//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/Scalar/IndVarSimplify.h"
+#include "llvm/Transforms/Scalar.h"
#include "llvm/Analysis/InductionVariable.h"
#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/iPHINode.h"
+#include "llvm/iOther.h"
+#include "llvm/Type.h"
+#include "llvm/Constants.h"
+#include "llvm/Support/CFG.h"
#include "Support/STLExtras.h"
+#include "Support/StatisticReporter.h"
-static bool TransformLoop(cfg::LoopInfo *Loops, cfg::Loop *Loop) {
+static Statistic<> NumRemoved ("indvars\t\t- Number of aux indvars removed");
+static Statistic<> NumInserted("indvars\t\t- Number of cannonical indvars added");
+
+
+// InsertCast - Cast Val to Ty, setting a useful name on the cast if Val has a
+// name...
+//
+static Instruction *InsertCast(Instruction *Val, const Type *Ty,
+ BasicBlock::iterator It) {
+ Instruction *Cast = new CastInst(Val, Ty);
+ if (Val->hasName()) Cast->setName(Val->getName()+"-casted");
+ Val->getParent()->getInstList().insert(It, Cast);
+ return Cast;
+}
+
+static bool TransformLoop(LoopInfo *Loops, Loop *Loop) {
// Transform all subloops before this loop...
bool Changed = reduce_apply_bool(Loop->getSubLoops().begin(),
Loop->getSubLoops().end(),
- std::bind1st(ptr_fun(TransformLoop), Loops));
+ std::bind1st(std::ptr_fun(TransformLoop), Loops));
// Get the header node for this loop. All of the phi nodes that could be
// induction variables must live in this basic block.
- BasicBlock *Header = (BasicBlock*)Loop->getBlocks().front();
+ //
+ BasicBlock *Header = Loop->getBlocks().front();
// Loop over all of the PHI nodes in the basic block, calculating the
// induction variables that they represent... stuffing the induction variable
// info into a vector...
//
- vector<InductionVariable> IndVars; // Induction variables for block
- for (BasicBlock::iterator I = Header->begin();
- PHINode *PN = dyn_cast<PHINode>(*I); ++I)
+ std::vector<InductionVariable> IndVars; // Induction variables for block
+ BasicBlock::iterator AfterPHIIt = Header->begin();
+ for (; PHINode *PN = dyn_cast<PHINode>(&*AfterPHIIt); ++AfterPHIIt)
IndVars.push_back(InductionVariable(PN, Loops));
+ // AfterPHIIt now points to first nonphi instruction...
- // If there are phi nodes in this basic block, there can't be indvars...
+ // If there are no phi nodes in this basic block, there can't be indvars...
if (IndVars.empty()) return Changed;
// Loop over the induction variables, looking for a cannonical induction
// Okay, we want to convert other induction variables to use a cannonical
// indvar. If we don't have one, add one now...
if (!Cannonical) {
+ // Create the PHI node for the new induction variable
+ PHINode *PN = new PHINode(Type::UIntTy, "cann-indvar");
+
+ // Insert the phi node at the end of the other phi nodes...
+ AfterPHIIt = ++Header->getInstList().insert(AfterPHIIt, PN);
+
+ // Create the increment instruction to add one to the counter...
+ Instruction *Add = BinaryOperator::create(Instruction::Add, PN,
+ ConstantUInt::get(Type::UIntTy,1),
+ "add1-indvar");
+
+ // Insert the add instruction after all of the PHI nodes...
+ Header->getInstList().insert(AfterPHIIt, Add);
+
+ // Figure out which block is incoming and which is the backedge for the loop
+ BasicBlock *Incoming, *BackEdgeBlock;
+ pred_iterator PI = pred_begin(Header);
+ assert(PI != pred_end(Header) && "Loop headers should have 2 preds!");
+ if (Loop->contains(*PI)) { // First pred is back edge...
+ BackEdgeBlock = *PI++;
+ Incoming = *PI++;
+ } else {
+ Incoming = *PI++;
+ BackEdgeBlock = *PI++;
+ }
+ assert(PI == pred_end(Header) && "Loop headers should have 2 preds!");
+
+ // Add incoming values for the PHI node...
+ PN->addIncoming(Constant::getNullValue(Type::UIntTy), Incoming);
+ PN->addIncoming(Add, BackEdgeBlock);
+
+ // Analyze the new induction variable...
