2006-09-06 Frank Ch. Eigler <fche@elastic.org>

	Add basic support for initialized globals.
	* parse.cxx (parse_global): Parse initialization clause, implement
	by rewriting to "probe begin { var = value }".
	* parse.h: Corresponding changes.
	* stap.1.in: Document optional initialization.

2006-09-06  Frank Ch. Eigler  <fche@elastic.org>

	* parseok/eighteen.stp, semok/twentythree.stp: New files for
	testing initialized globals.

7 files changed, 82 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 6949a7f5..56541d3d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2006-09-06  Frank Ch. Eigler  <fche@elastic.org>
+
+	Add basic support for initialized globals.
+	* parse.cxx (parse_global): Parse initialization clause, implement
+	by rewriting to "probe begin { var = value }".
+	* parse.h: Corresponding changes.
+	* stap.1.in: Document optional initialization.
+
 2006-09-04  Frank Ch. Eigler  <fche@elastic.org>
 
 	Improve unresolved target-symbol error messages.
diff --git a/parse.cxx b/parse.cxx
index 76c1003f..a61edc08 100644
--- a/parse.cxx
+++ b/parse.cxx
@@ -785,7 +785,7 @@ parser::parse ()
 	  else if (t->type == tok_keyword && t->content == "global")
 	    {
 	      context = con_global;
-	      parse_global (f->globals);
+	      parse_global (f->globals, f->probes);
 	    }
 	  else if (t->type == tok_keyword && t->content == "function")
 	    {
@@ -1024,7 +1024,7 @@ parser::parse_statement ()
 
 
 void
-parser::parse_global (vector <vardecl*>& globals)
+parser::parse_global (vector <vardecl*>& globals, vector<probe*>& probes)
 {
   const token* t0 = next ();
   if (! (t0->type == tok_keyword && t0->content == "global"))
@@ -1046,7 +1046,56 @@ parser::parse_global (vector <vardecl*>& globals)
       globals.push_back (d);
 
       t = peek ();
-      if (t && t->type == tok_operator && t->content == ",")
+      if (t && t->type == tok_operator && t->content == "=") // initialization
+        {
+          next ();
+
+          // Create synthetic "begin" probe to assign value to global.
+          //
+          // An alternative would be to store the initializer value
+          // within a new field of vardecl, and use e.g. the
+          // type-resolution stage to do the rewriting.  It could go
+          // farther: the initializer could live through till
+          // translation and be emitted as a plain C-level variable
+          // initializer.
+
+          literal* value = parse_literal ();
+
+          probe_point* pp = new probe_point;
+          probe_point::component* ppc = new probe_point::component;
+          ppc->functor = string("begin");
+          pp->tok = t;
+          pp->components.push_back (ppc);
+
+          probe* p = new probe;
+          p->tok = t;
+          p->locations.push_back (pp);
+
+          symbol* sym = new symbol;
+          sym->tok = t;
+          sym->name = d->name;
+
+          assignment* a = new assignment;
+          a->tok = t;
+          a->op = "=";
+          a->left = sym;
+          a->right = value;
+
+          expr_statement* es = new expr_statement;
+          es->tok = t;
+          es->value = a;
+
+          block* blk = new block;
+          blk->tok = t;
+          blk->statements.push_back (es);
+
+          p->body = blk;
+          probes.push_back (p);
+
+          t = peek ();
+        }
+
+      if (t && t->type == tok_operator && t->content == ",") // next global
 	{
 	  next ();
 	  continue;
diff --git a/parse.h b/parse.h
index 335cbe53..0b10010d 100644
--- a/parse.h
+++ b/parse.h
@@ -154,7 +154,7 @@ private:
 
 private: // nonterminals
   void parse_probe (std::vector<probe*>&, std::vector<probe_alias*>&);
-  void parse_global (std::vector<vardecl*>&);
+  void parse_global (std::vector<vardecl*>&, std::vector<probe*>&);
   void parse_functiondecl (std::vector<functiondecl*>&);
   embeddedcode* parse_embeddedcode ();
   probe_point* parse_probe_point ();
diff --git a/stap.1.in b/stap.1.in
index c7fb9b30..d0492c2c 100644
--- a/stap.1.in
+++ b/stap.1.in
@@ -266,11 +266,12 @@ probes and live as long as the entire systemtap session.  There is one
 namespace for all global variables, regardless of which script file
 they are found within.  A global declaration may be written at the
 outermost level anywhere, not within a block of code.  The following
-declaration marks "var1" and "var2" as global.  The translator will
+declaration marks a few variables as global.  The translator will
 infer for each its value type, and if it is used as an array, its key
-types.
+types.  Optionally, scalar globals may be initialized with a string
+or number literal.
 .RS
-.BR global " var1" , " var2"
+.BR global " var1" , " var2" , " var3=4"
 .RE
 .\" XXX add statistics type here once it's supported
 
diff --git a/testsuite/ChangeLog b/testsuite/ChangeLog
index 3bca1e4c..ee5664ca 100644
--- a/testsuite/ChangeLog
+++ b/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-09-06  Frank Ch. Eigler  <fche@elastic.org>
+
+	* parseok/eighteen.stp, semok/twentythree.stp: New files for
+	testing initialized globals.
+
 2006-08-21  Martin Hunt  <hunt@redhat.com>
 
 	* lib/stap_run.exp: Check for existence of installtest_p
diff --git a/testsuite/parseok/eighteen.stp b/testsuite/parseok/eighteen.stp
new file mode 100755
index 00000000..883a6514
--- /dev/null
+++ b/testsuite/parseok/eighteen.stp
@@ -0,0 +1,6 @@
+#! stap -p1
+
+global c, a = 1
+global b = "hello", d
+
+probe begin { }
diff --git a/testsuite/semok/twentythree.stp b/testsuite/semok/twentythree.stp
new file mode 100755
index 00000000..dbdaf7e5
--- /dev/null
+++ b/testsuite/semok/twentythree.stp
@@ -0,0 +1,6 @@
+#! stap -p2
+
+global c, a = 1
+global b = "hello", d
+
+probe begin { print (c = a) print (d = b) }