From 85c22c2486c79b463451aeeba56a33313d4e460d Mon Sep 17 00:00:00 2001
From: Timotej Kapus <tk1713@ic.ac.uk>
Date: Wed, 30 Oct 2019 10:48:05 +0000
Subject: [optimize-array] Fix value transformation

Value transformation operates on word instead of byte arrays.
That means the Read indicies need to be adjusted to reflect that.
Previously IndexCleanerVisitor tried to remove the multiplications in the index
to covert byte indicies to word indicies. However as the two added test cases show
this is not sufficent. Therefore we remove the IndexCleanerVisistor and just divide
the index with word size which should always be correct.
---
 lib/Expr/ArrayExprOptimizer.cpp | 17 +++++------------
 lib/Expr/ArrayExprVisitor.cpp   | 16 ----------------
 lib/Expr/ArrayExprVisitor.h     | 14 --------------
 3 files changed, 5 insertions(+), 42 deletions(-)

(limited to 'lib/Expr')

diff --git a/lib/Expr/ArrayExprOptimizer.cpp b/lib/Expr/ArrayExprOptimizer.cpp
index b55974d0..60f2ca6e 100644
--- a/lib/Expr/ArrayExprOptimizer.cpp
+++ b/lib/Expr/ArrayExprOptimizer.cpp
@@ -313,12 +313,9 @@ ref<Expr> ExprOptimizer::getSelectOptExpr(
         arrayValues.push_back(val);
       }
 
-      ref<Expr> index = read->index;
-      IndexCleanerVisitor ice;
-      ice.visit(index);
-      if (ice.getIndex().get()) {
-        index = ice.getIndex();
-      }
+      ref<Expr> index = UDivExpr::create(
+          read->index,
+          ConstantExpr::create(bytesPerElement, read->index->getWidth()));
 
       ref<Expr> opt =
           buildConstantSelectExpr(index, arrayValues, width, elementsInArray);
@@ -650,12 +647,8 @@ ref<Expr> ExprOptimizer::buildMixedSelectExpr(
       }
     }
 
-    ref<Expr> new_index = re->index;
-    IndexCleanerVisitor ice;
-    ice.visit(new_index);
-    if (ice.getIndex().get()) {
-      new_index = ice.getIndex();
-    }
+    ref<Expr> new_index = UDivExpr::create(
+        re->index, ConstantExpr::create(width / 8, re->index->getWidth()));
 
     int new_index_width = new_index->getWidth();
     // Iterate through all the ranges
diff --git a/lib/Expr/ArrayExprVisitor.cpp b/lib/Expr/ArrayExprVisitor.cpp
index 75604104..cada7867 100644
--- a/lib/Expr/ArrayExprVisitor.cpp
+++ b/lib/Expr/ArrayExprVisitor.cpp
@@ -256,19 +256,3 @@ ExprVisitor::Action ArrayValueOptReplaceVisitor::visitRead(const ReadExpr &re) {
   }
   return Action::doChildren();
 }
-
-ExprVisitor::Action IndexCleanerVisitor::visitMul(const MulExpr &e) {
-  if (mul) {
-    if (!isa<ConstantExpr>(e.getKid(0)))
-      index = e.getKid(0);
-    else if (!isa<ConstantExpr>(e.getKid(1)))
-      index = e.getKid(1);
-    mul = false;
-  }
-  return Action::doChildren();
-}
-
-ExprVisitor::Action IndexCleanerVisitor::visitRead(const ReadExpr &) {
-  mul = false;
-  return Action::doChildren();
-}
diff --git a/lib/Expr/ArrayExprVisitor.h b/lib/Expr/ArrayExprVisitor.h
index 37f14cd1..28f485d9 100644
--- a/lib/Expr/ArrayExprVisitor.h
+++ b/lib/Expr/ArrayExprVisitor.h
@@ -124,20 +124,6 @@ public:
                                        bool recursive = true)
       : ExprVisitor(recursive), optimized(_optimized) {}
 };
-
-class IndexCleanerVisitor : public ExprVisitor {
-private:
-  bool mul{true};
-  ref<Expr> index;
-
-protected:
-  Action visitMul(const MulExpr &) override;
-  Action visitRead(const ReadExpr &) override;
-
-public:
-  IndexCleanerVisitor() : ExprVisitor(true) {}
-  inline ref<Expr> getIndex() { return index; }
-};
 } // namespace klee
 
 #endif /* KLEE_ARRAYEXPRVISITOR_H */
-- 
cgit 1.4.1