diff options
| -rw-r--r-- | gcc/go/gofrontend/MERGE | 2 | ||||
| -rw-r--r-- | libgo/go/runtime/mcentral.go | 9 | ||||
| -rw-r--r-- | libgo/go/runtime/mgcsweep.go | 38 | ||||
| -rw-r--r-- | libgo/go/runtime/runtime1.go | 19 |
4 files changed, 13 insertions, 55 deletions
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index 74577f5..b1a6579 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -85857977230437f2b3dcbeea009efbb8b2789039 +b0ba5daa8216a0424b24f74466cedab0b986f3b4 The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/libgo/go/runtime/mcentral.go b/libgo/go/runtime/mcentral.go index 0196ba4..a60eb9f 100644 --- a/libgo/go/runtime/mcentral.go +++ b/libgo/go/runtime/mcentral.go @@ -56,15 +56,6 @@ retry: c.empty.insertBack(s) unlock(&c.lock) s.sweep(true) - - // With gccgo's conservative GC, the returned span may - // now be full. See the comments in mspan.sweep. - if uintptr(s.allocCount) == s.nelems { - s.freeindex = s.nelems - lock(&c.lock) - goto retry - } - goto havespan } if s.sweepgen == sg-1 { diff --git a/libgo/go/runtime/mgcsweep.go b/libgo/go/runtime/mgcsweep.go index bc53de4..539a982 100644 --- a/libgo/go/runtime/mgcsweep.go +++ b/libgo/go/runtime/mgcsweep.go @@ -326,39 +326,16 @@ func (s *mspan) sweep(preserve bool) bool { freeToHeap = true } nfreed := s.allocCount - nalloc - - // This check is not reliable with gccgo, because of - // conservative stack scanning. The test boils down to - // checking that no new bits have been set in gcmarkBits since - // the span was added to the sweep count. New bits are set by - // greyobject. Seeing a new bit means that a live pointer has - // appeared that was not found during the mark phase. That can - // not happen when pointers are followed strictly. However, - // with conservative checking, it is possible for a pointer - // that will never be used to appear live and to cause a mark - // to be added. That is unfortunate in that it causes this - // check to be inaccurate, and it will keep an object live - // unnecessarily, but provided the pointer is not really live - // it is not otherwise a problem. So we disable the test for gccgo. - nfreedSigned := int(nfreed) if nalloc > s.allocCount { - if usestackmaps { - print("runtime: nelems=", s.nelems, " nalloc=", nalloc, " previous allocCount=", s.allocCount, " nfreed=", nfreed, "\n") - throw("sweep increased allocation count") - } - - // For gccgo, adjust the freed count as a signed number. - nfreedSigned = int(s.allocCount) - int(nalloc) - if uintptr(nalloc) == s.nelems { - s.freeindex = s.nelems - } + print("runtime: nelems=", s.nelems, " nalloc=", nalloc, " previous allocCount=", s.allocCount, " nfreed=", nfreed, "\n") + throw("sweep increased allocation count") } s.allocCount = nalloc wasempty := s.nextFreeIndex() == s.nelems s.freeindex = 0 // reset allocation index to start of span. if trace.enabled { - getg().m.p.ptr().traceReclaimed += uintptr(nfreedSigned) * s.elemsize + getg().m.p.ptr().traceReclaimed += uintptr(nfreed) * s.elemsize } // gcmarkBits becomes the allocBits. @@ -374,7 +351,7 @@ func (s *mspan) sweep(preserve bool) bool { // But we need to set it before we make the span available for allocation // (return it to heap or mcentral), because allocation code assumes that a // span is already swept if available for allocation. - if freeToHeap || nfreedSigned <= 0 { + if freeToHeap || nfreed == 0 { // The span must be in our exclusive ownership until we update sweepgen, // check for potential races. if s.state != mSpanInUse || s.sweepgen != sweepgen-1 { @@ -387,11 +364,8 @@ func (s *mspan) sweep(preserve bool) bool { atomic.Store(&s.sweepgen, sweepgen) } - if spc.sizeclass() != 0 { - c.local_nsmallfree[spc.sizeclass()] += uintptr(nfreedSigned) - } - - if nfreedSigned > 0 && spc.sizeclass() != 0 { + if nfreed > 0 && spc.sizeclass() != 0 { + c.local_nsmallfree[spc.sizeclass()] += uintptr(nfreed) res = mheap_.central[spc].mcentral.freeSpan(s, preserve, wasempty) // mcentral.freeSpan updates sweepgen } else if freeToHeap { diff --git a/libgo/go/runtime/runtime1.go b/libgo/go/runtime/runtime1.go index e2567b3..2424f20 100644 --- a/libgo/go/runtime/runtime1.go +++ b/libgo/go/runtime/runtime1.go @@ -352,19 +352,12 @@ func parsedebugvars() { // defaults debug.cgocheck = 1 - // Unfortunately, because gccgo uses conservative stack scanning, - // we can not enable invalid pointer checking. It is possible for - // memory block M1 to point to M2, and for both to be dead. - // We release M2, causing the entire span to be released. - // Before we release M1, a stack pointer appears that point into it. - // This stack pointer is presumably dead, but causes M1 to be marked. - // We scan M1 and see the pointer to M2 on a released span. - // At that point, if debug.invalidptr is set, we crash. - // This is not a problem, assuming that M1 really is dead and - // the pointer we discovered to it will not be used. - if usestackmaps { - debug.invalidptr = 1 - } + // Gccgo uses conservative stack scanning, so we cannot check + // invalid pointers on stack. But we can still enable invalid + // pointer check on heap scanning. When scanning the heap, we + // ensure that we only trace allocated heap objects, which should + // not contain invalid pointers. + debug.invalidptr = 1 for p := gogetenv("GODEBUG"); p != ""; { field := "" |