Continuum Analytics: Documentation

# 4.3. Target information

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

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

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

## 4.3.1. Functions

`llvmlite.binding.``get_default_triple`()

  Return the default target triple LLVM is configured to produce code for, as a string. 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. An example when the default triple from `get_default_triple()` is not be suitable is 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). A string is returned 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`()

  Returns a dictionary-like object indicating the CPU features for current architecture and whether they are enabled for this CPU. The key-value pairs are the feature name as string and a boolean indicating whether the feature is available. The returned value is an instance of `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, this function will raise a `RuntimeError` exception.

`llvmlite.binding.``create_target_data`(data_layout)

  Create a `TargetData` representing the given data_layout (a string).

## 4.3.2. Classes

class `llvmlite.binding.``TargetData`

  A class providing 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 the LLVM type (as returned by `ValueRef.type`). An integer is returned.

  `get_pointee_abi_size`(type)

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

  `get_pointee_abi_alignment`(type)

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

class `llvmlite.binding.``Target`

  A class representing 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 LLVM is configured to produce code for. This is equivalent to calling `Target.from_triple(get_default_triple())`

  The following methods and attributes are available:

  `description`

    A description of the target.

  `name`

    The name of the target.

  `triple`

    The triple (a string) uniquely identifying the target, for example `"x86_64-pc-linux-gnu"`.

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

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

    Tip

    To list the available CPUs and features for a target, execute `llc -mcpu=help` on the command line.

class `llvmlite.binding.``TargetMachine`

  A class holding 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, suitable for use with the platform’s linker. A bytestring is returned.

  `set_asm_verbosity`(is_verbose)

    Set whether this target machine will emit assembly with human-readable comments describing control flow, debug information, and so on.

  `emit_assembly`(module)

    Return the compiled module‘s native assembler, as a string.

    `initialize_native_asmprinter()` must have been called first.

  `target_data`

    The `TargetData` associated with this target machine.

class `llvmlite.binding.``FeatureMap`

  For storing processor feature information in a dictionary-like object. This class extends `dict` and only adds 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 `sort` keyword argument is True (the default), the features are sorted by name to give a stable ordering between python session.