}
}
+void
+mono_x86_patch (unsigned char* code, gpointer target)
+{
+ x86_patch (code, (unsigned char*)target);
+}
typedef enum {
ArgInIReg,
guint32 freg_usage;
gboolean need_stack_align;
guint32 stack_align_amount;
+ gboolean vtype_retaddr;
+ /* The index of the vret arg in the argument list */
+ int vret_arg_index;
ArgInfo ret;
ArgInfo sig_cookie;
ArgInfo args [1];
static CallInfo*
get_call_info_internal (MonoGenericSharingContext *gsctx, CallInfo *cinfo, MonoMethodSignature *sig, gboolean is_pinvoke)
{
- guint32 i, gr, fr;
+ guint32 i, gr, fr, pstart;
MonoType *ret_type;
int n = sig->hasthis + sig->param_count;
guint32 stack_size = 0;
guint32 tmp_gr = 0, tmp_fr = 0, tmp_stacksize = 0;
add_valuetype (gsctx, sig, &cinfo->ret, sig->ret, TRUE, &tmp_gr, &tmp_fr, &tmp_stacksize);
- if (cinfo->ret.storage == ArgOnStack)
+ if (cinfo->ret.storage == ArgOnStack) {
+ cinfo->vtype_retaddr = TRUE;
/* The caller passes the address where the value is stored */
- add_general (&gr, &stack_size, &cinfo->ret);
+ }
break;
}
case MONO_TYPE_TYPEDBYREF:
- /* Same as a valuetype with size 24 */
- add_general (&gr, &stack_size, &cinfo->ret);
- ;
+ /* Same as a valuetype with size 12 */
+ cinfo->vtype_retaddr = TRUE;
break;
case MONO_TYPE_VOID:
cinfo->ret.storage = ArgNone;
}
}
- /* this */
- if (sig->hasthis)
- add_general (&gr, &stack_size, cinfo->args + 0);
+ pstart = 0;
+ /*
+ * To simplify get_this_arg_reg () and LLVM integration, emit the vret arg after
+ * the first argument, allowing 'this' to be always passed in the first arg reg.
+ * Also do this if the first argument is a reference type, since virtual calls
+ * are sometimes made using calli without sig->hasthis set, like in the delegate
+ * invoke wrappers.
+ */
+ if (cinfo->vtype_retaddr && !is_pinvoke && (sig->hasthis || (sig->param_count > 0 && MONO_TYPE_IS_REFERENCE (sig->params [0])))) {
+ if (sig->hasthis) {
+ add_general (&gr, &stack_size, cinfo->args + 0);
+ } else {
+ add_general (&gr, &stack_size, &cinfo->args [sig->hasthis + 0]);
+ pstart = 1;
+ }
+ add_general (&gr, &stack_size, &cinfo->ret);
+ cinfo->vret_arg_index = 1;
+ } else {
+ /* this */
+ if (sig->hasthis)
+ add_general (&gr, &stack_size, cinfo->args + 0);
+
+ if (cinfo->vtype_retaddr)
+ add_general (&gr, &stack_size, &cinfo->ret);
+ }
if (!sig->pinvoke && (sig->call_convention == MONO_CALL_VARARG) && (n == 0)) {
gr = PARAM_REGS;
add_general (&gr, &stack_size, &cinfo->sig_cookie);
}
- for (i = 0; i < sig->param_count; ++i) {
+ for (i = pstart; i < sig->param_count; ++i) {
ArgInfo *ainfo = &cinfo->args [sig->hasthis + i];
MonoType *ptype;
cinfo = get_call_info_internal (NULL, cinfo, csig, FALSE);
- if (MONO_TYPE_ISSTRUCT (csig->ret) && (cinfo->ret.storage == ArgOnStack)) {
+ arg_info [0].offset = offset;
+
+ if (csig->hasthis) {
args_size += sizeof (gpointer);
offset += 4;
}
- arg_info [0].offset = offset;
-
- if (csig->hasthis) {
+ if (MONO_TYPE_ISSTRUCT (csig->ret) && (cinfo->ret.storage == ArgOnStack)) {
