-//===- CleanupGCCOutput.cpp - Cleanup GCC Output --------------------------===//
+//===- DeadTypeElimination.cpp - Eliminate unused types for symbol table --===//
//
-// This pass is used to cleanup the output of GCC. GCC's output is
-// unneccessarily gross for a couple of reasons. This pass does the following
-// things to try to clean it up:
+// The LLVM Compiler Infrastructure
//
-// * 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
-// * Fix various problems that we might have in PHI nodes and casts
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
-// Note: This code produces dead declarations, it is a good idea to run DCE
-// after this pass.
+//===----------------------------------------------------------------------===//
+//
+// This pass is used to cleanup the output of GCC. It eliminate names for types
+// that are unused in the entire translation unit, using the FindUsedTypes pass.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/CleanupGCCOutput.h"
+#define DEBUG_TYPE "deadtypeelim"
+#include "llvm/Transforms/IPO.h"
#include "llvm/Analysis/FindUsedTypes.h"
#include "llvm/Module.h"
-#include "llvm/SymbolTable.h"
+#include "llvm/TypeSymbolTable.h"
#include "llvm/DerivedTypes.h"
-#include "llvm/iPHINode.h"
-#include "llvm/iMemory.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iOther.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "Support/StatisticReporter.h"
-#include <algorithm>
-#include <iostream>
-
-static Statistic<> NumTypeSymtabEntriesKilled("cleangcc\t- Number of unused typenames removed from symtab");
-static Statistic<> NumCastsMoved("cleangcc\t- Number of casts removed from head of basic block");
-static Statistic<> NumRefactoredPreds("cleangcc\t- Number of predecessor blocks refactored");
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
-using std::vector;
+STATISTIC(NumKilled, "Number of unused typenames removed from symtab");
namespace {
- struct CleanupGCCOutput : public FunctionPass {
- const char *getPassName() const { return "Cleanup GCC Output"; }
+ struct VISIBILITY_HIDDEN DTE : public ModulePass {
+ static char ID; // Pass identification, replacement for typeid
+ DTE() : ModulePass((intptr_t)&ID) {}
// doPassInitialization - For this pass, it removes global symbol table
// entries for primitive types. These are never used for linking in GCC and
//
// Also, initialize instance variables.
//
- bool doInitialization(Module *M);
-
- // runOnFunction - This method simplifies the specified function hopefully.
- //
- bool runOnFunction(Function *F);
-
- // doPassFinalization - Strip out type names that are unused by the program
- bool doFinalization(Module *M);
-
+ bool runOnModule(Module &M);
+
// getAnalysisUsage - This function needs FindUsedTypes to do its job...
//
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired(FindUsedTypes::ID);
+ AU.addRequired<FindUsedTypes>();
}
};
+ char DTE::ID = 0;
+ RegisterPass<DTE> X("deadtypeelim", "Dead Type Elimination");
}
-Pass *createCleanupGCCOutputPass() {
- return new CleanupGCCOutput();
+ModulePass *llvm::createDeadTypeEliminationPass() {
+ return new DTE();
}
-
-// ShouldNukSymtabEntry - Return true if this module level symbol table entry
+// ShouldNukeSymtabEntry - Return true if this module level symbol table entry
// should be eliminated.
//
-static inline bool ShouldNukeSymtabEntry(const std::pair<std::string,Value*>&E){
+static inline bool ShouldNukeSymtabEntry(const Type *Ty){
// Nuke all names for primitive types!
- if (cast<Type>(E.second)->isPrimitiveType()) return true;
+ if (Ty->isPrimitiveType() || Ty->isInteger())
+ return true;
// Nuke all pointers to primitive types as well...
- if (const PointerType *PT = dyn_cast<PointerType>(E.second))
- if (PT->getElementType()->isPrimitiveType()) return true;
+ if (const PointerType *PT = dyn_cast<PointerType>(Ty))
+ if (PT->getElementType()->isPrimitiveType() ||
+ PT->getElementType()->isInteger())
+ return true;
return false;
}
-// doInitialization - 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.
-//
-bool CleanupGCCOutput::doInitialization(Module *M) {
- bool Changed = false;
-
- if (M->hasSymbolTable()) {
- SymbolTable *ST = M->getSymbolTable();
-
- // 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...
- SymbolTable::VarMap &Plane = STI->second;
- for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
- if (ShouldNukeSymtabEntry(*PI)) { // Should we remove this entry?
-#if MAP_IS_NOT_BRAINDEAD
- PI = Plane.erase(PI); // STD C++ Map should support this!
