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go/test/escape_struct_param1.go

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cmd/internal/gc: improve flow of input params to output params This includes the following information in the per-function summary: outK = paramJ encoded in outK bits for paramJ outK = *paramJ encoded in outK bits for paramJ heap = paramJ EscHeap heap = *paramJ EscContentEscapes Note that (currently) if the address of a parameter is taken and returned, necessarily a heap allocation occurred to contain that reference, and the heap can never refer to stack, therefore the parameter and everything downstream from it escapes to the heap. The per-function summary information now has a tuneable number of bits (2 is probably noticeably better than 1, 3 is likely overkill, but it is now easy to check and the -m debugging output includes information that allows you to figure out if more would be better.) A new test was added to check pointer flow through struct-typed and *struct-typed parameters and returns; some of these are sensitive to the number of summary bits, and ought to yield better results with a more competent escape analysis algorithm. Another new test checks (some) correctness with array parameters, results, and operations. The old analysis inferred a piece of plan9 runtime was non-escaping by counteracting overconservative analysis with buggy analysis; with the bug fixed, the result was too conservative (and it's not easy to fix in this framework) so the source code was tweaked to get the desired result. A test was added against the discovered bug. The escape analysis was further improved splitting the "level" into 3 parts, one tracking the conventional "level" and the other two computing the highest-level-suffix-from-copy, which is used to generally model the cancelling effect of indirection applied to address-of. With the improved escape analysis enabled, it was necessary to modify one of the runtime tests because it now attempts to allocate too much on the (small, fixed-size) G0 (system) stack and this failed the test. Compiling src/std after touching src/runtime/*.go with -m logging turned on shows 420 fewer heap allocation sites (10538 vs 10968). Profiling allocations in src/html/template with for i in {1..5} ; do go tool 6g -memprofile=mastx.${i}.prof -memprofilerate=1 *.go; go tool pprof -alloc_objects -text mastx.${i}.prof ; done showed a 15% reduction in allocations performed by the compiler. Update #3753 Update #4720 Fixes #10466 Change-Id: I0fd97d5f5ac527b45f49e2218d158a6e89951432 Reviewed-on: https://go-review.googlesource.com/8202 Run-TryBot: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
2015-03-26 14:36:15 -06:00
// errorcheck -0 -m -l
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Test escape analysis for *struct function parameters.
// Note companion strict_param2 checks struct function parameters with similar tests.
package notmain
var Ssink *string
type U struct {
_sp *string
_spp **string
}
type V struct {
_u U
_up *U
_upp **U
}
func (u *U) SP() *string { // ERROR "leaking param: u to result ~r0 level=1$"
return u._sp
}
func (u *U) SPP() **string { // ERROR "leaking param: u to result ~r0 level=1$"
return u._spp
}
func (u *U) SPPi() *string { // ERROR "leaking param: u to result ~r0 level=2$"
return *u._spp
}
func tSPPi() {
s := "cat" // ERROR "moved to heap: s$"
ps := &s // ERROR "&s escapes to heap$"
pps := &ps // ERROR "tSPPi &ps does not escape$"
pu := &U{ps, pps} // ERROR "tSPPi &U literal does not escape$"
Ssink = pu.SPPi()
}
func tiSPP() {
s := "cat" // ERROR "moved to heap: s$"
ps := &s // ERROR "&s escapes to heap$"
pps := &ps // ERROR "tiSPP &ps does not escape$"
pu := &U{ps, pps} // ERROR "tiSPP &U literal does not escape$"
Ssink = *pu.SPP()
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of ps
func tSP() {
s := "cat" // ERROR "moved to heap: s$"
ps := &s // ERROR "&s escapes to heap$" "moved to heap: ps$"
pps := &ps // ERROR "&ps escapes to heap$"
pu := &U{ps, pps} // ERROR "tSP &U literal does not escape$"
Ssink = pu.SP()
}
func (v *V) u() U { // ERROR "leaking param: v to result ~r0 level=1$"
return v._u
}
func (v *V) UP() *U { // ERROR "leaking param: v to result ~r0 level=1$"
return v._up
}
func (v *V) UPP() **U { // ERROR "leaking param: v to result ~r0 level=1$"
return v._upp
}
func (v *V) UPPia() *U { // ERROR "leaking param: v to result ~r0 level=2$"
return *v._upp
}
func (v *V) UPPib() *U { // ERROR "leaking param: v to result ~r0 level=2$"
return *v.UPP()
}
