Implement code to convert %malloc and %free FUNCTION CALLS into the instruction equivalent

llvm-svn: 1065

include/llvm/Transforms/IPO.h

@@ -9,16 +9,24 @@
 #include "llvm/Pass.h"
 
 class CleanupGCCOutput : public Pass {
+  Method *Malloc, *Free;  // Pointers to external declarations, or null if none
 public:
+
+  inline CleanupGCCOutput() : Malloc(0), Free(0) {}
+
   // doPassInitialization - For this pass, it removes global symbol table
   // entries for primitive types.  These are never used for linking in GCC and
   // they make the output uglier to look at, so we nuke them.
   //
+  // Also, initialize instance variables.
+  //
   bool doPassInitialization(Module *M);
 
   // doPerMethodWork - This method simplifies the specified method hopefully.
   //
   bool doPerMethodWork(Method *M);
+private:
+  bool doOneCleanupPass(Method *M);
 };
 
 #endif

lib/Transforms/IPO/DeadTypeElimination.cpp

@@ -4,6 +4,12 @@
 // unneccessarily gross for a couple of reasons. This pass does the following
 // things to try to clean it up:
 //
+// * Eliminate names for GCC types that we know can't be needed by the user.
+// - Eliminate names for types that are unused in the entire translation unit
+//    but only if they do not name a structure type!
+// - Replace calls to 'sbyte *%malloc(uint)' and 'void %free(sbyte *)' with
+//   malloc and free instructions.
+//
 // Note:  This code produces dead declarations, it is a good idea to run DCE
 //        after this pass.
 //
@@ -11,6 +17,13 @@
 
 #include "llvm/Transforms/CleanupGCCOutput.h"
 #include "llvm/SymbolTable.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/iOther.h"
+#include "llvm/iMemory.h"
+
+static const Type *PtrArrSByte = 0; // '[sbyte]*' type
+static const Type *PtrSByte = 0;    // 'sbyte*' type
+
 
 static inline bool ShouldNukeSymtabEntry(const pair<string, Value*> &E) {
   // Nuke all names for primitive types!
@@ -31,9 +44,36 @@ static inline bool ShouldNukeSymtabEntry(const pair<string, Value*> &E) {
 bool CleanupGCCOutput::doPassInitialization(Module *M) {
   bool Changed = false;
 
+  if (PtrArrSByte == 0) {
+    PtrArrSByte = PointerType::get(ArrayType::get(Type::SByteTy));
+    PtrSByte    = PointerType::get(Type::SByteTy);
+  }
+
   if (M->hasSymbolTable()) {
-    // Grab the type plane of the module...
     SymbolTable *ST = M->getSymbolTable();
+
+    // Lookup %malloc and %free in the symbol table, for later use.  If they
+    // don't exist, or are not external, we do not worry about converting calls
+    // to that function into the appropriate instruction.
+    //
+    const PointerType *MallocType =   // Get the type for malloc
+      PointerType::get(MethodType::get(PointerType::get(Type::SByteTy),
+                                  vector<const Type*>(1, Type::UIntTy), false));
+    Malloc = cast_or_null<Method>(ST->lookup(MallocType, "malloc"));
+    if (Malloc && !Malloc->isExternal())
+      Malloc = 0;  // Don't mess with locally defined versions of the fn
+
+    const PointerType *FreeType =     // Get the type for free
+      PointerType::get(MethodType::get(Type::VoidTy,
+               vector<const Type*>(1, PointerType::get(Type::SByteTy)), false));
+    Free = cast_or_null<Method>(ST->lookup(FreeType, "free"));
+    if (Free && !Free->isExternal())
+      Free = 0;  // Don't mess with locally defined versions of the fn
+    
+
+    // Check the symbol table for superfluous type entries...
+    //
+    // Grab the 'type' plane of the module symbol...
     SymbolTable::iterator STI = ST->find(Type::TypeTy);
     if (STI != ST->end()) {
       // Loop over all entries in the type plane...
@@ -51,17 +91,92 @@ bool CleanupGCCOutput::doPassInitialization(Module *M) {
           ++PI;
         }
     }
-    
+  }
+
+  return Changed;
+}
+
+// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
+// with a value, then remove and delete the original instruction.
+//
+static void ReplaceInstWithValue(BasicBlock::InstListType &BIL,
+                                 BasicBlock::iterator &BI, Value *V) {
+  Instruction *I = *BI;
+  // Replaces all of the uses of the instruction with uses of the value
+  I->replaceAllUsesWith(V);
+
+  // Remove the unneccesary instruction now...
+  BIL.remove(BI);
+
+  // Make sure to propogate a name if there is one already...
+  if (I->hasName() && !V->hasName())
+    V->setName(I->getName(), BIL.getParent()->getSymbolTable());
+
+  // Remove the dead instruction now...
+  delete I;
+}
+
+
+// ReplaceInstWithInst - Replace the instruction specified by BI with the
+// instruction specified by I.  The original instruction is deleted and BI is
+// updated to point to the new instruction.
+//
+static void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
+                                BasicBlock::iterator &BI, Instruction *I) {
+  assert(I->getParent() == 0 &&
+         "ReplaceInstWithInst: Instruction already inserted into basic block!");
+
+  // Insert the new instruction into the basic block...
+  BI = BIL.insert(BI, I)+1;
+
+  // Replace all uses of the old instruction, and delete it.
+  ReplaceInstWithValue(BIL, BI, I);
+
+  // Reexamine the instruction just inserted next time around the cleanup pass
+  // loop.
+  --BI;
+}
+
+
+// doOneCleanupPass - Do one pass over the input method, fixing stuff up.
+//
+bool CleanupGCCOutput::doOneCleanupPass(Method *M) {
+  bool Changed = false;
+  for (Method::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) {
+    BasicBlock *BB = *MI;
+    BasicBlock::InstListType &BIL = BB->getInstList();
+
+    for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
+      Instruction *I = *BI;
+
+      if (CallInst *CI = dyn_cast<CallInst>(I)) {
+        if (CI->getCalledValue() == Malloc) {      // Replace call to malloc?
+          MallocInst *MallocI = new MallocInst(PtrArrSByte, CI->getOperand(1));
+          BI = BIL.insert(BI, MallocI)+1;
+          ReplaceInstWithInst(BIL, BI, new CastInst(MallocI, PtrSByte));
+          Changed = true;
+          continue;  // Skip the ++BI
+        } else if (CI->getCalledValue() == Free) { // Replace call to free?
+          ReplaceInstWithInst(BIL, BI, new FreeInst(CI->getOperand(1)));
+          Changed = true;
+          continue;  // Skip the ++BI
+        }
+      }
+
+      ++BI;
+    }
   }
 
   return Changed;
 }
 
 
+
+
 // doPerMethodWork - This method simplifies the specified method hopefully.
 //
 bool CleanupGCCOutput::doPerMethodWork(Method *M) {
   bool Changed = false;
-
+  while (doOneCleanupPass(M)) Changed = true;
   return Changed;
 }