[llvm] [RISCV] Add stack clash vector support (PR #119458)

[Raphael Moreira Zinsly via llvm-commits]

================
@@ -914,6 +966,20 @@ void RISCVFrameLowering::emitPrologue(MachineFunction &MF,
             .addImm(ShiftAmount)
             .setMIFlag(MachineInstr::FrameSetup);
       }
+      if (NeedProbe) {
+        // Do a probe if the align + size allocated just passed the probe size
+        // and was not yet probed.
+        uint64_t AllocatedStack = SecondSPAdjustAmount + RVVStackSize;
----------------
rzinsly wrote:

We can't know how much of the stack rvv allocated, but just by adding RVVStackSize we would likely pass the probe size.
In the end I was trying to just capture when we had a vector allocation as it would already probed the stack after the second adjustment.
Your question shows that the code is misleading, so I changed it to test for RVVStackSize instead.

https://github.com/llvm/llvm-project/pull/119458