func (v *V) USPa() *string { // ERROR "leaking param: v to result ~r0 level=1$"
return v._u._sp
}
func (v *V) USPb() *string { // ERROR "leaking param: v to result ~r0 level=1$"
return v.u()._sp
}
func (v *V) USPPia() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return *v._u._spp
}
func (v *V) USPPib() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v._u.SPPi() // ERROR "\(\*V\).USPPib v._u does not escape$"
}
func (v *V) UPiSPa() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v._up._sp
}
func (v *V) UPiSPb() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v._up.SP()
}
func (v *V) UPiSPc() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v.UP()._sp
}
func (v *V) UPiSPd() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v.UP().SP()
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s3
func tUPiSPa() {
s1 := "ant"
s2 := "bat" // ERROR "moved to heap: s2$"
s3 := "cat" // ERROR "moved to heap: s3$"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "&s2 escapes to heap$"
ps4 := &s4 // ERROR "&s4 escapes to heap$" "moved to heap: ps4$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPa &ps2 does not escape$" "tUPiSPa &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "&ps4 escapes to heap$" "&s3 escapes to heap$" "tUPiSPa &U literal does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&U literal escapes to heap$" "&ps6 escapes to heap$" "&s5 escapes to heap$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPa &V literal does not escape$" "tUPiSPa &u3 does not escape$"
Ssink = v.UPiSPa() // Ssink = &s3 (only &s3 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s3
func tUPiSPb() {
s1 := "ant"
s2 := "bat" // ERROR "moved to heap: s2$"
s3 := "cat" // ERROR "moved to heap: s3$"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "&s2 escapes to heap$"
ps4 := &s4 // ERROR "&s4 escapes to heap$" "moved to heap: ps4$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPb &ps2 does not escape$" "tUPiSPb &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "&ps4 escapes to heap$" "&s3 escapes to heap$" "tUPiSPb &U literal does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&U literal escapes to heap$" "&ps6 escapes to heap$" "&s5 escapes to heap$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPb &V literal does not escape$" "tUPiSPb &u3 does not escape$"
Ssink = v.UPiSPb() // Ssink = &s3 (only &s3 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s3
func tUPiSPc() {
s1 := "ant"
s2 := "bat" // ERROR "moved to heap: s2$"
s3 := "cat" // ERROR "moved to heap: s3$"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "&s2 escapes to heap$"
ps4 := &s4 // ERROR "&s4 escapes to heap$" "moved to heap: ps4$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPc &ps2 does not escape$" "tUPiSPc &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "&ps4 escapes to heap$" "&s3 escapes to heap$" "tUPiSPc &U literal does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&U literal escapes to heap$" "&ps6 escapes to heap$" "&s5 escapes to heap$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPc &V literal does not escape$" "tUPiSPc &u3 does not escape$"
Ssink = v.UPiSPc() // Ssink = &s3 (only &s3 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s3
func tUPiSPd() {
s1 := "ant"
s2 := "bat" // ERROR "moved to heap: s2$"
s3 := "cat" // ERROR "moved to heap: s3$"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "&s2 escapes to heap$"
ps4 := &s4 // ERROR "&s4 escapes to heap$" "moved to heap: ps4$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPd &ps2 does not escape$" "tUPiSPd &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "&ps4 escapes to heap$" "&s3 escapes to heap$" "tUPiSPd &U literal does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&U literal escapes to heap$" "&ps6 escapes to heap$" "&s5 escapes to heap$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPd &V literal does not escape$" "tUPiSPd &u3 does not escape$"
Ssink = v.UPiSPd() // Ssink = &s3 (only &s3 really escapes)
}
func (v V) UPiSPPia() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return *v._up._spp
}
func (v V) UPiSPPib() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v._up.SPPi()
}
func (v V) UPiSPPic() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return *v.UP()._spp // ERROR "V.UPiSPPic v does not escape$"
}
func (v V) UPiSPPid() *string { // ERROR "leaking param: v to result ~r0 level=2$"
return v.UP().SPPi() // ERROR "V.UPiSPPid v does not escape$"
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s4