-#else
- Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH*
- PI = Plane.begin();
-#endif
- ++NumTypeSymtabEntriesKilled;
- Changed = true;
- } else {
- ++PI;
- }
- }
- }
-
- return Changed;
-}
-
-
-// FixCastsAndPHIs - The LLVM GCC has a tendancy to intermix Cast instructions
-// in with the PHI nodes. These cast instructions are potentially there for two
-// different reasons:
-//
-// 1. The cast could be for an early PHI, and be accidentally inserted before
-// another PHI node. In this case, the PHI node should be moved to the end
-// of the PHI nodes in the basic block. We know that it is this case if
-// the source for the cast is a PHI node in this basic block.
-//
-// 2. If not #1, the cast must be a source argument for one of the PHI nodes
-// in the current basic block. If this is the case, the cast should be
-// lifted into the basic block for the appropriate predecessor.
+// run - 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 eliminate types that are never used
+// in the entire program as indicated by FindUsedTypes.
//
-static inline bool FixCastsAndPHIs(BasicBlock *BB) {
+bool DTE::runOnModule(Module &M) {
bool Changed = false;
- BasicBlock::iterator InsertPos = BB->begin();
-
- // Find the end of the interesting instructions...
- while (isa<PHINode>(*InsertPos) || isa<CastInst>(*InsertPos)) ++InsertPos;
-
- // Back the InsertPos up to right after the last PHI node.
- while (InsertPos != BB->begin() && isa<CastInst>(*(InsertPos-1))) --InsertPos;
+ TypeSymbolTable &ST = M.getTypeSymbolTable();
+ std::set<const Type *> UsedTypes = getAnalysis<FindUsedTypes>().getTypes();
- // No PHI nodes, quick exit.
- if (InsertPos == BB->begin()) return false;
-
- // Loop over all casts trapped between the PHI's...
- BasicBlock::iterator I = BB->begin();
- while (I != InsertPos) {
- if (CastInst *CI = dyn_cast<CastInst>(*I)) { // Fix all cast instructions
- Value *Src = CI->getOperand(0);
-
- // Move the cast instruction to the current insert position...
- --InsertPos; // New position for cast to go...
- std::swap(*InsertPos, *I); // Cast goes down, PHI goes up
+ // Check the symbol table for superfluous type entries...
+ //
+ // Grab the 'type' plane of the module symbol...
+ TypeSymbolTable::iterator TI = ST.begin();
+ TypeSymbolTable::iterator TE = ST.end();
+ while ( TI != TE ) {
+ // If this entry should be unconditionally removed, or if we detect that
+ // the type is not used, remove it.
+ const Type *RHS = TI->second;
+ if (ShouldNukeSymtabEntry(RHS) || !UsedTypes.count(RHS)) {
+ ST.remove(TI++);
+ ++NumKilled;
Changed = true;
-
- ++NumCastsMoved;
-
- if (isa<PHINode>(Src) && // Handle case #1
- cast<PHINode>(Src)->getParent() == BB) {
- // We're done for case #1
- } else { // Handle case #2
- // In case #2, we have to do a few things:
- // 1. Remove the cast from the current basic block.
- // 2. Identify the PHI node that the cast is for.
- // 3. Find out which predecessor the value is for.
- // 4. Move the cast to the end of the basic block that it SHOULD be
- //
-
- // Remove the cast instruction from the basic block. The remove only
- // invalidates iterators in the basic block that are AFTER the removed
- // element. Because we just moved the CastInst to the InsertPos, no
- // iterators get invalidated.
- //
- BB->getInstList().remove(InsertPos);
-
- // Find the PHI node. Since this cast was generated specifically for a
- // PHI node, there can only be a single PHI node using it.
- //
- assert(CI->use_size() == 1 && "Exactly one PHI node should use cast!");
- PHINode *PN = cast<PHINode>(*CI->use_begin());
-
- // Find out which operand of the PHI it is...
- unsigned i;
- for (i = 0; i < PN->getNumIncomingValues(); ++i)
- if (PN->getIncomingValue(i) == CI)
- break;
- assert(i != PN->getNumIncomingValues() && "PHI doesn't use cast!");
-
- // Get the predecessor the value is for...
- BasicBlock *Pred = PN->getIncomingBlock(i);
-
- // Reinsert the cast right before the terminator in Pred.
- Pred->getInstList().insert(Pred->end()-1, CI);
- Changed = true;
- }
} else {
- ++I;
+ ++TI;
+ // We only need to leave one name for each type.
