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Improve comments, doxygenize more 

llvm-svn: 3950
This commit is contained in:
Chris Lattner 2002-09-26 16:52:07 +00:00
parent 7b1dcc39c3
commit f64f2d3fb3
1 changed files with 36 additions and 20 deletions
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56
llvm/lib/Transforms/Scalar/LICM.cpp
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@ -23,7 +23,9 @@ namespace {
struct LICM : public FunctionPass, public InstVisitor<LICM> {
virtual bool runOnFunction(Function &F);
// This transformation requires natural loop information...
/// This transformation requires natural loop information & requires that
/// loop preheaders be inserted into the CFG...
///
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.preservesCFG();
AU.addRequiredID(LoopPreheadersID);
@ -36,13 +38,14 @@ namespace {
bool Changed; // Set to true when we change anything.
AliasAnalysis *AA; // Currently AliasAnalysis information
// visitLoop - Hoist expressions out of the specified loop...
/// visitLoop - Hoist expressions out of the specified loop...
///
void visitLoop(Loop *L);
// notInCurrentLoop - Little predicate that returns true if the specified
// basic block is in a subloop of the current one, not the current one
// itself.
//
/// notInCurrentLoop - Little predicate that returns true if the specified
/// basic block is in a subloop of the current one, not the current one
/// itself.
///
bool notInCurrentLoop(BasicBlock *BB) {
for (unsigned i = 0, e = CurLoop->getSubLoops().size(); i != e; ++i)
if (CurLoop->getSubLoops()[i]->contains(BB))
@ -50,29 +53,31 @@ namespace {
return false;
}
// hoist - When an instruction is found to only use loop invariant operands
// that is safe to hoist, this instruction is called to do the dirty work.
//
/// hoist - When an instruction is found to only use loop invariant operands
/// that is safe to hoist, this instruction is called to do the dirty work.
///
void hoist(Instruction &I);
// pointerInvalidatedByLoop - Return true if the body of this loop may store
// into the memory location pointed to by V.
//
/// pointerInvalidatedByLoop - Return true if the body of this loop may
/// store into the memory location pointed to by V.
///
bool pointerInvalidatedByLoop(Value *V);
// isLoopInvariant - Return true if the specified value is loop invariant
/// isLoopInvariant - Return true if the specified value is loop invariant
///
inline bool isLoopInvariant(Value *V) {
if (Instruction *I = dyn_cast<Instruction>(V))
return !CurLoop->contains(I->getParent());
return true; // All non-instructions are loop invariant
}
// visitBasicBlock - Run LICM on a particular block.
/// visitBasicBlock - Run LICM on a particular block.
///
void visitBasicBlock(BasicBlock *BB);
// Instruction visitation handlers... these basically control whether or not
// the specified instruction types are hoisted.
//
/// Instruction visitation handlers... these basically control whether or
/// not the specified instruction types are hoisted.
///
friend class InstVisitor<LICM>;
void visitBinaryOperator(Instruction &I) {
if (isLoopInvariant(I.getOperand(0)) && isLoopInvariant(I.getOperand(1)))
@ -99,6 +104,9 @@ namespace {
Pass *createLICMPass() { return new LICM(); }
/// runOnFunction - For LICM, this simply traverses the loop structure of the
/// function, hoisting expressions out of loops if possible.
///
bool LICM::runOnFunction(Function &) {
// get our loop information...
const std::vector<Loop*> &TopLevelLoops =
@ -116,6 +124,9 @@ bool LICM::runOnFunction(Function &) {
return Changed;
}
/// visitLoop - Hoist expressions out of the specified loop...
///
void LICM::visitLoop(Loop *L) {
// Recurse through all subloops before we process this loop...
std::for_each(L->getSubLoops().begin(), L->getSubLoops().end(),
@ -143,6 +154,8 @@ void LICM::visitLoop(Loop *L) {
CurLoop = 0;
}
/// visitBasicBlock - Run LICM on a particular block.
///
void LICM::visitBasicBlock(BasicBlock *BB) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
visit(*I);
@ -155,6 +168,9 @@ void LICM::visitBasicBlock(BasicBlock *BB) {
}
/// hoist - When an instruction is found to only use loop invariant operands
/// that is safe to hoist, this instruction is called to do the dirty work.
///
void LICM::hoist(Instruction &Inst) {
if (Inst.use_empty()) return; // Don't (re) hoist dead instructions!
//cerr << "Hoisting " << Inst;
@ -196,9 +212,9 @@ void LICM::visitLoadInst(LoadInst &LI) {
}
// pointerInvalidatedByLoop - Return true if the body of this loop may store
// into the memory location pointed to by V.
//
/// pointerInvalidatedByLoop - Return true if the body of this loop may store
/// into the memory location pointed to by V.
///
bool LICM::pointerInvalidatedByLoop(Value *V) {
// Check to see if any of the basic blocks in CurLoop invalidate V.
for (unsigned i = 0, e = CurLoop->getBlocks().size(); i != e; ++i)