Stream: git-wasmtime

Topic: wasmtime / PR #2468 Improve usability of constants

Wasmtime GitHub notifications bot (Dec 02 2020 at 22:48):

abrown requested cfallin and bnjbvr for a review on PR #2468.

Wasmtime GitHub notifications bot (Dec 02 2020 at 22:48):

abrown opened PR #2468 from improve-constants to main:

This adds a higher-level method, LowerCtx::emit_constant for lowering a constant in one of two ways:

• using a DataValue (instead of the previous u64), a value can be generated into a register using MachInst::gen_constant
• alternately, if MachInst::should_genenerate_constant_in_pool is true, then a value is emitted into the constant pool/island and loaded from memory at runtime; this path uses MachInst::gen_constant_in_pool.

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Wasmtime GitHub notifications bot (Dec 02 2020 at 22:48):

abrown requested cfallin and bnjbvr for a review on PR #2468.

Wasmtime GitHub notifications bot (Dec 02 2020 at 23:01):

abrown updated PR #2468 from improve-constants to main:

This adds a higher-level method, LowerCtx::emit_constant for lowering a constant in one of two ways:

• using a DataValue (instead of the previous u64), a value can be generated into a register using MachInst::gen_constant
• alternately, if MachInst::should_genenerate_constant_in_pool is true, then a value is emitted into the constant pool/island and loaded from memory at runtime; this path uses MachInst::gen_constant_in_pool.

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  description becomes long, the matter should probably be discussed in an issue
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• [ ] This PR contains test cases, if meaningful.

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Wasmtime GitHub notifications bot (Dec 02 2020 at 23:41):

cfallin submitted PR Review.

Wasmtime GitHub notifications bot (Dec 02 2020 at 23:41):

cfallin submitted PR Review.

Wasmtime GitHub notifications bot (Dec 02 2020 at 23:41):

cfallin created PR Review Comment:

s/in place/into a constant pool/, no? (Or perhaps "should be generated into a constant pool and loaded (if true); otherwise, it should be generated in place by an instruction or instruction sequence."

We should also clarify that if this function returns false, then gen_constant must be able to handle this value, and if true, then gen_constant_in_pool should.

Wasmtime GitHub notifications bot (Dec 02 2020 at 23:41):

cfallin created PR Review Comment:

Perhaps we can call this gen_constant_in_place now (analogous to ..._in_pool below)?

Wasmtime GitHub notifications bot (Dec 08 2020 at 15:02):

bnjbvr submitted PR Review.

Wasmtime GitHub notifications bot (Dec 08 2020 at 15:02):

bnjbvr created PR Review Comment:

Looks like there's a solution involving more traits that could avoid the assertions and the dummy unimplemented:

• have a trait ConstantGenerator that has a method "gen_constant"
• have a trait PooledConstantGenerator, that has three methods "gen_constant_without_pool", "gen_constant_with_pool", "must_generate_in_pool"
• then PooledConstantGenerator gets an blanket impl of ConstantGenerator based on these three functions above.

Then backends have to implement ConstantGenerator either directly, or via an opt-in choice to use the pooled variant. It's a bit more involved though...

Wasmtime GitHub notifications bot (Dec 08 2020 at 15:02):

bnjbvr edited PR Review Comment.

Wasmtime GitHub notifications bot (Dec 08 2020 at 15:16):

bnjbvr submitted PR Review.

Wasmtime GitHub notifications bot (Dec 08 2020 at 18:20):

cfallin submitted PR Review.

Wasmtime GitHub notifications bot (Dec 08 2020 at 18:20):

cfallin created PR Review Comment:

I like this scheme -- @abrown, does this seem reasonable to incorporate in your PR? I'd be happy to review it as a refactoring followup otherwise.

Wasmtime GitHub notifications bot (Dec 08 2020 at 18:41):

abrown submitted PR Review.

Wasmtime GitHub notifications bot (Dec 08 2020 at 18:41):

abrown created PR Review Comment:

I like it in principle! Let me dive back in and see how it comes out in practice.

Wasmtime GitHub notifications bot (Feb 10 2023 at 18:56):

abrown closed without merge PR #2468.

Last updated: Dec 23 2024 at 13:07 UTC