The new escape analysis implementation tries to emit debugging
diagnostics that are compatible with the existing implementation, but
there's a handful of cases that are easier to handle by updating the
test expectations instead.
For regress tests that need updating, the original file is copied to
oldescapeXXX.go.go with -newescape=false added to the //errorcheck
line, while the file is updated in place with -newescape=true and new
test requirements.
Notable test changes:
1) escape_because.go looks for a lot of detailed internal debugging
messages that are fairly particular to how esc.go works and that I
haven't attempted to port over to escape.go yet.
2) There are a lot of "leaking param: x to result ~r1 level=-1"
messages for code like
func(p *int) *T { return &T{p} }
that were simply wrong. Here &T must be heap allocated unconditionally
(because it's being returned); and since p is stored into it, p
escapes unconditionally too. esc.go incorrectly reports that p escapes
conditionally only if the returned pointer escaped.
3) esc.go used to print each "leaking param" analysis result as it
discovered them, which could lead to redundant messages (e.g., that a
param leaks at level=0 and level=1). escape.go instead prints
everything at the end, once it knows the shortest path to each sink.
4) esc.go didn't precisely model direct-interface types, resulting in
some values unnecessarily escaping to the heap when stored into
non-escaping interface values.
5) For functions written in assembly, esc.go only printed "does not
escape" messages, whereas escape.go prints "does not escape" or
"leaking param" as appropriate, consistent with the behavior for
functions written in Go.
6) 12 tests included "BAD" annotations identifying cases where esc.go
was unnecessarily heap allocating something. These are all fixed by
escape.go.
Updates #23109.
Change-Id: Iabc9eb14c94c9cadde3b183478d1fd54f013502f
Reviewed-on: https://go-review.googlesource.com/c/go/+/170447
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
For most nodes (e.g., OPTRLIT, OMAKESLICE, OCONVIFACE), escape
analysis prints "escapes to heap" or "does not escape" to indicate
whether that node's allocation can be heap or stack allocated.
These messages are also emitted for OADDR, even though OADDR does not
actually allocate anything itself. Moreover, it's redundant because
escape analysis already prints "moved to heap" diagnostics when an
OADDR node like "&x" causes x to require heap allocation.
Because OADDR nodes don't allocate memory, my escape analysis rewrite
doesn't naturally emit the "escapes to heap" / "does not escape"
diagnostics for them. It's also non-trivial to replicate the exact
semantics esc.go uses for OADDR.
Since there are so many of these messages, I'm disabling them in this
CL by themselves. I modified esc.go to suppress the Warnl calls
without any other behavior changes, and then used a shell script to
automatically remove any ERROR messages mentioned by run.go in
"missing error" or "no match for" lines.
Fixes#16300.
Updates #23109.
Change-Id: I3993e2743c3ff83ccd0893f4e73b366ff8871a57
Reviewed-on: https://go-review.googlesource.com/c/go/+/170319
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Consider the following code:
func f(x []*T) interface{} {
return x
}
It returns an interface that holds a heap copy of x (by calling
convT2I or friend), therefore x escape to heap. The current
escape analysis only recognizes that x flows to the result. This
is not sufficient, since if the result does not escape, x's
content may be stack allocated and this will result a
heap-to-stack pointer, which is bad.
Fix this by realizing that if a CONVIFACE escapes and we're
converting from a non-direct interface type, the data needs to
escape to heap.
Running "toolstash -cmp" on std & cmd, the generated machine code
are identical for all packages. However, the export data (escape
tags) differ in the following packages. It looks to me that all
are similar to the "f" above, where the parameter should escape
to heap.
