Generalize ExtendUsesToFormExtLoad to be usable for ANY_EXTEND,
in addition to ZERO_EXTEND and SIGN_EXTEND. Fix a bug in the
way it checked for live-out values, and simplify the way it
find users by using SDNode::use_iterator's (relatively) new
features. Also, make it slightly more permissive on targets
with free truncates.
In SelectionDAGBuild, avoid creating ANY_EXTEND nodes that are
larger than necessary. If the target's SwitchAmountTy has
enough bits, use it. This exposes the truncate to optimization
early, enabling more optimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68670 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e874f1b..5af12eb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2874,7 +2874,7 @@
}
// ExtendUsesToFormExtLoad - Trying to extend uses of a load to enable this:
-// "fold ({s|z}ext (load x)) -> ({s|z}ext (truncate ({s|z}extload x)))"
+// "fold ({s|z|a}ext (load x)) -> ({s|z|a}ext (truncate ({s|z|a}extload x)))"
// transformation. Returns true if extension are possible and the above
// mentioned transformation is profitable.
static bool ExtendUsesToFormExtLoad(SDNode *N, SDValue N0,
@@ -2889,8 +2889,10 @@
SDNode *User = *UI;
if (User == N)
continue;
+ if (UI.getUse().getResNo() != N0.getResNo())
+ continue;
// FIXME: Only extend SETCC N, N and SETCC N, c for now.
- if (User->getOpcode() == ISD::SETCC) {
+ if (ExtOpc != ISD::ANY_EXTEND && User->getOpcode() == ISD::SETCC) {
ISD::CondCode CC = cast<CondCodeSDNode>(User->getOperand(2))->get();
if (ExtOpc == ISD::ZERO_EXTEND && ISD::isSignedIntSetCC(CC))
// Sign bits will be lost after a zext.
@@ -2906,32 +2908,25 @@
}
if (Add)
ExtendNodes.push_back(User);
- } else {
- for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
- SDValue UseOp = User->getOperand(i);
- if (UseOp == N0) {
- // If truncate from extended type to original load type is free
- // on this target, then it's ok to extend a CopyToReg.
- if (isTruncFree && User->getOpcode() == ISD::CopyToReg)
- HasCopyToRegUses = true;
- else
- return false;
- }
- }
+ continue;
}
+ // If truncates aren't free and there are users we can't
+ // extend, it isn't worthwhile.
+ if (!isTruncFree)
+ return false;
+ // Remember if this value is live-out.
+ if (User->getOpcode() == ISD::CopyToReg)
+ HasCopyToRegUses = true;
}
if (HasCopyToRegUses) {
bool BothLiveOut = false;
for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
UI != UE; ++UI) {
- SDNode *User = *UI;
- for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
- SDValue UseOp = User->getOperand(i);
- if (UseOp.getNode() == N && UseOp.getResNo() == 0) {
- BothLiveOut = true;
- break;
- }
+ SDUse &Use = UI.getUse();
+ if (Use.getResNo() == 0 && Use.getUser()->getOpcode() == ISD::CopyToReg) {
+ BothLiveOut = true;
+ break;
}
}
if (BothLiveOut)
@@ -3013,8 +3008,8 @@
DoXform = ExtendUsesToFormExtLoad(N, N0, ISD::SIGN_EXTEND, SetCCs, TLI);
if (DoXform) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
- SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, N->getDebugLoc(),
- VT, LN0->getChain(),
+ SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, N->getDebugLoc(), VT,
+ LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(),
N0.getValueType(),
@@ -3034,8 +3029,8 @@
if (SOp == Trunc)
Ops.push_back(ExtLoad);
else
- Ops.push_back(DAG.getNode(ISD::SIGN_EXTEND, N->getDebugLoc(),
- VT, SOp));
+ Ops.push_back(DAG.getNode(ISD::SIGN_EXTEND,
+ N->getDebugLoc(), VT, SOp));
}
Ops.push_back(SetCC->getOperand(2));
@@ -3278,26 +3273,48 @@
}
// fold (aext (load x)) -> (aext (truncate (extload x)))
- if (ISD::isNON_EXTLoad(N0.getNode()) && N0.hasOneUse() &&
+ if (ISD::isNON_EXTLoad(N0.getNode()) &&
((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadExtLegal(ISD::EXTLOAD, N0.getValueType()))) {
- LoadSDNode *LN0 = cast<LoadSDNode>(N0);
- SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, N->getDebugLoc(), VT,
- LN0->getChain(),
- LN0->getBasePtr(), LN0->getSrcValue(),
- LN0->getSrcValueOffset(),
- N0.getValueType(),
- LN0->isVolatile(), LN0->getAlignment());
- CombineTo(N, ExtLoad);
- // Redirect any chain users to the new load.
- DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1),
- SDValue(ExtLoad.getNode(), 1));
- // If any node needs the original loaded value, recompute it.
- if (!LN0->use_empty())
- CombineTo(LN0, DAG.getNode(ISD::TRUNCATE, N0.getDebugLoc(),
- N0.getValueType(), ExtLoad),
- ExtLoad.getValue(1));
- return SDValue(N, 0); // Return N so it doesn't get rechecked!
+ bool DoXform = true;
+ SmallVector<SDNode*, 4> SetCCs;
+ if (!N0.hasOneUse())
+ DoXform = ExtendUsesToFormExtLoad(N, N0, ISD::ANY_EXTEND, SetCCs, TLI);
+ if (DoXform) {
+ LoadSDNode *LN0 = cast<LoadSDNode>(N0);
+ SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, N->getDebugLoc(), VT,
+ LN0->getChain(),
+ LN0->getBasePtr(), LN0->getSrcValue(),
+ LN0->getSrcValueOffset(),
+ N0.getValueType(),
+ LN0->isVolatile(), LN0->getAlignment());
+ CombineTo(N, ExtLoad);
+ SDValue Trunc = DAG.getNode(ISD::TRUNCATE, N0.getDebugLoc(),
+ N0.getValueType(), ExtLoad);
+ CombineTo(N0.getNode(), Trunc, ExtLoad.getValue(1));
+
+ // Extend SetCC uses if necessary.
+ for (unsigned i = 0, e = SetCCs.size(); i != e; ++i) {
+ SDNode *SetCC = SetCCs[i];
+ SmallVector<SDValue, 4> Ops;
+
+ for (unsigned j = 0; j != 2; ++j) {
+ SDValue SOp = SetCC->getOperand(j);
+ if (SOp == Trunc)
+ Ops.push_back(ExtLoad);
+ else
+ Ops.push_back(DAG.getNode(ISD::ANY_EXTEND,
+ N->getDebugLoc(), VT, SOp));
+ }
+
+ Ops.push_back(SetCC->getOperand(2));
+ CombineTo(SetCC, DAG.getNode(ISD::SETCC, N->getDebugLoc(),
+ SetCC->getValueType(0),
+ &Ops[0], Ops.size()));
+ }
+
+ return SDValue(N, 0); // Return N so it doesn't get rechecked!
+ }
}
// fold (aext (zextload x)) -> (aext (truncate (zextload x)))