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[[ BytecodeBlocks ]] Add bytecode blocks
This patch adds the ability to write bytecode directly inside 'bytecode' blocks in LCB: bytecode ... end bytecode Labels are local to the block and can be specified by using: myLabel: Temporaries are local to the block and can be specified by using: variable myTemp Temporaries, local variables and parameters can be used as register type arguments to opcodes. Module variables, defined constants and handler identifiers can be used as the 'source' parameter for the 'fetch' opcode. Module variables can be used as the 'dest' parameter for the 'source' opcode. Handler identifiers can be used as the 'handler' parameter for the 'invoke' opcode. The bytecode information is recorded in a simple array in script-builder.cpp - including name, opcode index and opcode parameter format. The script builder APIs have been thinned down to remove specific bytecode emission functions. Instead, bytecode is emitted using EmitBytecodeInModule. The emit module of lc-compile has been updated to use this.
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‎docs/guides/LiveCode Builder Bytecode Reference.md‎

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---
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group: reference
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---
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# LiveCode Builder Bytecode Reference
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## Introduction
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The LiveCode Builder Virtual Machine is a infinite register machine with a
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high-level and verifiable bytecode.
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All bytecode runs in the context of a module instance with executing handlers
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forming a stack of activation frames. Each frame contains an array of registers,
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the first part of which are parameters followed by handler-local variables and
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bytecode block registers.
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Most bytecode operations operate directly on registers, access to module level
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definitions (handlers, constants, variables) are indirected through the fetch
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and store operations.
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Each bytecode operation has an address which can be jumped to using the jump
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operations.
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## Operations
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### Jump
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jump <label>
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The jump operation sets the address of the next instruction to execute to
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that identified by <label>.
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### Jump If False
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jump_if_false <register>, <label>
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The jump_if_true operation checks the value in <register> and jumps to <label>
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if it is 'false'.
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If is a runtime error if <register> does not contain a boolean.
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### Jump If True
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jump_if_true <register>, <label>
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The jump_if_true operation checks the value in <register> and jumps to <label>
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if it is 'true'.
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If is a runtime error if <register> does not contain a boolean.
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### Assign Constant
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assign_constant <register>, <constant>
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The assign_constant operation copies <constant> into <register>. Here <constant>
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can be the nothing literal, the true or false literal, an integer literal, a
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real literal, a string literal, a list literal or array literal.
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If <register> is typed then it is a runtime error if the type of <constant>
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does not conform to that type.
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### Assign
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assign <dst-register>, <src-register>
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The assign operation copies the value in <src-register> to <dst-register>.
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If <dst-register> is typed then it is runtime error if the type of the value
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in <src-register> does not conform to that type.
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### Return
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return [ <result-reg> ]
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The return operation exits the current handler, returning to the instruction after
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the invoke operation which created it. If present, the value in <result-reg> is
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copied as the return value. If not present then the return value will be 'nothing'.
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Additionally any values in out or inout parameters are copied back to the caller.
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If <result-reg> is not present, then the return value will be 'nothing'.
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It is a runtime error if the type of the return value does not conform to the
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return type of the current handler's signature.
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It is a runtime error if any out or inout parameters are unassigned at the point
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of return.
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### Invoke
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invoke <handler>, <result>, <arg_1>, ..., <arg_n>
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The invoke operation creates a new frame copying values from the argument registers
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for any in or inout parameters. It then starts executing the bytecode attached
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to <handler>.
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If is a runtime error if the number of arguments provided is different from the
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signature of <handler>
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If it a runtime error if for in and inout parameters, the contents of <arg_i>
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does not conform to the type of the parameter required by the signature.
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### Invoke Indirect
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invoke <handler-reg>, <result>, <arg_1>, ..., <arg_n>
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The invoke indirect operation functions identically to the invoke operation
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except that it calls the handler in <handler-reg>.
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It is a runtime error if <handler-reg> does not contain a handler value.
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### Fetch
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fetch <dst-register>, <definition>
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The fetch operation copies the value of <definition> into <dst-register>. The
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<definition> may be a variable, constant or handler. In the case of a handler,
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a handler value is created.
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It is a runtime error if the type of the value of <definition> does not conform
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to the type of <dst-register>.
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### Store
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store <src-register>, <definition>
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The store operation copies the contents of <src-register> into <definition>. The
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<definition> must be a module level variable.
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It is a runtime error if the type of the value in <src-register> does not conform
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to the type of <definition>.
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### Assign List
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assign_list <dst-reg>, <element1-reg>, ..., <elementn-reg>
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The assign_array operation builds a list value from <element1-reg> up to
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<elementn-reg>.
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It is a runtime error if the type of <dst-reg> does not conform to list.
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### Assign Array
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assign_array <dst-reg>, <key1-reg>, <value1-reg>, ..., <keyn-reg>, <valuen-reg>
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The assign_array operation builds an array value from each key value pair
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<key1-reg>, <value1-reg> up to <keyn-reg>, <valuen-reg>.
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It is a runtime error if the type of <dst-reg> does not conform to array.
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### Reset
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reset <reg>
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The reset operation performs default initialization of <reg>. If the type of
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<reg> has no default value, it reverts to unassigned.

