Fix a RTL bug for libgccjit which fixes a 'unrecognizable insn' error when generating some code using target-specific builtins

Author: antoyo

gcc/emit-rtl.cc

@@ -6191,8 +6191,13 @@ init_emit_once (void)
   /* Don't use gen_rtx_CONST_INT here since gen_rtx_CONST_INT in this case
      tries to use these variables.  */
   for (i = - MAX_SAVED_CONST_INT; i <= MAX_SAVED_CONST_INT; i++)
-    const_int_rtx[i + MAX_SAVED_CONST_INT] =
-      gen_rtx_raw_CONST_INT (VOIDmode, (HOST_WIDE_INT) i);
+  {
+    // Do not initialize twice the constants because there are used elsewhere
+    // and libgccjit execute this function twice.
+    if (const_int_rtx[i + MAX_SAVED_CONST_INT] == NULL)
+      const_int_rtx[i + MAX_SAVED_CONST_INT] =
+        gen_rtx_raw_CONST_INT (VOIDmode, (HOST_WIDE_INT) i);
+  }
 
   if (STORE_FLAG_VALUE >= - MAX_SAVED_CONST_INT
       && STORE_FLAG_VALUE <= MAX_SAVED_CONST_INT)