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| author | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 18:28:14 -0800 |
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| committer | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 18:28:14 -0800 |
| commit | f72d5de56a522ac3be03873bdde26f23a5eeeb3c (patch) | |
| tree | 4b825dc642cb6eb9a060e54bf8d69288fbee4904 /docs/java-constraints.html | |
| parent | 31e30105703263782efd450d356cd67ea01af3b7 (diff) | |
auto import from //depot/cupcake/@135843
Diffstat (limited to 'docs/java-constraints.html')
| -rw-r--r-- | docs/java-constraints.html | 1080 |
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diff --git a/docs/java-constraints.html b/docs/java-constraints.html deleted file mode 100644 index 2410a1e7f..000000000 --- a/docs/java-constraints.html +++ /dev/null @@ -1,1080 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> - -<html> - <head> - <title>Java bytecode constraints</title> - <link rel=stylesheet href="java-constraints.css"> - </head> - - <body> - <h1> - Bytecode constraints - </h1> - - <p> - From the point of view of a piece of code written in the Java - programming language or targeted in the same way to <code>.class</code> - files, the Dalvik VM aims to behave in a way - that is fully consistent with the language's definition. - That is, the code running in Dalvik will behave the same as it - would have running in any other virtual machine. This includes - verification failures. - The Dx/Dalvik system will check roughly the same - constraints that any other VM would, except as noted in the file - <a href="verifier.html">verifier.html</a>. The following table briefly - lists all Dx/Dalvik verification constraints together their analogs - from the book <i>The Java<super>TM</super> Language Specification</i>, - second edition. In the numbering scheme, the first three - elements refer to the specification chapter, the fourth one to the - bullet inside that chapter. The failure mode specifies whether the - constraint will fail during the Dx conversion or during verification in - the VM itself. - </p> - - <h2> - Static constraints - </h2> - - <p> - Static constraints are constraints on individual elements of the bytecode. - They usually can be checked without employing control or data-flow analysis - techniques. - </p> - - <table> - <tr> - <th> - Identifier - </th> - - <th> - Description - </th> - - <th> - Spec equivalent - </th> - - <th> - Failure mode - </th> - </tr> - - <tr> - <td> - A1 - </td> - - <td> - The <code>code</code> array must not be empty. - </td> - - <td> - 4.8.1.1 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A2 - </td> - - <td> - The <code>code</code> array must not be larger than 65535 bytes. - </td> - - <td> - 4.8.1.2 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A3 - </td> - - <td> - The first opcode in <code>code</code> array must have index - <code>0</code>. - </td> - - <td> - 4.8.1.3 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A4 - </td> - - <td> - The <code>code</code> array must only contain valid opcodes. - </td> - - <td> - 4.8.1.4 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A5 - </td> - - <td> - The index of instruction <code>n+1</code> must equal the index of - instruction <code>n</code> plus the length of instruction - <code>n</code>, taking into account a possible <code>wide</code> - instruction. Opcodes modified by a <code>wide</code> instruction must - not be directly reachable. - </td> - - <td> - 4.8.1.5 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A6 - </td> - - <td> - The last instruction in <code>code</code> array must end at index - <code>code_length-1</code>. - </td> - - <td> - 4.8.1.6 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A7 - </td> - - <td> - All jump and branch targets must be opcodes within the same method. - Opcodes modified by a <code>wide</code> instruction must not be - directly reachable via a jump or branch instruction. - </td> - - <td> - 4.8.1.7 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A8 - </td> - - <td> - All targets of a <code>tableswitch</code> instruction must be opcodes - within the same method. Upper and lower bounds must be consistent. - Opcodes modified by a <code>wide</code> instruction must not be - directly reachable via a <code>tableswitch</code> instruction. - </td> - - <td> - 4.8.1.8 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A9 - </td> - - <td> - All targets of a <code>lookupswitch</code> instruction must be opcodes - within the same method. Its table must be consistent and sorted - low-to-high. Opcodes modified by a <code>wide</code> instruction must - not be directly reachable via a <code>lookupswitch</code> instruction. - </td> - - <td> - 4.8.1.9 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A10 - </td> - - <td> - The operands of <code>ldc</code> and <code>ldc_w</code> instructions - must be valid indices into the constant pool. The respective entries - must be of type <code>CONSTANT_Integer</code>, - <code>CONSTANT_Float</code>, or <code>CONSTANT_String</code>. - </td> - - <td> - 