Only perform LOD computation when it is necessary
If an image has a single mip level, and filtering isn't LOD dependent,
as is the case when using FILTER_MIN_POINT_MAG_LINEAR or
FILTER_MIN_LINEAR_MAG_POINT, LOD computation is not necessary in
order to perform image sampling and can be bypassed entirely.
Bug: b/179889245
Change-Id: Ic69fe0c45211ccbb66c88c502c2dba1c50630aa7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52688
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Commit-Queue: Alexis Hétu <sugoi@google.com>
diff --git a/src/Pipeline/SamplerCore.cpp b/src/Pipeline/SamplerCore.cpp
index 646d875..3d5521d 100644
--- a/src/Pipeline/SamplerCore.cpp
+++ b/src/Pipeline/SamplerCore.cpp
@@ -54,7 +54,15 @@
w = As<Float4>(face);
}
- if(function == Implicit || function == Bias || function == Grad || function == Query)
+ bool singleMipLevel = (state.minLod == state.maxLod) && (function != Query) && (function != Fetch);
+
+ // We can't skip the LOD computation for LOD query, where we have to return the proper value
+ if(singleMipLevel)
+ {
+ // Skip costly LOD computation if there's only 1 possible outcome
+ lod = state.minLod;
+ }
+ else if(function == Implicit || function == Bias || function == Grad || function == Query)
{
if(state.is1D())
{
@@ -108,8 +116,11 @@
c.y = Float4(lod); // Unclamped LOD.
}
- lod = Max(lod, state.minLod);
- lod = Min(lod, state.maxLod);
+ if (!singleMipLevel)
+ {
+ lod = Max(lod, state.minLod);
+ lod = Min(lod, state.maxLod);
+ }
if(function == Query)
{
