[llvm] [AMDGPU] Preserve WWM ownership of allocated AGPRs (PR #223278)

[Yaxun Liu via llvm-commits]

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@@ -361,6 +361,23 @@ void SIMachineFunctionInfo::shiftWwmVGPRsToLowestRange(
     WWMVGPRs[I] = NewReg;
     WWMReservedRegs.remove(Reg);
     WWMReservedRegs.insert(NewReg);
+
+    // Keep any spill slot allocated before PEI associated with the register
+    // after compaction. Rebuild the MapVector to preserve spill/restore order.
+    if (WWMSpills.contains(Reg)) {
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yxsamliu wrote:

Agreed. I changed the local patch to record the renamed registers and rebuild the map once, keeping its order. This uses the existing `MapVector` API.

https://github.com/llvm/llvm-project/pull/223278