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 toTarget.create_target_machine()
.
-
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.-
add_pass
(pm)¶ Add an optimization pass based on this data layout to the
PassManager
instance pm.
-
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 callingTarget.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.
-
classmethod
-
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.
-
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()
. Ifsort
keyword argument is True (the default), the features are sorted by name to give a stable ordering between python session.
-