Oops, forgot to add the pass itself!

llvm-svn: 122265

lib/Transforms/Utils/SimplifyInstructions.cpp

@@ -0,0 +1,69 @@
+//===------ 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/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Scalar.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) {
+      bool Changed = false;
+      const TargetData *TD = getAnalysisIfAvailable<TargetData>();
+      const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
+      for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+        for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
+          Instruction *I = BI++;
+          if (Value *V = SimplifyInstruction(I, TD, DT)) {
+            I->replaceAllUsesWith(V);
+            I->eraseFromParent();
+            Changed = true;
+            ++NumSimplified;
+          }
+        }
+      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();
+}