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Do not emit copies for physical register output if it's not used.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40722 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-08-02 05:29:38 +00:00
parent 0a2a515c5b
commit 33d5595d66
3 changed files with 32 additions and 2 deletions
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4
include/llvm/CodeGen/SelectionDAGNodes.h
View File

@ -858,6 +858,10 @@ public:
/// operation.
bool hasNUsesOfValue(unsigned NUses, unsigned Value) const;
/// hasAnyUseOfValue - Return true if there are any use of the indicated
/// value. This method ignores uses of other values defined by this operation.
bool hasAnyUseOfValue(unsigned Value) const;
/// isOnlyUse - Return true if this node is the only use of N.
///
bool isOnlyUse(SDNode *N) const;

3
lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
View File

@ -676,7 +676,8 @@ void ScheduleDAG::EmitNode(SDNode *Node,
if (HasPhysRegOuts) {
for (unsigned i = II.numDefs; i < NumResults; ++i) {
unsigned Reg = II.ImplicitDefs[i - II.numDefs];
EmitCopyFromReg(Node, i, Reg, VRBaseMap);
if (Node->hasAnyUseOfValue(i))
EmitCopyFromReg(Node, i, Reg, VRBaseMap);
}
}
} else {

27
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -3242,7 +3242,7 @@ bool SDNode::hasNUsesOfValue(unsigned NUses, unsigned Value) const {
// If there is only one value, this is easy.
if (getNumValues() == 1)
return use_size() == NUses;
if (Uses.size() < NUses) return false;
if (use_size() < NUses) return false;
SDOperand TheValue(const_cast<SDNode *>(this), Value);
@ -3265,6 +3265,31 @@ bool SDNode::hasNUsesOfValue(unsigned NUses, unsigned Value) const {
}
/// hasAnyUseOfValue - Return true if there are any use of the indicated
/// value. This method ignores uses of other values defined by this operation.
bool SDNode::hasAnyUseOfValue(unsigned Value) const {
assert(Value < getNumValues() && "Bad value!");
if (use_size() == 0) return false;
SDOperand TheValue(const_cast<SDNode *>(this), Value);
SmallPtrSet<SDNode*, 32> UsersHandled;
for (SDNode::use_iterator UI = Uses.begin(), E = Uses.end(); UI != E; ++UI) {
SDNode *User = *UI;
if (User->getNumOperands() == 1 ||
UsersHandled.insert(User)) // First time we've seen this?
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i)
if (User->getOperand(i) == TheValue) {
return true;
}
}
return false;
}
/// isOnlyUse - Return true if this node is the only use of N.
///
bool SDNode::isOnlyUse(SDNode *N) const {