TABLE OF CONTENTS In the preceding chapters, we have demonstrated many of the advantages of the Itanium architecture, how to write programs for the Itanium processor, and the tools of the Itanium software development kit. This chapter explains what is required to update existing C/C++ source code for compilation and execution by the Itanium processor. The chapter concludes with an example project using automation software to analyze and correct the source code.
Porting is the process of modifying the source code of applications, libraries, or drivers to ensure that their compiled and linked executable code provides equivalent functionality in a new environment. The new environment can be a new compiler, a new operating system, a new processor, or a combination of all three.
There are many advantages to porting existing applications to the Itanium platform. For example, it expands the market of proven applications, reduces time to market, and derives benefits from architectural capabilities such as addressability and file capacity, among others.
There is a common misconception that the number of changes required to accomplish a 64-bit port is relatively small. This is true in the literal case. Typically only a relatively small number (sometimes less than 1%) of the original lines of code must be altered to execute correctly. Unfortunately, three or four times as many lines must be modified to eliminate warnings of significant severity (more in a C++ compilation). Few development organizations will allow an application to be released with many (if any) high-severity warnings. In a 100,000-line application,...
