NVC - VHDL Compiler and Simulator

Unreleased changes

• The --disable-opt and --native elaborate options which were deprecated in version 1.3 have been removed.
• The JSON dumper which was unmaintained for several years has been removed.
• VHDL-2019 mode can be enabled with --std=2019. Please note there is very limited support for this standard at present.
• The new --no-save elaboration option skips saving the elaborated design and other generated files to the working library.

Version 1.7.0 - 2022-08-07

• Breaking change: In-tree builds are no longer supported: use a separate build directory instead.
• Breaking change: The --force-init command is deprecated and has no effect.
• Added support for VHDL-2008 type generics on packages and entities.
• Diagnostic messages have been enhanced with more contextual information.
• Added support for record element constraints and record fields with unconstrained array types.
• Alias of multidimensional array allowed in VHDL-2008 mode.
• Implemented VHDL-2008 rules for aggregates with slices.
• VHPI is now always enabled at build time and the --enable-vhpi configure option has no effect.
• Arithmetic operations that overflow the underlying machine type now produce an error (#101).
• Added support for VHDL-2008 force/release assignments.
• Basic support for external names in VHDL-2008.
• Matching case case? statements are supported in VHDL-2008 mode.
• Fixed several bugs in the implementation of guarded signals.
• Implemented VHDL-2008 rules for generic visibility.
• Shared variable declaration permitted in entity declaration.
• Case expression no longer requires a locally static subtype in VHDL-2008 mode (#460).
• The VHDL heap is now garbage collected as required by VHDL-2019 and the deallocate operator has no effect other than setting the access to null.
• A new global option -H specifies the size of the simulation heap and defaults to 16 megabytes.
• Concurrent procedure call allowed in entity statement part.
• Added support for 'SUBTYPE and 'ELEMENT attributes in VHDL-2008.
• The new top-level --init command creates a new empty library directory.
• The -a analysis command now reads from the standard input if the file name is -.
• Added support for array element constraints in VHDL-2008.
• The --prefer-explicit analysis option which was deprecated before the 1.0 release has been removed.
• A new --relaxed analysis option enables “relaxed rules” mode. This has the same effect as enabling all the existing --relax= options. However some constructs will still produce warnings.
• The --relax= analysis option is deprecated and is now equivalent to passing --relaxed. The individual options are ignored.
• Added support for generic subprograms in VHDL-2008.
• New command --install allows easy installation of common third-party packages such as OSVVM and UVVM.
• Identifiers in waveform dumps are now in lower case instead of upper case.
• The function CURRENT_DELTA_CYCLE in NVC.SIM_PKG can be used to query the current delta cycle number.

Version 1.6.2 - 2022-04-03

• Fix make -j with GNU make (#440).
• Subtraction from zero could return the wrong result in some circumstances.
• Fix incorrect code generation for access-to-array.
• Fix assertion failure with nested context.
• Generic declarations are now allowed to hide the entity name.
• Fix spurious error about duplicate declarations when using VHDL-2008 context declarations.
• Fix incorrect default generic value when component and entity specify generics in different order (#448).
• Postponed processes with sensitivity lists now work correctly.
• Unit tests no longer fail when built without debug symbols (#445).
• Simulation now correctly terminates when time reaches TIME'HIGH.
• Assertion failure and report messages were not printed during the initialisation phase of the simulation.

Version 1.6.1 - 2022-02-05

• Fix compatibility with BSD make (#440).
• Fix an out-of-memory condition when initialising processes (#441).
• Fix incorrect generic value in binding specification (#442).
• Fix spurious error in overload resolution if required arguments follow optional arguments (#443).
• Fix intermittent crash generating code for enumerated types (#444).
• Minor elaboration performance optimisation.

Version 1.6.0 - 2022-01-25

• Name resolution and overload resolution has been completely rewritten which should fix a number of long-standing issues.
• The elaboration phase was largely written which fixes a number of long-standing issues and significantly improves elaboration speed.
• VHDL-2008 IEEE standard libraries are now built and installed in addition to the VHDL-1993 libraries.
• The VHDL-1993 standard libraries are now derived from the Apache 2.0 licensed sources from VHDL-2019.
• There is now a project website at https://www.nickg.me.uk/nvc/. Please link to this in preference to the GitHub project page.
• Compiled VHDL code now includes DWARF debug information which is used for runtime stack trace if libdw or libdwarf is installed.
• Added support for VHDL-2008 reduction operators, match operators, and condition conversion.
• Added support for VHDL-2008 element resolution.
• Variable assignment now supports aggregate targets.
• The --relax=impure option allows pure functions to call impure functions.
• Added support for VHDL-2008 “all” sensitised processes.
• Added support for ports and generics in block statements.
• Added support for the ’BASE attribute.
• Type name now allowed in element association choice (#407).
• Implement textio READ procedure for REAL.
• LLVM 6.0 or later is now required to build.
• Added support for MINIMUM, MAXIMUM, and TO_STRING predefined operators in VHDL-2008.
• VCD files are now generated from FST data in a similar manner to fst2vcd(1). This should improve compatibility with other tools.
• Added support for ’LAST_ACTIVE attribute (#423).
• Added support for ’DRIVING and ’DRIVING_VALUE attributes.
• Added a new option --ieee-warnings=off to disable warning messages from the standard IEEE packages.
• Support for configurations has been significantly improved (#372).
• Added support for VHDL-2008 delimited comments.
• Added support for guard expressions on blocks.
• Added support for guarded signals.
• Added support for HREAD, HWRITE, and other TEXTIO additions in VHDL-2008.
• Code generation now happens in parallel when LLVM is built with multi-threading enabled.
• Link time optimisation (LTO) is now enabled for release builds where supported.
• The default assertion failure message for certain simple scalar comparisons now shows the values of the left and right hand sides.
• Added support for VHDL-2008 conditional variable assignment statements.
• Added support for VHDL-2008 extended bit string literals.
• Non-globally-static actuals allowed in port maps in VHDL-2008 mode.
• Added support for VHDL-2008 sequential conditional signal assignment statements.
• Added basic support for package generics and package instantiation.
• Nested arrays can now be included in the waveform dump but only if the --dump-arrays option is passed. This is disabled my default due the significant performance and memory overhead.
• Added support for record types in waveform dump (#216).
• Added support for foreign subprograms using the VHPIDIRECT protocol.
• Library build is now reproducible when running make -j.
• Fix a constant folding crash with nested records.
• Fixed a crash when a record aggregate contains an “others” association and the fields have array types with different lengths.
• Fixed a stack overflow when a subprogram with unconstrained array arguments is called repeatedly in a loop (#414).
• Fixed intermittent crash when evaluating nested constant records (#425).
• Fixed missing import libraries on Windows (#424).
• Standard libraries are now installed under $prefix/lib/nvc/ instead of $prefix/share/nvc.
• New configure option --disable-vital disables building the VITAL packages whose license status is unclear.
• Support for the LXT wave output format, which was deprecated in version 1.5, has been removed. Use the default FST format instead.
• The fetch-ieee.sh script which did nothing since the last release has been removed.
• The --codegen command, which has been deprecated since 1.3, was removed.
• The --profile option now prints internal simulation statistics instead of the top processes by CPU time.

