tree 06090bb6e91b1885f6be5adbac4a93dcb3953a73
parent d4483095765ecd7914fbc90dc254a1f98565a915
author Nicolas Capens <capn@google.com> 1628049820 -0400
committer Nicolas Capens <nicolascapens@google.com> 1628093940 +0000

Optimize OpImageFetch for single-level mipmaps

The initial implementation of single-level mipmap LOD optimization left
out Fetch operations due to causing test failures. The root cause is
that minLod == maxLod is being used to indicate during sampling routine
generation that the image has only a single mipmap level, but this is
also true when we have no sampler object, which leaves these fields
both initialized at 0.

This change changes their initial value to [-1000, 1000]. While any
arbitrary non-equal values could be used, this is inspired by OpenGL's
defaults for GL_TEXTURE_MIN_LOD and GL_TEXTURE_MAX_LOD.

We then set them both to 0 for Fetch operations if the image view has a
single level.

Bug: b/151263485
Change-Id: I2ab565f5126cc8f8137f051704a6350853396e50
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/56112
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Sean Risser <srisser@google.com>