Optimization for the following SIGN_EXTEND pairs:
v8i8 -> v8i64,
v8i8 -> v8i32,
v4i8 -> v4i64,
v4i16 -> v4i64
for AVX and AVX2.
Bug 14865.
llvm-svn: 172708
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a82410a..3e5a446 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4298,11 +4298,19 @@
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::SIGN_EXTEND, N->getDebugLoc(), VT, N0);
- // fold (sext (sext x)) -> (sext x)
- // fold (sext (aext x)) -> (sext x)
- if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
- return DAG.getNode(ISD::SIGN_EXTEND, N->getDebugLoc(), VT,
- N0.getOperand(0));
+ // Folding (sext (sext x)) is obvious, but we do it only after the type
+ // legalization phase. When the sequence is like {(T1->T2), (T2->T3)} and
+ // T1 or T3 (or the both) are illegal types, the TypeLegalizer may not
+ // give a good sequence for the (T1->T3) pair.
+ // So we give a chance to target specific combiner to optimize T1->T2 and T2->T3
+ // separately and may be fold them in a preceding of subsequent instruction.
+ if (Level >= AfterLegalizeTypes) {
+ // fold (sext (sext x)) -> (sext x)
+ // fold (sext (aext x)) -> (sext x)
+ if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
+ return DAG.getNode(ISD::SIGN_EXTEND, N->getDebugLoc(), VT,
+ N0.getOperand(0));
+ }
if (N0.getOpcode() == ISD::TRUNCATE) {
// fold (sext (truncate (load x))) -> (sext (smaller load x))
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 344d144..91491bf 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2554,9 +2554,7 @@
VT.getVectorNumElements() ==
Operand.getValueType().getVectorNumElements()) &&
"Vector element count mismatch!");
- if (OpOpcode == ISD::SIGN_EXTEND || OpOpcode == ISD::ZERO_EXTEND)
- return getNode(OpOpcode, DL, VT, Operand.getNode()->getOperand(0));
- else if (OpOpcode == ISD::UNDEF)
+ if (OpOpcode == ISD::UNDEF)
// sext(undef) = 0, because the top bits will all be the same.
return getConstant(0, VT);
break;
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f42884d..a8294b6 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -16970,14 +16970,37 @@
static SDValue PerformSExtCombine(SDNode *N, SelectionDAG &DAG,
TargetLowering::DAGCombinerInfo &DCI,
const X86Subtarget *Subtarget) {
+ EVT VT = N->getValueType(0);
+
+ if (!VT.isVector())
+ return SDValue();
+
+ SDValue In = N->getOperand(0);
+ EVT InVT = In.getValueType();
+ DebugLoc dl = N->getDebugLoc();
+ unsigned ExtenedEltSize = VT.getVectorElementType().getSizeInBits();
+
+ // Split SIGN_EXTEND operation to use vmovsx instruction when possible
+ if (InVT == MVT::v8i8) {
+ if (ExtenedEltSize > 16 && !Subtarget->hasInt256())
+ In = DAG.getNode(ISD::SIGN_EXTEND, dl, MVT::v8i16, In);
+ if (ExtenedEltSize > 32)
+ In = DAG.getNode(ISD::SIGN_EXTEND, dl, MVT::v8i32, In);
+ return DAG.getNode(ISD::SIGN_EXTEND, dl, VT, In);
+ }
+
+ if ((InVT == MVT::v4i8 || InVT == MVT::v4i16) &&
+ ExtenedEltSize > 32 && !Subtarget->hasInt256()) {
+ In = DAG.getNode(ISD::SIGN_EXTEND, dl, MVT::v4i32, In);
+ return DAG.getNode(ISD::SIGN_EXTEND, dl, VT, In);
+ }
if (!DCI.isBeforeLegalizeOps())
return SDValue();
if (!Subtarget->hasFp256())
return SDValue();
- EVT VT = N->getValueType(0);
- if (VT.isVector() && VT.getSizeInBits() == 256) {
+ if (VT.is256BitVector()) {
SDValue R = WidenMaskArithmetic(N, DAG, DCI, Subtarget);
if (R.getNode())
return R;