From 9bdeb8d433d41140755b56e1dc4384ec06006d5c Mon Sep 17 00:00:00 2001
From: Xuejun Yang <jxyang@cs.utah.edu>
Date: Fri, 17 Jun 2011 10:36:19 -0600
Subject: [PATCH] bug fix for union: consider callees when determining if a
 function reads union field

---
 src/Function.cpp  | 24 +++++++++++++-------
 src/Function.h    |  1 +
 src/Statement.cpp | 56 +++++++++++++++++++++++++----------------------
 src/Statement.h   |  2 ++
 4 files changed, 49 insertions(+), 34 deletions(-)

diff --git a/src/Function.cpp b/src/Function.cpp
index fce783f2d..f9e222494 100644
--- a/src/Function.cpp
+++ b/src/Function.cpp
@@ -601,21 +601,29 @@ Function::generate_body_with_known_params(const CGContext &prev_context, Effect&
 	ERROR_RETURN();
 	body->set_depth_protect(true);
 
+	compute_summary();
+	
+	make_return_const();
+	ERROR_RETURN();
+	
+	// Mark this function as built.
+	build_state = BUILT;
+}
+
+void
+Function::compute_summary(void) 
+{
+	FactMgr* fm = get_fact_mgr_for_func(this); 
 	// compute the pointers that are statically referenced in the function
 	// including ones referenced by its callees
 	body->get_referenced_ptrs(referenced_ptrs);
 
-	// Compute the function's externally visible effect.  Currently, this
-	// is just the effect on globals.
+	// Compute the function's externally visible effect.  
 	//effect.add_external_effect(*cg_context.get_effect_accum());
 	feffect.add_external_effect(fm->map_stm_effect[body]);
-	union_field_read = fm->map_stm_effect[body].union_field_is_read();
 	
-	make_return_const();
-	ERROR_RETURN();
-	
-	// Mark this function as built.
-	build_state = BUILT;
+	// determine whether an union field is read
+	union_field_read = body->read_union_field();
 }
 
 /*
diff --git a/src/Function.h b/src/Function.h
index c7f447512..e664b2614 100644
--- a/src/Function.h
+++ b/src/Function.h
@@ -78,6 +78,7 @@ class Function
 	static void doFinalization();
 
 	void generate_body_with_known_params(const CGContext &prev_context, Effect& effect_accum);
+	void compute_summary(void);
 
 	void Output(std::ostream &);
 	void OutputForwardDecl(std::ostream &);
diff --git a/src/Statement.cpp b/src/Statement.cpp
index d60cd7db3..45a23187e 100644
--- a/src/Statement.cpp
+++ b/src/Statement.cpp
@@ -51,6 +51,7 @@
 #include "Expression.h"
 #include "ExpressionFuncall.h"
 #include "FunctionInvocation.h"
+#include "FunctionInvocationUser.h"
 #include "FactPointTo.h"
 
 #include "Block.h" // temporary; don't want to depend on subclases!
@@ -672,6 +673,24 @@ Statement::is_jump_target_from_other_blocks(void) const
 	return false;
 }
 
+bool 
+Statement::read_union_field(void) const
+{
+	FactMgr* fm = get_fact_mgr_for_func(func);
+	assert(fm);
+	if (fm->map_stm_effect[this].union_field_is_read()) {
+		return true;
+	}
+	vector<const FunctionInvocationUser*> calls;
+	get_called_funcs(calls);
+	for (size_t i=0; i<calls.size(); i++) {
+		if (calls[i]->get_func()->union_field_read) {
+			return true;
+		}
+	}
+	return false;
+}
+
 /*
  * return true if s is contained inside this statement
  */
@@ -750,33 +769,18 @@ Statement::get_direct_invocation(void) const
 void 
 Statement::get_called_funcs(std::vector<const FunctionInvocationUser*>& funcs) const
 { 
-	if (eType == eAssign) {
-		((const StatementAssign*)this)->get_rhs()->get_called_funcs(funcs);
-	}
-	else if (eType == eInvoke) {
-		((const StatementExpr*)this)->get_invoke()->get_called_funcs(funcs);
-	}
-	else if (eType == eBlock) {
-		const Block* b = (const Block*)this;
-		size_t i;
-		for (i=0; i<b->stms.size(); i++) {
-			b->stms[i]->get_called_funcs(funcs);
-		}
+	size_t i;
+	vector<const Expression*> exprs;
+	vector<const Block*> blks;
+	get_exprs(exprs);
+	get_blocks(blks);
+	for (i=0; i<exprs.size(); i++) {
+		exprs[i]->get_called_funcs(funcs);
 	}
-	else if (eType == eIfElse) {
-		const StatementIf* si = (const StatementIf*)this;
-		si->get_test()->get_called_funcs(funcs);
-		si->get_true_branch()->get_called_funcs(funcs);
-		si->get_false_branch()->get_called_funcs(funcs);
-	}
-	else if (eType == eFor) {
-		const StatementFor* sf = (const StatementFor*)this;
-		sf->get_body()->get_called_funcs(funcs);
-	}
-	else if (eType == eArrayOp) {
-		const StatementArrayOp* sa = (const StatementArrayOp*)this;
-		if (sa->body) {
-			sa->body->get_called_funcs(funcs);
+	for (i=0; i<blks.size(); i++) {
+		for (size_t j=0; j<blks[i]->stms.size(); j++) {
+			const Statement* s = blks[i]->stms[j];
+			s->get_called_funcs(funcs);
 		}
 	}
 }
diff --git a/src/Statement.h b/src/Statement.h
index 4229f2272..99507d931 100644
--- a/src/Statement.h
+++ b/src/Statement.h
@@ -145,6 +145,8 @@ class Statement
 
 	bool is_jump_target_from_other_blocks(void) const;
 
+	bool read_union_field(void) const;
+
 	virtual void get_blocks(std::vector<const Block*>& /* blks */) const = 0;
 	virtual void get_exprs(std::vector<const Expression*>& /* exps */) const = 0;