args_size += sizeof (gpointer);
offset += 4;
}
ss_trigger_page = mono_valloc (NULL, mono_pagesize (), MONO_MMAP_READ);
bp_trigger_page = mono_valloc (NULL, mono_pagesize (), MONO_MMAP_READ|MONO_MMAP_32BIT);
mono_mprotect (bp_trigger_page, mono_pagesize (), 0);
+
+ mono_aot_register_jit_icall ("mono_x86_throw_exception", mono_x86_throw_exception);
+ mono_aot_register_jit_icall ("mono_x86_throw_corlib_exception", mono_x86_throw_corlib_exception);
}
/*
guint32 opts = 0;
*exclude_mask = 0;
+
+ if (mono_aot_only)
+ /* The cpuid function allocates from the global codeman */
+ return opts;
+
/* Feature Flags function, flags returned in EDX. */
if (cpuid (1, &eax, &ebx, &ecx, &edx)) {
if (edx & (1 << 15)) {
int eax, ebx, ecx, edx;
guint32 sse_opts = 0;
+ if (mono_aot_only)
+ /* The cpuid function allocates from the global codeman */
+ return sse_opts;
+
if (cpuid (1, &eax, &ebx, &ecx, &edx)) {
if (edx & (1 << 25))
- sse_opts |= 1 << SIMD_VERSION_SSE1;
+ sse_opts |= SIMD_VERSION_SSE1;
if (edx & (1 << 26))
- sse_opts |= 1 << SIMD_VERSION_SSE2;
+ sse_opts |= SIMD_VERSION_SSE2;
if (ecx & (1 << 0))
- sse_opts |= 1 << SIMD_VERSION_SSE3;
+ sse_opts |= SIMD_VERSION_SSE3;
if (ecx & (1 << 9))
- sse_opts |= 1 << SIMD_VERSION_SSSE3;
+ sse_opts |= SIMD_VERSION_SSSE3;
if (ecx & (1 << 19))
- sse_opts |= 1 << SIMD_VERSION_SSE41;
+ sse_opts |= SIMD_VERSION_SSE41;
if (ecx & (1 << 20))
- sse_opts |= 1 << SIMD_VERSION_SSE42;
+ sse_opts |= SIMD_VERSION_SSE42;
}
/* Yes, all this needs to be done to check for sse4a.
if ((((unsigned int) eax) >= 0x80000001) && (ebx == 0x68747541) && (ecx == 0x444D4163) && (edx == 0x69746E65)) {
cpuid (0x80000001, &eax, &ebx, &ecx, &edx);
if (ecx & (1 << 6))
- sse_opts |= 1 << SIMD_VERSION_SSE4a;
+ sse_opts |= SIMD_VERSION_SSE4a;
}
}
CallInfo *cinfo;
ArgInfo *ainfo;
LLVMCallInfo *linfo;
+ MonoType *t;
n = sig->param_count + sig->hasthis;
if (MONO_TYPE_ISSTRUCT (sig->ret) && cinfo->ret.storage == ArgInIReg) {
/* Vtype returned using a hidden argument */
linfo->ret.storage = LLVMArgVtypeRetAddr;
+ linfo->vret_arg_index = cinfo->vret_arg_index;
}
if (MONO_TYPE_ISSTRUCT (sig->ret) && cinfo->ret.storage != ArgInIReg) {
for (i = 0; i < n; ++i) {
ainfo = cinfo->args + i;
+ if (i >= sig->hasthis)
+ t = sig->params [i - sig->hasthis];
+ else
+ t = &mono_defaults.int_class->byval_arg;
+
linfo->args [i].storage = LLVMArgNone;
switch (ainfo->storage) {
linfo->args [i].storage = LLVMArgInFPReg;
break;
case ArgOnStack:
- if ((i >= sig->hasthis) && (MONO_TYPE_ISSTRUCT(sig->params [i - sig->hasthis]))) {
- linfo->args [i].storage = LLVMArgVtypeByVal;
+ if (MONO_TYPE_ISSTRUCT (t)) {
+ if (mono_class_value_size (mono_class_from_mono_type (t), NULL) == 0)
+ /* LLVM seems to allocate argument space for empty structures too */
+ linfo->args [i].storage = LLVMArgNone;
+ else
+ linfo->args [i].storage = LLVMArgVtypeByVal;
} else {
linfo->args [i].storage = LLVMArgInIReg;
- if (!sig->params [i - sig->hasthis]->byref) {
