Bytecode disassemby command, introduced in [Tcl 8.6.3], intended to produce machine-readable disassembly of Tcl's bytecode. The machine-readable format is a [dict].
    :   '''[tcl::unsupported::getbytecode proc''' ''procName''
    :   '''tcl::unsupported::getbytecode lambda''' ''lambdaTerm''
    :   '''tcl::unsupported::getbytecode script''' ''script''
    :   '''tcl::unsupported::getbytecode method''' ''class method''
    :   '''tcl::unsupported::getbytecode objmethod''' ''object method''
The different arguments control how the command looks up the bytecode to take apart.

!!!!!!
'''''WARNING!'''''<<br>>''The output format of this command, beyond being a dictionary, is '''not''' defined.<<br>>Future releases of Tcl may change it at any time.''
!!!!!!

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**Description of output**
***Main dictionary***
In 8.6.3, the following keys are in the dict:
   literals:   [list] of literal values
   variables:   [list] of descriptions of variables in the local variable table. Each variable is a pair, where the first element is a collection of flags (e.g., `arg` for “argument to procedure”, `scalar` for “simple non-array variable”, `temp` for “a temporary variable without name”), and the second is the name of the variable (omitted for temporaries).
   exception:   [list] of [dict]s describing the exception ranges.
   instructions:   [dict] of instructions, indexed by address (which is monotonically increasing, but not contiguous; bytecodes are not all the same). Each instruction is described by a [list] where the first element is the opcode and the subsequent elements are the arguments.
   auxiliary:   [list] of auxiliary metadata for instructions, used to store additional information for [foreach], [switch] (in jump-table form), and [dict update]. Each entry in the auxiliary metadata is represented by a dict where `name` maps to a description of what sort of metadata it is, and other elements are defined by the type.
   commands:   [list] of dicts describing the commands found in the script that caused the bytecode to be generated.
   script:   The whole Tcl script that was parsed to generate the bytecode.
   namespace:   The [namespace] that the script is bound to. (Note that [TclOO] methods mutate this.)
   stackdepth:   The depth of value stack required to evaluate the bytecode.
   exceptdepth:   The depth of exception handler stack required to evaluate the bytecode.
***Variable meaning flags***
   scalar:   This variable holds a single value.
   array:   This variable is an [array].
   link:   This variable is a link (e.g., local variable bound for [global], [variable] or [upvar]).
   arg:   This variable is an argument to the procedure or method.
   temp:   This variable is an unnamed temporary.
   resolved:   This variable is controlled by a variable resolver.
***Exception dictionary entries***
   type:   Type of exception range being described: '''loop''' or '''catch'''.
   level:   How deep in the stack of exception ranges is this one?
   from:   Instruction address at which this range starts.
   to:   Instruction address at which this range ends.
   break:   Location to jump to on `TCL_BREAK`. Only present for '''loop''' exception ranges.
   catch:   Location to jump to on any exception (''including'' both `TCL_BREAK` and `TCL_CONTINUE`). Only present for '''catch''' exception ranges.
   continue:   Location to jump to on `TCL_CONTINUE`. Only present for '''loop''' exception ranges.
***Argument meaning flags***
Arguments may be:
   * an immediate integer (may be an index into the exception table if the instruction is `beginCatch4`),
   * a `@` followed by an integer index into the literals list,
   * a ` %` followed by an index into the variables list,
   * a `.` followed by an immediate list index (may be end-relative),
   * a `=` followed by an index into the table of [string is] classes,
   * a `?` followed by an index into the auxiliary list, or
   * `pc ` followed by an address (for jump-like instructions).
***Auxiliary metadata types***
The first pair in the dictionary defines the `name` key, which describes the meaning of the other elements
****ForeachInfo****
Old-style foreach information. Should not normally be seen.
   data:   List of variables used to store lists being iterated over.
   loop:   Loop counter variable.
   assign:   List of lists of indices of variables to be assigned each step around the loop.
****NewForeachInfo****
   jumpOffset:   Offset of the start of the foreach loop (instruction after `foreach_start`) ''relative'' to the end of the foreach loop (`foreach_step`).
   assign:   List of lists of indices of variables to be assigned each step around the loop.
****DictUpdateInfo****
   variables:   List of indices into the variables list of variables to be written (matching order for arguments to [dict update]).
****JumptableInfo****
   mapping:   Dictionary mapping the value to match to the jump offset to use (i.e., ''relative'' to the `jumptable` instruction).
***Command dictionary entries***
   codefrom:   The index into the instructions of the start of the command.
   codeto:   The index into the instructions of the end of the command.
   scriptfrom:   The index into the script of the start of the command.
   scriptto:   The index into the script of the end of the command.
   script:   The section of script defining the command, as a string.

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**See also**
   * [tcl::unsupported::disassemble] for human-readable disassembly
<<categories>>Internals