[llvm-commits] CVS: llvm/lib/Analysis/InductionVariable.cpp
Chris Lattner
lattner at cs.uiuc.edu
Wed Sep 10 09:52:02 PDT 2003
Changes in directory llvm/lib/Analysis:
InductionVariable.cpp updated: 1.27 -> 1.28
---
Log message:
Simplification of trip counting machinery.
- make sure to check the indvar type before anything else (efficiency)
- Make sure to insert the 'add' into the program, even though it'll be
dead
- Wrap code at 80 columns
- Other minor cleanups to reduce indentation level
---
Diffs of the changes:
Index: llvm/lib/Analysis/InductionVariable.cpp
diff -u llvm/lib/Analysis/InductionVariable.cpp:1.27 llvm/lib/Analysis/InductionVariable.cpp:1.28
--- llvm/lib/Analysis/InductionVariable.cpp:1.27 Wed Sep 10 00:23:58 2003
+++ llvm/lib/Analysis/InductionVariable.cpp Wed Sep 10 09:51:49 2003
@@ -155,7 +155,9 @@
}
-Value* InductionVariable::getExecutionCount(LoopInfo *LoopInfo) {
+Value *InductionVariable::getExecutionCount(LoopInfo *LoopInfo) {
+ if (InductionType != Canonical) return 0;
+
DEBUG(std::cerr << "entering getExecutionCount\n");
// Don't recompute if already available
@@ -167,111 +169,104 @@
const Loop *L = LoopInfo ? LoopInfo->getLoopFor(Phi->getParent()) : 0;
if (!L) {
DEBUG(std::cerr << "null loop. oops\n");
- return NULL;
+ return 0;
}
// >1 backedge => cannot predict number of iterations
if (Phi->getNumIncomingValues() != 2) {
DEBUG(std::cerr << ">2 incoming values. oops\n");
- return NULL;
+ return 0;
}
// Find final node: predecesor of the loop header that's also an exit
BasicBlock *terminator = 0;
- BasicBlock *header = L->getHeader();
- for (pred_iterator PI = pred_begin(header), PE = pred_end(header);
- PI != PE; ++PI) {
+ for (pred_iterator PI = pred_begin(L->getHeader()),
+ PE = pred_end(L->getHeader()); PI != PE; ++PI)
if (L->isLoopExit(*PI)) {
terminator = *PI;
break;
}
- }
// Break in the loop => cannot predict number of iterations
// break: any block which is an exit node whose successor is not in loop,
// and this block is not marked as the terminator
//
const std::vector<BasicBlock*> &blocks = L->getBlocks();
- for (std::vector<BasicBlock*>::const_iterator i = blocks.begin(), e = blocks.end();
- i != e; ++i) {
- if (L->isLoopExit(*i) && (*i != terminator)) {
- for (succ_iterator SI = succ_begin(*i), SE = succ_end(*i); SI != SE; ++SI) {
- if (! L->contains(*SI)) {
+ for (std::vector<BasicBlock*>::const_iterator I = blocks.begin(),
+ e = blocks.end(); I != e; ++I)
+ if (L->isLoopExit(*I) && *I != terminator)
+ for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
+ if (!L->contains(*SI)) {
DEBUG(std::cerr << "break found in loop");
- return NULL;
+ return 0;
}
- }
- }
- }
BranchInst *B = dyn_cast<BranchInst>(terminator->getTerminator());
if (!B) {
- // this really should not happen
- DEBUG(std::cerr << "no terminator instruction!");
- return NULL;
+ DEBUG(std::cerr << "Terminator is not a cond branch!");
+ return 0;
}
SetCondInst *SCI = dyn_cast<SetCondInst>(B->getCondition());
-
- if (SCI && InductionType == Canonical) {
- DEBUG(std::cerr << "sci:" << *SCI);
- Value *condVal0 = SCI->getOperand(0);
- Value *condVal1 = SCI->getOperand(1);
- Value *indVar = 0;
-
- // the induction variable is the one coming from the backedge
- if (L->contains(Phi->getIncomingBlock(0))) {
- indVar = Phi->getIncomingValue(0);
- } else {
