GNU lightning

GNU lightning

Developer(s)	GNU Project
Initial release	January 19, 2001; 24 years ago (2001-01-19)[1]
Stable release	2.2.3[2]  / 8 February 2024
Repository	git.savannah.gnu.org/cgit/lightning.git
Operating system	Cross-platform
Platform	GNU
Type	Just-in-time compilation
License	2007: LGPL-3.0-or-later[a] 2002: LGPL-2.1-or-later[b]
Website	Official website

GNU lightning is a free-software library for generating assembly language code at run-time. Version 2.1.3, released in September 2019, supports backends for SPARC (32-bit), x86 (32- and 64-bit), MIPS, ARM (32- and 64-bit), ia64, HPPA, PowerPC (32-bit), Alpha, S390 and RISC-V (64-bit).[5][6]

Advantages over other libraries

The features GNU lightning provides make it useful for Just-in-Time Compilation. In comparison to libraries such as LLVM or libJIT, GNU lightning provides only a low-level interface for assembling from a standardized RISC assembly language—loosely based on the SPARC and MIPS architectures[7]—into the target architecture's machine language.

Disadvantages

It does not provide register allocation, data-flow or control-flow analysis, or optimization.^[citation needed] Starting from 2.x, it generates code via intermediate graph, rather than one by one from each of its standardized instructions. This change allows inter-instruction optimization such as register allocation and dead code elimination [1].

Instruction set

GNU lightning's instruction set is based loosely on existing RISC architectures.

Types

When required instructions handle data with these 9 types:

Type	C equivalent
c	signed char
uc	unsigned char
s	short
us	unsigned short
i	int
ui	unsigned int
l	long
f	float
d	double

Projects that use GNU lightning

GNU Smalltalk,[8] GNU Guile,[9] and CLISP[10] make use of GNU lightning for just-in-time compilation. GNU lightning was first developed as a tool to be used in GNU Smalltalk's dynamic translator from bytecodes to native code.[11] GNU Guile 2.9.2 and later stop using GNU lightning 2.x instead their own fork based on GNU lightning 1.4 for native code generation, because GNU lightning 2.x devotes more complexity to inter-instruction optimization.[12]

Notes

1. LGPL-3.0-or-later since 2007-07-01.[3]
2. LGPL-2.1-or-later from 2002-06-25 until 2007-07-01.[4]

References

1. "ChangeLog". GNU Project. Retrieved 2009-02-22.
2. Paulo César Pereira de Andrade (8 February 2024). "GNU lightning 2.2.3 released!". Retrieved 8 March 2024.
3. "README-hacking".
4. "lightning-1.1.1.tar.gz".
5. "GNU lightning". Retrieved 2020-01-15.
6. "GNU lightning 2.1.3 released!". 2019-09-18.
7. "Using and porting GNU lightning". Retrieved 2009-02-22.
8. "GNU Smalltalk project page". Retrieved 2014-05-17.
9. "Just-In-Time Native Code". Archived from the original on 2020-05-13. Retrieved 2019-03-11.
10. "Implementation notes for GNU CLISP". Retrieved 2009-02-23.
11. "GNU lightning user manual, acknowledgements". Retrieved 2014-05-17.
12. "lightening run-time code generation -- wingolog". Retrieved 2021-12-10.

External links

• GNU lightning on Free Software Directory