Be a bit more aggressive in bailing out of this routine. Spotted by

[oota-llvm.git] / lib / Transforms / Scalar / ADCE.cpp

diff --git a/lib/Transforms/Scalar/ADCE.cpp b/lib/Transforms/Scalar/ADCE.cpp
index bdf8029b18ef4694a8f8dd952ccd945497ec08da..b344952cc5fcaed42a60e05442db327d9bc65204 100644 (file)
--- a/lib/Transforms/Scalar/ADCE.cpp
+++ b/lib/Transforms/Scalar/ADCE.cpp
@@ -9,7 +9,7 @@
 //
 // This file implements the Aggressive Dead Code Elimination pass.  This pass
 // optimistically assumes that all instructions are dead until proven otherwise,
-// allowing it to eliminate dead computations that other DCE passes do not 
+// allowing it to eliminate dead computations that other DCE passes do not
 // catch, particularly involving loop computations.
 //
 //===----------------------------------------------------------------------===//
@@ -18,60 +18,61 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/BasicBlock.h"
 #include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CFG.h"
-#include "llvm/Support/Compiler.h"
 #include "llvm/Support/InstIterator.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
-
 using namespace llvm;
 
 STATISTIC(NumRemoved, "Number of instructions removed");
 
 namespace {
-  struct VISIBILITY_HIDDEN ADCE : public FunctionPass {
+  struct ADCE : public FunctionPass {
     static char ID; // Pass identification, replacement for typeid
-    ADCE() : FunctionPass(&ID) {}
-    
+    ADCE() : FunctionPass(ID) {
+      initializeADCEPass(*PassRegistry::getPassRegistry());
+    }
+
     virtual bool runOnFunction(Function& F);
-    
+
     virtual void getAnalysisUsage(AnalysisUsage& AU) const {
       AU.setPreservesCFG();
     }
-    
+
   };
 }
 
 char ADCE::ID = 0;
-static RegisterPass<ADCE> X("adce", "Aggressive Dead Code Elimination");
+INITIALIZE_PASS(ADCE, "adce", "Aggressive Dead Code Elimination", false, false)
 
 bool ADCE::runOnFunction(Function& F) {
   SmallPtrSet<Instruction*, 128> alive;
   SmallVector<Instruction*, 128> worklist;
-  
+
   // Collect the set of "root" instructions that are known live.
   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
     if (isa<TerminatorInst>(I.getInstructionIterator()) ||
-        I->mayWriteToMemory()) {
+        isa<DbgInfoIntrinsic>(I.getInstructionIterator()) ||
+        isa<LandingPadInst>(I.getInstructionIterator()) ||
+        I->mayHaveSideEffects()) {
       alive.insert(I.getInstructionIterator());
       worklist.push_back(I.getInstructionIterator());
     }
-  
+
   // Propagate liveness backwards to operands.
   while (!worklist.empty()) {
-    Instruction* curr = worklist.back();
-    worklist.pop_back();
-    
+    Instruction* curr = worklist.pop_back_val();
     for (Instruction::op_iterator OI = curr->op_begin(), OE = curr->op_end();
          OI != OE; ++OI)
       if (Instruction* Inst = dyn_cast<Instruction>(OI))
         if (alive.insert(Inst))
           worklist.push_back(Inst);
   }
-  
+
   // The inverse of the live set is the dead set.  These are those instructions
   // which have no side effects and do not influence the control flow or return
   // value of the function, and may therefore be deleted safely.
@@ -81,10 +82,10 @@ bool ADCE::runOnFunction(Function& F) {
       worklist.push_back(I.getInstructionIterator());
       I->dropAllReferences();
     }
-  
+
   for (SmallVector<Instruction*, 1024>::iterator I = worklist.begin(),
        E = worklist.end(); I != E; ++I) {
-    NumRemoved++;
+    ++NumRemoved;
     (*I)->eraseFromParent();
   }