1 files changed, 94 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp b/contrib/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
new file mode 100644
index 0000000..ac005f9
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
@@ -0,0 +1,94 @@
+//===------ SimplifyInstructions.cpp - Remove redundant instructions ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a utility pass used for testing the InstructionSimplify analysis.
+// The analysis is applied to every instruction, and if it simplifies then the
+// instruction is replaced by the simplification.  If you are looking for a pass
+// that performs serious instruction folding, use the instcombine pass instead.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "instsimplify"
+#include "llvm/Function.h"
+#include "llvm/Pass.h"
+#include "llvm/Type.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
+using namespace llvm;
+
+STATISTIC(NumSimplified, "Number of redundant instructions removed");
+
+namespace {
+  struct InstSimplifier : public FunctionPass {
+    static char ID; // Pass identification, replacement for typeid
+    InstSimplifier() : FunctionPass(ID) {
+      initializeInstSimplifierPass(*PassRegistry::getPassRegistry());
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+    }
+
+    /// runOnFunction - Remove instructions that simplify.
+    bool runOnFunction(Function &F) {
+      const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
+      const TargetData *TD = getAnalysisIfAvailable<TargetData>();
+      SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
+      bool Changed = false;
+
+      do {
+        for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
+             DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
+          for (BasicBlock::iterator BI = DI->begin(), BE = DI->end(); BI != BE;) {
+            Instruction *I = BI++;
+            // The first time through the loop ToSimplify is empty and we try to
+            // simplify all instructions.  On later iterations ToSimplify is not
+            // empty and we only bother simplifying instructions that are in it.
+            if (!ToSimplify->empty() && !ToSimplify->count(I))
+              continue;
+            // Don't waste time simplifying unused instructions.
+            if (!I->use_empty())
+              if (Value *V = SimplifyInstruction(I, TD, DT)) {
+                // Mark all uses for resimplification next time round the loop.
+                for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
+                     UI != UE; ++UI)
+                  Next->insert(cast<Instruction>(*UI));
+                I->replaceAllUsesWith(V);
+                ++NumSimplified;
+                Changed = true;
+              }
+            Changed |= RecursivelyDeleteTriviallyDeadInstructions(I);
+          }
+
+        // Place the list of instructions to simplify on the next loop iteration
+        // into ToSimplify.
+        std::swap(ToSimplify, Next);
+        Next->clear();
+      } while (!ToSimplify->empty());
+
+      return Changed;
+    }
+  };
+}
+
+char InstSimplifier::ID = 0;
+INITIALIZE_PASS(InstSimplifier, "instsimplify", "Remove redundant instructions",
+                false, false)
+char &llvm::InstructionSimplifierID = InstSimplifier::ID;
+
+// Public interface to the simplify instructions pass.
+FunctionPass *llvm::createInstructionSimplifierPass() {
+  return new InstSimplifier();
+}