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Josh Bleecher Snyder 9e619739fd cmd/compile: copy all fields during SubstAny
Consider these functions:

func f(a any) int
func g(a any) int

Prior to this change, since f and g have identical signatures,
they would share a single generated func type.

types.SubstAny makes a shallow type copy, even after instantiation,
f and g share a single generated Result type.
So if you instantiate f with any=T, call dowidth,
instantiate g with any=U, and call dowidth,
and if sizeof(T) != sizeof(U),
then the Offset of the result for f is now wrong.

I don't believe this happens at all right now, but it bit me hard when
experimenting with some other compiler changes.
And it's hard to debug. It results in rare stack corruption, causing
problems far from the actual source of the problem.

To fix this, change SubstAny to make deep copies of TSTRUCTs.

name        old alloc/op      new alloc/op      delta
Template         35.3MB ± 0%       35.4MB ± 0%  +0.23%  (p=0.008 n=5+5)
Unicode          29.1MB ± 0%       29.1MB ± 0%  +0.16%  (p=0.008 n=5+5)
GoTypes           122MB ± 0%        122MB ± 0%  +0.16%  (p=0.008 n=5+5)
Compiler          513MB ± 0%        514MB ± 0%  +0.19%  (p=0.008 n=5+5)
SSA              1.94GB ± 0%       1.94GB ± 0%  +0.01%  (p=0.008 n=5+5)
Flate            24.2MB ± 0%       24.2MB ± 0%  +0.08%  (p=0.008 n=5+5)
GoParser         28.5MB ± 0%       28.5MB ± 0%  +0.24%  (p=0.008 n=5+5)
Reflect          86.2MB ± 0%       86.3MB ± 0%  +0.09%  (p=0.008 n=5+5)
Tar              34.9MB ± 0%       34.9MB ± 0%  +0.13%  (p=0.008 n=5+5)
XML              47.0MB ± 0%       47.1MB ± 0%  +0.18%  (p=0.008 n=5+5)
[Geo mean]       80.9MB            81.0MB       +0.15%

name        old allocs/op     new allocs/op     delta
Template           348k ± 0%         349k ± 0%  +0.38%  (p=0.008 n=5+5)
Unicode            340k ± 0%         340k ± 0%  +0.21%  (p=0.008 n=5+5)
GoTypes           1.27M ± 0%        1.28M ± 0%  +0.27%  (p=0.008 n=5+5)
Compiler          4.90M ± 0%        4.92M ± 0%  +0.36%  (p=0.008 n=5+5)
SSA               15.3M ± 0%        15.3M ± 0%  +0.03%  (p=0.008 n=5+5)
Flate              232k ± 0%         233k ± 0%  +0.14%  (p=0.008 n=5+5)
GoParser           291k ± 0%         292k ± 0%  +0.42%  (p=0.008 n=5+5)
Reflect           1.05M ± 0%        1.05M ± 0%  +0.14%  (p=0.008 n=5+5)
Tar                343k ± 0%         344k ± 0%  +0.22%  (p=0.008 n=5+5)
XML                428k ± 0%         430k ± 0%  +0.36%  (p=0.008 n=5+5)
[Geo mean]         807k              809k       +0.25%

Change-Id: I62134db642206cded01920dc1d8a7da61f7ca0ac
Reviewed-on: https://go-review.googlesource.com/c/147038
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2018-11-05 23:12:50 +00:00
.github .github: don't render author-facing text in ISSUE_TEMPLATE 2018-11-02 04:47:34 +00:00
api syscall: FreeBSD 12 ino64 support 2018-10-05 21:38:13 +00:00
doc doc: document Go 1.10.5 2018-11-02 19:43:46 +00:00
lib/time lib/time: update vendored tzdata to release 2018e 2018-06-11 14:47:06 +00:00
misc cmd/cgo: accept expressions as untyped constants 2018-11-02 19:28:58 +00:00
src cmd/compile: copy all fields during SubstAny 2018-11-05 23:12:50 +00:00
test test: add test that gccgo failed to compile 2018-11-05 20:54:58 +00:00
.gitattributes
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: add VMware as author, Venil Noronha as contributor 2018-08-31 02:14:24 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: add VMware as author, Venil Noronha as contributor 2018-08-31 02:14:24 +00:00
favicon.ico website: recreate 16px and 32px favicon 2016-08-25 15:43:32 +00:00
LICENSE
PATENTS
README.md README: linkify some paths 2018-06-06 18:07:01 +00:00
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