// Forward declarations.
class LoopVectorizationLegality;
class LoopVectorizationCostModel;
+class LoopVectorizeHints;
/// Optimization analysis message produced during vectorization. Messages inform
/// the user why vectorization did not occur.
// non-speculated memory access when the condition was false, this would be
// caught by the runtime overlap checks).
if (Kind != LLVMContext::MD_tbaa &&
+ Kind != LLVMContext::MD_alias_scope &&
+ Kind != LLVMContext::MD_noalias &&
Kind != LLVMContext::MD_fpmath)
continue;
LoopVectorizationCostModel(Loop *L, ScalarEvolution *SE, LoopInfo *LI,
LoopVectorizationLegality *Legal,
const TargetTransformInfo &TTI,
- const DataLayout *DL, const TargetLibraryInfo *TLI)
- : TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI), DL(DL), TLI(TLI) {}
+ const DataLayout *DL, const TargetLibraryInfo *TLI,
+ const Function *F, const LoopVectorizeHints *Hints)
+ : TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI), DL(DL), TLI(TLI), TheFunction(F), Hints(Hints) {}
/// Information about vectorization costs
struct VectorizationFactor {
/// This method checks every power of two up to VF. If UserVF is not ZERO
/// then this vectorization factor will be selected if vectorization is
/// possible.
- VectorizationFactor selectVectorizationFactor(bool OptForSize,
- unsigned UserVF,
- bool ForceVectorization);
+ VectorizationFactor selectVectorizationFactor(bool OptForSize);
/// \return The size (in bits) of the widest type in the code that
/// needs to be vectorized. We ignore values that remain scalar such as
/// based on register pressure and other parameters.
/// VF and LoopCost are the selected vectorization factor and the cost of the
/// selected VF.
- unsigned selectUnrollFactor(bool OptForSize, unsigned UserUF, unsigned VF,
- unsigned LoopCost);
+ unsigned selectUnrollFactor(bool OptForSize, unsigned VF, unsigned LoopCost);
/// \brief A struct that represents some properties of the register usage
/// of a loop.
/// as a vector operation.
bool isConsecutiveLoadOrStore(Instruction *I);
+ /// Report an analysis message to assist the user in diagnosing loops that are
+ /// not vectorized.
+ void emitAnalysis(Report &Message) {
+ DebugLoc DL = TheLoop->getStartLoc();
+ if (Instruction *I = Message.getInstr())
+ DL = I->getDebugLoc();
+ emitOptimizationRemarkAnalysis(TheFunction->getContext(), DEBUG_TYPE,
+ *TheFunction, DL, Message.str());
+ }
+
/// The loop that we evaluate.
Loop *TheLoop;
/// Scev analysis.
const DataLayout *DL;
/// Target Library Info.
const TargetLibraryInfo *TLI;
+ const Function *TheFunction;
+ // Loop Vectorize Hint.
+ const LoopVectorizeHints *Hints;
};
/// Utility class for getting and setting loop vectorizer hints in the form
std::string emitRemark() const {
Report R;
- R << "vectorization ";
- switch (Force) {
- case LoopVectorizeHints::FK_Disabled:
- R << "is explicitly disabled";
- break;
- case LoopVectorizeHints::FK_Enabled:
- R << "is explicitly enabled";
- if (Width != 0 && Unroll != 0)
- R << " with width " << Width << " and interleave count " << Unroll;
- else if (Width != 0)
- R << " with width " << Width;
- else if (Unroll != 0)
- R << " with interleave count " << Unroll;
- break;
- case LoopVectorizeHints::FK_Undefined:
- R << "was not specified";
- break;
+ if (Force == LoopVectorizeHints::FK_Disabled)
+ R << "vectorization is explicitly disabled";
+ else {
+ R << "use -Rpass-analysis=loop-vectorize for more info";
+ if (Force == LoopVectorizeHints::FK_Enabled) {
+ R << " (Force=true";
+ if (Width != 0)
+ R << ", Vector Width=" << Width;
+ if (Unroll != 0)
+ R << ", Interleave Count=" << Unroll;
+ R << ")";
+ }
}
+
return R.str();
}
}
// Use the cost model.
