 <= Max_young_wosize, can allocate in minor heap */
        Alloc_small(accu, 2 + nvars, Closure_tag);
        for (i = 0; i < nvars; i++) Field(accu, i + 2) = sp[i];
      } else {
        /* PR#6385: must allocate in major heap */
        /* caml_alloc_shr and caml_initialize never trigger a GC,
           so no need to Setup_for_gc */
        accu = caml_alloc_shr(2 + nvars, Closure_tag);
        for (i = 0; i < nvars; i++) caml_initialize(&Field(accu, i + 2), sp[i]);
      }
      /* The code pointer is not in the heap, so no need to go through
         caml_initialize. */
      Code_val(accu) = pc + *pc;
      Closinfo_val(accu) = Make_closinfo(0, 2, 1);
      pc++;
      sp += nvars;
      Next;
    }

    Instruct(CLOSUREREC): {
      int nfuncs = *pc++;
      int nvars = *pc++;
      mlsize_t envofs = nfuncs * 3 - 1;
      mlsize_t blksize = envofs + nvars;
      int i;
      value * p;
      if (nvars > 0) *--sp = accu;
      if (blksize <= Max_young_wosize) {
        Alloc_small(accu, blksize, Closure_tag);
        p = &Field(accu, envofs);
        for (i = 0; i < nvars; i++, p++) *p = sp[i];
      } else {
        /* PR#6385: must allocate in major heap */
        /* caml_alloc_shr and caml_initialize never trigger a GC,
           so no need to Setup_for_gc */
        accu = caml_alloc_shr(blksize, Closure_tag);
        p = &Field(accu, envofs);
        for (i = 0; i < nvars; i++, p++) caml_initialize(p, sp[i]);
      }
      sp += nvars;
      /* The code pointers and infix headers are not in the heap,
         so no need to go through caml_initialize. */
      *--sp = accu;
      p = &Field(accu, 0);
      *p++ = (value) (pc + pc[0]);
      *p++ = Make_closinfo(0, envofs, nfuncs < 2);
      for (i = 1; i < nfuncs; i++) {
        *p++ = Make_header(i * 3, Infix_tag, Caml_white); /* color irrelevant */
        *--sp = (value) p;
        *p++ = (value) (pc + pc[i]);
        envofs -= 3;
        CAMLassert(i <= nfuncs - 1);
        *p++ = Make_closinfo(0, envofs, i == nfuncs - 1);
      }
      pc += nfuncs;
      Next;
    }

    Instruct(PUSHOFFSETCLOSURE):
      *--sp = accu; /* fallthrough */
    Instruct(OFFSETCLOSURE):
      accu = env + *pc++ * sizeof(value); Next;

    Instruct(PUSHOFFSETCLOSUREM3):
      *--sp = accu; /* fallthrough */
    Instruct(OFFSETCLOSUREM3):
      accu = env - 3 * sizeof(value); Next;
    Instruct(PUSHOFFSETCLOSURE0):
      *--sp = accu; /* fallthrough */
    Instruct(OFFSETCLOSURE0):
      accu = env; Next;
    Instruct(PUSHOFFSETCLOSURE3):
      *--sp = accu; /* fallthrough */
    Instruct(OFFSETCLOSURE3):
      accu = env + 3 * sizeof(value); Next;


/* Access to global variables */

    Instruct(PUSHGETGLOBAL):
      *--sp = accu;
      /* Fallthrough */
    Instruct(GETGLOBAL):
      accu = Field(caml_global_data, *pc);
      pc++;
      Next;

    Instruct(PUSHGETGLOBALFIELD):
      *--sp = accu;
      /* Fallthrough */
    Instruct(GETGLOBALFIELD): {
      accu = Field(caml_global_data, *pc);
      pc++;
      accu = Field(accu, *pc);
      pc++;
      Next;
    }

    Instruct(SETGLOBAL):
      caml_modify(&Field(caml_global_data, *pc), accu);
      accu = Val_unit;
      pc++;
      Next;

/* Allocation of blocks */

    Instruct(PUSHATOM0):
      *--sp = accu;
      /* Fallthrough */
    Instruct(ATOM0):
      accu = Atom(0); Next;

    Instruct(PUSHATOM):
      *--sp = accu;
      /* Fallthrough */
    Instruct(ATOM):
      accu = Atom(*pc++); Next;

