XLS Tools
An index of XLS developer tools.
bdd_stats
Constructs a binary decision diagram (BDD) using a given XLS function and prints various statistics about the BDD. BDD construction can be very slow in pathological cases and this utility is useful for identifying the underlying causes. Accepts arbitrary IR as input or a benchmark specified by name.
benchmark_main
Prints numerous metrics and other information about an XLS IR file including:
total delay, critical path, codegen information, optimization time, etc. This
tool may be run against arbitrary IR not just the fixed set of XLS benchmarks.
The output of this tool is scraped by run_benchmarks to construct a table
comparing metrics against a mint CL across the benchmark suite.
booleanify_main
Rewrites an XLS IR function in terms of its ops' fundamental AND/OR/NOT constituents, i.e., makes all operations boolean, thus it's "booleanifying" the function.
codegen_main
Lowers an XLS IR file into Verilog. Options include emitting a feedforward pipeline or a purely combinational block. Emits both a Verilog file and a module signature which includes metadata about the block. The tool does not run any XLS passes so unoptimized IR may fail if the IR contains constructs not expected by the backend.
For a detailed list of codegen options including I/O configurations, please visit the codegen options page.
delay_info_main
Dumps delay information about an XLS function including per-node delay information and critical-path.
eval_ir_main
Evaluates an XLS IR file with user-specified or random inputs. Includes features for evaluating the IR before and after optimizations which makes this tool very useful for identifying optimization bugs.
This tool accepts two [mutually exclusive] optional args,
--input_validator_expr and --input_validator_path, which allow the user to
specify an expression to "filter" potential input values to discard invalid
ones. For both, the filter must be a function, named validator, and must take
params of the same layout as the function under test. This function should
return true if the inputs are valid for the function and false otherwise.
--input_validator_expr lists the function as an inline command-line argument,
whereas --input_validator_path holds the path to a .x file containing the
validation function.
Jit Inspection Flags
eval_ir_main provides several flags which can be used to inspect the jit code
produced by our function jit. These flags all require that --use_llvm_jit=true
(the default). Currently these flags only work with xls-functions. See the
fuzzing documentation for more information about how the
information these flags reveal can be used.
This tool can also be used to generate and inspect the LLVM/ASM programs generated by the jit (for function programs). This can be used to diagnose issues found by the fuzzer.
--llvm_jit_ir_output=<file>controls where the unoptimized llvm ir for the function is saved.--llvm_jit_opt_ir_output=<file>does the same but with the IR after LLVM itself has optimized it.--llvm_jit_asm_output=<file>saves the result of converting the opt-ir into assembly for the current architecture.--llvm_jit_main_wrapper_output=<file>writes a bytecode file containing amain(int argc, char** argv)function which calls the function the jit creates. This can bellvm-linkd with thellvm_jit_ir_outputorllvm_jit_opt_ir_outputto create a program runnable byllior other llvm tools.--llvm_jit_main_wrapper_write_is_linked=true(default isfalse) makes the main wrapper call the posixwriteAPI to send the output to stdout. The data is written without any processing as a stream of bytes in the order it appears in memory. This flag is provided (and defaulted to off) because not all llvm analysis tools are always able to handle extern symbols in a reasonable way.
Note: LLVM can change significantly and bytecode is not always compatible
between versions. If possible, LLVM tools built at the same commit as the JIT
should be used to interact with the generated llvm bytecode. This can be done by
building the LLVM tools using bazel build from the XLS repo.
ir_minimizer_main
Tool for reducing IR to a minimal test case based on an external test.
ir_stats_main
Prints summary information/stats on an IR [Package] file. An example:
$ bazel-bin/xls/tools/ir_stats_main bazel-genfiles/xls/modules/fp32_add_2.ir
Package "fp32_add_2"
Function: "__float32__is_inf"
Signature: ((bits[1], bits[8], bits[23])) -> bits[1]
Nodes: 8
Function: "__float32__is_nan"
Signature: ((bits[1], bits[8], bits[23])) -> bits[1]
Nodes: 8
Function: "__fp32_add_2__fp32_add_2"
Signature: ((bits[1], bits[8], bits[23]), (bits[1], bits[8], bits[23])) -> (bits[1], bits[8], bits[23])
Nodes: 252
check_ir_equivalence
Verifies that two IR files (for example, optimized and unoptimized IR from the same source) are logically equivalent.
opt_main
Runs XLS IR through the optimization pipeline.
