Stream: git-wasmtime

Topic: wasmtime / issue #3370 Cranelift: support scalar types fo...

view this post on Zulip Wasmtime GitHub notifications bot (Sep 19 2021 at 02:17):

cfallin edited issue #3370:

Using cranelift 0.76, the following results in this error message: "'Unsupported type for imin instruction: i64', [...]\cranelift-codegen-0.76.0\src\isa\x64\lower.rs:2353:17"

function u0:0() -> f64 windows_fastcall {
block0:
    v0 = f64const 0.0
    v1 = iconst.i64 1
    v2 = iconst.i64 2
    v3 = imin v1, v2
    v4 = fcvt_from_sint.f64 v3
    return v4
}

Am I using imin incorrectly?

view this post on Zulip Wasmtime GitHub notifications bot (Sep 19 2021 at 17:26):

DGriffin91 commented on issue #3370:

Thanks for the explanation!

Sure! I would be interested in seeing where it would be implemented.

view this post on Zulip Wasmtime GitHub notifications bot (Sep 19 2021 at 18:17):

afonso360 commented on issue #3370:

That particular assert is being triggered when we try to lower the CLIF Opcode into a x86 machine instruction. That is done in the x64 backend lower.rs file, specifically line 2343.

The first step would be figuring out what assembly we want to generate for each instruction. rustc lowers this as a cmp and cmovg.

Reading the x64 backend a bit, it looks like we have helpers for emitting those instructions. emit_cmp and emit_cmoves. You can probably call those and generate the assembly sequence above.

While doing all these changes an easy way to test them is to build a CLIF test file, and run it using clif-util. Looking at our testsuite, it looks like we don't have any test files for imin, so its also a good idea to commit the test file that you generate when you implement this!

A simple testfile for imin.i64 could be:

test run
target x86_64 machinst

function %imin_i64(i64, i64) -> i64 {
block0(v0: i64,v1: i64):
    v2 = imin v0, v1
    return v2
}
; run: %imin_i64(0, 0) == 0
; run: %imin_i64(0, 1) == 0
; run: %imin_i64(-1, 0) == -1

Although you'd probably want to add tests for whatever other types / instructions you are implementing. You can then run this test file using cargo run test ./test-file.clif, which compiles the function and runs the tests in the comments.

If you want to view the disassembly of the code you are generating you can run cargo run compile --target x86_64 -D ./test-file.clif

Hope this helps, good luck!

view this post on Zulip Wasmtime GitHub notifications bot (Sep 19 2021 at 18:31):

afonso360 edited a comment on issue #3370:

That particular assert is being triggered when we try to lower the CLIF Opcode into a x86 machine instruction. That is done in the x64 backend lower.rs file, specifically line 2343.

The first step would be figuring out what assembly we want to generate for each instruction. rustc lowers this as a mov, cmp and cmovg. I'm not sure if this is the best instruction sequence, but maybe someone can comment on that later.

Reading the x64 backend a bit, it looks like we have helpers for emitting those instructions. emit_cmp and emit_cmoves. For mov, you can call Inst::gen_move which should generate the right thing. Between those three functions you should be able to generate assembly sequence above.

While doing all these changes an easy way to test them is to build a CLIF test file, and run it using clif-util. Looking at our testsuite, it looks like we don't have any test files for imin, so its also a good idea to commit the test file that you generate when you implement this!

A simple testfile for imin.i64 could be:

test run
target x86_64 machinst

function %imin_i64(i64, i64) -> i64 {
block0(v0: i64,v1: i64):
    v2 = imin v0, v1
    return v2
}
; run: %imin_i64(0, 0) == 0
; run: %imin_i64(0, 1) == 0
; run: %imin_i64(-1, 0) == -1

Although you'd probably want to add tests for whatever other types / instructions you are implementing. You can then run this test file using cargo run test ./test-file.clif, which compiles the function and runs the tests in the comments.

