//
//===----------------------------------------------------------------------===//
+#include "llvm/Optimizations/ConstantProp.h"
+#include "llvm/Optimizations/ConstantHandling.h"
#include "llvm/Module.h"
#include "llvm/Method.h"
#include "llvm/BasicBlock.h"
#include "llvm/iOther.h"
#include "llvm/ConstPoolVals.h"
#include "llvm/ConstantPool.h"
-#include "llvm/Opt/AllOpts.h"
-#include "llvm/Opt/ConstantHandling.h"
// Merge identical constant values in the constant pool.
//
// TODO: We can do better than this simplistic N^2 algorithm...
//
-bool DoConstantPoolMerging(Method *M) {
+bool opt::DoConstantPoolMerging(Method *M) {
return DoConstantPoolMerging(M->getConstantPool());
}
-bool DoConstantPoolMerging(ConstantPool &CP) {
+bool opt::DoConstantPoolMerging(ConstantPool &CP) {
bool Modified = false;
for (ConstantPool::plane_iterator PI = CP.begin(); PI != CP.end(); ++PI) {
for (ConstantPool::PlaneType::iterator I = (*PI)->begin();
ConstantFoldUnaryInst(Method *M, Method::inst_iterator &DI,
UnaryOperator *Op, ConstPoolVal *D) {
ConstPoolVal *ReplaceWith =
- ConstantFoldUnaryInstruction(Op->getInstType(), D);
+ opt::ConstantFoldUnaryInstruction(Op->getInstType(), D);
if (!ReplaceWith) return false; // Nothing new to change...
BinaryOperator *Op,
ConstPoolVal *D1, ConstPoolVal *D2) {
ConstPoolVal *ReplaceWith =
- ConstantFoldBinaryInstruction(Op->getInstType(), D1, D2);
+ opt::ConstantFoldBinaryInstruction(Op->getInstType(), D1, D2);
if (!ReplaceWith) return false; // Nothing new to change...
// Add the new value to the constant pool...
// constant value, convert it into an unconditional branch to the constant
// destination.
//
-bool ConstantFoldTerminator(TerminatorInst *T) {
+bool opt::ConstantFoldTerminator(TerminatorInst *T) {
// Branch - See if we are conditional jumping on constant
if (T->getInstType() == Instruction::Br) {
BranchInst *BI = (BranchInst*)T;
ConstPoolVal *D = Inst->getOperand(0)->castConstant();
if (D) return ConstantFoldUnaryInst(M, II, (UnaryOperator*)Inst, D);
} else if (Inst->isTerminator()) {
- return ConstantFoldTerminator((TerminatorInst*)Inst);
+ return opt::ConstantFoldTerminator((TerminatorInst*)Inst);
} else if (Inst->isPHINode()) {
PHINode *PN = (PHINode*)Inst; // If it's a PHI node and only has one operand
// returns true on failure, false on success...
//
-bool DoConstantPropogation(Method *M) {
+bool opt::DoConstantPropogation(Method *M) {
bool Modified = false;
// Fold constants until we make no progress...
//
//===----------------------------------------------------------------------===//
+#include "llvm/Optimizations/DCE.h"
+#include "llvm/Tools/STLExtras.h"
#include "llvm/Module.h"
#include "llvm/Method.h"
#include "llvm/BasicBlock.h"
#include "llvm/iTerminators.h"
#include "llvm/iOther.h"
-#include "llvm/Opt/AllOpts.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/CFG.h"
-#include "llvm/Tools/STLExtras.h"
#include <algorithm>
using namespace cfg;
return true; // Yes, we nuked at least one phi node
}
-bool DoRemoveUnusedConstants(SymTabValue *S) {
+bool opt::DoRemoveUnusedConstants(SymTabValue *S) {
bool Changed = false;
ConstantPool &CP = S->getConstantPool();
for (ConstantPool::plane_iterator PI = CP.begin(); PI != CP.end(); ++PI)
} while ((*I)->isPHINode());
}
+
+// SimplifyCFG - This function is used to do simplification of a CFG. For
+// example, it adjusts branches to branches to eliminate the extra hop, it
+// eliminates unreachable basic blocks, and does other "peephole" optimization
+// of the CFG. It returns true if a modification was made, and returns an
+// iterator that designates the first element remaining after the block that
+// was deleted.
+//
+// WARNING: The entry node of a method may not be simplified.