    Instruct(MAKEBLOCK): {
      mlsize_t wosize = *pc++;
      tag_t tag = *pc++;
      mlsize_t i;
      value block;
      if (wosize <= Max_young_wosize) {
        Alloc_small(block, wosize, tag);
        Field(block, 0) = accu;
        for (i = 1; i < wosize; i++) Field(block, i) = *sp++;
      } else {
        block = caml_alloc_shr(wosize, tag);
        caml_initialize(&Field(block, 0), accu);
        for (i = 1; i < wosize; i++) caml_initialize(&Field(block, i), *sp++);
      }
      accu = block;
      Next;
    }
    Instruct(MAKEBLOCK1): {
      tag_t tag = *pc++;
      value block;
      Alloc_small(block, 1, tag);
      Field(block, 0) = accu;
      accu = block;
      Next;
    }
    Instruct(MAKEBLOCK2): {
      tag_t tag = *pc++;
      value block;
      Alloc_small(block, 2, tag);
      Field(block, 0) = accu;
      Field(block, 1) = sp[0];
      sp += 1;
      accu = block;
      Next;
    }
    Instruct(MAKEBLOCK3): {
      tag_t tag = *pc++;
      value block;
      Alloc_small(block, 3, tag);
      Field(block, 0) = accu;
      Field(block, 1) = sp[0];
      Field(block, 2) = sp[1];
      sp += 2;
      accu = block;
      Next;
    }
    Instruct(MAKE_FAUX_MIXEDBLOCK): {
      mlsize_t wosize = *pc++;
      tag_t tag = *pc++;
      mlsize_t i;
      value block;
      if (wosize <= Max_young_wosize) {
        Alloc_small_with_reserved(block, wosize, tag,
                                  Faux_mixed_block_sentinel);
        Field(block, 0) = accu;
        for (i = 1; i < wosize; i++) Field(block, i) = *sp++;
      } else {
        block =
          caml_alloc_shr_reserved(wosize, tag, Faux_mixed_block_sentinel);
        caml_initialize(&Field(block, 0), accu);
        for (i = 1; i < wosize; i++) caml_initialize(&Field(block, i), *sp++);
      }
      accu = block;
      Next;
    }
    Instruct(MAKEFLOATBLOCK): {
      mlsize_t size = *pc++;
      mlsize_t i;
      value block;
      if (size <= Max_young_wosize / Double_wosize) {
        Alloc_small(block, size * Double_wosize, Double_array_tag);
      } else {
        block = caml_alloc_shr(size * Double_wosize, Double_array_tag);
      }
      Store_double_flat_field(block, 0, Double_val(accu));
      for (i = 1; i < size; i++){
        Store_double_flat_field(block, i, Double_val(*sp));
        ++ sp;
      }
      accu = block;
      Next;
    }

/* Access to components of blocks */

    Instruct(GETFIELD0):
      accu = Field(accu, 0); Next;
    Instruct(GETFIELD1):
      accu = Field(accu, 1); Next;
    Instruct(GETFIELD2):
      accu = Field(accu, 2); Next;
    Instruct(GETFIELD3):
      accu = Field(accu, 3); Next;
    Instruct(GETFIELD):
      accu = Field(accu, *pc); pc++; Next;
    Instruct(GETFLOATFIELD): {
      double d = Double_flat_field(accu, *pc++);
      Alloc_small(accu, Double_wosize, Double_tag);
      Store_double_val(accu, d);
      Next;
    }

    Instruct(SETFIELD0):
      caml_modify(&Field(accu, 0), *sp++);
      accu = Val_unit;
      Next;
    Instruct(SETFIELD1):
      caml_modify(&Field(accu, 1), *sp++);
      accu = Val_unit;
      Next;
    Instruct(SETFIELD2):
      caml_modify(&Field(accu, 2), *sp++);
      accu = Val_unit;
      Next;
    Instruct(SETFIELD3):
      caml_modify(&Field(accu, 3), *sp++);
      accu = Val_unit;
      Next;
    Instruct(SETFIELD):
      caml_modify(&Field(accu, *pc), *sp++);
      accu = Val_unit;
      pc++;
      Next;
    Instruct(SETFLOATFIELD):
      Store_double_flat_field(accu, *pc, Double_val(*sp));
      accu = Val_unit;
      sp++;
      pc++;
      Next;

