Tells the compiler to use a specific memory model to generate code and store data.
IDE Equivalent
NoneArchitectures
Intel® 64 architecture
Syntax
Linux: | -mcmodel=mem_model |
Mac OS X: | None |
Windows: | None |
Arguments
mem_model |
Is the memory model to use. Possible values are:
|
Default
-mcmodel=small |
On systems using Intel® 64 architecture, the compiler restricts code and data to the first 2GB of address space. Instruction Pointer (IP)-relative addressing can be used to access code and data. |
Description
This option tells the compiler to use a specific memory model to generate code and store data. It can affect code size and performance. If your program has global and static data with a total size smaller than 2GB, -mcmodel=small is sufficient. Global and static data larger than 2GB requires -mcmodel=medium or -mcmodel=large. Allocation of memory larger than 2GB can be done with any setting of -mcmodel.
IP-relative addressing requires only 32 bits, whereas absolute addressing requires 64-bits. IP-relative addressing is somewhat faster. So, the small memory model has the least impact on performance.
Note
When you specify -mcmodel=medium or -mcmodel=large, you must also specify compiler option -shared-intel to ensure that the correct dynamic versions of the Intel run-time libraries are used.
Alternate Options
None
Example
The following example shows how to compile using -mcmodel:
icl -shared-intel -mcmodel=medium -o prog prog.c