On Mon, Aug 28, 2017 at 2:50 PM, Matt Turner <matts...@gmail.com> wrote:
> On Mon, Aug 28, 2017 at 7:51 AM, Jason Ekstrand <ja...@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? > I don't believe so. > > 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. > Yes, that's correct. > For registers the behavior seems unspecified. I don't think we should > emit additional instructions for an unspecified case. > Unless that unspecified behavior is a GPU hang which I believe is possible if your register indirect goes into the weeds. > > 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). > Sure. I could reword things and say that it makes it ready for 64-bits. The only real "fix" there is to be more careful with our retyping. --Jason > I was hoping one of these changes somehow fixed FDO bug 101984 > (because I'm out of guesses!), but no such luck. :( >
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