[PATCH] D29741: [AMDGPU] Calculate number of min/max SGPRs/VGPRs for WavesPerEU instead of using switch statement

[Tony Tye via Phabricator via llvm-commits]

tony-tye added inline comments.


================
Comment at: lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp:211-233
 unsigned getMinNumSGPRs(const FeatureBitset &Features, unsigned WavesPerEU) {
   IsaVersion Version = getIsaVersion(Features);
   if (Version.Major >= 8) {
     switch (WavesPerEU) {
       case 0:  return 0;
       case 10: return 0;
       case 9:  return 0;
----------------
kzhuravl wrote:
> tony-tye wrote:
> > Should this also have a calculation that takes into account if a trap handler is present?
> I do not think so. `getMinNumSGPRs` is used to bump up granulated sgpr count in pgm rsrc1 register to match maximum number of requested waves per execution unit.
Right, but the value required to achieve that is based on determining how many registers the kernel must use. That value is reduced if there is a trap handler as the hardware will automatically allocate registers for the trap handler. It would also seem better if the hardcoded numbers here were replaced by the calculation that produces them which can then use the already existing target specific constants. If future hardware changes those limits then the calculation will still be correct.


https://reviews.llvm.org/D29741