Add new Pass infrastructure and some examples

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@836 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/ChangeAllocations.h

@@ -0,0 +1,39 @@
+//===- llvm/Transforms/LowerAllocations.h - Remove Malloc & Free -*- C++ -*--=//
+//
+// This file defines the interface to a pass that lowers malloc and free
+// instructions to calls to %malloc & %free functions.  This transformation is
+// a target dependant tranformation because we depend on the size of data types
+// and alignment constraints.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_LOWERALLOCATIONS_H
+#define LLVM_TRANSFORMS_LOWERALLOCATIONS_H
+
+#include "llvm/Transforms/Pass.h"
+class TargetData;
+
+class LowerAllocations : public ConcretePass<LowerAllocations> {
+  Method *MallocMeth;   // Methods in the module we are processing
+  Method *FreeMeth;     // Initialized by doPassInitializationVirt
+
+  const TargetData &DataLayout;
+public:
+  inline LowerAllocations(const TargetData &TD) : DataLayout(TD) {
+    MallocMeth = FreeMeth = 0;
+  }
+
+  // doPassInitialization - For the lower allocations pass, this ensures that a
+  // module contains a declaration for a malloc and a free function.
+  //
+  // This function is always successful.
+  //
+  bool doPassInitializationVirt(Module *M);
+
+  // doPerMethodWork - This method does the actual work of converting
+  // instructions over, assuming that the pass has already been initialized.
+  //
+  bool doPerMethodWorkVirt(Method *M);
+};
+
+#endif

include/llvm/Transforms/HoistPHIConstants.h

@@ -0,0 +1,20 @@
+//===- llvm/Transforms/HoistPHIConstants.h - Normalize PHI nodes -*- C++ -*--=//
+//
+// HoistPHIConstants - Remove literal constants that are arguments of PHI nodes
+// by inserting cast instructions in the preceeding basic blocks, and changing
+// constant references into references of the casted value.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_HOISTPHICONSTANTS_H
+#define LLVM_TRANSFORMS_HOISTPHICONSTANTS_H
+
+#include "llvm/Transforms/Pass.h"
+
+struct HoistPHIConstants : public StatelessPass<HoistPHIConstants> {
+  // doPerMethodWork - This method does the work.  Always successful.
+  //
+  static bool doPerMethodWork(Method *M);
+};
+
+#endif

