Unaligned access

[rachitagrawal]

I am working on a project and am getting some unaligned addresses generated. As far as I knew, gcc/g++ automatically generated aligned addresses. So, what could be the reason for unaligned addresses? Is there any flag in gcc where I can force it to generate aligned addresses?

Also, another important observation is that, mostly these unaligned addresses come from the dynamically loaded libraries.

Can someone please throw some light on this?

Thank you

[kbw]

Alignment is usually done with #pragmas in the struct definition, typically in a header file. Can you check the relevant header files to see how the structs/classes are declared?

How do you know you have alignment issues?

[rachitagrawal]

There is a tool by intel "Pin" that is used for instrumentation for executable. This gives you data addresses and instruction addresses. And when I checked these data addresses they have alignment issues.

Can there be a better method other than checking the definition of each structure? As I don't know which structure has the problem and the code is quite big.

[kbw]

Ah, I inferred somethong else from your first post. What exactly do you mean by

alignment issues

?

[rachitagrawal]

Memory addresses that are referred in the code, if they are aligned they should be in multiple of 2 or 4 based on kind of alignment we have. But when I see those addresses they are even odd as well. So, I don't know why that is happened, when gcc/g++ automatically aligns all data types.

[kbw]

It ought to be a compiler setting, but I can't find it on the Microsoft Compiler. There are some alignment options on gcc, but I can't find the one you need there either. Shocking.