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Enums that don't carry anything in their arms shouldn't use shape glue #2916

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bblum opened this issue Jul 14, 2012 · 3 comments
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Enums that don't carry anything in their arms shouldn't use shape glue #2916

bblum opened this issue Jul 14, 2012 · 3 comments
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A-codegen Area: Code generation C-enhancement Category: An issue proposing an enhancement or a PR with one. E-hard Call for participation: Hard difficulty. Experience needed to fix: A lot. I-slow Issue: Problems and improvements with respect to performance of generated code.
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old 1.0 milestone

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@bblum
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bblum commented Jul 14, 2012 

enum fast { x, y, z, w } 
enum slow<T> { a(T), b(T), c(T), d(T) }

fn foo(yy: fast, xx: fast) -> bool {
    ret yy == xx; 
}
fn bar(yy: slow<bool>, xx: slow<bool>) -> bool {
    ret yy == xx; 
}

Both foo and bar generate calls to upcall_cmp_type. It'd be nice if, for performance, the compiler could recognise that fast can be represented by a primitive and skip the upcalls.

Related to #2132.
@eholk
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eholk commented Jul 14, 2012

Oh sad, I was really hoping we handled at least this case.

@bblum
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bblum commented Jul 16, 2012

I know, right?

Found during ICFP (#2928).

@catamorphism
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Obsolete, shape glue is dead.

RalfJung pushed a commit to RalfJung/rust that referenced this issue Jun 29, 2023
@bors
Auto merge of rust-lang#2916 - ehuss:remove-workspace-hack, r=RalfJung
5d01a6b 
Remove rustc-workspace-hack

The `rustc-workspace-hack` dependency was removed in rust-lang#109133 and should no longer be needed.
celinval pushed a commit to celinval/rust-dev that referenced this issue Jun 4, 2024
@dependabot
Bump docker/login-action from 2 to 3 (rust-lang#2916)
abd3690 
Bumps [docker/login-action](https://github.com/docker/login-action) from
2 to 3.
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A-codegen Area: Code generation C-enhancement Category: An issue proposing an enhancement or a PR with one. E-hard Call for participation: Hard difficulty. Experience needed to fix: A lot. I-slow Issue: Problems and improvements with respect to performance of generated code.
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@eholk @catamorphism @bblum