4.8.1.10 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A11 - </td> - - <td> - The operands of <code>ldc2_w</code> instructions must be valid indices - into the constant pool. The respective entries must be of type - <code>CONSTANT_Long</code> or <code>CONSTANT_Double</code>. The - subsequent constant pool entry must be valid and remain unused. - </td> - - <td> - 4.8.1.11 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A12 - </td> - - <td> - The Operands of <code>get<kind></code> and - <code>put<kind></code> instructions must be valid indices into - constant pool. The respective entries must be of type - <code>CONSTANT_Fieldref</code>. - </td> - - <td> - 4.8.1.12 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A13 - </td> - - <td> - The first two operands of <code>invokevirtual</code>, - <code>invokespecial</code>, and <code>invokestatic</code> must form a - valid 16-bit index into the constant pool. The respective entries must - be of type <code>CONSTANT_Methodref</code>. - </td> - - <td> - 4.8.1.13 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A14 - </td> - - <td> - Methods whose names start with '<' must only be invoked implicitly by - the VM, not by class file code. The only exception is the instance - initializer, which may be invoked by <code>invokespecial</code>. - </td> - - <td> - 4.8.1.14 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A15 - </td> - - <td> - The first two operands of <code>invokeinterface</code> must form a - valid 16-bit index into the constant pool. The entry must be of type - <code>CONSTANT_Interface_Methodref</code>. The third operand must - specify number of local variables and the fourth operand must always - be zero. - </td> - - <td> - 4.8.1.15 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A16 - </td> - - <td> - The operands of <code>instanceof</code>, <code>checkcast</code>, - <code>new</code>, and <code>anewarray</code> instructions must - be a valid index into the constant pool. The first two operands of - <code>multianewarray</code> instruction must form a valid 16-bit index - into the constant pool. All respective entries must be of type - <code>CONSTANT_Class</code>. - </td> - - <td> - 4.8.1.16 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A17 - </td> - - <td> - The dimensions of an array created by <code>anewarray</code> - instructions must be less than <code>256</code>. - </td> - - <td> - 4.8.1.17 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A18 - </td> - - <td> - The <code>new</code> instruction must not reference array classes, - interfaces, or abstract classes. - </td> - - <td> - 4.8.1.18 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A19 - </td> - - <td> - The type referenced by a <code>multinewarray</code> instruction must - have at least as many dimensions as specified in the instruction. The - dimensions operand must not be <code>0</code> - </td> - - <td> - 4.8.1.19 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A20 - </td> - - <td> - The type referenced by a <code>newarray</code> instruction must be a - valid, non-reference type. - </td> - - <td> - 4.8.1.20 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A21 - </td> - - <td> - The index operand of instructions explicitly referencing single-width - local variables must be non-negative and smaller than - <code>max_locals</code>. - </td> - - <td> - 4.8.1.21 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A22 - </td> - - <td> - The index operand of instructions implicitly referencing single-width - local variables must be non-negative and smaller than - <code>max_locals</code>. - </td> - - <td> - 4.8.1.22 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A23 - </td> - - <td> - The index operand of instructions explicitly referencing double-width - local variables must be non-negative and smaller than - <code>max_locals-1</code>. - </td> - - <td> - 4.8.1.23 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A24 - </td> - - <td> - The index operand of instructions implicitly referencing double-width - local variables must be non-negative and smaller than - <code>max_locals-1</code>. - </td> - - <td> - 4.8.1.24 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A25 - </td> - - <td> - The index operand of <code>wide</code> instructions explicitly - referencing single-width local variables must be non-negative and - smaller than <code>max_locals</code>. - </td> - - <td> - 4.8.1.25 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - A26 - </td> - - <td> - The index operand of <code>wide</code> instructions explicitly - referencing double-width local variables must be non-negative and - smaller than <code>max_locals-1</code>. - </td> - - <td> - 4.8.1.25 - </td> - - <td> - DX - </td> - </tr> - </table> - - <h2> - Structural constraints - </h2> - - <p> - 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. - </p> - - <table> - <tr> - <th> - Identifier - </th> - - <th> - Description - </th> - - <th> - Spec equivalent - </th> - - <th> - Failure mode - </th> - </tr> - - <tr> - <td> - B1 - </td> - - <td> - The number and types of