+//
+bool opt::SimplifyCFG(Method::iterator &BBIt) {
+ assert(*BBIt && (*BBIt)->getParent() && "Block not embedded in method!");
+ BasicBlock *BB = *BBIt;
+ Method *M = BB->getParent();
+ assert(BB->getTerminator() && "Degenerate basic block encountered!");
+ assert(BB->getParent()->front() != BB && "Can't Simplify entry block!");
+
+ // Remove basic blocks that have no predecessors... which are unreachable.
+ if (pred_begin(BB) == pred_end(BB) &&
+ !BB->hasConstantPoolReferences()) {
+ //cerr << "Removing BB: \n" << BB;
+
+ // Loop through all of our successors and make sure they know that one
+ // of their predecessors is going away.
+ for_each(succ_begin(BB), succ_end(BB),
+ std::bind2nd(std::mem_fun(&BasicBlock::removePredecessor), BB));
+
+ while (!BB->empty()) {
+ Instruction *I = BB->back();
+ // If this instruction is used, replace uses with an arbitrary
+ // constant value. Because control flow can't get here, we don't care
+ // what we replace the value with. Note that since this block is
+ // unreachable, and all values contained within it must dominate their
+ // uses, that all uses will eventually be removed.
+ if (!I->use_empty()) ReplaceUsesWithConstant(I);
+
+ // Remove the instruction from the basic block
+ delete BB->getInstList().pop_back();
+ }
+ delete M->getBasicBlocks().remove(BBIt);
+ return true;
+ }
+
+ // Check to see if this block has no instructions and only a single
+ // successor. If so, replace block references with successor.
+ succ_iterator SI(succ_begin(BB));
+ if (SI != succ_end(BB) && ++SI == succ_end(BB)) { // One succ?
+ Instruction *I = BB->front();
+ if (I->isTerminator()) { // Terminator is the only instruction!
+ BasicBlock *Succ = *succ_begin(BB); // There is exactly one successor
+ //cerr << "Killing Trivial BB: \n" << BB;
+
+ if (Succ != BB) { // Arg, don't hurt infinite loops!
+ if (Succ->front()->isPHINode()) {
+ // If our successor has PHI nodes, then we need to update them to
+ // include entries for BB's predecessors, not for BB itself.
+ //
+ PropogatePredecessorsForPHIs(BB, Succ);
+ }
+
+ BB->replaceAllUsesWith(Succ);
+ BB = M->getBasicBlocks().remove(BBIt);
+
+ if (BB->hasName() && !Succ->hasName()) // Transfer name if we can
+ Succ->setName(BB->getName());
+ delete BB; // Delete basic block
+
+ //cerr << "Method after removal: \n" << M;
+ return true;
+ }
+ }
+ }
+
+ // Merge basic blocks into their predecessor if there is only one pred,
+ // and if there is only one successor of the predecessor.
+ pred_iterator PI(pred_begin(BB));
+ if (PI != pred_end(BB) && *PI != BB && // Not empty? Not same BB?
+ ++PI == pred_end(BB) && !BB->hasConstantPoolReferences()) {
+ BasicBlock *Pred = *pred_begin(BB);
+ TerminatorInst *Term = Pred->getTerminator();
+ assert(Term != 0 && "malformed basic block without terminator!");
+
+ // Does the predecessor block only have a single successor?
+ succ_iterator SI(succ_begin(Pred));
+ if (++SI == succ_end(Pred)) {
+ //cerr << "Merging: " << BB << "into: " << Pred;
+
+ // Delete the unconditianal branch from the predecessor...
+ BasicBlock::iterator DI = Pred->end();
+ assert(Pred->getTerminator() &&
+ "Degenerate basic block encountered!"); // Empty bb???
+ delete Pred->getInstList().remove(--DI); // Destroy uncond branch
+
+ // Move all definitions in the succecessor to the predecessor...
+ while (!BB->empty()) {
+ DI = BB->begin();
+ Instruction *Def = BB->getInstList().remove(DI); // Remove from front
+ Pred->getInstList().push_back(Def); // Add to end...
+ }
+
+ // Remove basic block from the method... and advance iterator to the
+ // next valid block...
+ BB = M->getBasicBlocks().remove(BBIt);
+
+ // Make all PHI nodes that refered to BB now refer to Pred as their
+ // source...