Standard flags include:
--top=NAME: Override/set the top function/proc. This is required if a function/proc is not already marked astopin the IR.--opt_level=NUMBER: Change the optimization level. This should be used with care as the differences between optimization levels are less defined for xls than they are in tools such asclang. Defaults to3.
Several flags which control the behavior of individual optimizations are also available. Care should be used when modifying the values of these flags.
--rm_rewrites_pb=FILE: Used to pass a proto describing the ram rewrites to be performed.--inline_procs=true|false: Whether to enable or disable inlining all procs into a single mega-proc. Defaults tofalse.--convert_array_index_to_select=NUMBER: Controls the maximum number of dimensions an array can have to allow xls to convert accesses to the array into select chains. This can have complicated impacts on the area and delay of the generated code.--use_context_narrowing_analysis=true|false: Controls whether to use contextual information to optimize range calculations. This can in some circumstances reveal additional optimization opportunities but it can be quite slow. Defaults tofalse.
Debugging/Experimenting with Optimizations
There are also several flags which are used for debugging and understanding the behavior of the standard optimization pipeline itself and the passes which make up the pipeline. These flags should mostly be used for testing and debugging purposes only.
--passes=PIPELINE_SPEC: Allows one to specify an explicit optimization pipeline to use instead of the standard one. The pipeline is specified by listing passes using their short-names. Different passes are space separated. Fixed-point combinations of passes are specified by surrounding them with square-brackets '[]'. For example, to run the pipeline 'inlining' then 'arith_simp' and 'dce' to fixed-point then 'narrowing' and a final 'dce' the flag would be set toinlining [ arith_simp dce ] narrowing dce. This can be used to test odd interactions between specific or single passes.--passes_bisect_limit=NUMBER: Tellsopt_mainto cease pipeline execution after runningNUMBERpasses. This can be used to narrow down misbehaving passes. This flag works with both custom--passespipelines and the standard pipeline.--ir_dump_path=FOLDER: Tellsopt_mainto dump files containing all the intermediate states of the optimizations IRs into files in that particular directory. Each file is named so they sort lexicographically in the order they were created. The names include the pass-number, the pass run and whether the pass made any changes to the output.--skip_passes=NAME1,NAME2,...: Tellsopt_mainto skip execution of specific named passes (specified using the short-name of the pass). This does not otherwise modify the pipeline being used and the pass is considered to have finished successfully without making any changes. Multiple passes may be passed at once separated by commas.
print_bom
Tool to calculate and print a summary of the BOM (bill of materials) elements
from ModuleSignatureProto protobuf files produced using the
--output_signature_path codegen argument.
Features include;
- Combining the data from multiple protobuf files.
- Output in fancy human readable table.
- Output machine readable CSV (common separate values) file for loading into other tools (like Google Sheets).
- Filtering output to a single value type like
BOM_KIND_ADDER.
Running the following commands;
bazel build //xls/examples/protobuf:varint_encode_sv
bazel run //xls/tools:print_bom -- --root_path $PWD/bazel-bin/xls/examples/protobuf/
should produce the following output;
Found 1 protobuf files.
