Index: llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
+++ llvm/lib/Target/AMDGPU/GCNNSAReassign.cpp
@@ -190,6 +190,14 @@
       if (MRI->getRegClass(Reg) != &AMDGPU::VGPR_32RegClass || Op.getSubReg())
         return NSA_Status::FIXED;
 
+      // InlineSpiller does not call LRM::assign() after an LI split leaving
+      // it in an inconsistent state, so we cannot call LRM::unassign().
+      // See llvm bug #48911.
+      // Skip reassign if a register has originated from such split.
+      // FIXME: Remove the workaround when bug #48911 is fixed.
+      if (VRM->getPreSplitReg(Reg))
+        return NSA_Status::FIXED;
+
       const MachineInstr *Def = MRI->getUniqueVRegDef(Reg);
 
       if (Def && Def->isCopy() && Def->getOperand(1).getReg() == PhysReg)
Index: llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
+++ llvm/lib/Target/AMDGPU/GCNRegBankReassign.cpp
@@ -471,6 +471,14 @@
   if (Reg.isPhysical() || !VRM->isAssignedReg(Reg))
     return false;
 
+  // InlineSpiller does not call LRM::assign() after an LI split leaving it
+  // in an inconsistent state, so we cannot call LRM::unassign().
+  // See llvm bug #48911.
+  // Skip reassign if a register has originated from such split.
+  // FIXME: Remove the workaround when bug #48911 is fixed.
+  if (VRM->getPreSplitReg(Reg))
+    return false;
+
   const MachineInstr *Def = MRI->getUniqueVRegDef(Reg);
 
