Combining GNAT with LLVM

Re:Combining GNAT with LLVM by 0xDEEPFAC on Tuesday October 01, 2019 @10:30AM (#21125677)

I wouldn't be so sure. Given that this is a new backend for GNAT and the first one is close to 25 years old I assume it will have more modern optimizations and experience behind it - presumably leading to something faster.

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Re:Combining GNAT with LLVM by earenndil on Tuesday October 01, 2019 @11:11AM (#21126179)

The 'old' backend is modern gcc, which is on par with or beats llvm.

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Re:Combining GNAT with LLVM by 0xDEEPFAC on Tuesday October 01, 2019 @11:20AM (#21126324)

I would say gcc and llvm are competitive - asserting gcc is faster at its current state is quite a claim.

Also, I was referring to AdaCore's implementation of the compiler backend. GNAT's architecture is structured like so:

GNAT Frontend (parsing, analysis, expansion) -> GNAT Backend (translation of frontend tree to something GNU or LLVM can understand) -> LLVM or GCC

This backend is quite complex and has a large role in how LLVM can optimize. My argument is that GNAT's GCC backend is 25 years old and a new backend written for LLVM probably generates better/cleaner code.

Also of note is that the GCC backend is written and C and the LLVM is actually written in Ada meaning its more uniform with the GNAT frontend.

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Re:Combining GNAT with LLVM by monocasa on Tuesday October 01, 2019 @12:02PM (#21126933)

On the other hand, the GCC implementation has 25 years performance optimizations across the whole battery of programs they run.

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