VMS Software / Documentation / VSI ASM V10.1-4

VSI ASM V10.1-4

Release Notes

Publication Date: July 2026

Operating System:
VSI OpenVMS x86-64 Version 9.2-2 or higher
Kit Name:
VSI-X86VMS-X86ASM-V1001-4

1. What's New in This Release

Important

X86ASM prefixes each compiler message with %facility-severity-ident followed by the actual message text. In the previous release, X86ASM (SYS$SYSTEM:LLVM-MC.EXE) incorrectly reported the facility as CXX. This has been fixed: messages now correctly report the facility as LLVMMC.

This kit includes the LLVM tool named "llvm-mc". This provides a native x86-64 assembler that is highly compatible with the gnu "gas" assembler.

The tool must be activated via an OpenVMS foreign command. Define the foreign command as follows:

$ llvmmc :== $sys$system:llvm-mc

The compiler version number is:

$ llvmmc --version
LLVM (http://llvm.org/):
  VSI version V10.1-4
  LLVM version 10.0.1
  Optimized build.
  Build date: 06-30-2026
  Target: x86_64-OpenVMS

A sample command to run the llvm-mc tool is as follows:

$ llvmmc --filetype=obj -o=objectfilename.obj sourcefilename.s

Here are some useful options for the command:

OptionDescription
--helpDisplays available options (help-hidden for more).
-o filenameSaves the output to the filename file. See the summary above for more details.
--filetype=[asm,null,obj]Sets the output file type. Setting this flag to asm will make the tool output text assembly. Setting this flag to obj will make the tool output an object file. Setting it to null causes no output to be created and can be used for timing purposes. The default value is asm.
--assembleAssembles an assembly file (default) and prints the result to assembly. Combined with the other llvm-mc flags, this can be useful in designing and testing instruction parsers as well as transcoding assembly from different dialects (for example, on Intel where you can use -output-asm-variant=1 to translate from AT&T to Intel assembly syntax). This can also be combined with show-encoding to understand how instructions are encoded.
--disassembleParses a series of hex bytes and prints the result out as assembly syntax.

2. Documentation

Documentation for the assembler can be found at https://llvm.org/docs/CommandGuide/llvm-mc.html.