[PHP] Only emit one copy of each distinct arginfo

Previously we emitted a separate one for every wrapped function,
but typically many functions have the same number of parameters
and combinations of parameters passed by reference or not.

This change significantly reduces both the size of the generated
wrapper, and of the compiled PHP extension module (e.g. by ~6% for
the stripped extension module for Xapian's PHP7 bindings).

CHANGES.current

@@ -12,6 +12,16 @@ Version 3.0.11 (in progress)
 	    for every other language - to generate foo_wrap.cpp you can run SWIG with
 	    -cppext cpp).  Fixes https://github.com/swig/swig/issues/571
 
+2016-11-30: olly
+	    [PHP] Only emit one copy of each distinct arginfo.  Previously we
+	    emitted a separate one for every wrapped function, but typically
+	    many functions have the same number of parameters and combinations
+	    of parameters passed by reference or not.
+
+	    This change significantly reduces both the size of the generated
+	    wrapper, and of the compiled PHP extension module (e.g. by ~6% for
+	    the stripped extension module for Xapian's PHP7 bindings).
+
 2016-11-28: wsfulton
             Fix %rename override of wildcard %rename for templates. For example:
 

Source/Modules/php.cxx

@@ -100,6 +100,11 @@ static String *s_oowrappers;
 static String *s_fakeoowrappers;
 static String *s_phpclasses;
 
+/* To reduce code size (generated and compiled) we only want to emit each
+ * different arginfo once, so we need to track which have been used.
+ */
+static Hash *arginfo_used;
+
 /* Variables for using PHP classes */
 static Node *current_class = 0;
 
@@ -473,6 +478,7 @@ public:
 
     /* start the arginfo section */
     s_arginfo = NewString("/* arginfo subsection */\n");
+    arginfo_used = NewHash();
 
     /* start the function entry section */
     s_entry = NewString("/* entry subsection */\n");
@@ -633,22 +639,35 @@ public:
   void create_command(String *cname, String *iname, Node *n) {
     // This is for the single main zend_function_entry record
     Printf(f_h, "ZEND_NAMED_FUNCTION(%s);\n", iname);
-    String * s = cs_entry;
-    if (!s) s = s_entry;
-    Printf(s, " SWIG_ZEND_NAMED_FE(%(lower)s,%s,swig_arginfo_%(lower)s)\n", cname, iname, cname);
 
-    // This is the above referenced arginfo structure.
+    // We want to only emit each different arginfo once, as that reduces the
+    // size of both the generated source code and the compiled extension
+    // module.  To do this, we name the arginfo to encode the number of
+    // parameters and which (if any) are passed by reference by using a
+    // sequence of 0s (for non-reference) and 1s (for by references).
     ParmList *l = Getattr(n, "parms");
-    Printf(s_arginfo, "ZEND_BEGIN_ARG_INFO_EX(swig_arginfo_%(lower)s, 0, 0, 0)\n", cname);
+    String * arginfo_code = NewStringEmpty();
     for (Parm *p = l; p; p = Getattr(p, "tmap:in:next")) {
       /* Ignored parameters */
       if (checkAttribute(p, "tmap:in:numinputs", "0")) {
 	continue;
       }
-      int byref = GetFlag(p, "tmap:in:byref");
-      Printf(s_arginfo, " ZEND_ARG_PASS_INFO(%d)\n", byref);
+      Append(arginfo_code, GetFlag(p, "tmap:in:byref") ? "1" : "0");
     }
-    Printf(s_arginfo, "ZEND_END_ARG_INFO()\n");
+
+    if (!GetFlag(arginfo_used, arginfo_code)) {
+      // Not had this one before, so emit it.
+      SetFlag(arginfo_used, arginfo_code);
+      Printf(s_arginfo, "ZEND_BEGIN_ARG_INFO_EX(swig_arginfo_%s, 0, 0, 0)\n", arginfo_code);
+      for (const char * p = Char(arginfo_code); *p; ++p) {
+	Printf(s_arginfo, " ZEND_ARG_PASS_INFO(%c)\n", *p);
+      }
+      Printf(s_arginfo, "ZEND_END_ARG_INFO()\n");
+    }
+
+    String * s = cs_entry;
+    if (!s) s = s_entry;
+    Printf(s, " SWIG_ZEND_NAMED_FE(%(lower)s,%s,swig_arginfo_%s)\n", cname, iname, arginfo_code);
   }
 
   /* ------------------------------------------------------------

Source/Modules/php5.cxx

@@ -100,6 +100,11 @@ static String *s_oowrappers;
 static String *s_fakeoowrappers;
 static String *s_phpclasses;
 
+/* To reduce code size (generated and compiled) we only want to emit each
+ * different arginfo once, so we need to track which have been used.
+ */
+static Hash *arginfo_used;
+
 /* Variables for using PHP classes */
 static Node *current_class = 0;
 
@@ -507,6 +512,7 @@ public:
 
     /* start the arginfo section */
     s_arginfo = NewString("/* arginfo subsection */\n");
+    arginfo_used = NewHash();
 
     /* start the function entry section */
     s_entry = NewString("/* entry subsection */\n");
@@ -667,22 +673,35 @@ public:
   void create_command(String *cname, String *iname, Node *n) {
     // This is for the single main zend_function_entry record
     Printf(f_h, "ZEND_NAMED_FUNCTION(%s);\n", iname);
-    String * s = cs_entry;
-    if (!s) s = s_entry;
-    Printf(s, " SWIG_ZEND_NAMED_FE(%(lower)s,%s,swig_arginfo_%(lower)s)\n", cname, iname, cname);
 
-    // This is the above referenced arginfo structure.
+    // We want to only emit each different arginfo once, as that reduces the
+    // size of both the generated source code and the compiled extension
+    // module.  To do this, we name the arginfo to encode the number of
+    // parameters and which (if any) are passed by reference by using a
+    // sequence of 0s (for non-reference) and 1s (for by references).
     ParmList *l = Getattr(n, "parms");
-    Printf(s_arginfo, "ZEND_BEGIN_ARG_INFO_EX(swig_arginfo_%(lower)s, 0, 0, 0)\n", cname);
+    String * arginfo_code = NewStringEmpty();
     for (Parm *p = l; p; p = Getattr(p, "tmap:in:next")) {
       /* Ignored parameters */
       if (checkAttribute(p, "tmap:in:numinputs", "0")) {
 	continue;
       }
-      int byref = GetFlag(p, "tmap:in:byref");
-      Printf(s_arginfo, " ZEND_ARG_PASS_INFO(%d)\n", byref);
+      Append(arginfo_code, GetFlag(p, "tmap:in:byref") ? "1" : "0");
     }
-    Printf(s_arginfo, "ZEND_END_ARG_INFO()\n");
+
+    if (!GetFlag(arginfo_used, arginfo_code)) {
+      // Not had this one before, so emit it.
+      SetFlag(arginfo_used, arginfo_code);
+      Printf(s_arginfo, "ZEND_BEGIN_ARG_INFO_EX(swig_arginfo_%s, 0, 0, 0)\n", arginfo_code);
+      for (const char * p = Char(arginfo_code); *p; ++p) {
+	Printf(s_arginfo, " ZEND_ARG_PASS_INFO(%c)\n", *p);
+      }
+      Printf(s_arginfo, "ZEND_END_ARG_INFO()\n");
+    }
+
+    String * s = cs_entry;
+    if (!s) s = s_entry;
+    Printf(s, " SWIG_ZEND_NAMED_FE(%(lower)s,%s,swig_arginfo_%s)\n", cname, iname, arginfo_code);
   }
 
   /* ------------------------------------------------------------