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-rw-r--r--xpcom/tests/SizeTest01.cpp107
1 files changed, 107 insertions, 0 deletions
diff --git a/xpcom/tests/SizeTest01.cpp b/xpcom/tests/SizeTest01.cpp
new file mode 100644
index 0000000000..790b0fa032
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+++ b/xpcom/tests/SizeTest01.cpp
@@ -0,0 +1,107 @@
+// 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);
+}