+ BB->replaceAllUsesWith(Pred);
+
+ // Inherit predecessors name if it exists...
+ if (BB->hasName() && !Pred->hasName()) Pred->setName(BB->getName());
+
+ delete BB; // You ARE the weakest link... goodbye
+ return true;
+ }
+ }
+
+ return false;
+}
+
static bool DoDCEPass(Method *M) {
Method::iterator BBIt, BBEnd = M->end();
if (M->begin() == BBEnd) return false; // Nothing to do
// Loop over all of the basic blocks (except the first one) and remove them
// if they are unneeded...
//
- for (BBIt = M->begin(), ++BBIt; BBIt != M->end(); ++BBIt) {
- BasicBlock *BB = *BBIt;
- assert(BB->getTerminator() && "Degenerate basic block encountered!");
-
- // Remove basic blocks that have no predecessors... which are unreachable.
- if (pred_begin(BB) == pred_end(BB) &&
- !BB->hasConstantPoolReferences() && 0) {
- //cerr << "Removing BB: \n" << BB;
-
- // Loop through all of our successors and make sure they know that one
- // of their predecessors is going away.
- for_each(succ_begin(BB), succ_end(BB),
- bind_obj(BB, &BasicBlock::removePredecessor));
-
- while (!BB->empty()) {
- Instruction *I = BB->front();
- // If this instruction is used, replace uses with an arbitrary
- // constant value. Because control flow can't get here, we don't care
- // what we replace the value with.
- if (!I->use_empty()) ReplaceUsesWithConstant(I);
-
- // Remove the instruction from the basic block
- delete BB->getInstList().remove(BB->begin());
- }
- delete M->getBasicBlocks().remove(BBIt);
- --BBIt; // remove puts use on the next block, we want the previous one
+ for (BBIt = M->begin(), ++BBIt; BBIt != M->end(); ) {
+ if (opt::SimplifyCFG(BBIt)) {
Changed = true;
- continue;
- }
-
- // Check to see if this block has no instructions and only a single
- // successor. If so, replace block references with successor.
- succ_iterator SI(succ_begin(BB));
- if (SI != succ_end(BB) && ++SI == succ_end(BB)) { // One succ?
- Instruction *I = BB->front();
- if (I->isTerminator()) { // Terminator is the only instruction!
- BasicBlock *Succ = *succ_begin(BB); // There is exactly one successor
- //cerr << "Killing Trivial BB: \n" << BB;
-
- if (Succ != BB) { // Arg, don't hurt infinite loops!
- if (Succ->front()->isPHINode()) {
- // If our successor has PHI nodes, then we need to update them to
- // include entries for BB's predecessors, not for BB itself.
- //
- PropogatePredecessorsForPHIs(BB, Succ);
- }
-
- BB->replaceAllUsesWith(Succ);
-
- BB = M->getBasicBlocks().remove(BBIt);
- --BBIt; // remove puts use on the next block, we want the previous one
-
- if (BB->hasName() && !Succ->hasName()) // Transfer name if we can
- Succ->setName(BB->getName());
- delete BB; // Delete basic block
-
- //cerr << "Method after removal: \n" << M;
- Changed = true;
- continue;
- }
- }
- }
-
- // Merge basic blocks into their predecessor if there is only one pred,
- // and if there is only one successor of the predecessor.
- pred_iterator PI(pred_begin(BB));
- if (PI != pred_end(BB) && *PI != BB && // Not empty? Not same BB?
- ++PI == pred_end(BB) && !BB->hasConstantPoolReferences()) {
- BasicBlock *Pred = *pred_begin(BB);
- TerminatorInst *Term = Pred->getTerminator();
- assert(Term != 0 && "malformed basic block without terminator!");
-
- // Does the predecessor block only have a single successor?
- succ_iterator SI(succ_begin(Pred));
- if (++SI == succ_end(Pred)) {
- //cerr << "Merging: " << BB << "into: " << Pred;
-
- // Delete the unconditianal branch from the predecessor...
- BasicBlock::iterator DI = Pred->end();
- assert(Pred->getTerminator() &&
- "Degenerate basic block encountered!"); // Empty bb???
- delete Pred->getInstList().remove(--DI); // Destroy uncond branch
-
- // Move all definitions in the succecessor to the predecessor...