- if (sig->params [i - sig->hasthis]->type == MONO_TYPE_R4) {
+ if (t->byref) {
+ if (t->type == MONO_TYPE_R4)
linfo->args [i].storage = LLVMArgInFPReg;
- } else if (sig->params [i - sig->hasthis]->type == MONO_TYPE_R8) {
+ else if (t->type == MONO_TYPE_R8)
linfo->args [i].storage = LLVMArgInFPReg;
- }
}
}
break;
ArgInfo *ainfo = cinfo->args + i;
MonoType *t;
+ if (cinfo->vtype_retaddr && cinfo->vret_arg_index == 1 && i == 0) {
+ /* Push the vret arg before the first argument */
+ MonoInst *vtarg;
+ MONO_INST_NEW (cfg, vtarg, OP_X86_PUSH);
+ vtarg->type = STACK_MP;
+ vtarg->sreg1 = call->vret_var->dreg;
+ MONO_ADD_INS (cfg->cbb, vtarg);
+ }
+
if (i >= sig->hasthis)
t = sig->params [i - sig->hasthis];
else
MONO_ADD_INS (cfg->cbb, vtarg);
mono_call_inst_add_outarg_reg (cfg, call, vtarg->dreg, cinfo->ret.reg, FALSE);
- } else {
+ } else if (cinfo->vtype_retaddr && cinfo->vret_arg_index == 0) {
MonoInst *vtarg;
MONO_INST_NEW (cfg, vtarg, OP_X86_PUSH);
vtarg->type = STACK_MP;
return code;
}
+gboolean
+mono_x86_have_tls_get (void)
+{
+#ifdef __APPLE__
+ guint32 *ins = (guint32*)pthread_getspecific;
+ /*
+ * We're looking for these two instructions:
+ *
+ * mov 0x4(%esp),%eax
+ * mov %gs:0x48(,%eax,4),%eax
+ */
+ return ins [0] == 0x0424448b && ins [1] == 0x85048b65 && ins [2] == 0x00000048;
+#else
+ return TRUE;
+#endif
+}
+
/*
* mono_x86_emit_tls_get:
* @code: buffer to store code to
guint8*
mono_x86_emit_tls_get (guint8* code, int dreg, int tls_offset)
{
-#ifdef TARGET_WIN32
+#if defined(__APPLE__)
+ x86_prefix (code, X86_GS_PREFIX);
+ x86_mov_reg_mem (code, dreg, 0x48 + tls_offset * 4, 4);
+#elif defined(TARGET_WIN32)
/*
* See the Under the Hood article in the May 1996 issue of Microsoft Systems
* Journal and/or a disassembly of the TlsGet () function.
x86_mov_reg_imm (code, ins->dreg, 0);
break;
case OP_LOAD_GOTADDR:
- x86_call_imm (code, 0);
- /*
- * The patch needs to point to the pop, since the GOT offset needs
- * to be added to that address.
- */
- mono_add_patch_info (cfg, code - cfg->native_code, MONO_PATCH_INFO_GOT_OFFSET, NULL);
- x86_pop_reg (code, ins->dreg);
- x86_alu_reg_imm (code, X86_ADD, ins->dreg, 0xf0f0f0f0);
+ g_assert (ins->dreg == MONO_ARCH_GOT_REG);
+ code = mono_arch_emit_load_got_addr (cfg->native_code, code, cfg, NULL);
break;
case OP_GOT_ENTRY:
mono_add_patch_info (cfg, offset, (MonoJumpInfoType)ins->inst_right->inst_i1, ins->inst_right->inst_p0);
x86_alu_reg_imm (code, X86_SUB, X86_ESP, MONO_ARCH_FRAME_ALIGNMENT - 4);
mono_add_patch_info (cfg, code - cfg->native_code, MONO_PATCH_INFO_BB, ins->inst_target_bb);
x86_call_imm (code, 0);
+ mono_cfg_add_try_hole (cfg, ins->inst_eh_block, code, bb);
x86_alu_reg_imm (code, X86_ADD, X86_ESP, MONO_ARCH_FRAME_ALIGNMENT - 4);
break;
case OP_START_HANDLER: {
#endif
}
else {
- g_assert (!cfg->compile_aot);
- x86_push_imm (code, cfg->domain);
+ if (cfg->compile_aot) {
+ /*
+ * This goes before the saving of callee saved regs, so save the got reg
+ * ourselves.
