Avoid some allocations in the macro parser #37318
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This avoids ~800,000 allocations in html5ever.
This avoids ~800,000 allocations in html5ever.
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r? @nrc |
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r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
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@eddyb tells me the 3rd commit is bogus, because those failure messages are not just used in panics. |
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r = me for the first two commits, but I agree with @eddyb that the third is a non-starter. Not sure how much he explained, but the parser used to use panic to give errors. That behaviour is mostly gone, but there are a few remnants left such as the macro parser, so this is an error message that is user facing whenever a macro doesn't apply. |
nnethercote
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@nrc: Thank you for the fast response. I've updated to fix the third commit. I had to use the turbofish in multiple calls like this |
| /// Fatal error (malformed macro?). Abort compilation. | ||
| Error(syntax_pos::Span, String) | ||
| } | ||
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| impl<T> ParseResult<T> { | ||
| pub fn msg(tok: Option<Token>) -> String { |
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can you make this a method on &self rather than a static method? That should avoid the turbo fish.
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Can't because it needs to be used in several places, without a ParseResult around.
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Then I would just make it a top-level function (with a more descriptive name), rather than a method
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Indeed, I suggested failure_message on IRC (with that same descriptivity goal).
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That's difficult, because the self is gone by the time the method is called in some cases. I'll make it a top-level fn instead.
| @@ -227,7 +231,11 @@ pub fn compile(sess: &ParseSess, def: &ast::MacroDef) -> SyntaxExtension { | |||
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| let argument_map = match parse(sess, &Vec::new(), arg_reader, &argument_gram) { | |||
| Success(m) => m, | |||
| Failure(sp, str) | Error(sp, str) => { | |||
| Failure(sp, tok) => { | |||
| let str = ParseResult::<i32>::msg(tok); | |||
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nit: str is a bad name because it is a very common type, so the code is a little jarring.
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All comments addressed! |
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@nnethercote There's still the matter of using |
This lets us delay creation of failure messages until they are needed, which avoids ~1.6M allocations in html5ever.
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Oh, that was a comment on IRC and I missed it. Thanks for the suggestion, I've updated again. |
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@bors r=nrc,eddyb |
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📌 Commit b817cf8 has been approved by |
…ddyb Avoid some allocations in the macro parser These three commits reduce the number of heap allocations done when compiling rustc-benchmarks/html5ever-2016-08-25 by 20%, from 16.5M to 13.3M. This speeds up (debug) compilation of it with a stage1 compiler by about 7%.
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⌛ Testing commit b817cf8 with merge a117bba... |
Avoid some allocations in the macro parser These three commits reduce the number of heap allocations done when compiling rustc-benchmarks/html5ever-2016-08-25 by 20%, from 16.5M to 13.3M. This speeds up (debug) compilation of it with a stage1 compiler by about 7%.
These three commits reduce the number of heap allocations done when compiling rustc-benchmarks/html5ever-2016-08-25 by 20%, from 16.5M to 13.3M. This speeds up (debug) compilation of it with a stage1 compiler by about 7%.