[llvm] Fix spilling of valuetypes to the stack if they are passed by addr. (#92658)

The previous code would spill the valuetype when it was passed by addr,
and another bblock could try to read from the unitialized stack location.

Author: vargaz

src/mono/mono/mini/mini-llvm.c

@@ -7812,10 +7812,10 @@ MONO_RESTORE_WARNING
 				LLVMTypeRef etype = type_to_llvm_type (ctx, t);
 
 				if (!addresses [ins->sreg1]) {
-					addresses [ins->sreg1] = create_address (ctx->module, build_named_alloca (ctx, t, "llvm_outarg_vt"), etype);
+					g_assert (!addresses [ins->dreg]);
+					addresses [ins->dreg] = create_address (ctx->module, build_named_alloca (ctx, t, "llvm_outarg_vt"), etype);
 					g_assert (values [ins->sreg1]);
-					LLVMBuildStore (builder, convert (ctx, values [ins->sreg1], etype), addresses [ins->sreg1]->value);
-					addresses [ins->dreg] = addresses [ins->sreg1];
+					LLVMBuildStore (builder, convert (ctx, values [ins->sreg1], etype), addresses [ins->dreg]->value);
 				} else if (ainfo->storage == LLVMArgVtypeAddr || values [ins->sreg1] == addresses [ins->sreg1]->value) {
 					/* LLVMArgVtypeByRef/LLVMArgVtypeAddr, have to make a copy */
 					addresses [ins->dreg] = build_alloca_address (ctx, t);