I am writing a tool to port games written in C/C++ from the 24bit eZ80 to Windows/Linux. One of the issues is that int24_t doesn't exist on x86/x64. typedef uint32_t uint24_t doesn't always work, e...

I narrowed down a problem in my GUI code to SetWindowTextW(HWND, wchar_t *) silently failing if the new window title is not aligned to two bytes. In this case, SetWindowText() returns 1 (success) b...

Data is usually aligned with its own data type, i.e a 32-bit int is usually aligned to 4 bytes, this makes loading/storing them more efficient for the processor. Now when does cache line alignment ...

I've used C pointers for some time now and everything has always worked as expected. However now I've run into the ISO standard that says "If the resulting pointer is not correctly aligned for...

I need to allocate large regions of memory (megabytes) with large alignments (also potentially in the megabyte range). The VirtualAlloc family of functions don't seem to provide options to do this....

Is there an attribute to enforce padding after a variable? I have a volatile (non-cached) variable declared as such: volatile int foo __attribute__((aligned(CACHE_LINE_SIZE)); I would like to prev...

Recently, I was made aware of the potential issues of memory alignment for Fixed-size vectorizable Eigen objects. The correct code as stated in the doc: class Foo { ... Eigen::Vector2d v; ... pu...

How does stack alignment work in ASMx64? When do you need to align the stack before a function call and how much do you need to subtract? I didn't understand what was the purpose of it. I know ther...

I have an object that has an address that is not 4-byte aligned. This causes a HardFault error in the cpu when there is a STR instruction saving 2 registers. This is the generated code: 00000000 &...

The _mm_load_ps() SSE intrinsic is defined as aligned, throwing exception if the address is not aligned. However, it seems visual studio generates unaligned read instead. Since not all compilers a...

I know this is a weird question to ask in Java, but is there a way to let Java dynamic memory allocation be aligned with some alignment constraints? For example, is it possible to dynamically alloc...

If I want to process data in a std::vector with SSE, I need 16 byte alignment. How can I achieve that? Do I need to write my own allocator? Or does the default allocator already align to 16 byte bo...

following excerpted from here pw = (widget *)malloc(sizeof(widget)); allocates raw storage. Indeed, the malloc call allocates storage that's big enough and suitably aligned to hold an object...

I just saw that C++23 plans to deprecate both std::aligned_storage and std::aligned_storage_t as well as std::aligned_union and std::aligned_union_t. Placement new'd objects in aligned storage are ...

Similar to what I've learned in C++, I believe it's the padding that causes a difference in the size of instances of both structs. type Foo struct { w byte //1 byte x byte //1 byte y uint64 //...

The following question is related, however answers are old, and comment from user Marc Glisse suggests there are new approaches since C++17 to this problem that might not be adequately discussed. ...

I'm taking this course, and I'm really struggling understanding the directive .align concept. Here's an example, which I couldn't understand: I know that inside the data segment, there are address...

What is the meaning of align an the start of a section? For example: align 4 a: dw 0 How does it save memory access?

Due to the 16 bytes alignment by default, does this imply the assertion in my question ?

env : x86-64; linux-centos; 8-cpu-core For testing 'false sharing performance' I wrote c++ code like this: volatile int32_t a; volatile int32_t b; int64_t p1[7]; volatile int64_t c; int64_t p...

I'm trying to understand why a struct that contains only int takes 8 bytes of memory inside a class. considering the following code; static void Main() { var rand = new Random(); var twoIntStruc...

I may be misunderstanding how cache fetches work, but I'm curious if there are any compiler optimizations for aligning small functions that are not inlined. If the cache-line-size is 64 bytes on a ...

Is it possible to make std::vector of custom structs allocate aligned memory for further processing with SIMD instructions? If it is possible to do with Allocator, does anyone happen to have such a...

I work with shared memory right now. I can't understand alignof and alignas. cppreference is unclear : alignof returns "alignment" but what is "alignment" ? number of bytes to add for the next bl...

64 bit architecture like x86-64 have word size of 64bits. In this case, if a memory access crosses over the word boundary, then it will require double the time to access data. So alignment is requi...