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Finally figured out how to deal with the interaction between generics
and inlining. The problem has been: what to do if you inline a function
that uses a new instantiated type that hasn't been seen in the current
package? This might mean that you need to do another round of
function/method instantiatiations after inlining, which might lead to
more inlining, etc. (which is what we currently do, but it's not clear
when you can stop the inlining/instantiation loop).
We had thought that one solution was to export instantiated types (even
if not marked as exportable) if they are referenced in exported
inlineable functions. But that was quite complex and required changing
the export format. But I realized that we really only need to make sure
the relevant dictionaries and shape instantiations for the instantiated
types are exported, not the instantiated type itself and its wrappers.
The instantiated type is naturally created as needed, and the wrappers
are generated automatically while writing out run-time type (making use
of the exported dictionaries and shape instantiations).
So, we just have to make sure that those dictionaries and shape
instantiations are exported, and then they will be available without any
extra round of instantiations after inlining. We now do this in
crawler.go. This is especially needed when the instantiated type is only
put in an interface, so relevant dictionaries/shape instantiations are
not directly referenced and therefore exported, but are still needed for
the itab.
This fix avoids the phase ordering problem where we might have to keep
creating new type instantiations and instantiated methods after each
round of inlining we do.
Removed the extra round of instantiation/inlining that were added in the
previous fix. The existing tests
test/typeparam{geninline.go,structinit.go} already test this situation
of inlining a function referencing a new instantiated type.
Added the original example from issue 50121 as test (has 5 packages),
since it found a problem with this code that the current simpler test
for 50121 did not find.
Change-Id: Iac5d0dddf4be19376f6de36ee20a83f0d8f213b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/375494
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
8 lines
192 B
Go
8 lines
192 B
Go
// rundir -G=3
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ignored
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