# Target information

Target information allows you to inspect and modify aspects of the code generation, such as which CPU is targeted or what optimization level is desired.

Minimal use of this module would be to create a `TargetMachine` for later use in code generation.

EXAMPLE:

    from llvmlite import binding
    target = binding.Target.from_default_triple()
    target_machine = target.create_target_machine()

## Functions

- llvmlite.binding.get_default_triple()

    Return a string representing the default target triple that LLVM is configured to produce code for. This represents the host’s architecture and platform.

- llvmlite.binding.get_process_triple()

    Return a target triple suitable for generating code for the current process.

    EXAMPLE: The default triple from `get_default_triple()` is not suitable when LLVM is compiled for 32-bit, but the process is executing in 64-bit mode.

- llvmlite.binding.get_object_format(triple=None)

    Get the object format for the given triple string, or the default triple if `None`. Returns a string such as `"ELF"`, `"COFF"` or `"MachO"`.

- llvmlite.binding.get_host_cpu_name()

    Get the name of the host’s CPU as a string. You can use the return value with `Target.create_target_machine()`.

- llvmlite.binding.get_host_cpu_features()

    Return a dictionary-like object indicating the CPU features for the current architecture and whether they are enabled for this CPU.

    The key-value pairs contain the feature name as a string and a boolean indicating whether the feature is available.

    The returned value is an instance of the `FeatureMap` class, which adds a new method `.flatten()` for returning a string suitable for use as the `features` argument to `Target.create_target_machine()`.

    If LLVM has not implemented this feature or it fails to get the information, a `RuntimeError` exception is raised.

- llvmlite.binding.create_target_data(data_layout)

    Create a `TargetData` representing the given data_layout string.

## Classes

class llvmlite.binding.TargetData

  Provides functionality around a given data layout. It specifies how the different types are to be represented in memory. Use `create_target_data()` to instantiate.

  - get_abi_size(type)

      Get the ABI-mandated size of a `TypeRef` object. Returns an integer.

  - get_abi_alignment(type)

      Similar to `get_abi_size()`, but returns the ABI-mandated alignment rather that the ABI size.

  - get_pointee_abi_size(type)

      Similar to `get_abi_size()`, but assumes that type is an LLVM pointer type and returns the ABI-mandated size of the type pointed to. This is useful for a global variable, whose type is really a pointer to the declared type.

  - get_pointee_abi_alignment(type)

      Similar to `get_pointee_abi_size()`, but returns the ABI-mandated alignment rather than the ABI size.

  - get_element_offset(type, position)

      Computes the byte offset of the struct element at position.

class llvmlite.binding.Target

  Represents a compilation target. The following factories are provided:

  - classmethod from_triple(triple)

      Create a new `Target` instance for the given triple string denoting the target platform.

  - classmethod from_default_triple()

      Create a new `Target` instance for the default platform that LLVM is configured to produce code for. This is equivalent to calling `Target.from_triple(get_default_triple())`.

  The following attributes and methods are available:

  - description

      A description of the target.

  - name

      The name of the target.

  - triple

      A string that uniquely identifies the target.

      EXAMPLE: `"x86_64-pc-linux-gnu"`

  - create_target_machine(cpu='', features='', opt=2, reloc='default', codemodel='jitdefault', abiname='')

      Create a new `TargetMachine` instance for this target and with the given options:

      - cpu is an optional CPU name to specialize for.

      - features is a comma-separated list of target-specific features to enable or disable.

      - opt is the optimization level, from 0 to 3.

      - reloc is the relocation model.

      - codemodel is the code model.

      - abiname is the name of the ABI.

      The defaults for reloc and codemodel are appropriate for JIT compilation.

      TIP: To list the available CPUs and features for a target, run the command `llc -mcpu=help`.

class llvmlite.binding.TargetMachine

  Holds all the settings necessary for proper code generation, including target information and compiler options. Instantiate using `Target.create_target_machine()`.

  - add_analysis_passes(pm)

      Register analysis passes for this target machine with the `PassManager` instance pm.

  - emit_object(module)

      Represent the compiled module—a `ModuleRef` instance—as a code object that is suitable for use with the platform’s linker. Returns a bytestring.

  - set_asm_verbosity(is_verbose)

      Set whether this target machine emits assembly with human-readable comments, such as those describing control flow or debug information.

  - emit_assembly(module)

      Return a string representing the compiled module’s native assembler. You must first call `initialize_native_asmprinter()`.

  - target_data

      The `TargetData` associated with this target machine.

class llvmlite.binding.FeatureMap

  Stores processor feature information in a dictionary-like object. This class extends `dict` and adds only the `.flatten()` method.

  flatten(sort=True)

    Returns a string representation of the stored information that is suitable for use in the `features` argument of `Target.create_target_machine()`.

    If the `sort` keyword argument is `True`—the default—the features are sorted by name to give a stable ordering between Python sessions.