arm64 is not a valid aot target.

[Andersbakken]

Without this aot files won't load on arm64 builds on mac.

[yamt]

can you explain a bit?

other people were saying it should be arm64.
see #1365

[Andersbakken]

wamrc doesn't appear to have an arm64 target. (Based on calling wamrc --target=help)

I can also confirm that my m3 mac is able to run an aarch64.v8 aot with this change.

[yamt]

wamrc doesn't appear to have an arm64 target. (Based on calling wamrc --target=help)

how about the default? (without --target option)

maybe we can make wamrc normalize it?
@eloparco how do you think?

[Andersbakken]

Hm. I get this then:

wamrc -o pyramid.arm64.aot pyramid.wasm --help
Create AoT compiler with:
  target:        arm64
  target cpu:    apple-m1
  target triple: arm64-pc-linux-gnu
  cpu features:
  opt level:     3
  size level:    1
  output format: AoT file
LLVM ERROR: Only small, tiny and large code models are allowed on AArch64
zsh: abort      wamrc -o pyramid.arm64.aot pyramid.wasm --help

Which kinda implies that it tried to do that but it aborted. Not sure what the code model thing is about tbh. Didn't see anything about it in the help.

[yamt]

Hm. I get this then:

wamrc -o pyramid.arm64.aot pyramid.wasm --help
Create AoT compiler with:
  target:        arm64
  target cpu:    apple-m1
  target triple: arm64-pc-linux-gnu
  cpu features:
  opt level:     3
  size level:    1
  output format: AoT file
LLVM ERROR: Only small, tiny and large code models are allowed on AArch64
zsh: abort      wamrc -o pyramid.arm64.aot pyramid.wasm --help

Which kinda implies that it tried to do that but it aborted. Not sure what the code model thing is about tbh. Didn't see anything about it in the help.

i agree it's a bit cryptic. it means --size-level.
see #3689

[Andersbakken]

While it claimed to create that format based on stdout I still get the same error when trying to load it (after reverting my patch). I think it just plain doesn't exist as a target. Mac is just aarch64 AFAICT.

AOT module load failed: invalid target type, expected arm64 but got aarch64v8

[yamt]

While it claimed to create that format based on stdout I still get the same error when trying to load it (after reverting my patch). I think it just plain doesn't exist as a target. Mac is just aarch64 AFAICT.

what's "it"? can you share the exact command line option?

AOT module load failed: invalid target type, expected arm64 but got aarch64v8

my understanding is:
historically arm64 is used for mac.
llvm treats it as an alias of aarch64 in some places.

[Andersbakken]

Sorry. That wasn't really clear.

My findings are that wasm-micro-runtime still says that this file is the wrong target type when loaded. E.g. The file appears to be aarch64 even when produced with the command line underneath.

main [src_kodak][abakken@b.local:~/dev/kodak/test/triangles-cpp] wamrc --size-level=3 -o triangles.arm64.aot ./triangles.wasm
Create AoT compiler with:
  target:        arm64
  target cpu:    apple-m1
  target triple: arm64-pc-linux-gnu
  cpu features:
  opt level:     3
  size level:    3
  output format: AoT file
Compile success, file triangles.arm64.aot was generated.

[Andersbakken]

I think I made a mistake in testing. It does indeed load it correctly now like you thought it would. I guess the only problem is that wamrc needs to get another valid --target. I'll see if I can come up with a pr for that. Sorry about the confusion.

[yamt]

i think the reported problem is still valid because there seems no way to cross-build "arm64" aot module.
the following is on x86-64 macOS.

spacetanuki% ./wamrc --target=arm64 -o aot ~/git/garbage/wasm/hello/hello.wasm 
Error: Invalid target. Use --target=help to list all supported targets
spacetanuki% ./wamrc --target=aarch64 -o aot ~/git/garbage/wasm/hello/hello.wasm
Create AoT compiler with:
  target:        aarch64v8
  target cpu:    
  target triple: aarch64v8-pc-linux-gnu
  cpu features:  
  opt level:     3
  size level:    3
  output format: AoT file
Compile success, file aot was generated.
spacetanuki% 

IMO, we should

• make wamrc normalize "arm64" to "aarch64v8".
• make aot_loader accept "aarch64v8" as your patch does. (and make it accept "arm64" as well if we care compatibility)

@eloparco how do you think? (i'm asking you because you made the "use arm64 for apple" change.)

[Andersbakken]

I guess it maybe was premature to close this pr. @yamt suggestions sound good to me. I've tried to update the patch to implement it that way. Maybe @eloparco could take a look?

I have verified that I can do the following now:

1. Run aot files on mac (m3) produced with default parameters with wamrc on mac
2. Run aot files on mac (m3) produced with --target=aarch64v8 with wamrc on any platform
3. Run aot files on mac(m3) produced with default parameters with previous version of wamrc on mac

[Andersbakken]

@wenyongh @yamt Would it be okay to land this?

[wenyongh]

Could you please use /* .. */ to comment the code like other places? This is C source code, we usually add comment like that.

[wenyongh]

And maybe we can remove the macro control (L549)? Just convert target arm64 to aarch64v8 unconditionally?

[Andersbakken]

Agree with both points. Will update.

[wenyongh]

@wenyongh @yamt Would it be okay to land this?

@Andersbakken I tried to look into the code, if IIUC, what the PR does are: (1) wamrc accepts --target=arm64, and emits target aarch64v8 in the aot file instead, (2) aot loader accepts arm64 in aot file for backward compatibility, and converts it into aarch64v8 instead, and it also sets host default arch to aarch64v8 when BUILD_TARGET macro is AARCH64, so check_machine_info runs succeeded no matter the input target in aot file is aarch64v8 or arm64. (3) change size-level to 3 when host is macos arm64.

I added several comments, could you help have a check? Thanks.

[Andersbakken]

@wenyongh @yamt Would it be okay to land this?

@Andersbakken I tried to look into the code, if IIUC, what the PR does are: (1) wamrc accepts --target=arm64, and emits target aarch64v8 in the aot file instead, (2) aot loader accepts arm64 in aot file for backward compatibility, and converts it into aarch64v8 instead, and it also sets host default arch to aarch64v8 when BUILD_TARGET macro is AARCH64, so check_machine_info runs succeeded no matter the input target in aot file is aarch64v8 or arm64. (3) change size-level to 3 when host is macos arm64.

I added several comments, could you help have a check? Thanks.

1. The intention was actually to try to get rid of arm64 as a valid target since it never was supported before but otherwise your summary sounds right.

[wenyongh]

LGTM

[Andersbakken]

LGTM

Thanks. I'll add the comment