Register Allocation

[anon10020]

Hello Sir,

As per 8.5"Variables" register allocation is done by compiler,
means which value will give to which register is decided by compiler.

So in the same slide

int var3 = var1 + var2;

said that var1 and var2 are used at same time so they will be in different registers at execution time.

So if RHS is extended to variable addition upto var'n' , then this n depends on number of registers and hence processor architecture.

So what is the value of n for x86 architecture and how it can be find out?

Regards,
Anon10020

[anup]

Anon10020,

The number of register varies across exact processor versions. You will need to find out the exact processor which you have (Windows from System properties and cat /proc/cpuinfo on Linux). The architecture manual of the processor will give you the information on number of registers. These architecture manuals are available free-of-cost from the vendor website. In this case, it is the website of Intel. Do note that the AMD processors, though x86, may have a different number of registers.

Thanks,

Anup