* "bazel-bin/xls/examples/protobuf/varint_encode_u32.sig.textproto"
+------------------------+----------------+-------------+--------------+-------+
| Kind | Op | Input Width | Output Width | Count |
+------------------------+----------------+-------------+--------------+-------+
| BOM_KIND_COMPARISON | ne | 4 | 1 | 1 |
| | | 7 | 1 | 2 |
| | | 11 | 1 | 1 |
| | | 18 | 1 | 1 |
| | | 25 | 1 | 1 |
+------------------------+----------------+-------------+--------------+-------+
| BOM_KIND_INSIGNIFICANT | array | 8 | 40 | 1 |
| | bit_slice | 32 | 4 | 1 |
| | | 32 | 7 | 4 |
| | | 32 | 11 | 1 |
| | | 32 | 18 | 1 |
| | | 32 | 25 | 1 |
| | concat | 1 | 2 | 1 |
| | | 2 | 3 | 1 |
| | | 4 | 8 | 1 |
| | | 7 | 8 | 4 |
| | literal | 0 | 1 | 2 |
| | | 0 | 2 | 2 |
| | | 0 | 3 | 2 |
| | | 0 | 4 | 2 |
| | | 0 | 7 | 2 |
| | | 0 | 11 | 1 |
| | | 0 | 18 | 1 |
| | | 0 | 25 | 1 |
| | tuple | 40 | 43 | 1 |
+------------------------+----------------+-------------+--------------+-------+
| BOM_KIND_MISC | input_port | 0 | 32 | 1 |
| | output_port | 43 | 0 | 1 |
| | register_read | 0 | 32 | 1 |
| | | 0 | 43 | 1 |
| | register_write | 32 | 0 | 1 |
| | | 43 | 0 | 1 |
+------------------------+----------------+-------------+--------------+-------+
| BOM_KIND_SELECT | sel | 2 | 2 | 2 |
| | | 3 | 3 | 2 |
+------------------------+----------------+-------------+--------------+-------+
To save the details about the comparison operators to a machine readable CSV file you can do;
bazel run //xls/tools:print_bom -- --root_path=$PWD/bazel-bin/xls/examples/protobuf/ --output_as=csv --op_kind=BOM_KIND_COMPARISON > my.csv
which will produce a CSV file which looks like the following;
Kind,Op,Input Width,Output Width,Count
BOM_KIND_COMPARISON,ne,4,1,1
BOM_KIND_COMPARISON,ne,7,1,2
BOM_KIND_COMPARISON,ne,11,1,1
BOM_KIND_COMPARISON,ne,18,1,1
BOM_KIND_COMPARISON,ne,25,1,1
dslx/interpreter_main
Interpreter for DSLX code and test-runner.
When tests are run this also cross-checks that the conversion to IR and JIT compilation of the IR produces the same values.
$ bazel run -c opt //xls/dslx:interpreter_main -- $PWD/xls/dslx/stdlib/std.x
[ RUN UNITTEST ] sizeof_signed_test
[ OK ]
...
Note that this binary takes a command line argument --dslx_path which
indicates where the binary should search for .x files on import (i.e. an
import resolution path). Try to use this sparingly, but it is useful for
pointing at installation locations where DSLX modules have been placed.
In a Bazel environment this binary is encapsulated in
an xls_dslx_test target
dslx/prove_quickcheck_test
Command line utility for attempting to prove a quickcheck property via SMT translation. Invoke this tool as:
prove_quickcheck_main $ENTRY_FILE $QUICKCHECK_NAME
And it will attempt to prove the given quickcheck property over the entire input domain. Example:
$ bazel run -c opt //xls/dslx:prove_quickcheck_main -- $PWD/xls/dslx/stdlib/std.x convert_to_from_bools
Proven! elapsed: 115.419669ms
NOTE: Currently an error code is returned if it cannot be proven, but it does
not dump a counterexample to terminal. A temporary workaround is to use
--alsologtostderr --v=1 until that functionality is completed.
dslx_fmt
Auto-formatter for DSLX code (i.e. .x files). This is analogous to rustfmt /
clang-format.
To format a file in-place, use the -i flag:
$ bazel build -c opt //xls/dslx:dslx_fmt
$ echo 'fn f(x:u32)->u32{x}' > /tmp/my_file.x
$ ./bazel-bin/xls/dslx/dslx_fmt -i /tmp/my_file.x
$ cat /tmp/my_file.x
fn f(x: u32) -> u32 { x }
Without the -i flag the formatted result is given in the standard output from
the tool and the input file path remains unchanged.
Note: there is also a Bazel build construct to ensure files remain
auto-formatted using the latest dslx_fmt results:
load("//xls/build_rules:xls_build_defs.bzl", "xls_dslx_fmt_test")
xls_dslx_fmt_test(
name = "my_file_dslx_fmt_test",
src = "my_file.x",
)
Also see the
Bazel rule documentation for xls_dslx_fmt_test.
proto_to_dslx_main
Takes in a proto schema and a textproto instance thereof and outputs a DSLX module containing a DSLX type and constant matching both inputs, respectively.
Not all protocol buffer types map to DSLX types, so there are some restrictions or other behaviors requiring explanation:
- Only scalar and repeated fields are supported (i.e., no maps or oneofs, etc.).
- Only recursively-integral messages are supported, that is to say, a message may contain submessages, as long as all non-Message fields are integral.
