[llvm] [llvm][arm] add T1 and T2 assembly options for vlldm and vlstm (PR #83116)

[Tomas Matheson via llvm-commits]

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@@ -1468,15 +1468,24 @@ void ARMExpandPseudo::CMSESaveClearFPRegsV8(
   if (passesFPReg)
     assert(STI->hasFPRegs() && "Subtarget needs fpregs");
 
-  // Lazy store all fp registers to the stack.
+  if (passesFPReg)
+    assert(STI->hasFPRegs() && "Subtarget needs fpregs");
+
+  // Lazy store all fp registers to the stack
   // This executes as NOP in the absence of floating-point support.
-  MachineInstrBuilder VLSTM = BuildMI(MBB, MBBI, DL, TII->get(ARM::VLSTM))
-                                  .addReg(ARM::SP)
-                                  .add(predOps(ARMCC::AL));
-  for (auto R : {ARM::VPR, ARM::FPSCR, ARM::FPSCR_NZCV, ARM::Q0, ARM::Q1,
-                 ARM::Q2, ARM::Q3, ARM::Q4, ARM::Q5, ARM::Q6, ARM::Q7})
-    VLSTM.addReg(R, RegState::Implicit |
-                        (LiveRegs.contains(R) ? 0 : RegState::Undef));
+  MachineInstrBuilder VLSTM =
+      BuildMI(MBB, MBBI, DL, TII->get(ARM::VLSTM))
+          .addReg(ARM::SP)
+          .add(predOps(ARMCC::AL))
+          .addImm(0); // Represents a pseoudo register list, has no effect on
+                      // the encoding.
+  // Mark non-live registers as undef
+  for (MachineOperand &MO : VLSTM->implicit_operands()) {
+    if (MO.isReg() && MO.isImplicit() && !MO.isDef()) {
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tmatheson-arm wrote:

Isn't `MO.isImplicit()` always true, since you are iterating over `VLSTM->implicit_operands()`?

https://github.com/llvm/llvm-project/pull/83116