| commit | a0894ea5b5c326f1ddc7c4c6674d5858f8761dc8 | [log] [tgz] |
|---|---|---|
| author | Matthew Dempsky <mdempsky@google.com> | Thu Sep 26 17:21:50 2019 -0700 |
| committer | Matthew Dempsky <mdempsky@google.com> | Mon Oct 07 18:50:14 2019 +0000 |
| tree | a31830cdd8398f774fd26a4a502d66d1eda2725f | |
| parent | 05a805a6de9c1b49ee1d5d55589a119cae5ab556 [diff] |
cmd/compile: reimplement parameter leak encoding
Currently, escape analysis is able to record at most one dereference
when a parameter leaks to the heap; that is, at call sites, it can't
distinguish between any of these three functions:
func x1(p ****int) { sink = *p }
func x2(p ****int) { sink = **p }
func x3(p ****int) { sink = ***p }
Similarly, it's limited to recording parameter leaks to only the first
4 parameters, and only up to 6 dereferences.
All of these limitations are due to the awkward encoding scheme used
at the moment.
This CL replaces the encoding scheme with a simple [8]uint8 array,
which can handle up to the first 7 parameters, and up to 254
dereferences, which ought to be enough for anyone. And if not, it's
much more easily increased.
Shrinks export data size geometric mean for Kubernetes by 0.07%.
Fixes #33981.
Change-Id: I10a94b9accac9a0c91490e0d6d458316f5ca1e13
Reviewed-on: https://go-review.googlesource.com/c/go/+/197680
Reviewed-by: Cherry Zhang <cherryyz@google.com>
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