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-rw-r--r--llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp119
1 files changed, 61 insertions, 58 deletions
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index 031f40e2caa..c70619cf27c 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -328,7 +328,7 @@ static BaseDefiningValueResult findBaseDefiningValue(Value *I);
/// If the later, the return pointer is a BDV (or possibly a base) for the
/// particular element in 'I'.
static BaseDefiningValueResult
-findBaseDefiningValueOfVector(Value *I, Value *Index = nullptr) {
+findBaseDefiningValueOfVector(Value *I) {
assert(I->getType()->isVectorTy() &&
cast<VectorType>(I->getType())->getElementType()->isPointerTy() &&
"Illegal to ask for the base pointer of a non-pointer type");
@@ -362,35 +362,12 @@ findBaseDefiningValueOfVector(Value *I, Value *Index = nullptr) {
if (isa<LoadInst>(I))
return BaseDefiningValueResult(I, true);
-
- // For an insert element, we might be able to look through it if we know
- // something about the indexes.
- if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(I)) {
- if (Index) {
- Value *InsertIndex = IEI->getOperand(2);
- // This index is inserting the value, look for its BDV
- if (InsertIndex == Index)
- return findBaseDefiningValue(IEI->getOperand(1));
- // Both constant, and can't be equal per above. This insert is definitely
- // not relevant, look back at the rest of the vector and keep trying.
- if (isa<ConstantInt>(Index) && isa<ConstantInt>(InsertIndex))
- return findBaseDefiningValueOfVector(IEI->getOperand(0), Index);
- }
- // If both inputs to the insertelement are known bases, then so is the
- // insertelement itself. NOTE: This should be handled within the generic
- // base pointer inference code and after http://reviews.llvm.org/D12583,
- // will be. However, when strengthening asserts I needed to add this to
- // keep an existing test passing which was 'working'. FIXME
- if (findBaseDefiningValue(IEI->getOperand(0)).IsKnownBase &&
- findBaseDefiningValue(IEI->getOperand(1)).IsKnownBase)
- return BaseDefiningValueResult(IEI, true);
-
+ if (isa<InsertElementInst>(I))
// We don't know whether this vector contains entirely base pointers or
// not. To be conservatively correct, we treat it as a BDV and will
// duplicate code as needed to construct a parallel vector of bases.
- return BaseDefiningValueResult(IEI, false);
- }
+ return BaseDefiningValueResult(I, false);
if (isa<ShuffleVectorInst>(I))
// We don't know whether this vector contains entirely base pointers or
@@ -528,27 +505,11 @@ static BaseDefiningValueResult findBaseDefiningValue(Value *I) {
// We may need to insert a parallel instruction to extract the appropriate
// element out of the base vector corresponding to the input. Given this,
// it's analogous to the phi and select case even though it's not a merge.
- if (auto *EEI = dyn_cast<ExtractElementInst>(I)) {
- Value *VectorOperand = EEI->getVectorOperand();
- Value *Index = EEI->getIndexOperand();
- auto VecResult = findBaseDefiningValueOfVector(VectorOperand, Index);
- Value *VectorBase = VecResult.BDV;
- if (VectorBase->getType()->isPointerTy())
- // We found a BDV for this specific element with the vector. This is an
- // optimization, but in practice it covers most of the useful cases
- // created via scalarization. Note: The peephole optimization here is
- // currently needed for correctness since the general algorithm doesn't
- // yet handle insertelements. That will change shortly.
- return BaseDefiningValueResult(VectorBase, VecResult.IsKnownBase);
- else {
- assert(VectorBase->getType()->isVectorTy());
- // Otherwise, we have an instruction which potentially produces a
- // derived pointer and we need findBasePointers to clone code for us
- // such that we can create an instruction which produces the
- // accompanying base pointer.
- return BaseDefiningValueResult(I, VecResult.IsKnownBase);
- }
- }
+ if (isa<ExtractElementInst>(I))
+ // Note: There a lot of obvious peephole cases here. This are deliberately
+ // handled after the main base pointer inference algorithm to make writing
+ // test cases to exercise that code easier.
+ return BaseDefiningValueResult(I, false);
// The last two cases here don't return a base pointer. Instead, they
// return a value which dynamically selects from among several base
@@ -587,7 +548,9 @@ static Value *findBaseOrBDV(Value *I, DefiningValueMapTy &Cache) {
/// Given the result of a call to findBaseDefiningValue, or findBaseOrBDV,
/// is it known to be a base pointer? Or do we need to continue searching.
