diff options
author | Russ Cox <rsc@golang.org> | 2014-06-11 17:00:17 -0400 |
---|---|---|
committer | Russ Cox <rsc@golang.org> | 2014-06-11 17:00:17 -0400 |
commit | d77639d287bafeaa77f7687514bb946cbc801472 (patch) | |
tree | 0c4797e2f40e09823ce3a835c2f9af033190d665 | |
parent | d04c3728c80df739eb0a59566f75ebe265ed8d69 (diff) | |
download | go-d77639d287bafeaa77f7687514bb946cbc801472.tar.gz |
[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 issue 8176.
LGTM=iant
R=iant
CC=golang-codereviews
https://codereview.appspot.com/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://codereview.appspot.com/108870044
???
LGTM=r
R=golang-codereviews, r
CC=bradfitz, golang-codereviews, iant
https://codereview.appspot.com/107930044
-rw-r--r-- | src/cmd/gc/esc.c | 27 | ||||
-rw-r--r-- | test/escape2.go | 22 |
2 files changed, 47 insertions, 2 deletions
diff --git a/src/cmd/gc/esc.c b/src/cmd/gc/esc.c index a75517813..78624d7cb 100644 --- a/src/cmd/gc/esc.c +++ b/src/cmd/gc/esc.c @@ -442,6 +442,18 @@ esc(EscState *e, Node *n, Node *up) if(n->op == OFOR || n->op == ORANGE) e->loopdepth++; + // type switch variables have no ODCL. + // process type switch as declaration. + // must happen before processing of switch body, + // so before recursion. + if(n->op == OSWITCH && n->ntest && n->ntest->op == OTYPESW) { + for(ll=n->list; ll; ll=ll->next) { // cases + // ll->n->nname is the variable per case + if(ll->n->nname) + ll->n->nname->escloopdepth = e->loopdepth; + } + } + esc(e, n->left, n); esc(e, n->right, n); esc(e, n->ntest, n); @@ -658,13 +670,24 @@ esc(EscState *e, Node *n, Node *up) // current loop depth is an upper bound on actual loop depth // of addressed value. n->escloopdepth = e->loopdepth; - // for &x, use loop depth of x. + // for &x, use loop depth of x if known. + // it should always be known, but if not, be conservative + // and keep the current loop depth. if(n->left->op == ONAME) { switch(n->left->class) { case PAUTO: + if(n->left->escloopdepth != 0) + n->escloopdepth = n->left->escloopdepth; + break; case PPARAM: case PPARAMOUT: - n->escloopdepth = n->left->escloopdepth; + // PPARAM is loop depth 1 always. + // PPARAMOUT is loop depth 0 for writes + // but considered loop depth 1 for address-of, + // so that writing the address of one result + // to another (or the same) result makes the + // first result move to the heap. + n->escloopdepth = 1; break; } } diff --git a/test/escape2.go b/test/escape2.go index 8cb3b6df6..28251aa98 100644 --- a/test/escape2.go +++ b/test/escape2.go @@ -1468,3 +1468,25 @@ func foo152() { v := NewV(u) println(v) } + +// issue 8176 - &x in type switch body not marked as escaping + +func foo153(v interface{}) *int { // ERROR "leaking param: v" + switch x := v.(type) { + case int: // ERROR "moved to heap: x" + return &x // ERROR "&x escapes to heap" + } + panic(0) +} + +// issue 8185 - &result escaping into result + +func f() (x int, y *int) { // ERROR "moved to heap: x" + y = &x // ERROR "&x escapes to heap" + return +} + +func g() (x interface{}) { // ERROR "moved to heap: x" + x = &x // ERROR "&x escapes to heap" + return +} |