func tUPiSPPia() {
s1 := "ant"
s2 := "bat"
s3 := "cat"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "tUPiSPPia &s2 does not escape$"
ps4 := &s4 // ERROR "&s4 escapes to heap$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPPia &ps2 does not escape$" "tUPiSPPia &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "tUPiSPPia &U literal does not escape$" "tUPiSPPia &ps4 does not escape$" "tUPiSPPia &s3 does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&ps6 escapes to heap$" "&s5 escapes to heap$" "tUPiSPPia &U literal does not escape$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPPia &V literal does not escape$" "tUPiSPPia &u3 does not escape$"
Ssink = v.UPiSPPia() // Ssink = *&ps4 = &s4 (only &s4 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s4
func tUPiSPPib() {
s1 := "ant"
s2 := "bat"
s3 := "cat"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "tUPiSPPib &s2 does not escape$"
ps4 := &s4 // ERROR "&s4 escapes to heap$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPPib &ps2 does not escape$" "tUPiSPPib &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "tUPiSPPib &U literal does not escape$" "tUPiSPPib &ps4 does not escape$" "tUPiSPPib &s3 does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&ps6 escapes to heap$" "&s5 escapes to heap$" "tUPiSPPib &U literal does not escape$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPPib &V literal does not escape$" "tUPiSPPib &u3 does not escape$"
Ssink = v.UPiSPPib() // Ssink = *&ps4 = &s4 (only &s4 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s4
func tUPiSPPic() {
s1 := "ant"
s2 := "bat"
s3 := "cat"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "tUPiSPPic &s2 does not escape$"
ps4 := &s4 // ERROR "&s4 escapes to heap$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPPic &ps2 does not escape$" "tUPiSPPic &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "tUPiSPPic &U literal does not escape$" "tUPiSPPic &ps4 does not escape$" "tUPiSPPic &s3 does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&ps6 escapes to heap$" "&s5 escapes to heap$" "tUPiSPPic &U literal does not escape$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPPic &V literal does not escape$" "tUPiSPPic &u3 does not escape$"
Ssink = v.UPiSPPic() // Ssink = *&ps4 = &s4 (only &s4 really escapes)
}
// BAD: need fine-grained (field-sensitive) analysis to avoid spurious escape of all but &s4
func tUPiSPPid() {
s1 := "ant"
s2 := "bat"
s3 := "cat"
s4 := "dog" // ERROR "moved to heap: s4$"
s5 := "emu" // ERROR "moved to heap: s5$"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "tUPiSPPid &s2 does not escape$"
ps4 := &s4 // ERROR "&s4 escapes to heap$"
ps6 := &s6 // ERROR "&s6 escapes to heap$" "moved to heap: ps6$"
u1 := U{&s1, &ps2} // ERROR "tUPiSPPid &ps2 does not escape$" "tUPiSPPid &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "tUPiSPPid &U literal does not escape$" "tUPiSPPid &ps4 does not escape$" "tUPiSPPid &s3 does not escape$"
u3 := &U{&s5, &ps6} // ERROR "&ps6 escapes to heap$" "&s5 escapes to heap$" "tUPiSPPid &U literal does not escape$"
v := &V{u1, u2, &u3} // ERROR "tUPiSPPid &V literal does not escape$" "tUPiSPPid &u3 does not escape$"
Ssink = v.UPiSPPid() // Ssink = *&ps4 = &s4 (only &s4 really escapes)
}
func (v *V) UPPiSPPia() *string { // ERROR "leaking param: v to result ~r0 level=4$"
return *(*v._upp)._spp
}
// This test isolates the one value that needs to escape, not because
// it distinguishes fields but because it knows that &s6 is the only
// value reachable by two indirects from v.
// The test depends on the level cap in the escape analysis tags
// being able to encode that fact.
func tUPPiSPPia() {
s1 := "ant"
s2 := "bat"
s3 := "cat"
s4 := "dog"
s5 := "emu"
s6 := "fox" // ERROR "moved to heap: s6$"
ps2 := &s2 // ERROR "tUPPiSPPia &s2 does not escape$"
ps4 := &s4 // ERROR "tUPPiSPPia &s4 does not escape$"
ps6 := &s6 // ERROR "&s6 escapes to heap$"
u1 := U{&s1, &ps2} // ERROR "tUPPiSPPia &ps2 does not escape$" "tUPPiSPPia &s1 does not escape$"
u2 := &U{&s3, &ps4} // ERROR "tUPPiSPPia &U literal does not escape$" "tUPPiSPPia &ps4 does not escape$" "tUPPiSPPia &s3 does not escape$"
u3 := &U{&s5, &ps6} // ERROR "tUPPiSPPia &U literal does not escape$" "tUPPiSPPia &ps6 does not escape$" "tUPPiSPPia &s5 does not escape$"
v := &V{u1, u2, &u3} // ERROR "tUPPiSPPia &V literal does not escape$" "tUPPiSPPia &u3 does not escape$"
Ssink = v.UPPiSPPia() // Ssink = *&ps6 = &s6 (only &s6 really escapes)
}
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