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

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Enums that don't carry anything in their arms shouldn't use shape glue#2916
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A-codegenArea: Code generationC-enhancementCategory: An issue proposing an enhancement or a PR with one.E-hardCall for participation: Hard difficulty. Experience needed to fix: A lot.I-slowIssue: Problems and improvements with respect to performance of generated code.
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old 1.0 milestone

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@bblum
bblum
opened on 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.

Activity

  1. eholk commented on Jul 14, 2012

    @eholk
    eholk
    on Jul 14, 2012
    Contributor

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

  2. bblum commented on Jul 16, 2012

    @bblum
    bblum
    on Jul 16, 2012
    ContributorAuthor

    I know, right?

    Found during ICFP (#2928).

  3. catamorphism commented on Dec 6, 2012

    @catamorphism
    catamorphism
    on Dec 6, 2012
    Contributor

    Obsolete, shape glue is dead.

  4. catamorphism
    closed this as completedon Dec 6, 2012
  5. RalfJung
    added a commit that references this issue on Jun 29, 2023

    Auto merge of rust-lang#2916 - ehuss:remove-workspace-hack, r=RalfJung

    5d01a6b
  6. celinval
    added a commit that references this issue on Jun 4, 2024

    Bump docker/login-action from 2 to 3 (rust-lang#2916)

    abd3690
  7. tshepang
    added a commit that references this issue on Jul 4, 2026

    Merge pull request rust-lang#2916 from rust-lang/tshepang/misc

    f070f47
  8. U007D
    added a commit that references this issue on Aug 21, 2026

    Merge rust-lang#2916

    912776f
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    A-codegenArea: Code generationC-enhancementCategory: An issue proposing an enhancement or a PR with one.E-hardCall for participation: Hard difficulty. Experience needed to fix: A lot.I-slowIssue: Problems and improvements with respect to performance of generated code.

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