This CL changes GOEXPERIMENT=unified to insert implicit conversions
for multi-valued expressions.
Unfortunately, IR doesn't have strong, first-class support for
multi-valued expressions, so this CL takes the approach of spilling
them to temporary variables, which can then be implicitly converted.
This is the same approach taken by walk, but doing it this early does
introduce some minor complications:
1. For select case clauses with comma-ok assignments (e.g., `case x,
ok := <-ch:`), the compiler middle end wants to see the OAS2RECV
assignment is the CommClause.Comm statement. So when constructing
select statements, we need to massage this around a little.
2. The extra temporary variables and assignments skew the existing
inlining heuristics. As mentioned, the temporaries/assignments will
eventually be added (and often optimized away again) anyway, but now
they're visible to the inliner. So this CL also kludges the inlining
heuristics in this case to keep things comparable.
Change-Id: I3e3ea756ad92472ebe28bae3963be61ed7684a75
Reviewed-on: https://go-review.googlesource.com/c/go/+/415244
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
The assignment `sink, *(&ok) = y.(int)` should (and does) escape a
value to the heap, but this detail is missed because the implicit
conversion of the multi-value expression `y.(int)` isn't visible to
escape analysis (because it's not inserted until desugaring during
walk).
For Unified IR, I plan to apply this desugaring earlier (because it's
necessary for correct dictionary handling), which means we'll
now (correctly) report the heap escape.
Due to limitations of the $GOROOT/test harness, the easiest way to
handle that GOEXPERIMENT=unified gets this right while
GOEXPERIMENT=nounified does not is to split the test case into
separate files. Hence this CL.
Change-Id: I91f3a6c015cbc646ab018747e152cac2874cf24c
Reviewed-on: https://go-review.googlesource.com/c/go/+/415241
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
