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texture_cache: Document the most important methods.

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This commit is contained in:
Fernando Sahmkow 2019-05-13 22:59:18 -04:00 committed by ReinUsesLisp
parent 4530511ee4
commit 6162cb922e
1 changed files with 87 additions and 8 deletions
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95
src/video_core/texture_cache/texture_cache.h
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@ -64,6 +64,10 @@ public:
}
}
/**
* `Guard` guarantees that rendertargets don't unregister themselves if the
* collide. Protection is currently only done on 3D slices.
**/
void Guard(bool new_guard) {
guard_cache = new_guard;
}
@ -293,6 +297,14 @@ private:
BufferCopy = 3,
};
/**
* `PickStrategy` takes care of selecting a proper strategy to deal with a texture recycle.
* @param overlaps, the overlapping surfaces registered in the cache.
* @param params, the paremeters on the new surface.
* @param gpu_addr, the starting address of the new surface.
* @param untopological, tells the recycler that the texture has no way to match the overlaps
* due to topological reasons.
**/
RecycleStrategy PickStrategy(std::vector<TSurface>& overlaps, const SurfaceParams& params,
const GPUVAddr gpu_addr, const bool untopological) {
if (Settings::values.use_accurate_gpu_emulation) {
@ -315,6 +327,18 @@ private:
return RecycleStrategy::Ignore;
}
/**
* `RecycleSurface` es a method we use to decide what to do with textures we can't resolve in
*the cache It has 2 implemented strategies: Ignore and Flush. Ignore just unregisters all the
*overlaps and loads the new texture. Flush, flushes all the overlaps into memory and loads the
*new surface from that data.
* @param overlaps, the overlapping surfaces registered in the cache.
* @param params, the paremeters on the new surface.
* @param gpu_addr, the starting address of the new surface.
* @param preserve_contents, tells if the new surface should be loaded from meory or left blank
* @param untopological, tells the recycler that the texture has no way to match the overlaps
* due to topological reasons.
**/
std::pair<TSurface, TView> RecycleSurface(std::vector<TSurface>& overlaps,
const SurfaceParams& params, const GPUVAddr gpu_addr,
const bool preserve_contents,
@ -343,6 +367,12 @@ private:
}
}
/**
* `RebuildSurface` this method takes a single surface and recreates into another that
* may differ in format, target or width alingment.
* @param current_surface, the registered surface in the cache which we want to convert.
* @param params, the new surface params which we'll use to recreate the surface.
**/
std::pair<TSurface, TView> RebuildSurface(TSurface current_surface,
const SurfaceParams& params) {
const auto gpu_addr = current_surface->GetGpuAddr();
@ -357,6 +387,14 @@ private:
return {new_surface, new_surface->GetMainView()};
}
/**
* `ManageStructuralMatch` this method takes a single surface and checks with the new surface's
* params if it's an exact match, we return the main view of the registered surface. If it's
* formats don't match, we rebuild the surface. We call this last method a `Mirage`. If formats
* match but the targets don't, we create an overview View of the registered surface.
* @param current_surface, the registered surface in the cache which we want to convert.
* @param params, the new surface params which we want to check.
**/
std::pair<TSurface, TView> ManageStructuralMatch(TSurface current_surface,
const SurfaceParams& params) {
const bool is_mirage = !current_surface->MatchFormat(params.pixel_format);
@ -370,10 +408,18 @@ private:
return {current_surface, current_surface->EmplaceOverview(params)};
}
std::optional<std::pair<TSurface, TView>> ReconstructSurface(std::vector<TSurface>& overlaps,
const SurfaceParams& params,
const GPUVAddr gpu_addr,
const u8* host_ptr) {
/**
* `TryReconstructSurface` unlike `RebuildSurface` where we know the registered surface
* matches the candidate in some way, we got no guarantess here. We try to see if the overlaps
* are sublayers/mipmaps of the new surface, if they all match we end up recreating a surface
* for them, else we return nothing.
* @param overlaps, the overlapping surfaces registered in the cache.
* @param params, the paremeters on the new surface.
* @param gpu_addr, the starting address of the new surface.