/* Array operations */

    Instruct(VECTLENGTH): {
      /* Todo: when FLAT_FLOAT_ARRAY is false, this instruction should
         be split into VECTLENGTH and FLOATVECTLENGTH because we know
         statically which one it is. */
      mlsize_t size = Wosize_val(accu);
      if (Tag_val(accu) == Double_array_tag) size = size / Double_wosize;
      accu = Val_long(size);
      Next;
    }
    Instruct(GETVECTITEM):
      accu = Field(accu, Long_val(sp[0]));
      sp += 1;
      Next;
    Instruct(SETVECTITEM):
      caml_modify(&Field(accu, Long_val(sp[0])), sp[1]);
      accu = Val_unit;
      sp += 2;
      Next;

/* Bytes/String operations */
    Instruct(GETSTRINGCHAR):
    Instruct(GETBYTESCHAR):
      accu = Val_int(Byte_u(accu, Long_val(sp[0])));
      sp += 1;
      Next;
    Instruct(SETBYTESCHAR):
      Byte_u(accu, Long_val(sp[0])) = Int_val(sp[1]);
      sp += 2;
      accu = Val_unit;
      Next;

/* Branches and conditional branches */

    Instruct(BRANCH):
      pc += *pc;
      Next;
    Instruct(BRANCHIF):
      if (accu != Val_false) pc += *pc; else pc++;
      Next;
    Instruct(BRANCHIFNOT):
      if (accu == Val_false) pc += *pc; else pc++;
      Next;
    Instruct(SWITCH): {
      uint32_t sizes = *pc++;
      if (Is_block(accu)) {
        intnat index = Tag_val(accu);
        CAMLassert ((uintnat) index < (sizes >> 16));
        pc += pc[(sizes & 0xFFFF) + index];
      } else {
        intnat index = Long_val(accu);
        CAMLassert ((uintnat) index < (sizes & 0xFFFF)) ;
        pc += pc[index];
      }
      Next;
    }
    Instruct(BOOLNOT):
      accu = Val_not(accu);
      Next;

/* Exceptions */

    Instruct(PUSHTRAP):
      sp -= 4;
      Trap_pc(sp) = pc + *pc;
      Trap_link_offset(sp) = Val_long(Caml_state->trapsp - sp);
      sp[2] = env;
      sp[3] = Val_long(extra_args);
      Caml_state->trapsp = sp;
      pc++;
      Next;

    Instruct(POPTRAP):
      if (caml_something_to_do) {
        /* We must check here so that if a signal is pending and its
           handler triggers an exception, the exception is trapped
           by the current try...with, not the enclosing one. */
        pc--; /* restart the POPTRAP after processing the signal */
        goto process_actions;
      }
      Caml_state->trapsp = sp + Long_val(Trap_link_offset(sp));
      sp += 4;
      Next;

    Instruct(RAISE_NOTRACE):
      Check_trap_barrier;
      goto raise_notrace;

    Instruct(RERAISE):
      Check_trap_barrier;
      if (Caml_state->backtrace_active) {
        *--sp = (value)(pc - 1);
        caml_stash_backtrace(accu, sp, 1);
      }
      goto raise_notrace;

    Instruct(RAISE):
      Check_trap_barrier;
      if (Caml_state->backtrace_active) {
        *--sp = (value)(pc - 1);
        caml_stash_backtrace(accu, sp, 0);
      }
    raise_notrace:
      if ((char *) Caml_state->trapsp
          >= (char *) Caml_state->stack_high - initial_sp_offset) {
        Caml_state->external_raise = initial_external_raise;
        Caml_state->external_raise_async = initial_external_raise_async;
        Caml_state->extern_sp = (value *) ((char *) Caml_state->stack_high
                                    - initial_sp_offset);
        caml_callback_depth--;
        return Make_exception_result(accu);
      }
      sp = Caml_state->trapsp;
      pc = Trap_pc(sp);
      Caml_state->trapsp = sp + Long_val(Trap_link_offset(sp));
      env = sp[2];
      extra_args = Long_val(sp[3]);
      sp += 4;
      Next;

/* Stack checks */

    check_stacks:
      if (sp < Caml_state->stack_threshold) {
        Caml_state->extern_sp = sp;
        caml_realloc_stack(Stack_threshold / sizeof(value));
        sp = Caml_state->extern_sp;
      }
      /* Fall through CHECK_SIGNALS */

/* Signal handling */

    Instruct(CHECK_SIGNALS):    /* accu not preserved */
      if (caml_something_to_do) goto process_actions;
      Next;

    process_actions:
      Setup_for_event;
      caml_process_pending_actions();
      Restore_after_event;
      Next;