include/llvm/Transforms/Pass.h

@@ -0,0 +1,200 @@
+//===- llvm/Transforms/Pass.h - Base class for XForm Passes ------*- C++ -*--=//
+//
+// This file defines a marker class that indicates that a specified class is a
+// transformation pass implementation.
+//
+// Pass's are designed this way so that it is possible to apply N passes to a
+// module, by first doing N Pass specific initializations for the module, then
+// looping over all of the methods in the module, doing method specific work
+// N times for each method.  Like this:
+//
+// for_each(Passes.begin(), Passes.end(), doPassInitialization(Module));
+// for_each(Method *M <- Module->begin(), Module->end())
+//   for_each(Passes.begin(), Passes.end(), doPerMethodWork(M));
+//
+// The other way to do things is like this:
+// for_each(Pass *P <- Passes.begin(), Passes.end()) {
+//   Passes->doPassInitialization(Module)
+//   for_each(Module->begin(), Module->end(), P->doPerMethodWork);
+// }
+//
+// But this can cause thrashing and poor cache performance, so we don't do it
+// that way.
+//
+// Because a transformation does not see all methods consecutively, it should
+// be careful about the state that it maintains... another pass may modify a
+// method between two invokacations of doPerMethodWork.
+//
+// Also, implementations of doMethodWork should not remove any methods from the
+// module.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_PASS_H
+#define LLVM_TRANSFORMS_PASS_H
+
+#include "llvm/Module.h"
+#include "llvm/Method.h"
+
+//===----------------------------------------------------------------------===//
+// Pass interface - Implemented by all 'passes'.
+//
+struct Pass {
+  //===--------------------------------------------------------------------===//
+  // The externally useful entry points
+  //
+
+  // runAllPasses - Run a bunch of passes on the specified module, efficiently.
+  static bool runAllPasses(Module *M, vector<Pass*> &Passes) {
+    for (unsigned i = 0; i < Passes.size(); ++i)
+      if (Passes[i]->doPassInitializationVirt(M)) return true;
+    
+    // Loop over all of the methods, applying all of the passes to them
+    for (Module::iterator I = M->begin(); I != M->end(); ++I)
+      for (unsigned i = 0; i < Passes.size(); ++i)
+        if (Passes[i]->doPerMethodWorkVirt(*I)) return true;
+    return false;
+  }
+
+  // runAllPassesAndFree - Run a bunch of passes on the specified module,
+  // efficiently.  When done, delete all of the passes.
+  //
+  static bool runAllPassesAndFree(Module *M, vector<Pass*> &Passes) {
+    // First run all of the passes
+    bool Result = runAllPasses(M, Passes);
+
+    // Free all of the passes.
+    for (unsigned i = 0; i < Passes.size(); ++i)
+      delete Passes[i];
+    return Result;
+  }
+
+
+  // run(Module*) - Run this pass on a module and all of the methods contained
+  // within it.  Returns false on success.
+  //
+  bool run(Module *M) {
+    if (doPassInitializationVirt(M)) return true;
+
+    // Loop over methods in the module.  doPerMethodWork could add a method to
+    // the Module, so we have to keep checking for end of method list condition.
+    //
+    for (Module::iterator I = M->begin(); I != M->end(); ++I)
+      if (doPerMethodWorkVirt(*I)) return true;
+    return false;
+  }
+
+  // run(Method*) - Run this pass on a module and one specific method.  Returns
+  // false on success.
+  //
+  bool run(Method *M) {
+    if (doPassInitializationVirt(M->getParent())) return true;
+    return doPerMethodWorkVirt(M);
+  }
+
+
+  //===--------------------------------------------------------------------===//
+  // Functions to be implemented by subclasses
+  //
+
+  // Destructor - Virtual so we can be subclassed
+  inline virtual ~Pass() {}
+
+  // doPassInitializationVirt - Virtual method overridden by subclasses to do
+  // any neccesary per-module initialization.  Returns false on success.
+  //
+  virtual bool doPassInitializationVirt(Module *M) = 0;
+
+  // doPerMethodWorkVirt - Virtual method overriden by subclasses to do the
+  // per-method processing of the pass.  Returns false on success.
+  //
+  virtual bool doPerMethodWorkVirt(Method *M) = 0;
+};
+
+
+//===----------------------------------------------------------------------===//
+// ConcretePass<t> class - This is used by implementations of passes to fill in
+// boiler plate code.  SubClass should be a concrete class that is derived from
+// ConcretePass.
+//
+// Deriving from this class is good because if new methods are added in the 
+// future, code for your pass won't have to change to stub out the unused
+// functionality.
+//
+template<class SubClass>
+struct ConcretePass : public Pass {
+
+  // doPassInitializationVirt - Default to success.
+  virtual bool doPassInitializationVirt(Module *M) { return false; }
+
+  // doPerMethodWorkVirt - Default to success.
+  virtual bool doPerMethodWorkVirt(Method *M) { return false; }
+};
+
+
+
+//===----------------------------------------------------------------------===//
+// StatelessPass<t> class - This is used by implementations of passes to fill in
+// boiler plate code.  Subclassing this class indicates that a class has no
+// state to keep around, so it's safe to invoke static versions of functions.
+// This can be more efficient that using virtual function dispatch all of the
+// time.
+//
+// SubClass should be a concrete class that is derived from StatelessPass.
+//
+template<class SubClass>
+struct StatelessPass : public ConcretePass<SubClass> {
+
+  //===--------------------------------------------------------------------===//
+  // The externally useful entry points - These are specialized to avoid the
+  // overhead of virtual method invokations if 
+  //
+  // run(Module*) - Run this pass on a module and all of the methods contained
+  // within it.  Returns false on success.
+  //
+  static bool run(Module *M) {
+    if (doPassInitialization(M->getParent())) return true;
+
+    // Loop over methods in the module.  doPerMethodWork could add a method to
+    // the Module, so we have to keep checking for end of method list condition.
+    //
+    for (Module::iterator I = M->begin(); I != M->end(); ++I)
+      if (doPerMethodWork(*I)) return true;
+    return false;
+  }
+
+  // run(Method*) - Run this pass on a module and one specific method.  Returns
+  // false on success.
+  //
+  static bool run(Method *M) {
+    if (doPassInitialization(M->getParent())) return true;
+    return doPerMethodWork(M);
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Default static method implementations, these should be defined in SubClass
+
+  static bool doPassInitialization(Module *M) { return false; }
+  static bool doPerMethodWork(Method *M) { return false; }
+
+
+  //===--------------------------------------------------------------------===//
+  // Virtual method forwarders...
+
+  // doPassInitializationVirt - For a StatelessPass, default to implementing in
+  // terms of the static method.
+  //
+  virtual bool doPassInitializationVirt(Module *M) {
+    return SubClass::doPassInitialization(M);
+  }
+
+  // doPerMethodWorkVirt - For a StatelessPass, default to implementing in
+  // terms of the static method.
+  //
+  virtual bool doPerMethodWorkVirt(Method *M) {
+    return SubClass::doPerMethodWork(M);
+  }
+};
+
+#endif
+

