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[interp] Fix unboxing during CALLI
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On interp we were storing function pointers as a simple InterpMethod. The problem is that, when loading an InterpMethod with a ldvirtftn opcode, the resulting method might need to have its this pointer unboxed, so this information needs to be embedded into the function pointer. We achieve this by passing function pointers in the interpreter via an InterpFtnDesc, which contains the need_unbox information. Each InterpMethod caches the function descriptors for both unboxing scenarios.

In order to interop with llvmonly we must use a MonoFtnDesc as a function pointer so this must point to point to an InterpFtnDesc in order to resolve normal interp calls.
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@BrzVlad
BrzVlad committed Oct 6, 2021
1 parent 6ef3fe0 commit da1f8eb
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Showing 5 changed files with 75 additions and 39 deletions.
12 changes: 10 additions & 2 deletions src/mono/mono/mini/interp/interp-internals.h
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,6 @@ typedef struct InterpFrame InterpFrame;
typedef void (*MonoFuncV) (void);
typedef void (*MonoPIFunc) (void *callme, void *margs);


typedef enum {
IMETHOD_CODE_INTERP,
IMETHOD_CODE_COMPILED,
Expand All @@ -97,6 +96,7 @@ typedef enum {

#define PROFILE_INTERP 0

typedef struct InterpFtnDesc InterpFtnDesc;
/*
* Structure representing a method transformed for the interpreter
*/
Expand Down Expand Up @@ -124,7 +124,8 @@ struct InterpMethod {
MonoType *rtype;
MonoType **param_types;
MonoJitInfo *jinfo;
MonoFtnDesc *ftndesc;
InterpFtnDesc *ftndesc;
InterpFtnDesc *ftndesc_unbox;

guint32 locals_size;
guint32 alloca_size;
Expand All @@ -146,6 +147,13 @@ struct InterpMethod {
#endif
};

struct InterpFtnDesc {
InterpMethod *imethod;
gboolean need_unbox;

MonoFtnDesc *desc;
};

/* Used for localloc memory allocation */
typedef struct _FrameDataFragment FrameDataFragment;
struct _FrameDataFragment {
Expand Down
95 changes: 62 additions & 33 deletions src/mono/mono/mini/interp/interp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -508,6 +508,38 @@ mono_interp_get_imethod (MonoMethod *method, MonoError *error)
return imethod;
}

static InterpFtnDesc*
interp_get_ftndesc (InterpMethod *imethod, gboolean need_unbox)
{
InterpFtnDesc **ftndesc_p;
InterpFtnDesc *ftndesc;
if (need_unbox)
ftndesc_p = &imethod->ftndesc_unbox;
else
ftndesc_p = &imethod->ftndesc;

ftndesc = *ftndesc_p;
if (ftndesc)
return ftndesc;

MonoJitMemoryManager *jit_mm = jit_mm_for_method (imethod->method);
jit_mm_lock (jit_mm);
ftndesc = *ftndesc_p;
if (ftndesc) {
jit_mm_unlock (jit_mm);
return ftndesc;
}

ftndesc = (InterpFtnDesc*)m_method_alloc0 (imethod->method, sizeof (InterpFtnDesc));
ftndesc->imethod = imethod;
ftndesc->need_unbox = need_unbox;
*ftndesc_p = ftndesc;
jit_mm_unlock (jit_mm);

return ftndesc;
}


#if defined (MONO_CROSS_COMPILE) || defined (HOST_WASM)
#define INTERP_PUSH_LMF_WITH_CTX_BODY(ext, exit_label) \
(ext).kind = MONO_LMFEXT_INTERP_EXIT;
Expand Down Expand Up @@ -1678,10 +1710,10 @@ interp_init_delegate (MonoDelegate *del, MonoError *error)
}

/* Convert a function pointer for a managed method to an InterpMethod* */
static InterpMethod*
ftnptr_to_imethod (gpointer addr)
static InterpFtnDesc*
ftnptr_to_interp_ftndesc (gpointer addr)
{
InterpMethod *imethod;
InterpFtnDesc *interp_ftndesc;

if (mono_llvm_only) {
ERROR_DECL (error);
Expand All @@ -1690,44 +1722,45 @@ ftnptr_to_imethod (gpointer addr)
g_assert (ftndesc);
g_assert (ftndesc->method);