- indVar = Phi->getIncomingValue(1);
+ if (!SCI) {
+ DEBUG(std::cerr << "Not a cond branch on setcc!\n");
+ return 0;
+ }
+
+ DEBUG(std::cerr << "sci:" << *SCI);
+ Value *condVal0 = SCI->getOperand(0);
+ Value *condVal1 = SCI->getOperand(1);
+ Value *indVar = 0;
+
+ // the induction variable is the one coming from the backedge
+ indVar = Phi->getIncomingValue(L->contains(Phi->getIncomingBlock(1)));
+
+
+ // Check to see if indVar is one of the parameters in SCI and if the other is
+ // loop-invariant, it is the UB
+ if (indVar == condVal0) {
+ if (isLoopInvariant(condVal1, L))
+ End = condVal1;
+ else {
+ DEBUG(std::cerr << "not loop invariant 1\n");
+ return 0;
}
-
- // check to see if indVar is one of the parameters in SCI
- // and if the other is loop-invariant, it is the UB
- if (indVar == condVal0) {
- if (isLoopInvariant(condVal1, L)) {
- End = condVal1;
- } else {
- DEBUG(std::cerr << "not loop invariant 1\n");
- }
- } else if (indVar == condVal1) {
- if (isLoopInvariant(condVal0, L)) {
- End = condVal0;
- } else {
- DEBUG(std::cerr << "not loop invariant 0\n");
- }
+ } else if (indVar == condVal1) {
+ if (isLoopInvariant(condVal0, L))
+ End = condVal0;
+ else {
+ DEBUG(std::cerr << "not loop invariant 0\n");
+ return 0;
}
+ } else {
+ DEBUG(std::cerr << "Loop condition doesn't directly uses indvar\n");
+ return 0;
+ }
- if (End) {
- switch (SCI->getOpcode()) {
- case Instruction::SetLT:
- case Instruction::SetNE: break; // already done
- case Instruction::SetLE: {
- // if compared to a constant int N, then predict N+1 iterations
- if (ConstantSInt *ubSigned = dyn_cast<ConstantSInt>(End)) {
- End = ConstantSInt::get(ubSigned->getType(), ubSigned->getValue()+1);
- DEBUG(std::cerr << "signed int constant\n");
- } else if (ConstantUInt *ubUnsigned = dyn_cast<ConstantUInt>(End)) {
- End = ConstantUInt::get(ubUnsigned->getType(),
- ubUnsigned->getValue()+1);
- DEBUG(std::cerr << "unsigned int constant\n");
- } else {
- DEBUG(std::cerr << "symbolic bound\n");
- //End = NULL;
- // new expression N+1
- End = BinaryOperator::create(Instruction::Add, End,
- ConstantUInt::get(ubUnsigned->getType(),
- 1));
- }
- break;
- }
- default: End = NULL; // cannot predict
- }
+ switch (SCI->getOpcode()) {
+ case Instruction::SetLT:
+ case Instruction::SetNE: return End; // already done
+ case Instruction::SetLE:
+ // if compared to a constant int N, then predict N+1 iterations
+ if (ConstantSInt *ubSigned = dyn_cast<ConstantSInt>(End)) {
+ DEBUG(std::cerr << "signed int constant\n");
+ return ConstantSInt::get(ubSigned->getType(), ubSigned->getValue()+1);
+ } else if (ConstantUInt *ubUnsigned = dyn_cast<ConstantUInt>(End)) {
+ DEBUG(std::cerr << "unsigned int constant\n");
+ return ConstantUInt::get(ubUnsigned->getType(),
+ ubUnsigned->getValue()+1);
+ } else {
+ DEBUG(std::cerr << "symbolic bound\n");
+ // new expression N+1, insert right before the SCI. FIXME: If End is loop
+ // invariant, then so is this expression. We should insert it in the loop
+ // preheader if it exists.
+ return BinaryOperator::create(Instruction::Add, End,
+ ConstantInt::get(End->getType(), 1),
+ "tripcount", SCI);
}
- return End;
- } else {
- DEBUG(std::cerr << "SCI null or non-canonical ind var\n");
+
+ default:
+ return 0; // cannot predict
}
- return NULL;
}
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