unnecessary push/pop fix

gcc/flags.h

@@ -454,3 +454,6 @@ extern int flag_hex_asm;
 /* Nonzero if generated DWARF debug info should match (buggy) original
    GCC 2.95.x behavior. */
 extern int flag_legacy_debug_info;
+
+/* Nonzero if prologue bug should be fixed.  */
+extern int flag_prologue_bugfix;

gcc/thumb.c

@@ -717,8 +717,11 @@ far_jump_used_p()
     rtx insn;
 
 #ifndef OLD_COMPILER
-    if (current_function_has_far_jump)
-        return 1;
+    if (!flag_prologue_bugfix)
+    {
+        if (current_function_has_far_jump)
+            return 1;
+    }
 #endif
 
     for (insn = get_insns(); insn; insn = NEXT_INSN(insn))

gcc/toplev.c

@@ -588,6 +588,9 @@ int flag_hex_asm = 0;
 /* Use old (buggy) DWARF line info generator. */
 int flag_legacy_debug_info = 0;
 
+/* Fix prologue bug in new compiler.  */
+int flag_prologue_bugfix = 0;
+
 typedef struct
 {
     char *string;
@@ -729,6 +732,13 @@ lang_independent_options f_options[] =
      "Use hex instead of decimal in assembly output"},
     {"legacy-debug-line-info", &flag_legacy_debug_info, 1,
      "Generate old (buggy) DWARF line info"},
+    #ifndef OLD_COMPILER
+    /* This flag fixes a bug in the newer agbcc version that causes `lr` to be
+       saved onto the stack in functions where it is not necessary. This is
+       needed to produce matching code for certain GBA games.  */
+    {"prologue-bugfix", &flag_prologue_bugfix, 1,
+     "Prevent unnecessary saving of the lr register to the stack"},
+#endif
 };
 
 #define NUM_ELEM(a)  (sizeof (a) / sizeof ((a)[0]))