imethod = ftndesc->interp_method;
if (!imethod) {
imethod = mono_interp_get_imethod (ftndesc->method, error);
interp_ftndesc = ftndesc->interp_ftndesc;
if (!interp_ftndesc) {
InterpMethod *imethod = mono_interp_get_imethod (ftndesc->method, error);
interp_ftndesc = interp_get_ftndesc (imethod, FALSE);
mono_error_assert_ok (error);
mono_memory_barrier ();
ftndesc->interp_method = imethod;
ftndesc->interp_ftndesc = interp_ftndesc;
}
} else {
/* Function pointers are represented by their InterpMethod */
imethod = (InterpMethod*)addr;
/* Function pointers are represented by a InterpFtnDesc structure */
interp_ftndesc = (InterpFtnDesc*)addr;
}
return imethod;
return interp_ftndesc;
}

static gpointer
imethod_to_ftnptr (InterpMethod *imethod)
interp_ftndesc_to_ftnptr (InterpFtnDesc *interp_ftndesc)
{
if (mono_llvm_only) {
ERROR_DECL (error);
/* Function pointers are represented by a MonoFtnDesc structure */
MonoFtnDesc *ftndesc = imethod->ftndesc;
MonoFtnDesc *ftndesc = interp_ftndesc->desc;
if (!ftndesc) {
ftndesc = mini_llvmonly_load_method_ftndesc (imethod->method, FALSE, FALSE, error);
ftndesc = mini_llvmonly_load_method_ftndesc (interp_ftndesc->imethod->method, FALSE, FALSE, error);
mono_error_assert_ok (error);
mono_memory_barrier ();
imethod->ftndesc = ftndesc;
interp_ftndesc->desc = ftndesc;
}
return ftndesc;
} else {
return imethod;
return interp_ftndesc;
}
}

static void
interp_delegate_ctor (MonoObjectHandle this_obj, MonoObjectHandle target, gpointer addr, MonoError *error)
{
/* addr is the result of an LDFTN opcode */
InterpMethod *imethod = ftnptr_to_imethod (addr);
InterpMethod *imethod = ftnptr_to_interp_ftndesc (addr)->imethod;

if (!(imethod->method->flags & METHOD_ATTRIBUTE_STATIC)) {
MonoMethod *invoke = mono_get_delegate_invoke_internal (mono_handle_class (this_obj));
Expand Down Expand Up @@ -3484,12 +3517,11 @@ interp_exec_method (InterpFrame *frame, ThreadContext *context, FrameClauseArgs
goto call;
}
MINT_IN_CASE(MINT_CALLI) {
MonoMethodSignature *csignature;

csignature = (MonoMethodSignature*)frame->imethod->data_items [ip [4]];
InterpFtnDesc *ftndesc;

/* In mixed mode, stay in the interpreter for simplicity even if there is an AOT version of the callee */
cmethod = ftnptr_to_imethod (LOCAL_VAR (ip [2], gpointer));
ftndesc = ftnptr_to_interp_ftndesc (LOCAL_VAR (ip [2], gpointer));
cmethod = ftndesc->imethod;

if (cmethod->method->flags & METHOD_ATTRIBUTE_PINVOKE_IMPL) {
cmethod = mono_interp_get_imethod (mono_marshal_get_native_wrapper (cmethod->method, FALSE, FALSE), error);
Expand All @@ -3499,15 +3531,11 @@ interp_exec_method (InterpFrame *frame, ThreadContext *context, FrameClauseArgs
return_offset = ip [1];
call_args_offset = ip [3];

if (csignature->hasthis) {
if (ftndesc->need_unbox) {
MonoObject *this_arg = LOCAL_VAR (call_args_offset, MonoObject*);

if (m_class_is_valuetype (this_arg->vtable->klass)) {
gpointer unboxed = mono_object_unbox_internal (this_arg);
LOCAL_VAR (call_args_offset, gpointer) = unboxed;
}
LOCAL_VAR (call_args_offset, gpointer) = mono_object_unbox_internal (this_arg);
}
ip += 5;
ip += 4;

goto call;
}
Expand Down Expand Up @@ -6508,17 +6536,18 @@ MINT_IN_CASE(MINT_BRTRUE_I8_SP) ZEROP_SP(gint64, !=); MINT_IN_BREAK;
MINT_IN_CASE(MINT_LDFTN) {
InterpMethod *m = (InterpMethod*)frame->imethod->data_items [ip [2]];

