[llvm] [RISCV] Use vsetvli instead of vlenb in Prologue/Epilogue (PR #113756)

[Craig Topper via llvm-commits]

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@@ -2195,6 +2203,17 @@ bool RISCVFrameLowering::canUseAsPrologue(const MachineBasicBlock &MBB) const {
   const MachineFunction *MF = MBB.getParent();
   const auto *RVFI = MF->getInfo<RISCVMachineFunctionInfo>();
 
+  // Make sure VTYPE and VL are not live-in since we will use vsetvli in the
+  // prologue to get the VLEN, and that will clobber these registers.
+  //
+  // We may do also check the stack has contain for the object with the
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topperc wrote:

"has contain for the object with the " -> "contains objects with"

https://github.com/llvm/llvm-project/pull/113756