[llvm] [RISCV] Stack clash protection for dynamic alloca (PR #122508)

[Craig Topper via llvm-commits]

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@@ -22559,3 +22564,96 @@ unsigned RISCVTargetLowering::getStackProbeSize(const MachineFunction &MF,
   StackProbeSize = alignDown(StackProbeSize, StackAlign.value());
   return StackProbeSize ? StackProbeSize : StackAlign.value();
 }
+
+SDValue RISCVTargetLowering::lowerDYNAMIC_STACKALLOC(SDValue Op,
+                                                     SelectionDAG &DAG) const {
+  MachineFunction &MF = DAG.getMachineFunction();
+  if (!hasInlineStackProbe(MF))
+    return SDValue();
+
+  MVT XLenVT = Subtarget.getXLenVT();
+  // Get the inputs.
+  SDNode *Node = Op.getNode();
+  SDValue Chain = Op.getOperand(0);
+  SDValue Size = Op.getOperand(1);
+
+  MaybeAlign Align =
+      cast<ConstantSDNode>(Op.getOperand(2))->getMaybeAlignValue();
+  SDLoc dl(Op);
+  EVT VT = Node->getValueType(0);
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topperc wrote:

Can we use `Op.getValueType()` here? Then `Node` is unneeded.

https://github.com/llvm/llvm-project/pull/122508