take care of some todos, transforming [us]mul_lohi into
a wider mul if the wider mul is legal.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121848 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6f0c167..be5a5bc 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2045,7 +2045,29 @@
SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHS);
if (Res.getNode()) return Res;
- // TODO: Transform smul_lohi to mul if the wider mul is legal!
+ EVT VT = N->getValueType(0);
+ DebugLoc DL = N->getDebugLoc();
+
+ // If the type twice as wide is legal, transform the mulhu to a wider multiply
+ // plus a shift.
+ if (VT.isSimple() && !VT.isVector()) {
+ MVT Simple = VT.getSimpleVT();
+ unsigned SimpleSize = Simple.getSizeInBits();
+ EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
+ if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
+ SDValue Lo = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(0));
+ SDValue Hi = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(1));
+ Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
+ // Compute the high part as N1.
+ Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
+ DAG.getConstant(SimpleSize, getShiftAmountTy()));
+ Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
+ // Compute the low part as N0.
+ Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
+ return CombineTo(N, Lo, Hi);
+ }
+ }
+
return SDValue();
}
@@ -2053,7 +2075,29 @@
SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHU);
if (Res.getNode()) return Res;
- // TODO: Transform umul_lohi to mul if the wider mul is legal!
+ EVT VT = N->getValueType(0);
+ DebugLoc DL = N->getDebugLoc();
+
+ // If the type twice as wide is legal, transform the mulhu to a wider multiply
+ // plus a shift.
+ if (VT.isSimple() && !VT.isVector()) {
+ MVT Simple = VT.getSimpleVT();
+ unsigned SimpleSize = Simple.getSizeInBits();
+ EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
+ if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
+ SDValue Lo = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(0));
+ SDValue Hi = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(1));
+ Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
+ // Compute the high part as N1.
+ Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
+ DAG.getConstant(SimpleSize, getShiftAmountTy()));
+ Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
+ // Compute the low part as N0.
+ Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
+ return CombineTo(N, Lo, Hi);
+ }
+ }
+
return SDValue();
}