From 71fc8bfef774108d9e4af4122eb7830081d66c46 Mon Sep 17 00:00:00 2001
From: Artur K <nemerle5@gmail.com>
Date: Sat, 17 Mar 2012 23:42:46 +0100
Subject: [PATCH] Added JumpTable class, and simplified LongJCond23/22 by using
 Assignment class as an parameter.

---
 include/Procedure.h |  9 +++++++++
 src/Procedure.cpp   | 25 +++++++++++++++++++++++++
 src/proplong.cpp    | 21 +++++++++++----------
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/include/Procedure.h b/include/Procedure.h
index 9c86e4d..8a62af8 100644
--- a/include/Procedure.h
+++ b/include/Procedure.h
@@ -77,6 +77,15 @@ struct Assignment
     COND_EXPR *lhs;
     COND_EXPR *rhs;
 };
+struct JumpTable
+{
+    uint32_t start;
+    uint32_t finish;
+    bool valid() {return start<finish;}
+    size_t size() { return (finish-start)/2;}
+    size_t entrySize() { return 2;}
+    void pruneEntries(uint16_t cs);
+};
 
 struct Function : public llvm::ilist_node<Function>
 {
diff --git a/src/Procedure.cpp b/src/Procedure.cpp
index 1a9d7af..db39e60 100644
--- a/src/Procedure.cpp
+++ b/src/Procedure.cpp
@@ -5,3 +5,28 @@
 //{
 //    return &m_type;
 //}
+
+/* Does some heuristic pruning.  Looks for ptrs. into the table
+ * and for addresses that don't appear to point to valid code.
+*/
+void JumpTable::pruneEntries(uint16_t cs)
+{
+    PROG *prg(Project::get()->binary());
+    for (uint32_t i = start; i < finish; i += 2)
+    {
+        uint32_t target = cs + LH(&prg->Image[i]);
+        if (target < finish && target >= start)
+            finish = target;
+        else if (target >= (uint32_t)prg->cbImage)
+            finish = i;
+    }
+    ICODE _Icode; // used as scan input
+    for (uint32_t i = start; i < finish; i += 2)
+    {
+        uint32_t target = cs + LH(&prg->Image[i]);
+        /* Be wary of 00 00 as code - it's probably data */
+        if (! (prg->Image[target] || prg->Image[target+1]) || scan(target, _Icode))
+            finish = i;
+    }
+
+}
diff --git a/src/proplong.cpp b/src/proplong.cpp
index 34bf367..a40a03c 100644
--- a/src/proplong.cpp
+++ b/src/proplong.cpp
@@ -83,7 +83,7 @@ static boolT isLong22 (iICODE pIcode, iICODE pEnd, iICODE &off)
  * @return number of ICODEs to skip
 
 */
-static int longJCond23 (COND_EXPR *rhs, COND_EXPR *lhs, iICODE pIcode, int arc, iICODE atOffset)
+static int longJCond23 (Assignment &asgn, iICODE pIcode, int arc, iICODE atOffset)
 {
     BB * pbb, * obb1, * obb2, * tbb;
     int skipped_insn=0;
@@ -142,8 +142,8 @@ static int longJCond23 (COND_EXPR *rhs, COND_EXPR *lhs, iICODE pIcode, int arc,
     iICODE atOffset1(atOffset),next1(++iICODE(pIcode));
     advance(atOffset1,1);
     /* Create new HLI_JCOND and condition */
-    lhs = COND_EXPR::boolOp (lhs, rhs, condOpJCond[atOffset1->ll()->getOpcode()-iJB]);
-    next1->setJCond(lhs);
+    asgn.lhs = COND_EXPR::boolOp (asgn.lhs, asgn.rhs, condOpJCond[atOffset1->ll()->getOpcode()-iJB]);
+    next1->setJCond(asgn.lhs);
     next1->copyDU(*pIcode, eUSE, eUSE);
     next1->du.use |= atOffset->du.use;
 
@@ -167,7 +167,7 @@ static int longJCond23 (COND_EXPR *rhs, COND_EXPR *lhs, iICODE pIcode, int arc,
  * the new edges for the remaining nodes.
  * @return number of ICODE's to skip
 */
-static int longJCond22 (COND_EXPR *rhs, COND_EXPR *lhs, iICODE pIcode,iICODE pEnd)
+static int longJCond22 (Assignment &asgn, iICODE pIcode,iICODE pEnd)
 {
 
     BB * pbb, * obb1, * tbb;
@@ -177,8 +177,8 @@ static int longJCond22 (COND_EXPR *rhs, COND_EXPR *lhs, iICODE pIcode,iICODE pEn
     iICODE icodes[] = { pIcode++,pIcode++,pIcode++,pIcode++ };
 
     /* Form conditional expression */
-    lhs = COND_EXPR::boolOp (lhs, rhs, condOpJCond[icodes[3]->ll()->getOpcode() - iJB]);
-    icodes[1]->setJCond(lhs);
+    asgn.lhs = COND_EXPR::boolOp (asgn.lhs, asgn.rhs, condOpJCond[icodes[3]->ll()->getOpcode() - iJB]);
+    icodes[1]->setJCond(asgn.lhs);
     icodes[1]->copyDU (*icodes[0], eUSE, eUSE);
     icodes[1]->du.use |= icodes[2]->du.use;
 
@@ -283,7 +283,7 @@ void Function::propLongStk (int i, const ID &pLocId)
         {
             if ( checkLongEq (pLocId.id.longStkId, pIcode, i, this, asgn, *l23->ll()) )
             {
-                advance(pIcode,longJCond23 (asgn.rhs, asgn.lhs, pIcode, arc, l23));
+                advance(pIcode,longJCond23 (asgn, pIcode, arc, l23));
             }
         }
 
@@ -293,7 +293,7 @@ void Function::propLongStk (int i, const ID &pLocId)
         {
             if ( checkLongEq (pLocId.id.longStkId, pIcode, i, this,asgn, *l23->ll()) )
             {
-                advance(pIcode,longJCond22 (asgn.rhs, asgn.lhs, pIcode,pEnd));
+                advance(pIcode,longJCond22 (asgn, pIcode,pEnd));
             }
         }
     }
@@ -460,7 +460,7 @@ int Function::findForwardLongUses(int loc_ident_idx, const ID &pLocId, iICODE be
             if (checkLongRegEq (pLocId.id.longId, pIcode, loc_ident_idx, this, asgn, *long_loc->ll()))
             {
                                 // reduce the advance by 1 here (loop increases) ?
-                advance(pIcode,longJCond23 (asgn.rhs, asgn.lhs, pIcode, arc, long_loc));
+                advance(pIcode,longJCond23 (asgn, pIcode, arc, long_loc));
             }
         }
 
@@ -470,7 +470,8 @@ int Function::findForwardLongUses(int loc_ident_idx, const ID &pLocId, iICODE be
         {
             if (checkLongRegEq (pLocId.id.longId, pIcode, loc_ident_idx, this, asgn, *long_loc->ll()) )
             {
-                advance(pIcode,longJCond22 (asgn.rhs, asgn.lhs, pIcode,pEnd) - 1);
+                // TODO: verify that removing -1 does not change anything !
+                advance(pIcode,longJCond22 (asgn, pIcode,pEnd));
             }
         }