Intrinsics that just load from memory can be treated like loads: they don't

have to serialize against each other.  This allows us to schedule lvx's
across each other, for example.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27346 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-04-02 03:41:14 +00:00
parent 5348e393df
commit e58a780166

View File

@ -1236,16 +1236,32 @@ static bool IntrinsicCannotAccessMemory(unsigned IntrinsicID) {
return false;
}
// IntrinsicOnlyReadsMemory - Return true if the specified intrinsic doesn't
// have any side-effects or if it only reads memory.
static bool IntrinsicOnlyReadsMemory(unsigned IntrinsicID) {
#define GET_SIDE_EFFECT_INFO
#include "llvm/Intrinsics.gen"
#undef GET_SIDE_EFFECT_INFO
return false;
}
/// visitTargetIntrinsic - Lower a call of a target intrinsic to an INTRINSIC
/// node.
void SelectionDAGLowering::visitTargetIntrinsic(CallInst &I,
unsigned Intrinsic) {
bool HasChain = !IntrinsicCannotAccessMemory(Intrinsic);
bool OnlyLoad = HasChain && IntrinsicOnlyReadsMemory(Intrinsic);
// Build the operand list.
std::vector<SDOperand> Ops;
if (HasChain) // If this intrinsic has side-effects, chainify it.
Ops.push_back(getRoot());
if (HasChain) { // If this intrinsic has side-effects, chainify it.
if (OnlyLoad) {
// We don't need to serialize loads against other loads.
Ops.push_back(DAG.getRoot());
} else {
Ops.push_back(getRoot());
}
}
// Add the intrinsic ID as an integer operand.
Ops.push_back(DAG.getConstant(Intrinsic, TLI.getPointerTy()));
@ -1295,8 +1311,13 @@ void SelectionDAGLowering::visitTargetIntrinsic(CallInst &I,
else
Result = DAG.getNode(ISD::INTRINSIC_VOID, VTs, Ops);
if (HasChain)
DAG.setRoot(Result.getValue(Result.Val->getNumValues()-1));
if (HasChain) {
SDOperand Chain = Result.getValue(Result.Val->getNumValues()-1);
if (OnlyLoad)
PendingLoads.push_back(Chain);
else
DAG.setRoot(Chain);
}
if (I.getType() != Type::VoidTy) {
if (const PackedType *PTy = dyn_cast<PackedType>(I.getType())) {
MVT::ValueType EVT = TLI.getValueType(PTy->getElementType());