ReleaseNotes.adoc

Bluespec Compiler (BSC) Release Notes

2022.01 Release

This release supports building and running on more systems, such as CentOS 7.9, FreeBSD, Arm-based Macs, systems with Tcl 8.5, and macOS when Tcl-Tk is installed via Homebrew.

This release also includes initial support for DPI instead of VPI (for imported C functions) and support for automatic linking with Verilator (using -vsim verilator). Feedback on both of these features is welcome!

Changes since release 2021.07:

General

• Update the install instructions

  • Show how to use Bluetcl to programmatically retrieve the BSC version

  • Show how to use Cabal v2-install

  • Show how to build a release without Asciidoctor

• Support building and running on more systems

Documentation

• Fix typos in the MIMO library documentation

• Document new -use-dpi flag

• Document Verilator as a new option for -vsim

Compiler

• Support optional use of DPI instead of VPI, for imported C functions (BDPI)

  • This is draft support; feedback welcome!

  • Size-polymorphic import-BDPI functions are not yet supported

  • A new flag, -use-dpi, must be provided when compiling and linking

• Checkout the Yices submodule at an official tagged version, 2.6.4

• Udpate the source to compile with GHC 9.2

  • Note that BSC triggers a bug in GHC 9.2.1 (#20639), which has been fixed in 9.2.2

Libraries

• Fix the modules in the Divide library

  • Fix bug when iterations-per-cycle is greater than one

  • Fix scheduling issues at the interface

  • Improve the provisos

• Fix divide and square root modules in the FloatingPoint library, to not require -aggressive-conditions flag for correct behavior

• Fix Prelude function hexDigitToInteger

Bluesim

• Eliminate error on exit when running on systems with Tcl 8.5

Verilog

• Support automatic linking with Verilog, using -vsim verilator

  • This is draft support; feedback welcome!

  • The -use-dpi flag is needed for designs with imported C, since Verilator does not support our VPI implementation

  • Designs with generated clocks may not link; ultimately, BSC may need a Verilator backend (separate from Verilog and Bluesim) to support arbitrary designs

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2021.07 Release

Welcome to the first release of open BSC! Thank you and congratulations to everyone involved!

We have decided on the convention YYYY.MM for naming releases. And we have decided on a release schedule of twice a year, in January and July. Therefore, this first release is 2021.07 and users can expect a next release, 2022.01, in six months. Patch releases, if needed, will be named 2021.07.1, etc.

This release has some incompatibilities with prior proprietary releases, but for the most part remains the same. Hopefully all projects using prior releases should find it accessible to migrate to this open release. But users should expect that more incompatible changes may be coming in future releases. Examples of changes to expect include:

• Renaming and reorganizing of directories in the release

• Renaming of Verilog primitives (for example, to start with a unique prefix such as __BSC_)

• Renaming of preprocessor macros (for example, changing the prefix BSV_ to BSC_)

• New preprocessor macros (for example, rather than having Vivado-specific versions of Verilog primitives in a separate directory, they may coexist in one file and users may need to define a macro such as VIVADO, to select for the target tool)

• Use of newer Verilog features (rather than restricting primitives and generated Verilog to the Verilog95 standard as much as possible)

The changes in this release are highlighted below. In addition, it is worth acknowledging the logistical and community changes. Most communication around open BSC happens on GitHub; however, we also now have mailing lists, hosted at Groups.io.

• To receive announcements about BSC and related projects, subscribe to b-lang-announce

• For questions and discussion about BSC source, subscribe to the developers' mailing list bsc-dev

• For any questions or discussion about Bluespec HDLs, using BSC, or related projects, subscribe to b-lang-discuss

Only the core BSC tools have been included in the open BSC project (compiler, standard libraries, Bluesim, and Bluetcl). Some libraries have been released in a separate GitHub repository, bsc-contrib. And BDW, the Bluespec Development Workstation GUI, has been released as its own GitHub project, bdw. Other features from the proprietary release (such as BlueNoC, SCE-MI, and other emulation tools and transactor libraries) have not been released.

