Fix IR test failure

Regenerate ARM IR snapshots to reflect the corrected lowering.

Restore ARM/RISC-V codegen files to original structure after earlier brace experiment.

Treat zero-length array compound literals as constant zero during lowering so scalar uses don't load garbage.

Author: lorettayao

src/arm-codegen.c

@@ -450,7 +450,7 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
             fatal("Unsupported truncation operation with invalid target size");
         }
         return;
-    case OP_sign_ext: {
+    case OP_sign_ext:
         /* Decode source size from upper 16 bits */
         int source_size = (rm >> 16) & 0xFFFF;
         if (source_size == 2) {
@@ -459,7 +459,6 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
             /* For other cases, use byte extension (original behavior) */
             emit(__sxtb(__AL, rd, rn, 0));
         }
-    }
         return;
     case OP_cast:
         /* Generic cast operation - for now, just move the value */

src/parser.c

@@ -2108,6 +2108,12 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
                 add_insn(parent, *bb, OP_allocat, compound_var, NULL, NULL, 0,
                          NULL);
                 parse_array_compound_literal(compound_var, parent, bb, true);
+                
+                if (compound_var->array_size == 0) {
+                    compound_var->init_val = 0;
+                    add_insn(parent, *bb, OP_load_constant, compound_var, NULL,
+                             NULL, 0, NULL);
+                }
                 opstack_push(compound_var);
                 consumed_close_brace = true;
             } else if (cast_ptr_level > 0) {