[llvm] [AArch64][SME] Introduce CHECK_MATCHING_VL pseudo for streaming transitions (PR #157510)

[Sander de Smalen via llvm-commits]

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@@ -2940,6 +2940,52 @@ AArch64TargetLowering::EmitDynamicProbedAlloc(MachineInstr &MI,
   return NextInst->getParent();
 }
 
+MachineBasicBlock *
+AArch64TargetLowering::EmitCheckMatchingVL(MachineInstr &MI,
+                                           MachineBasicBlock *MBB) const {
+  MachineFunction *MF = MBB->getParent();
+  const TargetInstrInfo *TII = Subtarget->getInstrInfo();
+  const BasicBlock *LLVM_BB = MBB->getBasicBlock();
+  DebugLoc DL = MI.getDebugLoc();
+  MachineFunction::iterator It = ++MBB->getIterator();
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sdesmalen-arm wrote:

This should use `getFirstNonPHI` instead of `++MBB->getIterator()`, in case the block has PHI nodes. (which would cause trouble).

https://github.com/llvm/llvm-project/pull/157510