[llvm] [RISCV][RFC] Prevent folding ADD_LO into load/store if we can't fold all uses. (PR #155935)

[Philip Reames via llvm-commits]

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@@ -2951,6 +2951,61 @@ static bool isWorthFoldingAdd(SDValue Add) {
   return true;
 }
 
+bool isRegImmLoadOrStore(SDNode *User, SDValue Add) {
+  // If the user is a load or store, then the offset is 0.
+  if (User->getOpcode() != ISD::LOAD && User->getOpcode() != ISD::STORE &&
+      User->getOpcode() != RISCVISD::LD_RV32 &&
+      User->getOpcode() != RISCVISD::SD_RV32 &&
+      User->getOpcode() != ISD::ATOMIC_LOAD &&
+      User->getOpcode() != ISD::ATOMIC_STORE)
+    return false;
+
+  // Don't allow stores of the value. It must be used as the address.
+  if (User->getOpcode() == ISD::STORE &&
+      cast<StoreSDNode>(User)->getValue() == Add)
+    return false;
+  if (User->getOpcode() == RISCVISD::SD_RV32 &&
+      (User->getOperand(0) == Add || User->getOperand(1) == Add))
+    return false;
+  if (User->getOpcode() == ISD::ATOMIC_STORE &&
+      cast<AtomicSDNode>(User)->getVal() == Add)
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preames wrote:

Same here, ignore.

https://github.com/llvm/llvm-project/pull/155935