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cmd/compile: stack allocation phase in large functions slows down SSA compiler #14775
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I'd like to push this off to 1.8; it's a hard problem, and we've made other progress for the pathological functions that trigger this:
and we have two more CLs queued up for 1.8 ( or possibly 1.7 if sufficiently horrible inputs appear) that will help some more:
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@randall77 @dr2chase Please change the milestone to Go1.8 if you're satisfied with what's already in 1.7. |
@dr2chase, what's the status of this? It's marked "Go1.8Early". |
Very little work on the stack allocation code, and instead we beat on the more tractable problem of SSA phi-function placement -- one of the 1.8early changes went into 1.7late because of a horrifying compilation problem there: https://go-review.googlesource.com/c/23136/ I took at stab at this once and didn't get it right. I'd guess that it's a least a week's work if I'm lucky, probably two. |
Tip is now faster than 1.6 (3.5 sec for 1.6, 3.2 sec for tip). Closing. |
Please answer these questions before submitting your issue. Thanks!
go version
)?devel for 1.7
go env
)?amd64
Downloaded Dave Cheney's genpkg to explore performance problems.
with results
Not that much slowdown and memory consumption.
Much slowdown and memory consumption.
Note that two similar bugs are filed, one against the ssa.go variable lookup code, the other against regalloc/stackalloc, since the fixes are independent.
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