- Since DSLX doesn't support variable arrays and Protocol Buffers don't
support fixed-length repeated fields. To unify this, all instances of
repeated-field-containing Messages must have the same size of their repeated
members (declared as arrays in DSLX). This size will be calculated as the
maximum size of any instance of that repeated field across all instances in
the input textproto. For example, if a message
Foohas a repeated fieldbar, and this message is present multiple times in the input textproto, say as:foo: { bar: 1 } foo: { bar: 1 bar: 2 } foo: { bar: 1 bar: 2 bar: 3 }the DSLX version of
Foowill declarebarhas a 3-element array. An accessory field,bar_count, will also be created, which will contain the number of valid entries in an actual instance ofFoo::bar.The "Fields" example in
./xls/tools/testdata/proto_to_dslx_main.*demonstrates this behavior.
repl
Allows you to interactively run various parts of the compiler, including
parsing/type checking (:reload), lowering/optimization (:ir), Verilog
codegen (:verilog [identifier]), and LLVM codegen (:llvm, not yet
implemented). You can also inspect the IR types of identifiers with :type, and
even imported identifiers can be accessed with :type foo::bar.
simulate_module_main
Runs a Verilog block emitted by XLS through a Verilog simulator. Requires both the Verilog text and the module signature which includes metadata about the block.
smtlib_emitter_main
Simple driver for Z3IrTranslator - converts a given IR function into its Z3 representation and outputs that translation as SMTLIB2.
First obtain an XLS IR file:
$ bazel build -c opt //xls/examples:tiny_adder.opt.ir
And then feed that XLS IR file into this binary:
$ bazel run -c opt //xls/tools:smtlib_emitter_main -- --ir_path \
$PWD/bazel-bin/xls/examples/tiny_adder.opt.ir
(bvadd (concat #b0 x) (concat #b0 y))
To turn it into "gate level" SMTLib, we can do a pre-pass through the
booleanify_main tool:
$ bazel run -c opt //xls/tools:booleanify_main -- --ir_path \
$PWD/bazel-bin/xls/examples/tiny_adder.opt.ir \
> /tmp/tiny_adder.boolified.ir
$ bazel run -c opt //xls/tools:smtlib_emitter_main -- \
--ir_path /tmp/tiny_adder.boolified.ir
(let ((a!1 (bvand (bvor ((_ extract 0 0) x) ((_ extract 0 0) y))
(bvnot (bvand ((_ extract 0 0) x) ((_ extract 0 0) y))))))
(let ((a!2 (bvor (bvand (bvor #b0 #b0) (bvnot (bvand #b0 #b0)))
(bvor (bvand ((_ extract 0 0) x) ((_ extract 0 0) y))
(bvand a!1 #b0))))
(a!3 (bvand (bvand (bvor #b0 #b0) (bvnot (bvand #b0 #b0)))
(bvor (bvand ((_ extract 0 0) x) ((_ extract 0 0) y))
(bvand a!1 #b0)))))
(concat (bvand a!2 (bvnot a!3))
(bvand (bvor a!1 #b0) (bvnot (bvand a!1 #b0))))))
solver
Uses a SMT solver (i.e. Z3) to prove properties of an XLS IR program from the command line. Currently the set of "predicates" that the solver supports from the command line are limited, but in theory it is capable of solving for arbitrary IR-function-specified predicates.
This can be used to uncover opportunities for optimization that were missed, or to prove equivalence of transformed representations with their original version.
cell_library_extract_formula
Parses a cell library ".lib" file and extracts boolean formulas from it that determine the functionality of cells. This is useful for LEC of the XLS IR against the post-synthesis netlist.
dslx/highlight_main
Performs terminal-based color code highlighting of a DSL file.
dslx/type_system/typecheck_main
Dumps type information that has been deduced for a given DSL file.
Development Tools
clang-tidy
For C++ development, you might need a compilation database to have good support
in your IDE. You can create the compile_commands.json by running this script.
dev_utils/make-compilation-db.sh
To run clang-tidy and create a report of things that might be worthwhile fixing, use the following script:
dev_utils/run-clang-tidy-cached.sh
(Note, this will be pretty slow on the first run, but it caches results and will only reprocess changed files in subsequent runs).
The output of the clang-tidy runs shows up in the xls_clang-tidy.out file
which is formatted just like an output from a compiler. So to quickly work with
these, you can use cat xls_clang-tidy.out as your 'compiler invocation' in
your IDE (e.g. M-x compile in emacs) and step through next-error locations as
usual.
Golden Comparison Files
To re-generate golden reference files (for all test targets that use golden reference file comparisons), run:
dev_utils/rebuild_golden_files.sh