-Oa: Alias Analysis Options

Group

OPTIMIZATIONS

Scope

Function

Syntax
  -Oa (addr|ANSI|type|none)
  
  
Arguments

addr: All objects in same address area may overlap (safe mode, default)

ANSI: use ANSI99 rules

type: only objects in same address area with same type may overlap

none: assume no objects do overlap

Default

addr

Defines

None

Pragmas

None

Description

These four different options allow the programmer to control the alias behavior of the compiler. The option -oaaddr is the default because it is safe for all C programs. Use option -oaansi if the source code follows the ANSI C99 alias rules. If objects with different types never overlap in your program, use option -oatype. If your program doesn't have aliases at all, use option -oanone (or the ICG option -ona, which is supported for compatibility reasons).

Examples
  -oaANSI