kc3-lang/angle

2024-12-10T22:01:28

Vulkan: Prevent crash with D/S FF without D/S attachment The spec says that the values for gl_LastFragDepth/StencilARM are undefined if there is no depth/stencil attachment. This "just" works on tiling GPUs, because reading input attachments simply translates to reading _something_ from the tile memory. For ANGLE, the situation is a little more complicated. ANGLE has to bind descriptors for input attachments (because non-tilers read from the input attachment descriptor instead of using the knowledge that input and color/depth/stencil attachments are one and the same thing in tile memory). When a depth/stencil attachment is missing, there is no image to bind to the descriptor set. ANGLE cannot skip binding an image to the descriptor set, because OpImageRead (translated from subpassLoad()) attempts to access the input descriptor; skipping this causes an internal crash in SwiftShader for example. ANGLE cannot bind a bogus image as input attachment, as Vulkan requires that input attachments are also color/depth/stencil attachments. ANGLE _could_ bind a bogus image as input attachment and also as depth/stencil attachment. This is rather risky, as it then also has to be careful to make sure that depth/stencil attachment is never actually used (i.e. it affects the depth/stencil state, load/store ops etc). In this change, the shader itself is modified to remove references to the depth/stencil input attachments if the attachment is missing. This is rather inefficient, as it means the pipeline warmup will not produce a usable pipeline, but it's accepted as a workaround for something apps shouldn't really be doing. Bug: angleproject:376572258 Change-Id: I0de68252b61615cb82cba7d1730699aadf41e92f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6085368 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Yuxin Hu <yuxinhu@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>