Specify the -errchk=longptr64 option to generate LP64 warnings. Use lint to check code that is written for both the 32-bit and the 64-bit compilation environment. Use the lint Utility to Detect Problems with 64-bit long and Pointer Types Because the size of long and pointer change in the LP64 data model, this change alone is the principal cause of ILP32-to-LP64 conversion problems. It is not unusual for current 32-bit applications to assume that the int type, long type, and pointers are the same size.
The remaining C integer types and the floating-point types are the same in both data-type models. The data-type model for 64-bit applications is the LP64 data model, so named because long and pointer types grow to 64 bits. The C data-type model for 32-bit applications is the ILP32 model, so named because the int and long types, and pointers, are 32-bit data types. The biggest difference between the 32-bit and the 64-bit compilation environments is the change in data-type models. Consider the Differences Between the 32-bit and 64-bit Data Models
This article discusses how to avoid or eliminate these problems. Also, problems with sign extension can occur when assigning expressions using types shorter than the size of an int to an unsigned long or a pointer. This can cause trouble with data truncation when assigning pointer or long types to int types. When converting 32-bit programs to 64-bit programs, only long types and pointer types change in size from 32 bits to 64 bits integers of type int stay at 32 bits in size. The principal cause of problems when converting 32-bit applications to 64-bit applications is the change in size of the int type with respect to the long and pointer types. This article applies to the Oracle Developer Studio (previously known as Oracle Solaris Studio) compilers.
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