Highlights since proprietary release 2019.05:

Licensing

• FlexLM licensing has been removed from BSC and Bluesim, along with related flags

• Source is provided under the BSD-3-Clause license, except for some components where specified (under other open/copyleft licenses)

Documentation

• The documentation for standard libraries, that was previously found in the BSV Language Manual, has been collected into a stand-alone document, now residing in the bsc repo so that it can be updated as the libraries are updated

• BDW documentation has been removed from the User Guide and placed in its own document in the bdw repo; the remainder of the User Guide resides in the bsc repo where hopefully it can be updated as features are updated

General

• Users no longer need to set BLUESPECDIR — the executables will expect the directory to sit at a known location relative to the executables

• The locations for C++ libraries (SAT, VPI, Bluesim) are no longer under a CXXFAMILY directory (for example, g++4_64)

• Version information no longer includes a date, just a build number (usually a git hash) and a version name (now reported as a single string instead of three separate fields)

Compiler

• Removed unnecessary library requirements (X11, Tcl/Tk)

  • Previously, the BSC executable required dynamic linking with Tcl, Tk, and X11 libraries — which were legitimately needed for Bluetcl and Bluewish, but not for BSC

• Removed Prelude directory and consolidated all the libraries into the Libraries directory

• Flags and special support for BlueNoC/SCE-MI have been removed

• New flags -show-timestamps and -show-version

• New flag -quiet and its short form -q

• Yices is now the default SMT solver and the library is now included

  • Support is updated to the latest version (2.6.2)

  • Bugs have been fixed in BSC’s use of Yices

• Support for CUDD solver removed, along with associated flags for scheduler effort and BDD cache size

• Better code generation for tagged unions and for enums that are non-consecutive or non-zero-based

  • Pack-unpack of types results in pure wires in more cases

  • More optimized code should occur in other situations, with fewer unnecessary case-statements

• Improved the handling of struct/union fields (in patterns, selection, and value construction)

  • The BSV parser now accepts a pattern syntax for matching structs

  • BSV syntax for struct vs tagged union can no longer be used interchangeably (users may need to add or remove the tagged keyword in existing code); this also means that clash between namespaces is no longer a problem

  • BH/Classic still uses the same syntax for both structs and constructors with named fields, so the type checker still uses heuristics to decide which is intended — this process has been improved

  • Parsing/type-checking is now more strict about when named vs unnamed fields can be used

  • Empty braces (without any listed fields) are disallowed in BSV syntax in situations where this does not make sense

• Record updates are now allowed on interfaces

• In BH/Classic, prefix is no longer a reserved keyword, and is now supported as an alternate to prefixs port renaming pragma

• Type-level strings are now supported, as a new string kind (alongside numeric and star kinds)

  • The pseudo-function stringOf exists for converting a string type to a string value (along the lines of valueOf for numeric types)

• Fixed some combsched internal errors in scheduling

• Fixed an internal error on mutually recursive type class instances

• Fixed an issue where parallel calls to BSC would conflict if they used the C preprocessor, because it created a temporary file with a hard-coded name (fixed to use a unique name now)

• Fixed a bug in static evaluation of SLE/SLT on 0-width values

• Other efficiency improvements, error message improvements, and bug fixes

  • Releases are also built with newer GHC versions, which ought to improve performance

Libraries

• Experimental support in the Prelude for datatype-generic functions, based on GHC’s Generics: https://hackage.haskell.org/package/base/docs/GHC-Generics.html

• New CShow library (implemented with Generics), which provides a CShow typeclass that acts similar to FShow but prints values in BH/Classic syntax

• An instance of FShow is derived for Either

• The DefaultValue typeclass is now in Prelude, so it is automatically available and does not require importing a separate package

• The guarded parameter on FIFO primitives was fixed to be of type Bool rather than Integer

• Fix to SquareRoot library

Bluetcl

• The executable links with the locally installed Tcl/Tk and Itlk/Itk (rather than being compiled with source snapshots for specific versions) which also means that any locally installed Tcl libraries are available for use in Bluetcl

• The separate bluewish executable has been removed — now that local libraries are used, Bluetcl users can require the local Tk package, to pull in Tk/X11 support

• Removed unnecessary library requirements (X11, Tk)

  • Bluetcl can be run on systems where Tk/X11 is not available, as long as the Bluetcl commands don’t request it

• TCLLIBPATH and BLUETCLLIBPATH environment variables are supported, for listing directories to add to the search path for packages

Bluesim

• Fixed code generation for conditionally called ActionValue methods/tasks

• Improved a scaling issue in Bluesim linking

• Handles SIGPIPE the same as Ctrl-C

Verilog

• Fixed typos in the Quartus versions of the Verilog primitives for BRAMs

• Fixed BSC linking for Icarus Verilog, so that the Verilog search path is also used for finding preprocessor include files

• BSC linking now supported for Questa (using -vsim questa)

• BSC linking for ModelSim updated to remove deprecated flag

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