+ IndVars.push_back(InductionVariable(PN, Loops));
+ assert(IndVars.back().InductionType == InductionVariable::Cannonical &&
+ "Just inserted cannonical indvar that is not cannonical!");
+ Cannonical = &IndVars.back();
+ ++NumInserted;
+ Changed = true;
+ }
+
+ DEBUG(std::cerr << "Induction variables:\n");
+
+ // Get the current loop iteration count, which is always the value of the
+ // cannonical phi node...
+ //
+ PHINode *IterCount = Cannonical->Phi;
+
+ // Loop through and replace all of the auxillary induction variables with
+ // references to the primary induction variable...
+ //
+ for (unsigned i = 0; i < IndVars.size(); ++i) {
+ InductionVariable *IV = &IndVars[i];
+
+ DEBUG(IV->print(std::cerr));
+
+ // Don't modify the cannonical indvar or unrecognized indvars...
+ if (IV != Cannonical && IV->InductionType != InductionVariable::Unknown) {
+ Instruction *Val = IterCount;
+ if (!isa<ConstantInt>(IV->Step) || // If the step != 1
+ !cast<ConstantInt>(IV->Step)->equalsInt(1)) {
+ std::string Name; // Create a scale by the step value...
+ if (IV->Phi->hasName()) Name = IV->Phi->getName()+"-scale";
+
+ // If the types are not compatible, insert a cast now...
+ if (Val->getType() != IV->Step->getType())
+ Val = InsertCast(Val, IV->Step->getType(), AfterPHIIt);
+
+ Val = BinaryOperator::create(Instruction::Mul, Val, IV->Step, Name);
+ // Insert the phi node at the end of the other phi nodes...
+ Header->getInstList().insert(AfterPHIIt, Val);
+ }
+ if (!isa<Constant>(IV->Start) || // If the start != 0
+ !cast<Constant>(IV->Start)->isNullValue()) {
+ std::string Name; // Create a offset by the start value...
+ if (IV->Phi->hasName()) Name = IV->Phi->getName()+"-offset";
+
+ // If the types are not compatible, insert a cast now...
+ if (Val->getType() != IV->Start->getType())
+ Val = InsertCast(Val, IV->Start->getType(), AfterPHIIt);
+
+ Val = BinaryOperator::create(Instruction::Add, Val, IV->Start, Name);
+ // Insert the phi node at the end of the other phi nodes...
+ Header->getInstList().insert(AfterPHIIt, Val);
+ }
+
+ // If the PHI node has a different type than val is, insert a cast now...
+ if (Val->getType() != IV->Phi->getType())
+ Val = InsertCast(Val, IV->Phi->getType(), AfterPHIIt);
+
+ // Replace all uses of the old PHI node with the new computed value...
+ IV->Phi->replaceAllUsesWith(Val);
+
+ // Move the PHI name to it's new equivalent value...
+ std::string OldName = IV->Phi->getName();
+ IV->Phi->setName("");
+ Val->setName(OldName);
+
+ // Delete the old, now unused, phi node...
+ Header->getInstList().erase(IV->Phi);
+ Changed = true;
+ ++NumRemoved;
+ }
}
return Changed;
}
-bool InductionVariableSimplify::doit(Method *M) {
- // Figure out the loop structure of the method...
- cfg::LoopInfo Loops(M);
+namespace {
+ struct InductionVariableSimplify : public FunctionPass {
+ virtual bool runOnFunction(Function &) {
+ LoopInfo &LI = getAnalysis<LoopInfo>();
+
+ // Induction Variables live in the header nodes of loops
+ return reduce_apply_bool(LI.getTopLevelLoops().begin(),
+ LI.getTopLevelLoops().end(),
+ std::bind1st(std::ptr_fun(TransformLoop), &LI));
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LoopInfo>();
+ AU.preservesCFG();
+ }
+ };
+ RegisterOpt<InductionVariableSimplify> X("indvars",
+ "Cannonicalize Induction Variables");
+}
- // Induction Variables live in the header nodes of the loops of the method...
- return reduce_apply_bool(Loops.getTopLevelLoops().begin(),
- Loops.getTopLevelLoops().end(),
- std::bind1st(std::ptr_fun(TransformLoop), &Loops));
+Pass *createIndVarSimplifyPass() {
+ return new InductionVariableSimplify();
}
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