- while (!BB->empty()) {
- DI = BB->begin();
- Instruction *Def = BB->getInstList().remove(DI); // Remove from front
- Pred->getInstList().push_back(Def); // Add to end...
- }
-
- // Remove basic block from the method... and advance iterator to the
- // next valid block...
- BB = M->getBasicBlocks().remove(BBIt);
- --BBIt; // remove puts us on the NEXT bb. We want the prev BB
- Changed = true;
-
- // Make all PHI nodes that refered to BB now refer to Pred as their
- // source...
- BB->replaceAllUsesWith(Pred);
-
- // Inherit predecessors name if it exists...
- if (BB->hasName() && !Pred->hasName()) Pred->setName(BB->getName());
-
- // You ARE the weakest link... goodbye
- delete BB;
-
- //WriteToVCG(M, "MergedInto");
- }
+ } else {
+ ++BBIt;
}
}
// Remove unused constants
- Changed |= DoRemoveUnusedConstants(M);
- return Changed;
+ return Changed | opt::DoRemoveUnusedConstants(M);
}
// It is possible that we may require multiple passes over the code to fully
// eliminate dead code. Iterate until we are done.
//
-bool DoDeadCodeElimination(Method *M) {
+bool opt::DoDeadCodeElimination(Method *M) {
bool Changed = false;
while (DoDCEPass(M)) Changed = true;
return Changed;
}
-bool DoDeadCodeElimination(Module *C) {
- bool Val = ApplyOptToAllMethods(C, DoDeadCodeElimination);
+bool opt::DoDeadCodeElimination(Module *C) {
+ bool Val = C->reduceApply(DoDeadCodeElimination);
+
while (DoRemoveUnusedConstants(C)) Val = true;
return Val;
}
//
//===----------------------------------------------------------------------===//
-#include "llvm/Opt/AllOpts.h"
+#include "llvm/Optimizations/ConstantProp.h"
+#include "llvm/Optimizations/ConstantHandling.h"
#include "llvm/Method.h"
#include "llvm/BasicBlock.h"
#include "llvm/ConstPoolVals.h"
#include "llvm/ConstantPool.h"
-#include "llvm/Opt/ConstantHandling.h"
#include "llvm/InstrTypes.h"
#include "llvm/iOther.h"
#include "llvm/iTerminators.h"
+#include "llvm/Tools/STLExtras.h"
//#include "llvm/Assembly/Writer.h"
#include <algorithm>
#include <map>
#include <set>
-
// InstVal class - This class represents the different lattice values that an
// instruction may occupy. It is a simple class with value semantics. The
// potential constant value that is pointed to is owned by the constant pool
MadeChanges = true;
continue; // Skip the ++II at the end of the loop here...
} else if (Inst->isTerminator()) {
- MadeChanges |= ConstantFoldTerminator((TerminatorInst*)Inst);
+ MadeChanges |= opt::ConstantFoldTerminator((TerminatorInst*)Inst);
}
++II;
// introduced constants that already exist, and we don't want to pollute later
// stages with extraneous constants.
//
- return MadeChanges | DoConstantPoolMerging(M->getConstantPool());
+ return MadeChanges | opt::DoConstantPoolMerging(M->getConstantPool());
}
markOverdefined(I);
} else if (VState.isConstant()) { // Propogate constant value
ConstPoolVal *Result =
- ConstantFoldUnaryInstruction(I->getInstType(), VState.getConstant());
+ opt::ConstantFoldUnaryInstruction(I->getInstType(),
+ VState.getConstant());
if (Result) {
// This instruction constant folds! The only problem is that the value
markOverdefined(I);
} else if (V1State.isConstant() && V2State.isConstant()) {
ConstPoolVal *Result =
- ConstantFoldBinaryInstruction(I->getInstType(), V1State.getConstant(),
- V2State.getConstant());
-
+ opt::ConstantFoldBinaryInstruction(I->getInstType(),
+ V1State.getConstant(),
+ V2State.getConstant());
if (Result) {
// This instruction constant folds! The only problem is that the value
// returned is newly allocated. Make sure to stick it into the methods
// DoSparseConditionalConstantProp - Use Sparse Conditional Constant Propogation
// to prove whether a value is constant and whether blocks are used.
//
-bool DoSparseConditionalConstantProp(Method *M) {
+bool opt::DoSparseConditionalConstantProp(Method *M) {
SCCP S(M);
return S.doSCCP();
}
-
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