+ UsedTypes.erase(RHS);
}
}
return Changed;
}
-// RefactorPredecessor - When we find out that a basic block is a repeated
-// predecessor in a PHI node, we have to refactor the function until there is at
-// most a single instance of a basic block in any predecessor list.
-//
-static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
- Function *M = BB->getParent();
- assert(find(pred_begin(BB), pred_end(BB), Pred) != pred_end(BB) &&
- "Pred is not a predecessor of BB!");
-
- // Create a new basic block, adding it to the end of the function.
- BasicBlock *NewBB = new BasicBlock("", M);
-
- // Add an unconditional branch to BB to the new block.
- NewBB->getInstList().push_back(new BranchInst(BB));
-
- // Get the terminator that causes a branch to BB from Pred.
- TerminatorInst *TI = Pred->getTerminator();
-
- // Find the first use of BB in the terminator...
- User::op_iterator OI = find(TI->op_begin(), TI->op_end(), BB);
- assert(OI != TI->op_end() && "Pred does not branch to BB!!!");
-
- // Change the use of BB to point to the new stub basic block
- *OI = NewBB;
-
- // Now we need to loop through all of the PHI nodes in BB and convert their
- // first incoming value for Pred to reference the new basic block instead.
- //
- for (BasicBlock::iterator I = BB->begin();
- PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
- int BBIdx = PN->getBasicBlockIndex(Pred);
- assert(BBIdx != -1 && "PHI node doesn't have an entry for Pred!");
-
- // The value that used to look like it came from Pred now comes from NewBB
- PN->setIncomingBlock((unsigned)BBIdx, NewBB);
- }
-}
-
-
-// runOnFunction - Loop through the function and fix problems with the PHI nodes
-// in the current function. The problem is that PHI nodes might exist with
-// multiple entries for the same predecessor. GCC sometimes generates code that
-// looks like this:
-//
-// bb7: br bool %cond1004, label %bb8, label %bb8
-// bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
-//
-// which is completely illegal LLVM code. To compensate for this, we insert
-// an extra basic block, and convert the code to look like this:
-//
-// bb7: br bool %cond1004, label %bbX, label %bb8
-// bbX: br label bb8
-// bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
-//
-//
-bool CleanupGCCOutput::runOnFunction(Function *M) {
- bool Changed = false;
- // Don't use iterators because invalidation gets messy...
- for (unsigned MI = 0; MI < M->size(); ++MI) {
- BasicBlock *BB = M->getBasicBlocks()[MI];
-
- Changed |= FixCastsAndPHIs(BB);
-
- if (isa<PHINode>(BB->front())) {
- const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
-
- // Handle the problem. Sort the list of predecessors so that it is easy
- // to decide whether or not duplicate predecessors exist.
- vector<BasicBlock*> SortedPreds(Preds);
- sort(SortedPreds.begin(), SortedPreds.end());
-
- // Loop over the predecessors, looking for adjacent BB's that are equal.
- BasicBlock *LastOne = 0;
- for (unsigned i = 0; i < Preds.size(); ++i) {
- if (SortedPreds[i] == LastOne) { // Found a duplicate.
- RefactorPredecessor(BB, SortedPreds[i]);
- ++NumRefactoredPreds;
- Changed = true;
- }
- LastOne = SortedPreds[i];
- }
- }
- }
- return Changed;
-}
-
-bool CleanupGCCOutput::doFinalization(Module *M) {
- bool Changed = false;
-
- if (M->hasSymbolTable()) {
- SymbolTable *ST = M->getSymbolTable();
- const std::set<const Type *> &UsedTypes =
- getAnalysis<FindUsedTypes>().getTypes();
-
- // Check the symbol table for superfluous type entries that aren't used in
- // the program
- //
- // 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...
- SymbolTable::VarMap &Plane = STI->second;
- for (SymbolTable::VarMap::iterator PI = Plane.begin(); PI != Plane.end();)
- if (!UsedTypes.count(cast<Type>(PI->second))) {
-#if MAP_IS_NOT_BRAINDEAD
- PI = Plane.erase(PI); // STD C++ Map should support this!
-#else
- Plane.erase(PI); // Alas, GCC 2.95.3 doesn't *SIGH*
- PI = Plane.begin(); // N^2 algorithms are fun. :(
-#endif
- Changed = true;
- } else {
- ++PI;
- }
- }
- }
- return Changed;
-}
+// vim: sw=2
projects / oota-llvm.git / blobdiff