[llvm] [AArch64] merge index address with large offset into base address (PR #75343)

[David Sherwood via llvm-commits]

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@@ -481,6 +505,16 @@ static unsigned getPreIndexedOpcode(unsigned Opc) {
   }
 }
 
+static unsigned getBaseAddressOpcode(unsigned Opc) {
+  // TODO: Add more index address loads/stores.
+  switch (Opc) {
+  default:
+    llvm_unreachable("Opcode has no base address equivalent!");
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david-arm wrote:

At first glance this doesn't look right to me. Are there any checks to actually prevent us getting here with other opcodes? If not, then I think you may need to fill in the remaining opcodes in the switch statement, similar to `getPostIndexedOpcode`.

https://github.com/llvm/llvm-project/pull/75343