**/
std::optional<std::pair<TSurface, TView>> TryReconstructSurface(std::vector<TSurface>& overlaps,
const SurfaceParams& params,
const GPUVAddr gpu_addr) {
if (params.target == SurfaceTarget::Texture3D) {
return {};
}
@ -412,12 +458,30 @@ private:
return {{new_surface, new_surface->GetMainView()}};
}
/**
* `GetSurface` gets the starting address and parameters of a candidate surface and tries
* to find a matching surface within the cache. This is done in 3 big steps. The first is to
* check the 1st Level Cache in order to find an exact match, if we fail, we move to step 2.
* Step 2 is checking if there are any overlaps at all, if none, we just load the texture from
* memory else we move to step 3. Step 3 consists on figuring the relationship between the
* candidate texture and the overlaps. We divide the scenarios depending if there's 1 or many
* overlaps. If there's many, we just try to reconstruct a new surface out of them based on the
* candidate's parameters, if we fail, we recycle. When there's only 1 overlap then we have to
* check if the candidate is a view (layer/mipmap) of the overlap or if the registered surface
* is a mipmap/layer of the candidate. In this last case we reconstruct a new surface.
* @param gpu_addr, the starting address of the candidate surface.
* @param params, the paremeters on the candidate surface.
* @param preserve_contents, tells if the new surface should be loaded from meory or left blank.
**/
std::pair<TSurface, TView> GetSurface(const GPUVAddr gpu_addr, const SurfaceParams& params,
bool preserve_contents) {
const auto host_ptr{memory_manager->GetPointer(gpu_addr)};
const auto cache_addr{ToCacheAddr(host_ptr)};
// Step 1
// Check Level 1 Cache for a fast structural match. If candidate surface
// matches at certain level we are pretty much done.
if (l1_cache.count(cache_addr) > 0) {
TSurface current_surface = l1_cache[cache_addr];
if (!current_surface->MatchesTopology(params)) {
@ -437,31 +501,43 @@ private:
}
}
// Step 2
// Obtain all possible overlaps in the memory region
const std::size_t candidate_size = params.GetGuestSizeInBytes();
auto overlaps{GetSurfacesInRegion(cache_addr, candidate_size)};
// If none are found, we are done. we just load the surface and create it.
if (overlaps.empty()) {
return InitializeSurface(gpu_addr, params, preserve_contents);
}
// Step 3
// Now we need to figure the relationship between the texture and its overlaps
// we do a topological test to ensure we can find some relationship. If it fails
// inmediatly recycle the texture
for (auto surface : overlaps) {
if (!surface->MatchesTopology(params)) {
return RecycleSurface(overlaps, params, gpu_addr, preserve_contents, true);
}
}
// Split cases between 1 overlap or many.
if (overlaps.size() == 1) {
TSurface current_surface = overlaps[0];
// First check if the surface is within the overlap. If not, it means
// two things either the candidate surface is a supertexture of the overlap
// or they don't match in any known way.
if (!current_surface->IsInside(gpu_addr, gpu_addr + candidate_size)) {
if (current_surface->GetGpuAddr() == gpu_addr) {
std::optional<std::pair<TSurface, TView>> view =
ReconstructSurface(overlaps, params, gpu_addr, host_ptr);
TryReconstructSurface(overlaps, params, gpu_addr);
if (view.has_value()) {
return *view;
}
}
return RecycleSurface(overlaps, params, gpu_addr, preserve_contents, false);
}
// Now we check if the candidate is a mipmap/layer of the overlap
std::optional<TView> view =
current_surface->EmplaceView(params, gpu_addr, candidate_size);
if (view.has_value()) {
@ -472,15 +548,18 @@ private:
}
return {current_surface, *view};
}
return RecycleSurface(overlaps, params, gpu_addr, preserve_contents, false);
} else {
// If there are many overlaps, odds are they are subtextures of the candidate
// surface. We try to construct a new surface based on the candidate parameters,
// using the overlaps. If a single overlap fails, this will fail.
std::optional<std::pair<TSurface, TView>> view =
ReconstructSurface(overlaps, params, gpu_addr, host_ptr);
TryReconstructSurface(overlaps, params, gpu_addr);
if (view.has_value()) {
return *view;
}
return RecycleSurface(overlaps, params, gpu_addr, preserve_contents, false);
}
// We failed all the tests, recycle the overlaps into a new texture.
return RecycleSurface(overlaps, params, gpu_addr, preserve_contents, false);
}
std::pair<TSurface, TView> InitializeSurface(GPUVAddr gpu_addr, const SurfaceParams& params,