[llvm] [AMDGPU] Introduce subtarget features `FeatureLDSAllocGranularity<size>` and expose them to the frontend (PR #220394)

[Chinmay Deshpande via llvm-commits]

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@@ -3236,6 +3236,11 @@ def AMDGPUFrontendVisibleFeatures {
   FeatureSupportsXNACK, FeatureSupportsSRAMECC, FeatureXNACKOnOffModes,
   FeatureSGPRInitBug, FeatureApertureRegs, FeatureGetDoorbellID,
   FeatureAGPRAlloc, Feature1536VGPRs,
+  FeatureAddressableLocalMemorySize32768,
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chinmaydd wrote:

Suggestion accepted, updated this PR to introduce new subtarget features `FeatureLDSAllocGranularity<size>` so that we dont need to key on the memory size.

@frederik-h I'd recommend we get this stack in first before the one you have so that we can be rid of making the changes to `AMDGPUBaseInfo`

https://github.com/llvm/llvm-project/pull/220394