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cmd/compile: getcallerpc ought to be intrinsified #17327

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dr2chase opened this issue Oct 3, 2016 · 6 comments
Closed

cmd/compile: getcallerpc ought to be intrinsified #17327

dr2chase opened this issue Oct 3, 2016 · 6 comments
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early-in-cycle A change that should be done early in the 3 month dev cycle. FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. Performance
Milestone
Go1.10

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@dr2chase
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dr2chase commented Oct 3, 2016

Reasons:

  • getcallerpc gets called in many places; even in assembly language, a call is a call
  • the compiler has a pretty good idea of where it put the caller's PC.
  • taking the address of the first parameter reduces opportunities for optimization somewhat, though of course SSA could be smarter about noescape functions.
  • relying on the first parameter having an address in the caller's frame with a firm relationship to the saved return PC locks down our existing calling conventions; there are other obstacles to changing them and we might not change this part of them, but it's not a feature.
@crawshaw
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crawshaw commented Oct 3, 2016

getcallerpc is on the entersyscall critical path so it may have positive effects on unexpected benchmarks.

@quentinmit quentinmit changed the title getcallerpc ought to be intrinsified cmd/compile: getcallerpc ought to be intrinsified Oct 3, 2016
@quentinmit quentinmit added the NeedsFix The path to resolution is known, but the work has not been done. label Oct 3, 2016
@quentinmit quentinmit added this to the Go1.8 milestone Oct 3, 2016
@rsc
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rsc commented Oct 21, 2016

If you want to do this for Go 1.8, please do it soon.

@cherrymui
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getcallerpc currently has stack barrier logic in it. Maybe do it after removing stack barrier?

@dr2chase
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This looks iffy for 1.8, but I'll see.

@mdempsky mdempsky self-assigned this Oct 26, 2016
@mdempsky mdempsky modified the milestones: Go1.9, Go1.8 Nov 1, 2016
@navytux navytux mentioned this issue Mar 15, 2017
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@josharian
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Definitely missed the 1.9 window on this. Marking 1.10Early.

@josharian josharian modified the milestones: Go1.10Early, Go1.9 May 17, 2017
@bradfitz bradfitz added early-in-cycle A change that should be done early in the 3 month dev cycle. and removed early-in-cycle A change that should be done early in the 3 month dev cycle. labels Jun 14, 2017
@bradfitz bradfitz modified the milestones: Go1.10Early, Go1.10 Jun 14, 2017
@gopherbot
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Change https://golang.org/cl/31851 mentions this issue: cmd/compile: add intrinsic for reading caller's pc

@golang golang locked and limited conversation to collaborators Sep 22, 2018
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early-in-cycle A change that should be done early in the 3 month dev cycle. FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. Performance
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Go1.10
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@bradfitz @mdempsky @josharian @rsc @quentinmit @crawshaw @dr2chase @gopherbot @cherrymui