- LoopVectorizationCostModel CM(L, SE, LI, &LVL, *TTI, DL, TLI);
+ LoopVectorizationCostModel CM(L, SE, LI, &LVL, *TTI, DL, TLI, F, &Hints);
// Check the function attributes to find out if this function should be
// optimized for size.
// Select the optimal vectorization factor.
const LoopVectorizationCostModel::VectorizationFactor VF =
- CM.selectVectorizationFactor(OptForSize, Hints.getWidth(),
- Hints.getForce() ==
- LoopVectorizeHints::FK_Enabled);
+ CM.selectVectorizationFactor(OptForSize);
// Select the unroll factor.
const unsigned UF =
- CM.selectUnrollFactor(OptForSize, Hints.getUnroll(), VF.Width, VF.Cost);
+ CM.selectUnrollFactor(OptForSize, VF.Width, VF.Cost);
DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in "
<< DebugLocStr << '\n');
// identified reduction value with an outside user.
if (!hasOutsideLoopUser(TheLoop, it, AllowedExit))
continue;
- emitAnalysis(Report(it) << "value that could not be identified as "
- "reduction is used outside the loop");
+ emitAnalysis(Report(it) << "value could not be identified as "
+ "an induction or reduction variable");
return false;
}
continue;
}
- emitAnalysis(Report(it) << "unvectorizable operation");
+ emitAnalysis(Report(it) << "value that could not be identified as "
+ "reduction is used outside the loop");
DEBUG(dbgs() << "LV: Found an unidentified PHI."<< *Phi <<"\n");
return false;
}// end of PHI handling
ReductionKind Kind,
ReductionInstDesc &Prev) {
bool FP = I->getType()->isFloatingPointTy();
- bool FastMath = (FP && I->isCommutative() && I->isAssociative());
+ bool FastMath = FP && I->hasUnsafeAlgebra();
switch (I->getOpcode()) {
default:
return ReductionInstDesc(false, I);
return ReductionInstDesc(Kind == RK_IntegerXor, I);
case Instruction::FMul:
return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
+ case Instruction::FSub:
case Instruction::FAdd:
return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
case Instruction::FCmp:
}
LoopVectorizationCostModel::VectorizationFactor
-LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
- unsigned UserVF,
- bool ForceVectorization) {
+LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize) {
// Width 1 means no vectorize
VectorizationFactor Factor = { 1U, 0U };
if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
+ emitAnalysis(Report() << "runtime pointer checks needed. Enable vectorization of this loop with '#pragma clang loop vectorize(enable)' when compiling with -Os");
DEBUG(dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n");
return Factor;
}
if (!EnableCondStoresVectorization && Legal->NumPredStores) {
+ emitAnalysis(Report() << "store that is conditionally executed prevents vectorization");
DEBUG(dbgs() << "LV: No vectorization. There are conditional stores.\n");
return Factor;
}
if (OptForSize) {
// If we are unable to calculate the trip count then don't try to vectorize.
if (TC < 2) {
+ emitAnalysis(Report() << "unable to calculate the loop count due to complex control flow");
DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
return Factor;
}
// If the trip count that we found modulo the vectorization factor is not
// zero then we require a tail.
if (VF < 2) {
+ emitAnalysis(Report() << "cannot optimize for size and vectorize at the same time. Enable vectorization of this loop with '#pragma clang loop vectorize(enable)' when compiling with -Os");
DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
return Factor;
}
}
+ int UserVF = Hints->getWidth();
if (UserVF != 0) {
assert(isPowerOf2_32(UserVF) && "VF needs to be a power of two");
DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n");
unsigned Width = 1;
DEBUG(dbgs() << "LV: Scalar loop costs: " << (int)ScalarCost << ".\n");
+ bool ForceVectorization = Hints->getForce() == LoopVectorizeHints::FK_Enabled;
// Ignore scalar width, because the user explicitly wants vectorization.
if (ForceVectorization && VF > 1) {
Width = 2;
unsigned
LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
- unsigned UserUF,
unsigned VF,
unsigned LoopCost) {
// to the increased register pressure.
// Use the user preference, unless 'auto' is selected.
+ int UserUF = Hints->getUnroll();
if (UserUF != 0)
return UserUF;
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