Add comments explaining why it's not necessary to include the

is-function-local flag in metadata uniquing bits.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112528 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-08-30 21:18:41 +00:00
parent 973a074345
commit 56b092e4cd

View File

@ -190,6 +190,8 @@ MDNode *MDNode::getMDNode(LLVMContext &Context, Value *const *Vals,
// Add all the operand pointers. Note that we don't have to add the
// isFunctionLocal bit because that's implied by the operands.
// Note that if the operands are later nulled out, the node will be
// removed from the uniquing map.
FoldingSetNodeID ID;
for (unsigned i = 0; i != NumVals; ++i)
ID.AddPointer(Vals[i]);
@ -276,6 +278,8 @@ Value *MDNode::getOperand(unsigned i) const {
void MDNode::Profile(FoldingSetNodeID &ID) const {
// Add all the operand pointers. Note that we don't have to add the
// isFunctionLocal bit because that's implied by the operands.
// Note that if the operands are later nulled out, the node will be
// removed from the uniquing map.
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
ID.AddPointer(getOperand(i));
}
@ -326,7 +330,8 @@ void MDNode::replaceOperand(MDNodeOperand *Op, Value *To) {
// If we are dropping an argument to null, we choose to not unique the MDNode
// anymore. This commonly occurs during destruction, and uniquing these
// brings little reuse.
// brings little reuse. Also, this means we don't need to include
// isFunctionLocal bits in FoldingSetNodeIDs for MDNodes.
if (To == 0) {
setIsNotUniqued();
return;