‎docs/guides/LiveCode Builder Language Reference.md‎

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| SetStatement
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| GetStatement
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| CallStatement
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| BytecodeStatement
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There are a number of built-in statements which define control flow,
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variables, and basic variable transfer. The remaining syntax for
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> **Note:** All handlers return a value, even if it is nothing. This
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> means that calling a handler will always change **the result**.
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### Bytecode Statements
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BytecodeStatement
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: 'bytecode' SEPARATOR
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{ BytecodeOperation }
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'end'
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BytecodeOperation
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: <Label: Identifier> ':'
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| 'register' <Name: Identifier> [ 'as' <Type: Type> ]
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| <Opcode: Identifier> { BytecodeArgument , ',' }
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BytecodeArgument
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: ConstantValueExpression
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| Identifier
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The bytecode statement allows bytecode to be written directly for the LiveCode
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Builder Virtual Machine.
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Bytecode operation arguments can either be a constant expression, the name of a
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definition in current scope, the name of a register, or the name of a label in
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the current bytecode block. The exact opcodes and allowed arguments are defined
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in the LiveCode Builder Bytecode Reference.
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Labels are local to the current bytecode block, and can be used as the target
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of one of the jump instructions.
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Register definitions define a named register which is local to the current
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bytecode block. Registers are the same as handler-local variables except
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that they do not undergo default initialization.
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> **Note:** Bytecode blocks are not intended for general use and the actual
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> available operations are subject to change.
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## Expressions
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Expression

‎docs/lcb/notes/17821.md‎

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# LiveCode Builder Language
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## Bytecode Blocks
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* bytecode can now be directly written in handlers using a bytecode block:
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bytecode
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register tTemp
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assign_constant tTemp, 1
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end bytecode
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* for more details on what bytecode operations can be used see the LiveCode
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Builder Bytecode Reference
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* bytecode blocks are not for general use and the current set of bytecode
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operations are subject to change

