Regression in by-val self u8s #7285

brson · 2013-06-21T23:24:12Z

trait to_float {
    fn to_float(self) -> float;
}

impl to_float for u8 {
    fn to_float(self) -> float { 0.0 }
}

pub fn main() {
    println("hello, world");
}

rustc: /opt/dev/rust2/src/llvm/lib/IR/Instructions.cpp:2290: static llvm::CastInst* llvm::CastInst::Create(llvm::Instruction::CastOps, llvm::Value*, llvm::Type*, const llvm::Twine&, llvm::Instruction*): Assertion `castIsValid(op, S, Ty) && "Invalid cast!"' failed.

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Currently we pass all "self" arguments by reference, for the pointer variants this means that we end up with double indirection which causes a unnecessary performance hit. The fix itself is pretty straight-forward and just means that "self" needs to be handled like any other argument, except for by-value "self" which still needs to be passed by reference. This is because non-pointer types can't just be stuffed into the environment slot which is used to pass "self". What made things tricky is that there was also a bug in the typechecker where the method map entries are created. For type impls, that stored the base type instead of the actual self-type in the method map, e.g. Foo instead of &Foo for &self. That worked with pass-by-reference, but fails with pass-by-value which needs the real type. Code that makes use of methods seems to be about 10% faster with this change. Also, build times are reduced by about 4%. Fixes rust-lang#4355, rust-lang#4402, rust-lang#5280, rust-lang#4406 and rust-lang#7285

Currently we pass all "self" arguments by reference, for the pointer variants this means that we end up with double indirection which causes a unnecessary performance hit. The fix itself is pretty straight-forward and just means that "self" needs to be handled like any other argument, except for by-value "self" which still needs to be passed by reference. This is because non-pointer types can't just be stuffed into the environment slot which is used to pass "self". What made things tricky is that there was also a bug in the typechecker where the method map entries are created. For type impls, that stored the base type instead of the actual self-type in the method map, e.g. Foo instead of &Foo for &self. That worked with pass-by-reference, but fails with pass-by-value which needs the real type. Code that makes use of methods seems to be about 10% faster with this change. Also, build times are reduced by about 4%. Fixes #4355, #4402, #5280, #4406 and #7285

thestinger · 2013-07-10T06:00:53Z

Fixed by #7452.

Move mini-macro to tests/ui/auxilary changelog: none Merges `/mini-macro` into `/tests/ui/auxilary/proc_macro_derive.rs`. The mini-macro crate is an artifact of the distant past. A lot has changed (rust-lang#2284) and it doesn't make sense as a top-level crate anymore. Especially since we can use the auxilary folder to accompolish the same thing.

dotdash mentioned this issue Jun 28, 2013

Avoid double indirection for the "self" arg in methods #7452

Merged

thestinger closed this as completed Jul 10, 2013

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Regression in by-val self u8s #7285

Regression in by-val self u8s #7285

brson commented Jun 21, 2013

thestinger commented Jul 10, 2013

Regression in by-val self u8s #7285

Regression in by-val self u8s #7285

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brson commented Jun 21, 2013

thestinger commented Jul 10, 2013