+ */
+ x86_push_reg (code, MONO_ARCH_GOT_REG);
+ code = mono_arch_emit_load_got_addr (cfg->native_code, code, cfg, NULL);
+ x86_push_imm (code, 0);
+ } else {
+ x86_push_imm (code, cfg->domain);
+ }
code = emit_call (cfg, code, MONO_PATCH_INFO_INTERNAL_METHOD, (gpointer)"mono_jit_thread_attach");
x86_alu_reg_imm (code, X86_ADD, X86_ESP, 4);
+ if (cfg->compile_aot)
+ x86_pop_reg (code, MONO_ARCH_GOT_REG);
}
}
if (method->save_lmf) {
pos += sizeof (MonoLMF);
- if (cfg->compile_aot)
- cfg->disable_aot = TRUE;
-
/* save the current IP */
- mono_add_patch_info (cfg, code + 1 - cfg->native_code, MONO_PATCH_INFO_IP, NULL);
- x86_push_imm_template (code);
+ if (cfg->compile_aot) {
+ /* This pushes the current ip */
+ x86_call_imm (code, 0);
+ } else {
+ mono_add_patch_info (cfg, code + 1 - cfg->native_code, MONO_PATCH_INFO_IP, NULL);
+ x86_push_imm_template (code);
+ }
cfa_offset += sizeof (gpointer);
/* save all caller saved regs */
x86_alu_reg_imm (code, X86_ADD, X86_EAX, G_STRUCT_OFFSET (MonoJitTlsData, lmf));
#endif
} else {
+ if (cfg->compile_aot)
+ code = mono_arch_emit_load_got_addr (cfg->native_code, code, cfg, NULL);
code = emit_call (cfg, code, MONO_PATCH_INFO_INTERNAL_METHOD, (gpointer)"mono_get_lmf_addr");
}
return (MonoVTable*) regs [MONO_ARCH_RGCTX_REG];
}
+GSList*
+mono_arch_get_cie_program (void)
+{
+ GSList *l = NULL;
+
+ mono_add_unwind_op_def_cfa (l, (guint8*)NULL, (guint8*)NULL, X86_ESP, 4);
+ mono_add_unwind_op_offset (l, (guint8*)NULL, (guint8*)NULL, X86_NREG, -4);
+
+ return l;
+}
+
MonoInst*
mono_arch_emit_inst_for_method (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSignature *fsig, MonoInst **args)
{
guint32
mono_x86_get_this_arg_offset (MonoGenericSharingContext *gsctx, MonoMethodSignature *sig)
{
- CallInfo *cinfo = NULL;
- int offset;
-
- if (MONO_TYPE_ISSTRUCT (sig->ret)) {
- cinfo = get_call_info (gsctx, NULL, sig, FALSE);
-
- offset = cinfo->args [0].offset;
- } else {
- offset = 0;
- }
-
- return offset;
+ return 0;
}
gpointer
gpointer res;
int offset;
- /*
- * Avoid expensive calls to get_generic_context_from_code () + get_call_info
- * if possible.