include/llvm/Transforms/PrintModulePass.h

@@ -0,0 +1,35 @@
+//===- llvm/Transforms/PrintModulePass.h - Printing Pass ---------*- C++ -*--=//
+//
+// This file defines a simple pass to print out methods of a module as they are
+// processed.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_PRINTMODULE_H
+#define LLVM_TRANSFORMS_PRINTMODULE_H
+
+#include "llvm/Transforms/Pass.h"
+#include "llvm/Assembly/Writer.h"
+
+class PrintModulePass : public ConcretePass<PrintModulePass> {
+  string Banner;          // String to print before each method
+  ostream *Out;           // ostream to print on
+  bool DeleteStream;      // Delete the ostream in our dtor?
+public:
+  inline PrintModulePass(const string &B, ostream *o = &cout, bool DS = false) 
+    : Banner(B), Out(o), DeleteStream(DS) {}
+
+  ~PrintModulePass() {
+    if (DeleteStream) delete Out;
+  }
+
+  // doPerMethodWork - This pass just prints a banner followed by the method as
+  // it's processed.
+  //
+  bool doPerMethodWorkVirt(Method *M) {
+    (*Out) << Banner << M;
+    return false;
+  }
+};
+
+#endif

lib/Transforms/HoistPHIConstants.cpp

@@ -0,0 +1,61 @@
+//===- llvm/Transforms/HoistPHIConstants.h - Normalize PHI nodes ------------=//
+//
+// HoistPHIConstants - Remove literal constants that are arguments of PHI nodes
+// by inserting cast instructions in the preceeding basic blocks, and changing
+// constant references into references of the casted value.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/HoistPHIConstants.h"
+#include "llvm/iOther.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Method.h"
+#include <map>
+
+typedef pair<BasicBlock *, Value*> BBConstTy;
+typedef map<BBConstTy, CastInst *> CachedCopyMap;
+
+static Value *NormalizePhiOperand(PHINode *PN, Value *CPV,
+                                  BasicBlock *Pred, CachedCopyMap &CopyCache) {
+  
+  // Check if we've already inserted a copy for this constant in Pred
+  // Note that `copyCache[Pred]' will create an empty vector the first time
+  //
+  CachedCopyMap::iterator CCI = CopyCache.find(BBConstTy(Pred, CPV));
+  if (CCI != CopyCache.end()) return CCI->second;
+  
+  // Create a copy instruction and add it to the cache...
+  CastInst *Inst = new CastInst(CPV, CPV->getType());
+  CopyCache.insert(make_pair(BBConstTy(Pred, CPV), Inst));
+    
+  // Insert the copy just before the terminator inst of the predecessor BB
+  assert(Pred->getTerminator() && "Degenerate BB encountered!");
+  Pred->getInstList().insert(Pred->getInstList().end()-1, Inst);
+  
+  return Inst;
+}
+
+
+//---------------------------------------------------------------------------
+// Entry point for normalizing constant args in PHIs
+//---------------------------------------------------------------------------
+
+bool HoistPHIConstants::doPerMethodWork(Method *M) {
+  CachedCopyMap Cache;
+  
+  for (Method::iterator BI = M->begin(), BE = M->end(); BI != BE; ++BI)
+    for (BasicBlock::iterator II = (*BI)->begin(); II != (*BI)->end(); ++II) {
+      Instruction *Inst = *II;
+      if (!isa<PHINode>(Inst)) break;   // All PHIs occur at top of BB!
+      
+      PHINode *PN = cast<PHINode>(Inst);
+      for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i) {
+        Value *Op = PN->getIncomingValue(i);
+        if (isa<ConstPoolVal>(Op))
+          PN->setIncomingValue(i,
+                NormalizePhiOperand(PN, Op, PN->getIncomingBlock(i), Cache));
+      }
+    }
+
+  return false;
+}