   Register PhysReg = VRM->getPhys(Reg);
Index: llvm/test/CodeGen/AMDGPU/nsa-reassign.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/nsa-reassign.mir
@@ -0,0 +1,72 @@
+# RUN: llc -march=amdgcn -mcpu=gfx1010 -verify-machineinstrs -run-pass greedy,amdgpu-nsa-reassign,virtregrewriter,si-shrink-instructions -o - %s | FileCheck -check-prefix=GCN %s
+
+--- |
+  define amdgpu_kernel void @nsa_reassign() #0 { ret void }
+  define amdgpu_kernel void @do_not_reassign_spill() #0 { ret void }
+
+  attributes #0 = { "amdgpu-num-vgpr"="8" }
+...
+
+# GCN-LABEL: name: nsa_reassign
+# GCN: IMAGE_SAMPLE_C_L_V1_V8_gfx10
+---
+name:            nsa_reassign
+tracksRegLiveness: true
+machineFunctionInfo:
+  stackPtrOffsetReg:  $sgpr32
+stack:
+  - { id: 0, type: default, offset: 0, size: 4, alignment: 4 }
+registers:
+  - { id: 0, class: vgpr_32, preferred-register: '$vgpr0' }
+  - { id: 1, class: vgpr_32, preferred-register: '$vgpr1' }
+  - { id: 2, class: vgpr_32, preferred-register: '$vgpr2' }
+  - { id: 3, class: vgpr_32, preferred-register: '$vgpr3' }
+  - { id: 4, class: vgpr_32, preferred-register: '$vgpr4' }
+  - { id: 5, class: vgpr_32, preferred-register: '$vgpr5' }
+  - { id: 6, class: vgpr_32, preferred-register: '$vgpr6' }
+  - { id: 7, class: vgpr_32, preferred-register: '$vgpr7' }
+body:             |
+  bb.0:
+    %0 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %1 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %2 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %3 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %4 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %5 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %6 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %7:vgpr_32 = IMAGE_SAMPLE_C_L_V1_V5_nsa_gfx10 %0, %2, %4, %5, %6, undef $sgpr0_sgpr1_sgpr2_sgpr3_sgpr4_sgpr5_sgpr6_sgpr7, undef $sgpr8_sgpr9_sgpr10_sgpr11, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, implicit $exec :: (dereferenceable load 4 from custom "ImageResource")
+    S_ENDPGM 0, implicit %7
+...
+
+# GCN-LABEL: do_not_reassign_spill
+# GCN: IMAGE_SAMPLE_C_L_V1_V5_nsa_gfx10
+---
+name:            do_not_reassign_spill
+tracksRegLiveness: true
+machineFunctionInfo:
+  stackPtrOffsetReg:  $sgpr32
+stack:
+  - { id: 0, type: default, offset: 0, size: 4, alignment: 4 }
+registers:
+  - { id: 0, class: vgpr_32, preferred-register: '$vgpr0' }
+  - { id: 1, class: vgpr_32, preferred-register: '$vgpr1' }
+  - { id: 2, class: vgpr_32, preferred-register: '$vgpr2' }
+  - { id: 3, class: vgpr_32, preferred-register: '$vgpr3' }
+  - { id: 4, class: vgpr_32, preferred-register: '$vgpr4' }
+  - { id: 5, class: vgpr_32, preferred-register: '$vgpr5' }
+  - { id: 6, class: vgpr_32, preferred-register: '$vgpr6' }
+  - { id: 7, class: vgpr_32, preferred-register: '$vgpr7' }
+body:             |
+  bb.0:
+    %0 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %1 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %2 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %3 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %4 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %5 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %6 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    S_NOP 0, implicit-def dead $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7
+    S_NOP 0, implicit %0, implicit %1, implicit %2, implicit %3, implicit %4, implicit %5, implicit %6
+    %7:vgpr_32 = IMAGE_SAMPLE_C_L_V1_V5_nsa_gfx10 %0, %2, %4, %5, %6, undef $sgpr0_sgpr1_sgpr2_sgpr3_sgpr4_sgpr5_sgpr6_sgpr7, undef $sgpr8_sgpr9_sgpr10_sgpr11, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, implicit $exec :: (dereferenceable load 4 from custom "ImageResource")
+    S_ENDPGM 0, implicit %7
+...
Index: llvm/test/CodeGen/AMDGPU/regbank-reassign-split.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/regbank-reassign-split.mir
@@ -0,0 +1,38 @@
+# RUN: llc -march=amdgcn -mcpu=gfx1010 -verify-machineinstrs -run-pass greedy,amdgpu-regbanks-reassign,virtregrewriter -o - %s | FileCheck -check-prefix=GCN %s
+
+--- |
+  define amdgpu_kernel void @do_not_reassign_spill() #0 { ret void }
+
+  attributes #0 = { "amdgpu-num-vgpr"="8" }
+...
+
+# GCN-LABEL: do_not_reassign_spill{{$}}
+# GCN: V_AND_B32_e32 killed $vgpr1, killed $vgpr5,
+---
+name:            do_not_reassign_spill
+tracksRegLiveness: true
+machineFunctionInfo:
+  stackPtrOffsetReg:  $sgpr32
+stack:
+  - { id: 0, type: default, offset: 0, size: 4, alignment: 4 }
+registers:
+  - { id: 0, class: vgpr_32, preferred-register: '$vgpr0' }
+  - { id: 1, class: vgpr_32, preferred-register: '$vgpr1' }
+  - { id: 2, class: vgpr_32, preferred-register: '$vgpr2' }
+  - { id: 3, class: vgpr_32, preferred-register: '$vgpr3' }
+  - { id: 4, class: vgpr_32, preferred-register: '$vgpr4' }
+  - { id: 5, class: vgpr_32, preferred-register: '$vgpr5' }
+  - { id: 6, class: vgpr_32 }
+body: |
+  bb.0:
+    %0 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %1 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %2 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %3 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %4 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    %5 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load 4 from %stack.0, align 4, addrspace 5)
+    S_NOP 0, implicit-def dead $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7
+    S_NOP 0, implicit %0, implicit %1, implicit %2, implicit %3, implicit %4, implicit %5
+    %6 = V_AND_B32_e32 %1, %5, implicit $exec
+    S_ENDPGM 0, implicit %6
+...