diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -578,11 +578,20 @@
   if (!RegsOverlap) {
     for (auto Def = MI, E = MBB.begin(); Def != E; ) {
       --Def;
-      if (!Def->definesRegister(SrcReg, &RI))
+
+      if (!Def->modifiesRegister(SrcReg, &RI))
         continue;
+
       if (Def->getOpcode() != AMDGPU::V_ACCVGPR_WRITE_B32_e64)
         break;
 
+      // The 0th operand of ACCVGPR_WRITE on gfx908 will always be the register
+      // that potentially contains the bits we are interested in
+      assert(Def->getOperand(0).isReg());
+
+      if (Def->getOperand(0).getReg() != SrcReg)
+        break;
+
       MachineOperand &DefOp = Def->getOperand(1);
       assert(DefOp.isReg() || DefOp.isImm());
 
diff --git a/llvm/test/CodeGen/AMDGPU/accvgpr-copy.mir b/llvm/test/CodeGen/AMDGPU/accvgpr-copy.mir
--- a/llvm/test/CodeGen/AMDGPU/accvgpr-copy.mir
+++ b/llvm/test/CodeGen/AMDGPU/accvgpr-copy.mir
@@ -900,9 +900,11 @@
     ; GFX908-NEXT: $vgpr1 = V_ACCVGPR_READ_B32_e64 $agpr1, implicit $exec, implicit $agpr0_agpr1
     ; GFX908-NEXT: $agpr2 = V_ACCVGPR_WRITE_B32_e64 $vgpr1, implicit $exec, implicit-def $agpr1_agpr2
     ; GFX908-NEXT: $vgpr0 = V_ACCVGPR_READ_B32_e64 $agpr0, implicit $exec, implicit $agpr0_agpr1
-    ; GFX908-NEXT: $agpr1 = V_ACCVGPR_WRITE_B32_e64 $vgpr0, implicit $exec, implicit $exec, implicit-def $agpr1_agpr2
-    ; GFX908-NEXT: $agpr4 = V_ACCVGPR_WRITE_B32_e64 $vgpr0, implicit $exec, implicit-def $agpr3_agpr4, implicit $agpr1_agpr2
-    ; GFX908-NEXT: $agpr3 = V_ACCVGPR_WRITE_B32_e64 $vgpr0, implicit $exec, implicit killed $agpr1_agpr2, implicit $exec
+    ; GFX908-NEXT: $agpr1 = V_ACCVGPR_WRITE_B32_e64 killed $vgpr0, implicit $exec, implicit $exec, implicit-def $agpr1_agpr2
+    ; GFX908-NEXT: $vgpr0 = V_ACCVGPR_READ_B32_e64 $agpr2, implicit $exec, implicit $agpr1_agpr2
+    ; GFX908-NEXT: $agpr4 = V_ACCVGPR_WRITE_B32_e64 killed $vgpr0, implicit $exec, implicit-def $agpr3_agpr4
+    ; GFX908-NEXT: $vgpr255 = V_ACCVGPR_READ_B32_e64 killed $agpr1, implicit $exec, implicit killed $agpr1_agpr2
+    ; GFX908-NEXT: $agpr3 = V_ACCVGPR_WRITE_B32_e64 killed $vgpr255, implicit $exec, implicit $exec
     ; GFX90A-LABEL: name: a2_to_a2_implicit_defs
     ; GFX90A: liveins: $agpr0_agpr1
     ; GFX90A-NEXT: {{  $}}
@@ -1000,6 +1002,9 @@
     S_ENDPGM 0, implicit $agpr0_agpr1_agpr2, implicit $vgpr1
 ...
 
+
+
+
 ---
 name:            a4_to_a4
 tracksRegLiveness: true