// Remove and return a potential pointer to a stack object.
// Returns 0 if there are no more pointers available.
//
// This prefers non-conservative pointers so we scan stack objects
// precisely if there are any non-conservative pointers to them.
func (s *stackScanState) getPtr() (p uintptr, conservative bool) {
	for _, head := range []**stackWorkBuf{&s.buf, &s.cbuf} {
		buf := *head
		if buf == nil {
			// Never had any data.

// to make as many tranposes redudant as possible, we can "push" transposes
// back so that they fuse later on. These patterns handles 2 such cases in
// a conservative fashion; on-net it will never add to the number of transposes
// in the graph.

// ewise(tpose(x), tpose(y)) -> tpose(ewise(x, y))
//    iff tpose(x) or tpose(y) has one use and have same permutation.
//

  return result;
}

bool MayCallFunction(const Node& n, const FunctionLibraryDefinition* flib_def) {
  if (flib_def->Contains(n.type_string())) {
    return true;
  }

  // This is a conservative check: there may be nodes with a `func`
  // attribute that do not make function calls.
  return absl::c_any_of(n.def().attr(),
                        [](const std::pair<string, AttrValue>& name_attr_pair) {

	// (4) Attribute value selectors as in a[href="http://example.com/"]
	//
	// We conservatively treat all strings as URLs, but make some
	// allowances to avoid confusion.
	//
	// In (1), our conservative assumption is justified.
	// In (2), valid font names do not contain ':', '?', or '#', so our
	// conservative assumption is fine since we will never transition past
	// urlPartPreQuery.

			pos = t.obj.pos
		}
		check.indent++
		check.trace(pos, "validType(%s) nest %v, path %v", typ, pathString(makeObjList(nest)), pathString(makeObjList(path)))
		defer func() {
			check.indent--
		}()
	}

	switch t := typ.(type) {
	case nil:
		// We should never see a nil type but be conservative and panic
		// only in debug mode.
		if debug {

			pos = t.obj.pos
		}
		check.indent++
		check.trace(pos, "validType(%s) nest %v, path %v", typ, pathString(makeObjList(nest)), pathString(makeObjList(path)))
		defer func() {
			check.indent--
		}()
	}

	switch t := typ.(type) {
	case nil:
		// We should never see a nil type but be conservative and panic
		// only in debug mode.
		if debug {

func (a *addrRanges) add(r addrRange) {
	// The copies in this function are potentially expensive, but this data
	// structure is meant to represent the Go heap. At worst, copying this
	// would take ~160µs assuming a conservative copying rate of 25 GiB/s (the
	// copy will almost never trigger a page fault) for a 1 TiB heap with 4 MiB
	// arenas which is completely discontiguous. ~160µs is still a lot, but in

                 << "); this could lead to overly conservative execution order";
    // Note: By not incrementing `resource_type_id` we still maintain
    // correctness, we might only handle different resource types as the same
    // type (for ID `kMaxResourceTypeId`) which is overly conservative.
  } else {
    ++resource_type_id;
  }
}

// as meaning "read more flags from the file foo", so we must
// guard against any command-line argument beginning with @,
// even things like "-I @foo".
// We use load.SafeArg (which is even more conservative)
// to reject these.
//
// Even worse, gcc -I@foo (one arg) turns into cc1 -I @foo (two args),
// so although gcc doesn't expand the @foo, cc1 will.
// So out of paranoia, we reject @ at the beginning of every

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