Fix Arm calling convention by push/pop operations

Author: DrXiao

src/arm-codegen.c

@@ -69,6 +69,8 @@ void update_elf_offset(ph2_ir_t *ph2_ir)
         return;
     case OP_read:
     case OP_write:
+    case OP_push:
+    case OP_pop:
     case OP_jump:
     case OP_call:
     case OP_load_func:
@@ -284,6 +286,12 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
         else
             abort();
         return;
+    case OP_push:
+        emit(__stmdb(__AL, 1, __sp, rn));
+        return;
+    case OP_pop:
+        emit(__add_i(__AL, __sp, __sp, rn * 4));
+        return;
     case OP_branch:
         emit(__teq(rn));
         if (ph2_ir->is_branch_detached) {

src/defs.h

@@ -268,6 +268,7 @@ typedef enum {
     OP_call,     /* function call */
     OP_indirect, /* indirect call with function pointer */
     OP_return,   /* explicit return */
+    OP_pop,      /* eliminate arguments */
 
     OP_allocat, /* allocate space on stack */
     OP_assign,

src/reg-alloc.c

@@ -768,12 +768,29 @@ void reg_alloc(void)
                     if (!callee_func->num_params)
                         spill_alive(bb, insn);
 
-                    if (dynlink)
+                    if (dynlink) {
                         callee_func->is_used = true;
+                        /* Push args to stack for Arm output */
+                        if (!callee_func->bbs && args > 4) {
+                            int regs = 0;
+                            for (int i = 4; i < args; i++)
+                                regs |= (1 << i);
+                            ir = bb_add_ph2_ir(bb, OP_push);
+                            ir->src0 = regs;
+                        }
+                    }
 
                     ir = bb_add_ph2_ir(bb, OP_call);
                     strcpy(ir->func_name, insn->str);
 
+                    if (dynlink) {
+                        /* Pop args from stack for Arm output */
+                        if (!callee_func->bbs && args > 4) {
+                            ir = bb_add_ph2_ir(bb, OP_pop);
+                            ir->src0 = args - 4;
+                        }
+                    }
+
                     is_pushing_args = false;
                     args = 0;