Index: clang/lib/CodeGen/CGExprAgg.cpp
===================================================================
--- clang/lib/CodeGen/CGExprAgg.cpp
+++ clang/lib/CodeGen/CGExprAgg.cpp
@@ -127,6 +127,8 @@
   }
 
   void VisitConstantExpr(ConstantExpr *E) {
+    EnsureDest(E->getType());
+
     if (llvm::Value *Result = ConstantEmitter(CGF).tryEmitConstantExpr(E)) {
       CGF.EmitAggregateStore(Result, Dest.getAddress(),
                              E->getType().isVolatileQualified());
Index: clang/test/CodeGenCXX/cxx20-consteval-crash.cpp
===================================================================
--- clang/test/CodeGenCXX/cxx20-consteval-crash.cpp
+++ clang/test/CodeGenCXX/cxx20-consteval-crash.cpp
@@ -12,3 +12,15 @@
 // CHECK-NEXT: @_ZN7PR507872x2E = global i32* @_ZN7PR507872x_E, align 4
 }
 
+namespace PR51484 {
+// This code would previously cause a crash.
+struct X { int val; };
+consteval X g() { return {0}; }
+void f() { g(); }
+
+// CHECK: define dso_local void @_ZN7PR514841fEv() #0 {
+// CHECK: entry:
+// CHECK-NOT: call i32 @_ZN7PR514841gEv()
+// CHECK:  ret void
+// CHECK: }
+}