io/ioutil/ioutil.go:118
old: leaking param: r to result ~r1 level=0
new: leaking param: r
image/image.go:943
old: leaking param: p to result ~r0 level=1
new: leaking param content: p
net/url/url.go:200
old: leaking param: s to result ~r2 level=0
new: leaking param: s
(as a consequence)
net/url/url.go:183
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:194
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:699
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:775
old: (*URL).String u does not escape
new: leaking param content: u
net/url/url.go:1038
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:1099
old: (*URL).MarshalBinary u does not escape
new: leaking param content: u
flag/flag.go:235
old: leaking param: s to result ~r0 level=1
new: leaking param content: s
go/scanner/errors.go:105
old: leaking param: p to result ~r0 level=0
new: leaking param: p
database/sql/sql.go:204
old: leaking param: ns to result ~r0 level=0
new: leaking param: ns
go/constant/value.go:303
old: leaking param: re to result ~r2 level=0, leaking param: im to result ~r2 level=0
new: leaking param: re, leaking param: im
go/constant/value.go:846
old: leaking param: x to result ~r1 level=0
new: leaking param: x
encoding/xml/xml.go:518
old: leaking param: d to result ~r1 level=2
new: leaking param content: d
encoding/xml/xml.go:122
old: leaking param: leaking param: t to result ~r1 level=0
new: leaking param: t
crypto/x509/verify.go:506
old: leaking param: c to result ~r8 level=0
new: leaking param: c
crypto/x509/verify.go:563
old: leaking param: c to result ~r3 level=0, leaking param content: c
new: leaking param: c
crypto/x509/verify.go:615
old: (nothing)
new: leaking closure reference c
crypto/x509/verify.go:996
old: leaking param: c to result ~r1 level=0, leaking param content: c
new: leaking param: c
net/http/filetransport.go:30
old: leaking param: fs to result ~r1 level=0
new: leaking param: fs
net/http/h2_bundle.go:2684
old: leaking param: mh to result ~r0 level=2
new: leaking param content: mh
net/http/h2_bundle.go:7352
old: http2checkConnHeaders req does not escape
new: leaking param content: req
net/http/pprof/pprof.go:221
old: leaking param: name to result ~r1 level=0
new: leaking param: name
cmd/internal/bio/must.go:21
old: leaking param: w to result ~r1 level=0
new: leaking param: w
Fixes#29353.
Change-Id: I7e7798ae773728028b0dcae5bccb3ada51189c68
Reviewed-on: https://go-review.googlesource.com/c/162829
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Chase <drchase@google.com>
File is compiled with "-l" flag, so go:noinline is redundant.
Change-Id: Ia269f3b9de9466857fc578ba5164613393e82369
Reviewed-on: https://go-review.googlesource.com/133295
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Make OAS2 and OAS2FUNC sink locations point to the assignment position,
not the nth LHS position.
Fixes#26987
Change-Id: Ibeb9df2da754da8b6638fe1e49e813f37515c13c
Reviewed-on: https://go-review.googlesource.com/129315
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The escape_because.go test file (which tests the "because" escape
explainations printed by `-m -m`) cointains a machine-generated list
of all the escape reasons seen in the escape tests.
The list appears to be outdated; moreove a new escape reason was added
in CL 102895. This change re-generates the list.
Change-Id: Idc721c6bbfe9516895b5cf1e6d09b77deda5a3dd
Reviewed-on: https://go-review.googlesource.com/103375
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change makes `-m -m` print a better explanation for the case
where a slice is marked as escaping and heap-allocated because it
has a non-constant len/cap.
Fixes#24578
Change-Id: I0ebafb77c758a99857d72b365817bdba7b446cc0
Reviewed-on: https://go-review.googlesource.com/102895
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
Sometimes neither the src nor the dst of an escape edge
contains the line number appropriate to the edge, so add
a field so that can be set correctly.
Also updated some of the explanations to be less jargon-y
and perhaps more informative, and folded bug example into
test.
Cleaned up some of the function/method names in esc.go
and did a quick sanity check that each "bundling" function
was actually called often enough to justify its existence.
Fixes#17459.
Change-Id: Ieba53ab0a6ba1f7a6c4962bc0b702ede9cc3a3cc
Reviewed-on: https://go-review.googlesource.com/31660
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This should probably be considered "experimental" at this stage, but
what it needs is feedback from adventurous adopters. I think the data
structure used for describing escape reasons might be extendable to
allow a cleanup of the underlying algorithms, which suffers from
insufficiently separated concerns (the graph does not deal well with
escape level adjustments, so it is augmented by a second custom-walk
portion of the "flood" phase. It would be better to put it all,
including level adjustments, in a single graph structure, and then
simply flood the graph.
Tweaked to avoid allocations in the no-logging case.
Modified run.go to ignore lines with leading "#" in the output (since
it can never match a line), and in -update_errors to ignore leading
tabs in output lines and to normalize embedded filenames.
Currently requires -m -m because otherwise the noise/update
burden for the other escape tests is considerable.
There is a partial test. Existing escape analysis tests seem to
cover all except the panic case and what looks like it might be
unreachable code in escape analysis.
Fixes#10526.
Change-Id: I2524fdec54facae48b00b2548e25d9e46fcaf832
Reviewed-on: https://go-review.googlesource.com/18041
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
