[llvm] [AMDGPU] Max. WG size-induced occupancy limits max. waves/EU (PR #137807)

[Matt Arsenault via llvm-commits]

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@@ -255,6 +256,14 @@ class AMDGPUInformationCache : public InformationCache {
     return Status;
   }
 
+  /// Returns the minimum amount of LDS space used by a workgroup running
+  /// function \p F.
+  static unsigned getLDSSize(const Function &F) {
+    return AMDGPU::getIntegerPairAttribute(F, "amdgpu-lds-size",
+                                           {0, UINT32_MAX}, true)
+        .first;
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arsenm wrote:

This also won't be set in the middle end where AMDGPUAttributor runs. If it's too optimistic, that's probably OK

https://github.com/llvm/llvm-project/pull/137807