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cmd/compile: implement global new(T) without calling newobject #29691

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josharian opened this issue Jan 11, 2019 · 5 comments
Open

cmd/compile: implement global new(T) without calling newobject #29691

josharian opened this issue Jan 11, 2019 · 5 comments
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done. Performance
Milestone
Backlog

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@josharian
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package p

var x = new(int)

This generates init code to call newobject (including a write barrier, which I thought wasn't supposed to happen any more?). Instead, we should make a BSS int symbol, and then make x contain a relocation to that symbol.

cc @randall77 @mvdan
@josharian josharian added Performance NeedsFix The path to resolution is known, but the work has not been done. labels Jan 11, 2019
@josharian josharian added this to the Go1.13 milestone Jan 11, 2019
@randall77
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No, we still need a write barrier when initializing a global location.

The write barriers I changed recently removes them when initializing the contents of the results of a newobject call. Not sure if you're referring to that.

Yes, we can and should allocate the int statically. Small caveat: watch out for #29068.

@Skarlso
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Skarlso commented Feb 27, 2019

Hi @josharian! Can I help?

@josharian
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Go for it. You'll be looking at sinit.go. It's not particularly clear code, even by compiler standards. I recommend writing yourself a few simplified examples to work off of.

@Skarlso
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Skarlso commented Feb 27, 2019

Sounds lovely. :D But at least I'll learn while trying to figure it out. Which is always good. :)

@Skarlso
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Skarlso commented Mar 17, 2019

Picking this up now. Sorry, was pre-occupied with another issue on packages. :)

@andybons andybons modified the milestones: Go1.13, Go1.14 Jul 8, 2019
@rsc rsc modified the milestones: Go1.14, Backlog Oct 9, 2019
@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Jul 13, 2022
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compiler/runtime Issues related to the Go compiler and/or runtime. NeedsFix The path to resolution is known, but the work has not been done. Performance
Projects
Go Compiler / Runtime
Status: Triage Backlog
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Backlog
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@josharian @rsc @Skarlso @andybons @randall77 @gopherbot