Portability and migration

The options in this category can help you maintain application behavior compatibility on past, current, and future hardware, operating systems and compilers, or help move your applications to an XL compiler with minimal change.
Table 1. Portability and migration options
Option name Description
-fpack-struct (-qalign)

Specifies the alignment of data objects in storage, which avoids performance problems with misaligned data.
-qxlcompatmacros
The option -qxlcompatmacros controls definition of the following legacy macros: __xlC__, __xlC_ver__, C++ only begins__IBMCPP__C++ only ends, C only begins__IBMC__, and __xlc__C only ends.
  • when you migrate programs from IBM® XL C/C++ for AIX® to IBM XL C/C++ for Linux for little endian distributions;
  • when you migrate programs from IBM XL C/C++ for Linux for big endian distributions to IBM XL C/C++ for Linux for little endian distributions.
  • when you migrate programs from earlier versions of IBM XL C/C++ for Linux for little endian distributions to the latest.
Parent topic: Summary of compiler options by functional category


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