Static constraints are constraints on individual elements of the bytecode. They usually can be checked without employing control or data-flow analysis techniques.
| Identifier | Description | Spec equivalent |
|---|---|---|
| A1 |
The insns array must not be empty.
|
4.8.1.1 |
| A2 |
The first opcode in the insns array must have index zero.
|
4.8.1.3 |
| A3 |
The insns array must only contain valid Dalvik opcodes.
|
4.8.1.4 |
| A4 |
The index of instruction n+1 must equal the index of
instruction n plus the length of instruction
n, taking into account possible operands.
|
4.8.1.5 |
| A5 |
The last instruction in the insns array must end at index
insns_size-1.
|
4.8.1.6 |
| A6 |
All goto and if-<kind> targets must
be opcodes within in the same method.
|
4.8.1.7 |
| A7 |
All targets of a packed-switch instruction must be
opcodes within in the same method. The size and the list of targets
must be consistent.
|
4.8.1.8 |
| A8 |
All targets of a sparse-switch instruction must be
opcodes within in the same method. The corresponding table must be
consistent and sorted low-to-high.
|
4.8.1.9 |
| A9 |
The B operand of the const-string and
const-string/jumbo instructions must be a valid index
into the string constant pool.
|
4.8.1.10 |
| A10 |
The C operand of the iget<kind> and
iput<kind> instructions must be a valid index into
the field constant pool. The referenced entry must represent an
instance field.
|
4.8.1.12 |
| A11 |
The C operand of the sget<kind> and
sput<kind> instructions must be a valid index into
the field constant pool. The referenced entry must represent a static
field.
|
4.8.1.12 |
| A12 |
The C operand of the invoke-virtual,
invoke-super, invoke-static instructions must be a valid index into the
method constant pool. In all cases, the referenced
method_id must belong to a class (not an interface).
|
4.8.1.13 |
| A13 |
The B operand of the invoke-virtual/range,
invoke-super/range, invoke-direct/range, and
invoke-static/range instructions must be a valid index
into the method constant pool. In all cases, the referenced
method_id must belong to a class (not an interface).
|
4.8.1.13 |
| A14 |
A method the name of which starts with a '<' must only be invoked
implicitly by the VM, not by code originating from a Dex file. The
only exception is the instance initializer, which may be invoked by
invoke-direct.
|
4.8.1.14 |
| A15 |
The C operand of the invoke-interface
instruction must be a valid index into the method constant pool. The
referenced method_id must belong to an interface (not a
class).
|
4.8.1.15 |
| A16 |
The B operand of the invoke-interface/range
instruction must be a valid index into the method constant pool.
The referenced method_id must belong to an interface (not
a class).
|
4.8.1.15 |
| A17 |
The B operand of the const-class,
check-cast, new-instance, and
filled-new-array/range instructions must be a valid index
into the type constant pool.
|
4.8.1.16 |
| A18 |
The C operand of the instance-of,
new-array, and filled-new-array
instructions must be a valid index into the type constant pool.
|
4.8.1.16 |
| A19 |
The dimensions of an array created by a new-array
instruction must be less than 256.
|
4.8.1.17 |
| A20 |
The new instruction must not refer to array classes,
interfaces, or abstract classes.
|
4.8.1.18 |
| A21 |
The type referred to by a new-array instruction must be
a valid, non-reference type.
|
4.8.1.20 |
| A22 |
All registers referred to by an instruction in a single-width
(non-pair) fashion must be valid for the current method. That is,
their indices must be non-negative and smaller than
registers_size.
|
4.8.1.21 |
| A23 |
All registers referred to by an instruction in a double-width (pair)
fashion must be valid for the current method. That is, their indices
must be non-negative and smaller than registers_size-1.
|
4.8.1.23 |
Structural constraints are constraints on relationships between several elements of the bytecode. They usually can't be checked without employing control or data-flow analysis techniques.
| Identifier | Description | Spec equivalent |
|---|---|---|
| B1 | The number and types of arguments (registers and immediate values) must always match the instruction. | 4.8.2.1 |
| B2 | Register pairs must never be broken up. | 4.8.2.3 |
| B3 | A register (or pair) has to be assigned first before it can be read. | 4.8.2.4 |
| B4 |
An invoke-direct instruction must only invoke an instance
initializer or a method in the current class or one of its
superclasses.
|
4.8.2.7 |
| B5 | An instance initializer must only be invoked on an uninitialized instance. | 4.8.2.8 |
| B6 | Instance methods may only be invoked on and instance fields may only be accessed on already initialized instances. | 4.8.2.9 |
| B7 |
A register which holds the result of a new-instance
instruction must not be used if the same
new-instance instruction is again executed before
the instance is initialized.
|
4.8.2.10 |
| B8 |
An instance initializer must call another instance initializer (same
class or superclass) before any instance members can be accessed.
Exceptions are non-inherited instance fields, which can be assigned
before calling another initializer, and the Object class
in general.
|
4.8.2.11 |
| B9 | All actual method arguments must be assignment-compatible with their respective formal arguments. | 4.8.2.12 |
| B10 | For each instance method invocation, the actual instance must be assignment-compatible with the class or interface specified in the instruction. | 4.8.2.13 |
| B11 |
A return<kind> instruction must match its
method's return type.
|
4.8.2.14 |
| B12 | When accessing protected members of a superclass, the actual type of the instance being accessed must be either the current class or one of its subclasses. | 4.8.2.15 |
| B13 | The type of a value stored into a static field must be assignment-compatible with or convertible to the field's type. | 4.8.2.16 |
| B14 | The type of a value stored into a field must be assignment-compatible with or convertible to the field's type. | 4.8.2.17 |
| B15 | The type of every value stored into an array must be assignment-compatible with the array's component type. | 4.8.2.18 |
| B16 |
The A operand of a throw instruction must
be assignment-compatible with java.lang.Throwable.
|
4.8.2.19 |
| B17 |
The last reachable instruction of a method must either be a backwards
goto or branch, a return, or a
throw instruction. It must not be possible to leave the
insns array at the bottom.
|
4.8.2.20 |
| B18 | The unassigned half of a former register pair may not be read (is considered invalid) until it has been re-assigned by some other instruction. | 4.8.2.3, 4.8.2.4 |
| B19 |
A move-result<kind> instruction must be immediately
preceded (in the insns array) by an
invoke-<kind> instruction. The only exception is
the move-result-object instruction, which may also be
preceded by a filled-new-array instruction.
|
- |
| B20 |
A move-result<kind> instruction must be immediately
preceded (in actual control flow) by a matching
return-<kind> instruction (it must not be jumped
to). The only exception is the move-result-object
instruction, which may also be preceded by a
filled-new-array instruction.
|
- |
| B21 |
A move-exception instruction must only appear as the
first instruction in an exception handler.
|
- |
| B22 |
The packed-switch-data, sparse-switch-data,
and fill-array-data pseudo-instructions must not be
reachable by control flow.
|
- |