Header alignment in StackAllocator

[txemagon]

Maybe is a misunderstanding but I think the header in the StackAllocator is placed at the beginning of the block, then there is an adjustment, and finally the new data (to which the pointer is returned).

That, as I understand it, leaves the header unreachable since the adjustment length is what the header is.

                                                 +---- aligned mem pos. (and pointer returned by the allocator)
                                                 v
| o l d · d a t a | adj | e m p t y · s p a c e | n e w · d a t a| 
                                DE AD BE EF

So when freeing the memory the adjustement isn't next to the new data.

Despite no incidence when aligning on a per byte strategy. Which I believe is the case:

Read in ECSMM.h: 62

void* pMemory = m_MemoryAllocator->allocate(memSize, alignof(u8));

with other alignments will corrupt the free operation with a wild pointer.

I'd like to suggest changing

StackAllocator.cpp: 49

		// store alignment in allocation meta info
		asMeta->adjustment = adjustment;

		// determine aligned memory address
		asUptr += adjustment;

to

	// determine aligned memory address
	asUptr += adjustment;

	// store alignment in allocation meta info in the previous block
	(asMeta-1)->adjustment = adjustment;
	/*
	 * todo: move header before data
                            adjustment              asUptr new emplacement
	                            v                          v
	  | u·s·e·d  m·e·m·o·r·y || 0 | 1 | 2 | 3 | 4 | adj |  new data
	                                  ^
	                                  L empty bytes
	 */

since (asMeta-1) is pointer arithmetics measured in AllocMetaInfo size.

Thanks a lot for sharing your code. There isn't a single file in which I hadn't learn something about C++ programing.
Regards.