xpcom/tests/SizeTest01.cpp
author Doug Thayer <dothayer@mozilla.com>
Fri, 01 Mar 2019 18:29:09 +0000
changeset 520116 8b3fe0426ffc1b3a2ad044ef6cdde6c4f736f8e2
parent 507657 09c71a7cf75aeaf2963050e315276fb9a866fd62
permissions -rw-r--r--
Bug 1442694 - Fix failures due to removing selected tab r=Gijs This adds test which reproduce the failure as well as the fix. Essentially, if we hit the edited case in SessionStore with `tab` equal to `tabbrowser.tabs[t]`, we remove the tab and then try to pin it, which obviously blows up. Note: the additional method in SessionStore.jsm was largely to get around complexity requirements inside restoreWindow. Cleaner solutions welcome. Differential Revision: https://phabricator.services.mozilla.com/D21383

// Test01.cpp

#include "nsINode.h"
#include "nsCOMPtr.h"
#include "nsString.h"

NS_DEF_PTR(nsINode);

/*
        This test file compares the generated code size of similar functions
   between raw COM interface pointers (|AddRef|ing and |Release|ing by hand) and
   |nsCOMPtr|s.

        Function size results were determined by examining dissassembly of the
   generated code. mXXX is the size of the generated code on the Macintosh. wXXX
   is the size on Windows. For these tests, all reasonable optimizations were
   enabled and exceptions were disabled (just as we build for release).

        The tests in this file explore only the simplest functionality:
   assigning a pointer to be reference counted into a [raw, nsCOMPtr] object;
   ensuring that it is |AddRef|ed and |Release|d appropriately; calling through
   the pointer to a function supplied by the underlying COM interface.

        Windows:
                raw_optimized
   31 bytes raw, nsCOMPtr*
   34 nsCOMPtr_optimized*
   38 nsCOMPtr_optimized
   42 nsCOMPtr
   46

        Macintosh:
                raw_optimized, nsCOMPtr_optimized
   112 bytes 	(1.0000) nsCOMPtr
   120					(1.0714)	i.e., 7.14% bigger than
   raw_optimized et al
                raw
   140 				(1.2500)

        The overall difference in size between Windows and Macintosh is caused
   by the the PowerPC RISC architecture where every instruction is 4 bytes.

        On Macintosh, nsCOMPtr generates out-of-line destructors which are
        not referenced, and which can be stripped by the linker.
*/

void Test01_raw(nsINode* aDOMNode, nsString* aResult)
// m140, w34
{
  /*
          This test is designed to be more like a typical large function where,
          because you are working with several resources, you don't just return
     when one of them is |nullptr|.  Similarly: |Test01_nsCOMPtr00|, and
     |Test01_nsIPtr00|.
  */

  nsINode* node = aDOMNode;
  NS_IF_ADDREF(node);

  if (node) node->GetNodeName(*aResult);

  NS_IF_RELEASE(node);
}

void Test01_raw_optimized(nsINode* aDOMNode, nsString* aResult)
// m112, w31
{
  /*
          This test simulates smaller functions where you _do_ just return
          |nullptr| at the first sign of trouble.  Similarly:
     |Test01_nsCOMPtr01|, and |Test01_nsIPtr01|.
  */

  /*
          This test produces smaller code that |Test01_raw| because it avoids
          the three tests: |NS_IF_...|, and |if ( node )|.
  */

  // -- the following code is assumed, but is commented out so we compare only
  //		 the relevent generated code

  //		if ( !aDOMNode )
  //			return;

  nsINode* node = aDOMNode;
  NS_ADDREF(node);
  node->GetNodeName(*aResult);
  NS_RELEASE(node);
}

void Test01_nsCOMPtr(nsINode* aDOMNode, nsString* aResult)
// m120, w46/34
{
  nsCOMPtr<nsINode> node = aDOMNode;

  if (node) node->GetNodeName(*aResult);
}

void Test01_nsCOMPtr_optimized(nsINode* aDOMNode, nsString* aResult)
// m112, w42/38
{
  //		if ( !aDOMNode )
  //			return;

  nsCOMPtr<nsINode> node = aDOMNode;
  node->GetNodeName(*aResult);
}