- */
- if (MONO_TYPE_ISSTRUCT (sig->ret)) {
- if (!gsctx && code)
- gsctx = mono_get_generic_context_from_code (code);
- cinfo = get_call_info (gsctx, NULL, sig, FALSE);
-
- offset = cinfo->args [0].offset;
- } else {
- offset = 0;
- }
+ offset = 0;
/*
* The stack looks like:
* <other args>
* <this=delegate>
- * <possible vtype return address>
* <return addr>
* <4 pointers pushed by mono_arch_create_trampoline_code ()>
*/
#define MAX_ARCH_DELEGATE_PARAMS 10
-gpointer
-mono_arch_get_delegate_invoke_impl (MonoMethodSignature *sig, gboolean has_target)
+static gpointer
+get_delegate_invoke_impl (gboolean has_target, guint32 param_count, guint32 *code_len)
{
guint8 *code, *start;
- if (sig->param_count > MAX_ARCH_DELEGATE_PARAMS)
- return NULL;
-
- /* FIXME: Support more cases */
- if (MONO_TYPE_ISSTRUCT (sig->ret))
- return NULL;
-
/*
* The stack contains:
* <delegate>
*/
if (has_target) {
- static guint8* cached = NULL;
- if (cached)
- return cached;
-
start = code = mono_global_codeman_reserve (64);
/* Replace the this argument with the target */
x86_jump_membase (code, X86_EAX, G_STRUCT_OFFSET (MonoDelegate, method_ptr));
g_assert ((code - start) < 64);
-
- mono_debug_add_delegate_trampoline (start, code - start);
-
- mono_memory_barrier ();
-
- cached = start;
} else {
- static guint8* cache [MAX_ARCH_DELEGATE_PARAMS + 1] = {NULL};
int i = 0;
/* 8 for mov_reg and jump, plus 8 for each parameter */
- int code_reserve = 8 + (sig->param_count * 8);
-
- for (i = 0; i < sig->param_count; ++i)
- if (!mono_is_regsize_var (sig->params [i]))
- return NULL;
-
- code = cache [sig->param_count];
- if (code)
- return code;
+ int code_reserve = 8 + (param_count * 8);
/*
* The stack contains:
x86_mov_reg_membase (code, X86_ECX, X86_ESP, 4, 4);
/* move args up */
- for (i = 0; i < sig->param_count; ++i) {
+ for (i = 0; i < param_count; ++i) {
x86_mov_reg_membase (code, X86_EAX, X86_ESP, (i+2)*4, 4);
x86_mov_membase_reg (code, X86_ESP, (i+1)*4, X86_EAX, 4);
}
x86_jump_membase (code, X86_ECX, G_STRUCT_OFFSET (MonoDelegate, method_ptr));
g_assert ((code - start) < code_reserve);
+ }
+
+ mono_debug_add_delegate_trampoline (start, code - start);
+
+ if (code_len)
+ *code_len = code - start;
+
+ return start;
+}
+
+GSList*
+mono_arch_get_delegate_invoke_impls (void)
+{
+ GSList *res = NULL;
+ guint8 *code;
+ guint32 code_len;
+ int i;
+
+ code = get_delegate_invoke_impl (TRUE, 0, &code_len);
+ res = g_slist_prepend (res, mono_tramp_info_create (g_strdup ("delegate_invoke_impl_has_target"), code, code_len, NULL, NULL));
+
+ for (i = 0; i < MAX_ARCH_DELEGATE_PARAMS; ++i) {
+ code = get_delegate_invoke_impl (FALSE, i, &code_len);
+ res = g_slist_prepend (res, mono_tramp_info_create (g_strdup_printf ("delegate_invoke_impl_target_%d", i), code, code_len, NULL, NULL));
+ }
+
+ return res;
+}
+
+gpointer
+mono_arch_get_delegate_invoke_impl (MonoMethodSignature *sig, gboolean has_target)
+{
+ guint8 *code, *start;
+
+ if (sig->param_count > MAX_ARCH_DELEGATE_PARAMS)
+ return NULL;
- mono_debug_add_delegate_trampoline (start, code - start);
+ /* FIXME: Support more cases */
+ if (MONO_TYPE_ISSTRUCT (sig->ret))
+ return NULL;
+
+ /*
+ * The stack contains:
+ * <delegate>
+ * <return addr>
+ */
+
+ if (has_target) {
+ static guint8* cached = NULL;
+ if (cached)
+ return cached;
+
+ if (mono_aot_only)
+ start = mono_aot_get_trampoline ("delegate_invoke_impl_has_target");
+ else
+ start = get_delegate_invoke_impl (TRUE, 0, NULL);
+
+ mono_memory_barrier ();
+
+ cached = start;
+ } else {
+ static guint8* cache [MAX_ARCH_DELEGATE_PARAMS + 1] = {NULL};
+ int i = 0;
+
+ for (i = 0; i < sig->param_count; ++i)
+ if (!mono_is_regsize_var (sig->params [i]))
+ return NULL;
+
+ code = cache [sig->param_count];
+ if (code)
+ return code;
+
+ if (mono_aot_only) {
+ char *name = g_strdup_printf ("delegate_invoke_impl_target_%d", sig->param_count);
+ start = mono_aot_get_trampoline (name);
+ g_free (name);
+ } else {
+ start = get_delegate_invoke_impl (FALSE, sig->param_count, NULL);
+ }
mono_memory_barrier ();
#endif /* MONO_ARCH_SIMD_INTRINSICS */
}
+/*MONO_ARCH_HAVE_HANDLER_BLOCK_GUARD*/
+gpointer
+mono_arch_install_handler_block_guard (MonoJitInfo *ji, MonoJitExceptionInfo *clause, MonoContext *ctx, gpointer new_value)
+{
+ int offset;
+ gpointer *sp, old_value;
+ char *bp;
+ const unsigned char *handler;
+
+ /*Decode the first instruction to figure out where did we store the spvar*/
+ /*Our jit MUST generate the following:
+ mov %esp, -?(%ebp)
+ Which is encoded as: 0x89 mod_rm.