LOCAL_VAR (ip [1], gpointer) = imethod_to_ftnptr (m);
LOCAL_VAR (ip [1], gpointer) = interp_ftndesc_to_ftnptr (interp_get_ftndesc (m, FALSE));
ip += 3;
MINT_IN_BREAK;
}
MINT_IN_CASE(MINT_LDVIRTFTN) {
InterpMethod *m = (InterpMethod*)frame->imethod->data_items [ip [3]];
InterpMethod *virtual_method = (InterpMethod*)frame->imethod->data_items [ip [3]];
MonoObject *o = LOCAL_VAR (ip [2], MonoObject*);
NULL_CHECK (o);

m = get_virtual_method (m, o->vtable);
LOCAL_VAR (ip [1], gpointer) = imethod_to_ftnptr (m);
InterpMethod *res_method = get_virtual_method (virtual_method, o->vtable);
gboolean need_unbox = m_class_is_valuetype (res_method->method->klass) && !m_class_is_valuetype (virtual_method->method->klass);
LOCAL_VAR (ip [1], gpointer) = interp_ftndesc_to_ftnptr (interp_get_ftndesc (res_method, need_unbox));
ip += 4;
MINT_IN_BREAK;
}
Expand All @@ -6529,7 +6558,7 @@ MINT_IN_CASE(MINT_BRTRUE_I8_SP) ZEROP_SP(gint64, !=); MINT_IN_BREAK;

InterpMethod *m = mono_interp_get_imethod (cmethod, error);
mono_error_assert_ok (error);
LOCAL_VAR (ip [1], gpointer) = imethod_to_ftnptr (m);
LOCAL_VAR (ip [1], gpointer) = interp_ftndesc_to_ftnptr (interp_get_ftndesc (m, FALSE));
ip += 3;
MINT_IN_BREAK;
}
Expand Down Expand Up @@ -6711,7 +6740,7 @@ MINT_IN_CASE(MINT_BRTRUE_I8_SP) ZEROP_SP(gint64, !=); MINT_IN_BREAK;
mono_error_assert_ok (error);
}
g_assert (del->interp_method);
LOCAL_VAR (ip [1], gpointer) = imethod_to_ftnptr (del->interp_method);
LOCAL_VAR (ip [1], gpointer) = interp_ftndesc_to_ftnptr (interp_get_ftndesc (del->interp_method, FALSE));
ip += 3;
MINT_IN_BREAK;
}
Expand Down
2 changes: 1 addition & 1 deletion src/mono/mono/mini/interp/mintops.def
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Original file line number Diff line number Diff line change
Expand Up @@ -664,7 +664,7 @@ OPDEF(MINT_CALL, "call", 4, 1, 1, MintOpMethodToken)
OPDEF(MINT_CALLVIRT, "callvirt", 4, 1, 1, MintOpMethodToken)
OPDEF(MINT_CALLVIRT_FAST, "callvirt.fast", 5, 1, 1, MintOpMethodToken)
OPDEF(MINT_CALL_DELEGATE, "call.delegate", 5, 1, 1, MintOpTwoShorts)
OPDEF(MINT_CALLI, "calli", 5, 1, 2, MintOpMethodToken)
OPDEF(MINT_CALLI, "calli", 4, 1, 2, MintOpNoArgs)
OPDEF(MINT_CALLI_NAT, "calli.nat", 8, 1, 2, MintOpMethodToken)
OPDEF(MINT_CALLI_NAT_DYNAMIC, "calli.nat.dynamic", 5, 1, 2, MintOpMethodToken)
OPDEF(MINT_CALLI_NAT_FAST, "calli.nat.fast", 7, 1, 2, MintOpMethodToken)
Expand Down
1 change: 0 additions & 1 deletion src/mono/mono/mini/interp/transform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3511,7 +3511,6 @@ interp_transform_call (TransformData *td, MonoMethod *method, MonoMethod *target
interp_add_ins (td, MINT_CALLI);
interp_ins_set_dreg (td->last_ins, dreg);
interp_ins_set_sregs2 (td->last_ins, fp_sreg, MINT_CALL_ARGS_SREG);
td->last_ins->data [0] = get_data_item_index (td, (void *)csignature);
}
} else {
InterpMethod *imethod = mono_interp_get_imethod (target_method, error);
Expand Down
4 changes: 2 additions & 2 deletions src/mono/mono/mini/mini.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1146,8 +1146,8 @@ typedef struct
gpointer addr;
gpointer arg;
MonoMethod *method;
/* InterpMethod* */
gpointer interp_method;
/* InterpFtnDesc* */
gpointer interp_ftndesc;
} MonoFtnDesc;

typedef enum {
Expand Down

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