This was assuming it could use all memory before, which is
a bad decision because it restricts occupancy.
By default, only try to use enough space that could reduce
occupancy to 7, an arbitrarily chosen limit.
Based on the exist LDS usage, try to round up to the limit
in the current tier instead of further hurting occupancy.
This isn't ideal, because it doesn't accurately know how much
space is going to be used for alignment padding.
llvm-svn: 269708
Summary:
For GL_ARB_compute_shader we need to support workgroup sizes of at least 1024. However, if we want to allow large workgroup sizes, we may need to use less registers, as we have to run more waves per SIMD.
This patch adds an attribute to specify the maximum work group size the compiled program needs to support. It defaults, to 256, as that has no wave restrictions.
Reducing the number of registers available is done similarly to how the registers were reserved for chips with the sgpr init bug.
Reviewers: mareko, arsenm, tstellarAMD, nhaehnle
Subscribers: FireBurn, kerberizer, llvm-commits, arsenm
Differential Revision: http://reviews.llvm.org/D18340
Patch By: Bas Nieuwenhuizen
llvm-svn: 266337
Matt Arsenault