[Mesa-dev] [PATCH 7/7] i965/fs: Fix readInvocationARB and readFirstInvocationARB
mattst88 at gmail.com
Mon Aug 28 21:50:02 UTC 2017
On Mon, Aug 28, 2017 at 7:51 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> The readInvocationARB built-in maps fairly nicely to our BROADCAST
> opcode. However, the current implementation isn't quite right. This
> commit fixes three different issues:
> 1) It was blindly taking component 0 of the index value even if that
> channel is disabled. We need emit_uniformize() to fix this.
Do we have a test that this fixes?
> 2) It didn't handle invalid index values particularly gracefully.
> These can actually cause assertion failures in the compiler because
> we may try to access out-of-bounds on a register. This commit
> solves this by using invocation & (dispatch_width - 1).
For immediates, the fix seems fine and I assume that's the only thing
that can cause assertion failures.
For registers the behavior seems unspecified. I don't think we should
emit additional instructions for an unspecified case.
> 3) Neither readInvocationARB nor readFirstInvocationARB properly
> handled 64-bit types because they manually stomped the destination
> type to D regardless of bit-size.
"regardless of bit-size" is a bit misleading when all possible types
are 32-bit. That criticism isn't fair when the GL extension doesn't
require 64-bit types (and I don't know why we would patch the code to
support them before something actually exercises it).
I was hoping one of these changes somehow fixed FDO bug 101984
(because I'm out of guesses!), but no such luck. :(
More information about the mesa-dev