[AArch64] Fix stp kill when merging forward. (#152994)

As an alternative to #149177, iterate through all instructions in
`AArch64LoadStoreOptimizer`.

Author: rj-jesus

llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp

@@ -1193,7 +1193,8 @@ AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
       //   USE kill %w1   ; need to clear kill flag when moving STRWui downwards
       //   STRW %w0
       Register Reg = getLdStRegOp(*I).getReg();
-      for (MachineInstr &MI : make_range(std::next(I), Paired))
+      for (MachineInstr &MI :
+           make_range(std::next(I->getIterator()), Paired->getIterator()))
         MI.clearRegisterKills(Reg, TRI);
     }
   }

llvm/test/CodeGen/AArch64/sve-vls-ldst-opt.mir

@@ -72,3 +72,21 @@ body: |
 # CHECK: STURQi killed renamable $q1, renamable $x1, 16 :: (store (s128))
 # CHECK: STURQi killed renamable $q2, renamable $x1, 48 :: (store (s128))
 # CHECK: STR_ZXI killed renamable $z3, renamable $x1, 4 :: (store (<vscale x 1 x s128>))
+---
+name: clear-kill-in-bundle-forward
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $x0, $z0
+    STR_ZXI $z0, $x0, 0 :: (store (<vscale x 1 x s128>))
+    BUNDLE implicit-def $z1, implicit killed $z0 {
+      $z1 = ADD_ZZZ_D killed $z0, $z0
+    }
+    STR_ZXI renamable $z1, $x0, 1 :: (store (<vscale x 1 x s128>))
+    RET_ReallyLR
+...
+# CHECK-LABEL: name: clear-kill-in-bundle-forward
+# CHECK: BUNDLE implicit-def $z1, implicit $z0 {
+# CHECK:   $z1 = ADD_ZZZ_D $z0, $z0
+# CHECK: }
+# CHECK: STPQi $q0, $q1, $x0, 0 :: (store (<vscale x 1 x s128>))