/* Calling C functions */

    Instruct(C_CALL1):
      Setup_for_c_call;
      accu = ((primitive_arity_1) Primitive(*pc))(accu);
      Restore_after_c_call;
      pc++;
      Next;
    Instruct(C_CALL2):
      Setup_for_c_call;
      accu = ((primitive_arity_2) Primitive(*pc))(accu, sp[2]);
      Restore_after_c_call;
      sp += 1;
      pc++;
      Next;
    Instruct(C_CALL3):
      Setup_for_c_call;
      accu = ((primitive_arity_3)Primitive(*pc))(accu, sp[2], sp[3]);
      Restore_after_c_call;
      sp += 2;
      pc++;
      Next;
    Instruct(C_CALL4):
      Setup_for_c_call;
      accu = ((primitive_arity_4) Primitive(*pc))(accu, sp[2], sp[3], sp[4]);
      Restore_after_c_call;
      sp += 3;
      pc++;
      Next;
    Instruct(C_CALL5):
      Setup_for_c_call;
      accu = ((primitive_arity_5) Primitive(*pc))(accu, sp[2], sp[3], sp[4], sp[5]);
      Restore_after_c_call;
      sp += 4;
      pc++;
      Next;
    Instruct(C_CALLN): {
      int nargs = *pc++;
      *--sp = accu;
      Setup_for_c_call;
      accu = ((primitive_arity_n) Primitive(*pc))(sp + 2, nargs);
      Restore_after_c_call;
      sp += nargs;
      pc++;
      Next;
    }

/* Integer constants */

    Instruct(CONST0):
      accu = Val_int(0); Next;
    Instruct(CONST1):
      accu = Val_int(1); Next;
    Instruct(CONST2):
      accu = Val_int(2); Next;
    Instruct(CONST3):
      accu = Val_int(3); Next;

    Instruct(PUSHCONST0):
      *--sp = accu; accu = Val_int(0); Next;
    Instruct(PUSHCONST1):
      *--sp = accu; accu = Val_int(1); Next;
    Instruct(PUSHCONST2):
      *--sp = accu; accu = Val_int(2); Next;
    Instruct(PUSHCONST3):
      *--sp = accu; accu = Val_int(3); Next;

    Instruct(PUSHCONSTINT):
      *--sp = accu;
      /* Fallthrough */
    Instruct(CONSTINT):
      accu = Val_int(*pc);
      pc++;
      Next;

/* Integer arithmetic */

    Instruct(NEGINT):
      accu = (value)(2 - (intnat)accu); Next;
    Instruct(ADDINT):
      accu = (value)((intnat) accu + (intnat) *sp++ - 1); Next;
    Instruct(SUBINT):
      accu = (value)((intnat) accu - (intnat) *sp++ + 1); Next;
    Instruct(MULINT):
      accu = Val_long(Long_val(accu) * Long_val(*sp++)); Next;

    Instruct(DIVINT): {
      intnat divisor = Long_val(*sp++);
      if (divisor == 0) { Setup_for_c_call; caml_raise_zero_divide(); }
      accu = Val_long(Long_val(accu) / divisor);
      Next;
    }
    Instruct(MODINT): {
      intnat divisor = Long_val(*sp++);
      if (divisor == 0) { Setup_for_c_call; caml_raise_zero_divide(); }
      accu = Val_long(Long_val(accu) % divisor);
      Next;
    }
    Instruct(ANDINT):
      accu = (value)((intnat) accu & (intnat) *sp++); Next;
    Instruct(ORINT):
      accu = (value)((intnat) accu | (intnat) *sp++); Next;
    Instruct(XORINT):
      accu = (value)(((intnat) accu ^ (intnat) *sp++) | 1); Next;
    Instruct(LSLINT):
      accu = (value)((((intnat) accu - 1) << Long_val(*sp++)) + 1); Next;
    Instruct(LSRINT):
      accu = (value)((((uintnat) accu) >> Long_val(*sp++)) | 1); Next;
    Instruct(ASRINT):
      accu = (value)((((intnat) accu) >> Long_val(*sp++)) | 1); Next;

#define Integer_comparison(typ,opname,tst) \
    Instruct(opname): \
      accu = Val_int((typ) accu tst (typ) *sp++); Next;

    Integer_comparison(intnat,EQ, ==)
    Integer_comparison(intnat,NEQ, !=)
    Integer_comparison(intnat,LTINT, <)
    Integer_comparison(intnat,LEINT, <=)
    Integer_comparison(intnat,GTINT, >)
    Integer_comparison(intnat,GEINT, >=)
    Integer_comparison(uintnat,ULTINT, <)
    Integer_comparison(uintnat,UGEINT, >=)

