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cmd/compile: slow bitmap generation for large array of zero-size elements #20739

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mdempsky opened this issue Jun 20, 2017 · 3 comments
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cmd/compile: slow bitmap generation for large array of zero-size elements #20739

mdempsky opened this issue Jun 20, 2017 · 3 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
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Go1.10

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@mdempsky
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This (nonsense, but valid) program takes a very long time to compile because of stack bitmap generation:

package f

func F() {
    var x struct {
            x *int
            w [1e10][1e10][1e10][0]*int
            y *int
    }
    println(&x)
}

The easy fix is to short-circuit generating stack bitmaps for zero-size types.
@mdempsky mdempsky added this to the Go1.10 milestone Jun 20, 2017
@bradfitz bradfitz added the NeedsFix The path to resolution is known, but the work has not been done. label Jun 20, 2017
@meggamind
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Can I pick this issue ?

@mdempsky mdempsky self-assigned this Jun 22, 2017
@mdempsky
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@meggamind Thanks, but I already have a fix + general cleanup for the issue. I would suggest another issue.

You're of course welcome to still look into it if you're just looking for practice working on the compiler.

@gopherbot
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Change https://golang.org/cl/64471 mentions this issue: cmd/compile: refactor onebitwalktype1

@golang golang locked and limited conversation to collaborators Sep 20, 2018
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
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@bradfitz @mdempsky @gopherbot @meggamind