arguments (operands and local variables) must - always match the instruction. - </td> - - <td> - 4.8.2.1 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B2 - </td> - - <td> - The operand stack must have the same depth for all executions paths - leading to an instruction. - </td> - - <td> - 4.8.2.2 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B3 - </td> - - <td> - Local variable pairs must never be broken up. - </td> - - <td> - 4.8.2.3 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B4 - </td> - - <td> - A local variable (or pair) has to be assigned first before it can be - read. - </td> - - <td> - 4.8.2.4 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B5 - </td> - - <td> - The operand stack must never grow beyond <code>max_stack</code>. - </td> - - <td> - 4.8.2.5 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B6 - </td> - - <td> - The operand stack must never underflow. - </td> - - <td> - 4.8.2.6 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B7 - </td> - - <td> - An <code>invokespecial</code> instruction must only invoke an instance - initializer or a method in the current class or one of its - superclasses. - </td> - - <td> - 4.8.2.7 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B8 - </td> - - <td> - An instance initializer must only be invoked on an uninitialized - instance residing on the operand stack. - </td> - - <td> - 4.8.2.8 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B9 - </td> - - <td> - Instance methods may only be invoked on and instance fields may only - be accessed on already initialized instances. - </td> - - <td> - 4.8.2.9 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B10 - </td> - - <td> - The must be no backwards branches with uninitialized instances on the - operand stack or in local variables. There must be no code protected - by an exception handler that contains local variables with - uninitialized instances. - </td> - - <td> - 4.8.2.10 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B11 - </td> - - <td> - 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 <code>Object</code> class - in general. - </td> - - <td> - 4.8.2.11 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B12 - </td> - - <td> - All actual method arguments must be assignment-compatible with formal - arguments. - </td> - - <td> - 4.8.2.12 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B13 - </td> - - <td> - For each instance method invocation, the actual instance must be - assignment-compatible with the class or interface specified in the - instruction. - </td> - - <td> - 4.8.2.13 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B14 - </td> - - <td> - A returns instruction must match its method's return type. - </td> - - <td> - 4.8.2.14 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B15 - </td> - - <td> - 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. - </td> - - <td> - 4.8.2.15 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B16 - </td> - - <td> - The type of a value stored into a static field must be - assignment-compatible with or convertible to the field's type. - </td> - - <td> - 4.8.2.16 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B17 - </td> - - <td> - The type of a value stored into a field must be assignment-compatible - with or convertible to the field's type. - </td> - - <td> - 4.8.2.17 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B18 - </td> - - <td> - The type of every value stored into an array must be - assignment-compatible with the array's component type. - </td> - - <td> - 4.8.2.18 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B19 - </td> - - <td> - The operand of an <code>athrow</code> instruction must be - assignment-compatible with <code>java.lang.Throwable</code>. - </td> - - <td> - 4.8.2.19 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B20 - </td> - - <td> - The last reachable instruction of a method must either be a backwards - jump or branch, a return, or an <code>athrow</code> instruction. It - must not be possible to leave the <code>code</code> array at the - bottom. - </td> - - <td> - 4.8.2.20 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B21 - </td> - - <td> - Local variable values must not be used as return addresses. - </td> - - <td> - 4.8.2.21 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B22 - </td> - - <td> - There must be a single, uniquely determined return instruction per - subroutine call. - </td> - - <td> - 4.8.2.22 - </td> - - <td> - VM - </td> - </tr> - - <tr> - <td> - B23 - </td> - - <td> - Subroutine calls must not be directly or indirectly self-recursive. - </td> - - <td> - 4.8.2.23 - </td> - - <td> - DX - </td> - </tr> - - <tr> - <td> - B24 - </td> - - <td> - <code>ReturnAddress</code> instances must not be reused. If a - subroutine returns to a <code>ReturnAddress</code> further up the - stack than where its original call instruction is located, then all - <code>ReturnAddress</code> instances further down the stack must - never be used. - </td> - - <td> - 4.8.2.24 - </td> - - <td> - DX - </td> - </tr> - - </table> - </body> -</html> |