[release-branch.go1.3] cmd/gc: two escape analysis fixes
««« CL
108860043 /
f153208c0a0e
cmd/gc: fix escape analysis for &x inside switch x := v.(type)
The analysis for &x was using the loop depth on x set
during x's declaration. A type switch creates a list of
implicit declarations that were not getting initialized
with loop depths.
Fixes #8176.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/
108860043
»»»
««« CL
108870044 /
331dbd4a6334
cmd/gc: fix &result escaping into result
There is a hierarchy of location defined by loop depth:
-1 = the heap
0 = function results
1 = local variables (and parameters)
2 = local variable declared inside a loop
3 = local variable declared inside a loop inside a loop
etc
In general if an address from loopdepth n is assigned to
something in loop depth m < n, that indicates an extended
lifetime of some form that requires a heap allocation.
Function results can be local variables too, though, and so
they don't actually fit into the hierarchy very well.
Treat the address of a function result as level 1 so that
if it is written back into a result, the address is treated
as escaping.
Fixes issue 8185 .
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/
108870044
»»»
LGTM=r
R=golang-codereviews, r
CC=bradfitz, golang-codereviews, iant
https://golang.org/cl/
107930044