Breadcrumbs report race conditions w/ Vulkan Validation Layers

[darksylinc]

Tested versions

4.4-master

System information

Godot v4.4.dev (1a34f5d) - Ubuntu 24.04.1 LTS 24.04 on X11 - X11 display driver, Multi-window, 2 monitors - Vulkan (Mobile) - dedicated AMD Radeon RX 6800 XT (RADV NAVI21) - AMD Ryzen 9 5900X 12-Core Processor (24 threads)

Issue description

My PR #90993 introduced TheForge's code for breadcrumbs.

But as @DarioSamo pointed out, the problem is that when Validation Layers are set to "synchronization" debugging, it spams the log.

The problem arises from the fact that breadcrumbs are always writing to the same 4-byte region from the GPU without any barriers.

Adding barriers is undesired because this functionality is there merely to aid developers understand what Godot was doing on the GPU when device was lost; making error reports much friendlier. It should not penalize performance.

Solution:

1. Make the breadcrumb buffer an ever-growing buffer, until frame reset. On report, we report the last N breadcrumbs.
   • The buffer should have a tweakable hard limit on how much it can grow. If it does we'll warn it was exceeded and wrap around (which will unavoidable cause a validation warning).
2. Add an --accurate-breadcrumb flag that will force a full barrier between each breadcrumb command. This ensures the breadcrumb is 100% accurate and make it much easier to identify the offending command.

Steps to reproduce

1. Open vkconfig and set it to sync validation.
2. Run Godot with --gpu-validation

IMPORTANT

I will implement this. This ticket is for tracking the problem.

Minimal reproduction project (MRP)

N / A