[LLVMdev] ARM64 -> AArch64 merge status

[James Molloy]

Hi all,

 

It’s been two weeks since I sent the last merge progress email, so here is
an update.

 

TL;DR: Almost done!

 

Tim is considering suggesting making the final switchover sometime next
week. This would be the final push, where AArch64 gets deleted and ARM64
gets renamed to AArch64, and would signal the end of the merge process. If
any of you know of any reason why these two loving backends cannot be
merged, speak now or forever hold your peace! J

 

Times are incredibly approximate and are in man-days/weeks.

 

·         Requirement: No regressions

o   Correctness

§  [1w] Regression tests

·         All Clang regression tests ported.

·         Almost all LLVM regression tests ported – the only thing left is
MC-level diagnostics tests. These are in progress (Bradley) – currently 25%
of the way through the diagnostics test file.

§   [?] QuIC internal tests

·         No further information available, but no public bugs raised.

§  [DONE] ARM internal tests

·         All test suites pass.

§  [0d] Apple internal tests

·         Tim says we’re “looking reasonable” here J

·         This only blocks a “go/no-go”, and there are no actual actions
here at the moment (according to Tim)

§  [DONE] LLVM test suite

§  [DONE] MC Hammer

§  [DONE] Emperor

·         This is a random test suite so has the possibility to uncover more
problems. Our acceptance criterion is 3 days runtime without finding any
bugs, which we have now hit.

o   Performance

§  No precise fixed performance baseline

§  [DONE] Investigate significant performance regressions – justify fix/not
fix.

·         No performance blockers reported.

 

·         Requirement: Feature parity

o   [DONE] Big endian

§  Big endian support is now complete and all known bugs are fixed upstream.
This includes NEON instruction selection.

§  I’m still running testing to validate, but this can be thought of as
complete.

o   [DONE] Support for no fpu/no neon/ no crc

o   [DONE] A53 scheduler

o   [DONE] Inline assembly

o   [DONE] Predefines

o   [DONE] Conditionalise cyclone/Darwin

§  Only the “LDR q” -> “LDP d, d” splitting pass to really conditionalise –
only benchmarks will really show though.

o   [?] ADRP CSE

§  This optimization, being worked on by Jiangning, has been half ported to
ARM64. But it hasn’t been committed to AArch64 yet, so it can’t be
considered a merge blocker.

§  Jiangning and Quentin are working together on testing and benchmarking
this patch.

o   [2d] fastcc & guaranteed tail opt

§  Fastcc support (proper tail call optimization) is in progress (Jiangning)

o   [2d?] Post-increment NEON ld/st

§  Post-indexed NEON loads and stores are in progress (Hao)

 

Cheers,

 

James

 
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