Implement vector constants which are splat of
integers with mov + vdup. 8003375. This is
currently disabled by default because LICM will
not hoist a VDUP, so it pessimizes the code if
the construct occurs inside a loop (8248029).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109799 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 56d2440..69b24d0 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -57,6 +57,13 @@
cl::desc("Generate tail calls (TEMPORARY OPTION)."),
cl::init(true));
+// This option should go away when Machine LICM is smart enough to hoist a
+// reg-to-reg VDUP.
+static cl::opt<bool>
+EnableARMVDUPsplat("arm-vdup-splat", cl::Hidden,
+ cl::desc("Generate VDUP for integer constant splats (TEMPORARY OPTION)."),
+ cl::init(false));
+
static cl::opt<bool>
EnableARMLongCalls("arm-long-calls", cl::Hidden,
cl::desc("Generate calls via indirect call instructions"),
@@ -3257,9 +3264,30 @@
return true;
}
+// If N is an integer constant that can be moved into a register in one
+// instruction, return an SDValue of such a constant (will become a MOV
+// instruction). Otherwise return null.
+static SDValue IsSingleInstrConstant(SDValue N, SelectionDAG &DAG,
+ const ARMSubtarget *ST, DebugLoc dl) {
+ uint64_t Val;
+ if (!isa<ConstantSDNode>(N))
+ return SDValue();
+ Val = cast<ConstantSDNode>(N)->getZExtValue();
+
+ if (ST->isThumb1Only()) {
+ if (Val <= 255 || ~Val <= 255)
+ return DAG.getConstant(Val, MVT::i32);
+ } else {
+ if (ARM_AM::getSOImmVal(Val) != -1 || ARM_AM::getSOImmVal(~Val) != -1)
+ return DAG.getConstant(Val, MVT::i32);
+ }
+ return SDValue();
+}
+
// If this is a case we can't handle, return null and let the default
// expansion code take care of it.
-static SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) {
+static SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
+ const ARMSubtarget *ST) {
BuildVectorSDNode *BVN = cast<BuildVectorSDNode>(Op.getNode());
DebugLoc dl = Op.getDebugLoc();
EVT VT = Op.getValueType();
@@ -3319,15 +3347,41 @@
if (isOnlyLowElement)
return DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, VT, Value);
- // If all elements are constants, fall back to the default expansion, which
- // will generate a load from the constant pool.
+ unsigned EltSize = VT.getVectorElementType().getSizeInBits();
+
+ if (EnableARMVDUPsplat) {
+ // Use VDUP for non-constant splats. For f32 constant splats, reduce to
+ // i32 and try again.
+ if (usesOnlyOneValue && EltSize <= 32) {
+ if (!isConstant)
+ return DAG.getNode(ARMISD::VDUP, dl, VT, Value);
+ if (VT.getVectorElementType().isFloatingPoint()) {
+ SmallVector<SDValue, 8> Ops;
+ for (unsigned i = 0; i < NumElts; ++i)
+ Ops.push_back(DAG.getNode(ISD::BIT_CONVERT, dl, MVT::i32,
+ Op.getOperand(i)));
+ SDValue Val = DAG.getNode(ISD::BUILD_VECTOR, dl, MVT::v4i32, &Ops[0],
+ NumElts);
+ return DAG.getNode(ISD::BIT_CONVERT, dl, VT,
+ LowerBUILD_VECTOR(Val, DAG, ST));
+ }
+ SDValue Val = IsSingleInstrConstant(Value, DAG, ST, dl);
+ if (Val.getNode())
+ return DAG.getNode(ARMISD::VDUP, dl, VT, Val);
+ }
+ }
+
+ // If all elements are constants and the case above didn't get hit, fall back
+ // to the default expansion, which will generate a load from the constant
+ // pool.
if (isConstant)
return SDValue();
- // Use VDUP for non-constant splats.
- unsigned EltSize = VT.getVectorElementType().getSizeInBits();
- if (usesOnlyOneValue && EltSize <= 32)
- return DAG.getNode(ARMISD::VDUP, dl, VT, Value);
+ if (!EnableARMVDUPsplat) {
+ // Use VDUP for non-constant splats.
+ if (usesOnlyOneValue && EltSize <= 32)
+ return DAG.getNode(ARMISD::VDUP, dl, VT, Value);
+ }
// Vectors with 32- or 64-bit elements can be built by directly assigning
// the subregisters. Lower it to an ARMISD::BUILD_VECTOR so the operands
@@ -3647,7 +3701,7 @@
case ISD::SRA_PARTS: return LowerShiftRightParts(Op, DAG);
case ISD::CTTZ: return LowerCTTZ(Op.getNode(), DAG, Subtarget);
case ISD::VSETCC: return LowerVSETCC(Op, DAG);
- case ISD::BUILD_VECTOR: return LowerBUILD_VECTOR(Op, DAG);
+ case ISD::BUILD_VECTOR: return LowerBUILD_VECTOR(Op, DAG, Subtarget);
case ISD::VECTOR_SHUFFLE: return LowerVECTOR_SHUFFLE(Op, DAG);
case ISD::EXTRACT_VECTOR_ELT: return LowerEXTRACT_VECTOR_ELT(Op, DAG);
case ISD::CONCAT_VECTORS: return LowerCONCAT_VECTORS(Op, DAG);