static bool isKnownBaseResult(Value *V) {
- if (!isa<PHINode>(V) && !isa<SelectInst>(V) && !isa<ExtractElementInst>(V)) {
+ if (!isa<PHINode>(V) && !isa<SelectInst>(V) &&
+ !isa<ExtractElementInst>(V) && !isa<InsertElementInst>(V) &&
+ !isa<ShuffleVectorInst>(V)) {
// no recursion possible
return true;
}
@@ -755,7 +718,8 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
#ifndef NDEBUG
auto isExpectedBDVType = [](Value *BDV) {
- return isa<PHINode>(BDV) || isa<SelectInst>(BDV) || isa<ExtractElementInst>(BDV);
+ return isa<PHINode>(BDV) || isa<SelectInst>(BDV) ||
+ isa<ExtractElementInst>(BDV) || isa<InsertElementInst>(BDV);
};
#endif
@@ -795,10 +759,12 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
visitIncomingValue(Sel->getFalseValue());
} else if (auto *EE = dyn_cast<ExtractElementInst>(Current)) {
visitIncomingValue(EE->getVectorOperand());
+ } else if (auto *IE = dyn_cast<InsertElementInst>(Current)) {
+ visitIncomingValue(IE->getOperand(0)); // vector operand
+ visitIncomingValue(IE->getOperand(1)); // scalar operand
} else {
- // There are two classes of instructions we know we don't handle.
- assert(isa<ShuffleVectorInst>(Current) ||
- isa<InsertElementInst>(Current));
+ // There is one known class of instructions we know we don't handle.
+ assert(isa<ShuffleVectorInst>(Current));
llvm_unreachable("unimplemented instruction case");
}
}
@@ -849,11 +815,16 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
} else if (PHINode *Phi = dyn_cast<PHINode>(v)) {
for (Value *Val : Phi->incoming_values())
calculateMeet.meetWith(getStateForInput(Val));
- } else {
+ } else if (auto *EE = dyn_cast<ExtractElementInst>(v)) {
// The 'meet' for an extractelement is slightly trivial, but it's still
// useful in that it drives us to conflict if our input is.
- auto *EE = cast<ExtractElementInst>(v);
calculateMeet.meetWith(getStateForInput(EE->getVectorOperand()));
+ } else {
+ // Given there's a inherent type mismatch between the operands, will
+ // *always* produce Conflict.
+ auto *IE = cast<InsertElementInst>(v);
+ calculateMeet.meetWith(getStateForInput(IE->getOperand(0)));
+ calculateMeet.meetWith(getStateForInput(IE->getOperand(1)));
}
BDVState oldState = states[v];
@@ -899,6 +870,13 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
BaseInst->setMetadata("is_base_value", MDNode::get(I->getContext(), {}));
states[I] = BDVState(BDVState::Base, BaseInst);
}
+
+ // Since we're joining a vector and scalar base, they can never be the
+ // same. As a result, we should always see insert element having reached
+ // the conflict state.
+ if (isa<InsertElementInst>(I)) {
+ assert(State.isConflict());
+ }
if (!State.isConflict())
continue;
@@ -920,14 +898,22 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
(I->getName() + ".base").str() : "base_select";
return SelectInst::Create(Sel->getCondition(), Undef,
Undef, Name, Sel);
- } else {
- auto *EE = cast<ExtractElementInst>(I);
+ } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
UndefValue *Undef = UndefValue::get(EE->getVectorOperand()->getType());
std::string Name = I->hasName() ?
(I->getName() + ".base").str() : "base_ee";
return ExtractElementInst::Create(Undef, EE->getIndexOperand(), Name,
EE);
+ } else {
+ auto *IE = cast<InsertElementInst>(I);
+ UndefValue *VecUndef = UndefValue::get(IE->getOperand(0)->getType());
+ UndefValue *ScalarUndef = UndefValue::get(IE->getOperand(1)->getType());
+ std::string Name = I->hasName() ?
+ (I->getName() + ".base").str() : "base_ie";
+ return InsertElementInst::Create(VecUndef, ScalarUndef,
+ IE->getOperand(2), Name, IE);
}
+
};
Instruction *BaseInst = MakeBaseInstPlaceholder(I);
// Add metadata marking this as a base value
@@ -1029,14 +1015,31 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
Value *Base = getBaseForInput(InVal, BaseSel);
BaseSel->setOperand(i, Base);
}
- } else {
- auto *BaseEE = cast<ExtractElementInst>(state.getBase());
+ } else if (auto *BaseEE = dyn_cast<ExtractElementInst>(state.getBase())) {
Value *InVal = cast<ExtractElementInst>(v)->getVectorOperand();
// Find the instruction which produces the base for each input. We may
// need to insert a bitcast.
Value *Base = getBaseForInput(InVal, BaseEE);
BaseEE->setOperand(0, Base);
+ } else {
+ auto *BaseIE = cast<InsertElementInst>(state.getBase());
+ auto *BdvIE = cast<InsertElementInst>(v);
+ auto UpdateOperand = [&](int OperandIdx) {
+ Value *InVal = BdvIE->getOperand(OperandIdx);
+ Value *Base = findBaseOrBDV(InVal, cache);
+ if (!isKnownBaseResult(Base)) {
+ // Either conflict or base.
+ assert(states.count(Base));
+ Base = states[Base].getBase();
+ assert(Base != nullptr && "unknown BDVState!");
+ }
+ assert(Base && "can't be null");
+ BaseIE->setOperand(OperandIdx, Base);
+ };
+ UpdateOperand(0); // vector operand
+ UpdateOperand(1); // scalar operand
}
+
}
// Now that we're done with the algorithm, see if we can optimize the
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