Index: llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h
===================================================================
--- llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h
+++ llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h
@@ -90,6 +90,22 @@
 }
 ///}
 
+struct ICstRegMatch {
+  Register &CR;
+  ICstRegMatch(Register &C) : CR(C) {}
+  bool match(const MachineRegisterInfo &MRI, Register Reg) {
+    if (auto MaybeCst = getConstantVRegValWithLookThrough(
+            Reg, MRI, /*LookThroughInstrs*/ true,
+            /*HandleFConstants*/ false)) {
+      CR = MaybeCst->VReg;
+      return true;
+    }
+    return false;
+  }
+};
+
+inline ICstRegMatch m_ICst(Register &Reg) { return ICstRegMatch(Reg); }
+
 // TODO: Rework this for different kinds of MachineOperand.
 // Currently assumes the Src for a match is a register.
 // We might want to support taking in some MachineOperands and call getReg on