Modified the throw context example with concrete types but not concrete values. #219
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…e values. Addresses @aheejin's request in a previous review comment: WebAssembly#180 (comment) Originally I wrote this using - `val_{i32} = (i32.const 1)`, - `val_{f32} = (f32.const 2.0)`, and - `val_{i64} = (i64.const 3)`, but the example seemed then really long. To keep the example relatively short I switched to the current version.
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@aheejin is the example clear enough now or do you think it's better to use the concrete values, so |
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@rossberg incidentally, this also addresses your previous comment about using "let ... be .. ". |
document/core/exec/runtime.rst
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| In other words, when a throw occurs, normal execution halts and exceptional execution begins, until the throw | ||
| is the continuation (i.e., in the place of a :math:`\_`) of a throw context in a catching try block. |
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Not strictly related to this PR, but I'm not sure if I understand this sentence.
- What does a hole represent? (I know this is a basic question, but "block context" says it is "the next step of computation is taking place".. Is that also the case here? Which next step are we talking about?)
- This sentence sounds like we have two separate moments of "exception execution begins" and "(until) the throw is the continuation". I thought the exception execution begins when the
throwis executed... Are they two different things?
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By the way this is a general question, so please don't consider this question as a blocker for landing this PR.
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This sentence sounds like we have two separate moments of "exception execution begins" and "(until) the throw is the continuation". I thought the exception execution begins when the throw is executed... Are they two different things?
@aheejin this is exactly what I meant, so by "exceptional execution" I meant the execution of the throw, so the popping of values and labels until the first catching try block is reached. I was only trying to describe the execution of a throw instruction, but I see now I overcomplicated it, making it seem as if there are more than one execution steps during "exceptional execution".
About the hole, I think of the hole as the position of the stack pointer of the Wasm stack machine, but I see how mentioning the hole here can be confusing as well. Thank you for pointing this out!
Rephrasing these two lines to:
In other words, a thrown exception is caught when it's the continuation of a throw context in a catching try block, i.e., it's inside a catching try block, which is the innermost with respect to the throw.
Is it clearer like this?
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when it's the continuation of a throw context in a catching try block,
What's 'it' here? It looks to be "a thrown exception" looking at the first part of the sentence, but I'm not sure what it means that an exception is a continuation of a throw context.
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By "the thrown exception" I meant the instruction that throws the exception, i.e., val* (throw a).
I guess it's better to call it "the exception throw" instead, reformulating.
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This is now entirely removed, after this discussion.
Co-authored-by: Andreas Rossberg <[email protected]>
…to core-spec-throw-contexts-concrete-example # Conflicts: # document/core/exec/runtime.rst
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All review comments should be addressed now, pending for approval. |
Addresses @aheejin's request in a previous review comment:
#180 (comment)
Originally I wrote this using
val_{i32} = (i32.const 1),val_{f32} = (f32.const 2.0), andval_{i64} = (i64.const 3),but the example seemed then really long.
To keep the example relatively short I switched to the current version.