Version 1.5.3 - 2021-11-13

• Handle access(2) returning EPERM in macOS sandbox (#421).
• Fix race when multiple processes concurrently update a library.
• Fix --syntax command when file contains multiple design units.
• Allow constant folding of nand/nor/xor/xnor.
• Fix potential out of memory condition when evaluating complex assert expressions.
• Fix incorrect result of mod operator with negative operands.
• Fixed intermittent crash when evaluating nested constant records (#425).
• Buffer too small for printing TIME’HIGH (#98).

Version 1.5.2 - 2021-07-28

• Link libexecinfo on FreeBSD.
• Implement textio READ procedure for BIT and TIME (#408).
• Fixed a crash when a long running procedure suspends in a loop (#412).
• Fix static linking with LLVM 12.0.
• Fix crash when assigning to a signal declared in a package.
• Fix incorrect recording of dependencies which caused a failure to load generated DLLs on Windows.
• Fix file locking error when a library is located on NFS (#417).
• Optimise loading large library index from disk.
• Fix a crash when using ’VALUE with enumeration subtypes (#419).
• Fix a crash when a signal with more than 256 elements is declared in a package (#420).

Version 1.5.1 - 2021-04-09

• Fix a compiler warning in vcode.c.
• Disable VHDL backtrace on non-Linux systems as the symbol names cannot be parsed reliably (#385).
• Update to latest pc_from_uncontext.m4 for Apple M1 support.
• Fix incorrect application of LRM rules for building an equivalent wait statement for concurrent statements.
• Library build is now reproducible when running make -j (#409).
• Fix assertion failure with nested record type (#404).
• Use Pandoc to generate the manual page.

Version 1.5 - 2020-07-19

• IEEE library sources are now distributed
• Updated FST library to match GtkWave 3.3.79
• The LXT wave output format is deprecated, use FST instead
• Fix incorrect file name in assertion message
• Fix crash while recovering from parse error
• Add --dump-json command to print AST as JSON (from Sebastien Van Cauwenberghe)
• Fix crash when using LLVM 7 and later
• Fix spurious assertion failure in std.textio.readline
• Reals are now rounded to the nearest integer as specified by the LRM
• Fix crash when constant folding uses too much memory
• Improved memory management in evaluator (thanks to Frank Mori Hess)
• Various other minor fixes and improvements

Version 1.4 - 2018-07-16

• Windows with MSYS2 is now fully supported
• Continuous integration for OS X and Windows using Travis and AppVeyor
• Record resolution functions are now supported
• The --relax=prefer-explicit option now works correctly

Version 1.3 - 2017-12-31

• Native code is always generated on platforms that support it
• Initial support for VHDL-2017 conditional compilation blocks
• The TCL shell has been removed
• Various code generation and constant folding fixes
• Fix crash when build IEEE library from non-clean tree
• ORC is used for JIT if LLVM version is 3.9 or later
• LLVM 3.8 or later is now required
• Added -O0 to -O3 options to control LLVM optimisation level
• The --disable-opt option is deprecated, use -O0 instead
• The elaborate --native option is now a global option and should be placed before the -e command
• The --codegen command is deprecated, use --native when analysing to generate native shared libraries for packages

Version 1.2 - 2017-05-04

• Compile time evaluation now uses vcode
• Record aggregates can now be constant folded (#305)
• The TCL shell is deprecated and will be removed in the next release
• Compatible with LLVM 4.0
• Functions returning records can now be constant folded (#315)
• LLVM 3.4 or later is now required

Version 1.1 - 2016-11-05

• Improvements to based literal parsing
• Improved stack traces on Linux when libdw-dev installed
• Fixed elaboration of subprograms in entity declarations
• Improved elaboration performance when design contains many signals
• Fixed various bugs involving record signals
• Fixed sensitivity list generation for concurrent procedure calls
• Improvements to simulation performance
• Implemented vhpi_get_phys
• Added command --list to print all units in a library
• Rewrote the run_regr program in C so make check no longer requires Ruby
• The --relax=generic-static option is now renamed to --relax=locally-static and applies in wider range of contexts

Version 1.0 - 2016-05-01

• First stable release