lib/Transforms/Utils/LowerAllocations.cpp

@@ -0,0 +1,121 @@
+//===- llvm/Transforms/LowerAllocations.h - Remove Malloc & Free Insts ------=//
+//
+// This file implements a pass that lowers malloc and free instructions to
+// calls to %malloc & %free functions.  This transformation is a target
+// dependant tranformation because we depend on the size of data types and
+// alignment constraints.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/LowerAllocations.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/iMemory.h"
+#include "llvm/iOther.h"
+#include "llvm/SymbolTable.h"
+
+// doPassInitialization - For the lower allocations pass, this ensures that a
+// module contains a declaration for a malloc and a free function.
+//
+// This function is always successful.
+//
+bool LowerAllocations::doPassInitializationVirt(Module *M) {
+  const MethodType *MallocType = 
+    MethodType::get(PointerType::get(Type::UByteTy),
+                    vector<const Type*>(1, Type::UIntTy), false);
+
+  SymbolTable *SymTab = M->getSymbolTableSure();
+  
+  // Check for a definition of malloc
+  if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) {
+    MallocMeth = cast<Method>(V);      // Yup, got it
+  } else {                             // Nope, add one
+    M->getMethodList().push_back(MallocMeth = new Method(MallocType, "malloc"));
+  }
+
+  const MethodType *FreeType = 
+    MethodType::get(Type::VoidTy,
+                    vector<const Type*>(1, PointerType::get(Type::UByteTy)),
+		    false);
+
+  // Check for a definition of free
+  if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) {
+    FreeMeth = cast<Method>(V);      // Yup, got it
+  } else {                             // Nope, add one
+    M->getMethodList().push_back(FreeMeth = new Method(FreeType, "free"));
+  }
+
+  return false;  // Always successful
+}
+
+// doPerMethodWork - This method does the actual work of converting
+// instructions over, assuming that the pass has already been initialized.
+//
+bool LowerAllocations::doPerMethodWorkVirt(Method *M) {
+  assert(MallocMeth && FreeMeth && M && "Pass not initialized!");
+
+  // Loop over all of the instructions, looking for malloc or free instructions
+  for (Method::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) {
+    BasicBlock *BB = *BBI;
+    for (unsigned i = 0; i < BB->size(); ++i) {
+      BasicBlock::InstListType &BBIL = BB->getInstList();
+      if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) {
+        BBIL.remove(BBIL.begin()+i);   // remove the malloc instr...
+        
+        const Type *AllocTy = cast<PointerType>(MI->getType())->getValueType();
+
+        // If the user is allocating an unsized array with a dynamic size arg,
+        // start by getting the size of one element.
+        //
+        if (const ArrayType *ATy = dyn_cast<ArrayType>(AllocTy)) 
+          if (ATy->isUnsized()) AllocTy = ATy->getElementType();
+
+        // Get the number of bytes to be allocated for one element of the
+        // requested type...
+        unsigned Size = DataLayout.getTypeSize(AllocTy);
+
+        // malloc(type) becomes sbyte *malloc(constint)
+        Value *MallocArg = ConstPoolUInt::get(Type::UIntTy, Size);
+        if (MI->getNumOperands() && Size == 1) {
+          MallocArg = MI->getOperand(0);         // Operand * 1 = Operand
+        } else if (MI->getNumOperands()) {
+          // Multiply it by the array size if neccesary...
+          MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0),
+                                             MallocArg);
+          BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg));
+        }
+
+        // Create the call to Malloc...
+        CallInst *MCall = new CallInst(MallocMeth,
+                                       vector<Value*>(1, MallocArg));
+        BBIL.insert(BBIL.begin()+i, MCall);
+
+        // Create a cast instruction to convert to the right type...
+        CastInst *MCast = new CastInst(MCall, MI->getType());
+        BBIL.insert(BBIL.begin()+i+1, MCast);
+
+        // Replace all uses of the old malloc inst with the cast inst
+        MI->replaceAllUsesWith(MCast);
+        delete MI;                          // Delete the malloc inst
+      } else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) {
+        BBIL.remove(BB->getInstList().begin()+i);
+
+        // Cast the argument to free into a ubyte*...
+        CastInst *MCast = new CastInst(FI->getOperand(0), 
+                                       PointerType::get(Type::UByteTy));
+        BBIL.insert(BBIL.begin()+i, MCast);
+
+        // Insert a call to the free function...
+        CallInst *FCall = new CallInst(FreeMeth,
+                                       vector<Value*>(1, MCast));
+        BBIL.insert(BBIL.begin()+i+1, FCall);
+
+        // Delete the old free instruction
+        delete FI;
+      }
+    }
+  }
+
+  return false;   // Always successful
+}
+