+ mod_rm (esp, ebp, imm) which can be: (imm will never be zero)
+ mod (reg + imm8): 01 reg(esp): 100 rm(ebp): 101 -> 01100101 (0x65)
+ mod (reg + imm32): 10 reg(esp): 100 rm(ebp): 101 -> 10100101 (0xA5)
+ */
+ handler = clause->handler_start;
+
+ if (*handler != 0x89)
+ return NULL;
+
+ ++handler;
+
+ if (*handler == 0x65)
+ offset = *(signed char*)(handler + 1);
+ else if (*handler == 0xA5)
+ offset = *(int*)(handler + 1);
+ else
+ return NULL;
+
+ /*Load the spvar*/
+ bp = MONO_CONTEXT_GET_BP (ctx);
+ sp = *(gpointer*)(bp + offset);
+
+ old_value = *sp;
+ if (old_value < ji->code_start || (char*)old_value > ((char*)ji->code_start + ji->code_size))
+ return old_value;
+
+ *sp = new_value;
+
+ return old_value;
+}
+
+/*
+ * mono_aot_emit_load_got_addr:
+ *
+ * Emit code to load the got address.
+ * On x86, the result is placed into EBX.
+ */
+guint8*
+mono_arch_emit_load_got_addr (guint8 *start, guint8 *code, MonoCompile *cfg, MonoJumpInfo **ji)
+{
+ x86_call_imm (code, 0);
+ /*
+ * The patch needs to point to the pop, since the GOT offset needs
+ * to be added to that address.
+ */
+ if (cfg)
+ mono_add_patch_info (cfg, code - cfg->native_code, MONO_PATCH_INFO_GOT_OFFSET, NULL);
+ else
+ *ji = mono_patch_info_list_prepend (*ji, code - start, MONO_PATCH_INFO_GOT_OFFSET, NULL);
+ x86_pop_reg (code, MONO_ARCH_GOT_REG);
+ x86_alu_reg_imm (code, X86_ADD, MONO_ARCH_GOT_REG, 0xf0f0f0f0);
+
+ return code;
+}
+
+/*
+ * mono_ppc_emit_load_aotconst:
+ *
+ * Emit code to load the contents of the GOT slot identified by TRAMP_TYPE and
+ * TARGET from the mscorlib GOT in full-aot code.
+ * On x86, the GOT address is assumed to be in EBX, and the result is placed into
+ * EAX.
+ */
+guint8*
+mono_arch_emit_load_aotconst (guint8 *start, guint8 *code, MonoJumpInfo **ji, int tramp_type, gconstpointer target)
+{
+ /* Load the mscorlib got address */
+ x86_mov_reg_membase (code, X86_EAX, MONO_ARCH_GOT_REG, sizeof (gpointer), 4);
+ *ji = mono_patch_info_list_prepend (*ji, code - start, tramp_type, target);
+ /* arch_emit_got_access () patches this */
+ x86_mov_reg_membase (code, X86_EAX, X86_EAX, 0xf0f0f0f0, 4);
+
+ return code;
+}
+
+/* Can't put this into mini-x86.h */
+gpointer
+mono_x86_get_signal_exception_trampoline (MonoTrampInfo **info, gboolean aot);
+
+GSList *
+mono_arch_get_trampolines (gboolean aot)
+{
+ MonoTrampInfo *info;
+ GSList *tramps = NULL;
+
+ mono_x86_get_signal_exception_trampoline (&info, aot);
+
+ tramps = g_slist_append (tramps, info);
+
+ return tramps;
+}
+
+
#if __APPLE__
#define DBG_SIGNAL SIGBUS
#else
projects / mono.git / blobdiff