[llvm] [AArch64] Fix variadic tail-calls on ARM64EC (PR #79774)

[Eli Friedman via llvm-commits]

================
@@ -7991,11 +7991,22 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
   }
 
   if (IsVarArg && Subtarget->isWindowsArm64EC()) {
+    SDValue ParamPtr = StackPtr;
+    if (IsTailCall) {
+      const AArch64FrameLowering *TFI =
+          MF.getSubtarget<AArch64Subtarget>().getFrameLowering();
----------------
efriedma-quic wrote:

Unused variable?

https://github.com/llvm/llvm-project/pull/79774