#define Integer_branch_comparison(typ,opname,tst,debug) \
    Instruct(opname): \
      if ( *pc++ tst (typ) Long_val(accu)) { \
        pc += *pc ; \
      } else { \
        pc++ ; \
      } ; Next;

    Integer_branch_comparison(intnat,BEQ, ==, "==")
    Integer_branch_comparison(intnat,BNEQ, !=, "!=")
    Integer_branch_comparison(intnat,BLTINT, <, "<")
    Integer_branch_comparison(intnat,BLEINT, <=, "<=")
    Integer_branch_comparison(intnat,BGTINT, >, ">")
    Integer_branch_comparison(intnat,BGEINT, >=, ">=")
    Integer_branch_comparison(uintnat,BULTINT, <, "<")
    Integer_branch_comparison(uintnat,BUGEINT, >=, ">=")

    Instruct(OFFSETINT):
      accu += *pc << 1;
      pc++;
      Next;
    Instruct(OFFSETREF):
      Field(accu, 0) += *pc << 1;
      accu = Val_unit;
      pc++;
      Next;
    Instruct(ISINT):
      accu = Val_long(accu & 1);
      Next;

/* Object-oriented operations */

#define Lookup(obj, lab) Field (Field (obj, 0), Int_val(lab))

    Instruct(GETMETHOD):
      accu = Lookup(sp[0], accu);
      Next;

#define CAML_METHOD_CACHE
#ifdef CAML_METHOD_CACHE
    Instruct(GETPUBMET): {
      /* accu == object, pc[0] == tag, pc[1] == cache */
      value meths = Field (accu, 0);
      value ofs;
#ifdef CAML_TEST_CACHE
      static int calls = 0, hits = 0;
      if (calls >= 10000000) {
        fprintf(stderr, "cache hit = %d%%\n", hits / 100000);
        calls = 0; hits = 0;
      }
      calls++;
#endif
      *--sp = accu;
      accu = Val_int(*pc++);
      ofs = *pc & Field(meths,1);
      if (*(value*)(((char*)&Field(meths,3)) + ofs) == accu) {
#ifdef CAML_TEST_CACHE
        hits++;
#endif
        accu = *(value*)(((char*)&Field(meths,2)) + ofs);
      }
      else
      {
        int li = 3, hi = Field(meths,0), mi;
        while (li < hi) {
          mi = ((li+hi) >> 1) | 1;
          if (accu < Field(meths,mi)) hi = mi-2;
          else li = mi;
        }
        *pc = (li-3)*sizeof(value);
        accu = Field (meths, li-1);
      }
      pc++;
      Next;
    }
#else
    Instruct(GETPUBMET):
      *--sp = accu;
      accu = Val_int(*pc);
      pc += 2;
      /* Fallthrough */
#endif
    Instruct(GETDYNMET): {
      /* accu == tag, sp[0] == object, *pc == cache */
      value meths = Field (sp[0], 0);
      int li = 3, hi = Field(meths,0), mi;
      while (li < hi) {
        mi = ((li+hi) >> 1) | 1;
        if (accu < Field(meths,mi)) hi = mi-2;
        else li = mi;
      }
      accu = Field (meths, li-1);
      Next;
    }

/* Debugging and machine control */

    Instruct(STOP):
      Caml_state->external_raise = initial_external_raise;
      Caml_state->external_raise_async = initial_external_raise_async;
      Caml_state->extern_sp = sp;
      caml_callback_depth--;
      return accu;

    Instruct(EVENT):
      if (--caml_event_count == 0) {
        Setup_for_debugger;
        caml_debugger(EVENT_COUNT, Val_unit);
        Restore_after_debugger;
      }
      Restart_curr_instr;

    Instruct(BREAK):
      Setup_for_debugger;
      caml_debugger(BREAKPOINT, Val_unit);
      Restore_after_debugger;
      Restart_curr_instr;

    Instruct(PERFORM):
    Instruct(RESUME):
    Instruct(RESUMETERM):
    Instruct(REPERFORMTERM):
      caml_fatal_error("Effect primitives not supported on runtime4");

#ifndef THREADED_CODE
    default:
#ifdef _MSC_VER
      __assume(0);
#else
      caml_fatal_error("bad opcode (%"
                           ARCH_INTNAT_PRINTF_FORMAT "x)",
                           (intnat) *(pc-1));
#endif
    }
  }
#endif
}