[llvm] [RISCV] Software guard direct calls in large code model (PR #109377)

[Craig Topper via llvm-commits]

================
@@ -19736,16 +19739,32 @@ SDValue RISCVTargetLowering::LowerCall(CallLoweringInfo &CLI,
   // Emit the call.
   SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
 
+  // Use software guarded branch for large code model non-indirect calls
+  // Tail call to external symbol will have a null CLI.CB and we need another
+  // way to determine the callsite type
+  bool NeedSWGuarded = false;
+  if (getTargetMachine().getCodeModel() == CodeModel::Large &&
+      Subtarget.hasStdExtZicfilp() &&
+      ((CLI.CB && !CLI.CB->isIndirectCall()) || CalleeIsLargeExternalSymbol))
+    NeedSWGuarded = true;
+
   if (IsTailCall) {
     MF.getFrameInfo().setHasTailCall();
-    SDValue Ret = DAG.getNode(RISCVISD::TAIL, DL, NodeTys, Ops);
+    SDValue Ret;
+    if (NeedSWGuarded)
+      Ret = DAG.getNode(RISCVISD::SW_GUARDED_TAIL, DL, NodeTys, Ops);
----------------
topperc wrote:

```
unsigned CallOpc = NeedSWGuarded ? RISCVISD::SW_GUARDED_TAIL : RISCVISD::TAIL;
SDValue Ret = DAG.getNode(CallOpc, DL, NodeTys, Ops);
```

https://github.com/llvm/llvm-project/pull/109377