diff --git a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -185,6 +185,11 @@
   if (!MI.getOperand(0).isReg())
     TII->commuteInstruction(MI, false, 0, 1);
 
+  // cmpk requires src0 to be a register
+  const MachineOperand &Src0 = MI.getOperand(0);
+  if (!Src0.isReg())
+    return;
+
   const MachineOperand &Src1 = MI.getOperand(1);
   if (!Src1.isImm())
     return;
diff --git a/llvm/test/CodeGen/AMDGPU/cmp_shrink.mir b/llvm/test/CodeGen/AMDGPU/cmp_shrink.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/cmp_shrink.mir
@@ -0,0 +1,11 @@
+# RUN: llc -march=amdgcn -mcpu=gfx900 -run-pass si-shrink-instructions -verify-machineinstrs %s -o - | FileCheck -check-prefix=GCN %s
+
+# GCN-LABEL: name: not_shrink_icmp
+# GCN: bb.0:
+# GCN-NOT: S_CMPK_GT_I32
+---
+name:             not_shrink_icmp
+body:             |
+  bb.0:
+    S_CMP_GT_I32 1, 65, implicit-def $scc
+...