If you want to view the disassembly of the code you are generating you can run cargo run compile --target x86_64 -D ./test-file.clif

Hope this helps, good luck!

view this post on Zulip Wasmtime GitHub notifications bot (Sep 19 2021 at 18:31):

afonso360 edited a comment on issue #3370:

That particular assert is being triggered when we try to lower the CLIF Opcode into a x86 machine instruction. That is done in the x64 backend lower.rs file, specifically line 2343.

The first step would be figuring out what assembly we want to generate for each instruction. rustc lowers this as a mov, cmp and cmovg. I'm not too familiar with x86 to be sure if this is the best instruction sequence, but maybe someone can comment on that later.

Reading the x64 backend a bit, it looks like we have helpers for emitting those instructions. emit_cmp and emit_cmoves. For mov, you can call Inst::gen_move which should generate the right thing. Between those three functions you should be able to generate assembly sequence above.

While doing all these changes an easy way to test them is to build a CLIF test file, and run it using clif-util. Looking at our testsuite, it looks like we don't have any test files for imin, so its also a good idea to commit the test file that you generate when you implement this!

A simple testfile for imin.i64 could be:

test run
target x86_64 machinst

function %imin_i64(i64, i64) -> i64 {
block0(v0: i64,v1: i64):
    v2 = imin v0, v1
    return v2
}
; run: %imin_i64(0, 0) == 0
; run: %imin_i64(0, 1) == 0
; run: %imin_i64(-1, 0) == -1

Although you'd probably want to add tests for whatever other types / instructions you are implementing. You can then run this test file using cargo run test ./test-file.clif, which compiles the function and runs the tests in the comments.

If you want to view the disassembly of the code you are generating you can run cargo run compile --target x86_64 -D ./test-file.clif

Hope this helps, good luck!

view this post on Zulip Wasmtime GitHub notifications bot (Sep 20 2021 at 15:08):

akirilov-arm labeled issue #3370:

Using cranelift 0.76, the following results in this error message: "'Unsupported type for imin instruction: i64', [...]\cranelift-codegen-0.76.0\src\isa\x64\lower.rs:2353:17"

function u0:0() -> f64 windows_fastcall {
block0:
    v0 = f64const 0.0
    v1 = iconst.i64 1
    v2 = iconst.i64 2
    v3 = imin v1, v2
    v4 = fcvt_from_sint.f64 v3
    return v4
}

Am I using imin incorrectly?

view this post on Zulip Wasmtime GitHub notifications bot (Sep 20 2021 at 15:08):

akirilov-arm labeled issue #3370:

Using cranelift 0.76, the following results in this error message: "'Unsupported type for imin instruction: i64', [...]\cranelift-codegen-0.76.0\src\isa\x64\lower.rs:2353:17"

function u0:0() -> f64 windows_fastcall {
block0:
    v0 = f64const 0.0
    v1 = iconst.i64 1
    v2 = iconst.i64 2
    v3 = imin v1, v2
    v4 = fcvt_from_sint.f64 v3
    return v4
}

Am I using imin incorrectly?

view this post on Zulip Wasmtime GitHub notifications bot (Sep 20 2021 at 15:08):

akirilov-arm labeled issue #3370:

Using cranelift 0.76, the following results in this error message: "'Unsupported type for imin instruction: i64', [...]\cranelift-codegen-0.76.0\src\isa\x64\lower.rs:2353:17"

function u0:0() -> f64 windows_fastcall {
block0:
    v0 = f64const 0.0
    v1 = iconst.i64 1
    v2 = iconst.i64 2
    v3 = imin v1, v2
    v4 = fcvt_from_sint.f64 v3
    return v4
}

Am I using imin incorrectly?

view this post on Zulip Wasmtime GitHub notifications bot (Sep 23 2021 at 10:34):

akirilov-arm commented on issue #3370:

This issue also looks like a duplicate of #1505.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 24 2022 at 12:00):

afonso360 commented on issue #3370:

This seems to have been fixed in #3748 for types i64 and smaller, we are still crashing on i128.

Last updated: Oct 23 2024 at 20:03 UTC