[llvm] [AMDGPU] Avoid wmma bank conflict for GFX11 and GFX12 (PR #205530)

[Matthias Gehre via llvm-commits]

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@@ -617,6 +617,19 @@ class SIMachineFunctionInfo final : public AMDGPUMachineFunctionInfo,
   // load/store is enabled.
   IndexedMap<uint32_t, VGPRBlock2IndexFunctor> MaskForVGPRBlockOps;
 
+  // Maps each virtual register that is an operand of a bank-sensitive v_wmma_*
+  // (matrix sources a multiple of 128 bits) to that instruction's other operand
+  // registers. Populated once by GCNPreRAOptimizations and consumed by
+  // SIRegisterInfo::getRegAllocationHints for VGPR bank-conflict avoidance, so
+  // the hint hook does not rescan the function for every virtual register.
+  DenseMap<Register, SmallVector<Register, 3>> WMMABankSiblings;
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mgehre-amd wrote:

This variable seems unused? There are getters but they are not called

https://github.com/llvm/llvm-project/pull/205530