[llvm] [RISCV] Support postRA vsetvl insertion pass (PR #70549)

[Luke Lau via llvm-commits]

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@@ -1005,39 +1121,44 @@ void RISCVInsertVSETVLI::insertVSETVLI(MachineBasicBlock &MBB,
     // Use X0, X0 form if the AVL is the same and the SEW+LMUL gives the same
     // VLMAX.
     if (Info.hasSameAVL(PrevInfo) && Info.hasSameVLMAX(PrevInfo)) {
-      BuildMI(MBB, InsertPt, DL, TII->get(RISCV::PseudoVSETVLIX0))
-          .addReg(RISCV::X0, RegState::Define | RegState::Dead)
-          .addReg(RISCV::X0, RegState::Kill)
-          .addImm(Info.encodeVTYPE())
-          .addReg(RISCV::VL, RegState::Implicit);
+      auto NeedFixupMI =
+          BuildMI(MBB, InsertPt, DL, TII->get(RISCV::PseudoVSETVLIX0))
+              .addReg(RISCV::X0, RegState::Define | RegState::Dead)
+              .addReg(RISCV::X0, RegState::Kill)
+              .addImm(Info.encodeVTYPE())
+              .addReg(RISCV::VL, RegState::Implicit);
+      fixupLIAfterInsertMI(NeedFixupMI, LIS);
       return;
     }
 
     // If our AVL is a virtual register, it might be defined by a VSET(I)VLI. If
     // it has the same VLMAX we want and the last VL/VTYPE we observed is the
     // same, we can use the X0, X0 form.
-    if (Info.hasSameVLMAX(PrevInfo) && Info.hasAVLReg()) {
-      MachineInstr *DefMI = MRI->getUniqueVRegDef(Info.getAVLReg());
-      assert(DefMI);
-      if (isVectorConfigInstr(*DefMI)) {
-        VSETVLIInfo DefInfo = getInfoForVSETVLI(*DefMI);
+    if (Info.hasSameVLMAX(PrevInfo) && Info.hasAVLReg() &&
+        Info.hasAVLRegDefMI()) {
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lukel97 wrote:

Shouldn't hasAVLReg be true iff hasAVLRegDefMI is true too?

https://github.com/llvm/llvm-project/pull/70549