‎libscript/include/libscript/script.h‎

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////////////////////////////////////////////////////////////////////////////////
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enum MCScriptBytecodeParameterType
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{
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// Invalid index was passed to describe
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kMCScriptBytecodeParameterTypeUnknown,
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// The parameter should be a label index
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kMCScriptBytecodeParameterTypeLabel,
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// The parameter should be a register
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kMCScriptBytecodeParameterTypeRegister,
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// The parameter should be a constant pool index
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kMCScriptBytecodeParameterTypeConstant,
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// The parameter should be a fetchable definition (variable, constant, handler)
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kMCScriptBytecodeParameterTypeDefinition,
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// The parameter should be a variable definition
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kMCScriptBytecodeParameterTypeVariable,
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// The parameter should be a handler definition
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kMCScriptBytecodeParameterTypeHandler,
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};
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bool MCScriptCopyBytecodeNames(MCProperListRef& r_proper_list);
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bool MCScriptLookupBytecode(const char *opname, uindex_t& r_opcode);
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const char *MCScriptDescribeBytecode(uindex_t opcode);
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MCScriptBytecodeParameterType MCScriptDescribeBytecodeParameter(uindex_t opcode, uindex_t index);
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bool MCScriptCheckBytecodeParameterCount(uindex_t opcode, uindex_t proposed_count);
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////////////////////////////////////////////////////////////////////////////////
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typedef struct MCScriptModuleBuilder *MCScriptModuleBuilderRef;
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enum MCScriptModuleKind
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void MCScriptContinueRecordTypeInModule(MCScriptModuleBuilderRef builder, MCNameRef name, uindex_t type);
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void MCScriptEndRecordTypeInModule(MCScriptModuleBuilderRef builder, uindex_t& r_new_type);
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void MCScriptAddDefinitionToModule(MCScriptModuleBuilderRef builder, uindex_t& r_index);
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void MCScriptAddDefinitionToModule(MCScriptModuleBuilderRef builder, MCScriptDefinitionKind kind, uindex_t& r_index);
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void MCScriptAddTypeToModule(MCScriptModuleBuilderRef builder, MCNameRef name, uindex_t type, uindex_t index);
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void MCScriptAddConstantToModule(MCScriptModuleBuilderRef builder, MCNameRef name, uindex_t const_idx, uindex_t index);
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void MCScriptDeferLabelForBytecodeInModule(MCScriptModuleBuilderRef builder, uindex_t& r_label);
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void MCScriptResolveLabelForBytecodeInModule(MCScriptModuleBuilderRef builder, uindex_t label);
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void MCScriptEmitJumpInModule(MCScriptModuleBuilderRef builder, uindex_t target_label);
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void MCScriptEmitJumpIfUndefinedInModule(MCScriptModuleBuilderRef builder, uindex_t value_reg, uindex_t target_label);
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void MCScriptEmitJumpIfDefinedInModule(MCScriptModuleBuilderRef builder, uindex_t value_reg, uindex_t target_label);
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void MCScriptEmitJumpIfFalseInModule(MCScriptModuleBuilderRef builder, uindex_t value_reg, uindex_t target_label);
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void MCScriptEmitJumpIfTrueInModule(MCScriptModuleBuilderRef builder, uindex_t value_reg, uindex_t target_label);
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void MCScriptEmitAssignConstantInModule(MCScriptModuleBuilderRef builder, uindex_t dst_reg, uindex_t const_idx);
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void MCScriptEmitAssignInModule(MCScriptModuleBuilderRef builder, uindex_t dst_reg, uindex_t src_reg);
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void MCScriptEmitBeginAssignListInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitContinueAssignListInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitEndAssignListInModule(MCScriptModuleBuilderRef builder);
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void MCScriptEmitBeginAssignArrayInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitContinueAssignArrayInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitEndAssignArrayInModule(MCScriptModuleBuilderRef builder);
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void MCScriptEmitReturnInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitReturnUndefinedInModule(MCScriptModuleBuilderRef builder);
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void MCScriptBeginInvokeInModule(MCScriptModuleBuilderRef builder, uindex_t handler_index, uindex_t result_reg);
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void MCScriptBeginInvokeIndirectInModule(MCScriptModuleBuilderRef builder, uindex_t handler_reg, uindex_t result_reg);
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void MCScriptContinueInvokeInModule(MCScriptModuleBuilderRef builder, uindex_t arg_reg);
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void MCScriptEndInvokeInModule(MCScriptModuleBuilderRef builder);
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void MCScriptEmitFetchInModule(MCScriptModuleBuilderRef builder, uindex_t dst_reg, uindex_t index, uindex_t level);
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void MCScriptEmitStoreInModule(MCScriptModuleBuilderRef builder, uindex_t src_reg, uindex_t index, uindex_t level);
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void MCScriptEmitResetInModule(MCScriptModuleBuilderRef builder, uindex_t reg);
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void MCScriptEmitPositionInModule(MCScriptModuleBuilderRef builder, MCNameRef file, uindex_t line);
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void MCScriptEmitBytecodeInModule(MCScriptModuleBuilderRef builder, uindex_t opcode, ...);
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void MCScriptEmitBytecodeInModuleV(MCScriptModuleBuilderRef builder, uindex_t opcode, va_list args);
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void MCScriptEmitBytecodeInModuleA(MCScriptModuleBuilderRef builder, uindex_t opcode, uindex_t *arguments, uindex_t argument_count);
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void MCScriptEmitPositionForBytecodeInModule(MCScriptModuleBuilderRef builder, MCNameRef file, uindex_t line);
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////////////////////////////////////////////////////////////////////////////////
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