Initial KLEE checkin.

 - Lots more tweaks, documentation, and web page content is needed,
   but this should compile & work on OS X & Linux.


git-svn-id: https://llvm.org/svn/llvm-project/klee/trunk@72205 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 83 insertions, 0 deletions

diff --git a/lib/Module/PhiCleaner.cpp b/lib/Module/PhiCleaner.cpp
new file mode 100644
index 00000000..3d8d7867
--- /dev/null
+++ b/lib/Module/PhiCleaner.cpp
@@ -0,0 +1,83 @@
+//===-- PhiCleaner.cpp ----------------------------------------------------===//
+//
+//                     The KLEE Symbolic Virtual Machine
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Passes.h"
+
+#include <set>
+
+using namespace llvm;
+
+char klee::PhiCleanerPass::ID = 0;
+
+bool klee::PhiCleanerPass::runOnFunction(Function &f) {
+  bool changed = false;
+  
+  for (Function::iterator b = f.begin(), be = f.end(); b != be; ++b) {
+    BasicBlock::iterator it = b->begin();
+
+    if (it->getOpcode() == Instruction::PHI) {
+      PHINode *reference = cast<PHINode>(it);
+      
+      std::set<Value*> phis;
+      phis.insert(reference);
+
+      unsigned numBlocks = reference->getNumIncomingValues();
+      for (++it; isa<PHINode>(*it); ++it) {
+        PHINode *pi = cast<PHINode>(it);
+
+        assert(numBlocks == pi->getNumIncomingValues());
+
+        // see if it is out of order
+        unsigned i;
+        for (i=0; i<numBlocks; i++)
+          if (pi->getIncomingBlock(i) != reference->getIncomingBlock(i))
+            break;
+
+        if (i!=numBlocks) {
+          std::vector<Value*> values;
+          values.reserve(numBlocks);
+          for (unsigned i=0; i<numBlocks; i++)
+            values[i] = pi->getIncomingValueForBlock(reference->getIncomingBlock(i));
+          for (unsigned i=0; i<numBlocks; i++) {
+            pi->setIncomingBlock(i, reference->getIncomingBlock(i));
+            pi->setIncomingValue(i, values[i]);
+          }
+          changed = true;
+        }
+
+        // see if it uses any previously defined phi nodes
+        for (i=0; i<numBlocks; i++) {
+          Value *value = pi->getIncomingValue(i);
+
+          if (phis.find(value) != phis.end()) {
+            // fix by making a "move" at the end of the incoming block
+            // to a new temporary, which is thus known not to be a phi
+            // result. we could be somewhat more efficient about this
+            // by sharing temps and by reordering phi instructions so
+            // this isn't completely necessary, but in the end this is
+            // just a pathological case which does not occur very
+            // often.
+            Instruction *tmp = 
+              new BitCastInst(value, 
+                              value->getType(),
+                              value->getName() + ".phiclean",
+                              pi->getIncomingBlock(i)->getTerminator());
+            pi->setIncomingValue(i, tmp);
+          }
+
+          changed = true;
+        }
+        
+        phis.insert(pi);
+      }
+    }
+  }
+
+  return changed;
+}