Reapply r141365 now that PR11107 is fixed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141591 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelDAGToDAG.cpp b/lib/Target/ARM/ARMISelDAGToDAG.cpp
index ce877b0..5ee009c 100644
--- a/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -47,6 +47,11 @@
cl::desc("Check fp vmla / vmls hazard at isel time"),
cl::init(true));
+static cl::opt<bool>
+DisableARMIntABS("disable-arm-int-abs", cl::Hidden,
+ cl::desc("Enable / disable ARM integer abs transform"),
+ cl::init(false));
+
//===--------------------------------------------------------------------===//
/// ARMDAGToDAGISel - ARM specific code to select ARM machine
/// instructions for SelectionDAG operations.
@@ -252,6 +257,9 @@
ARMCC::CondCodes CCVal, SDValue CCR,
SDValue InFlag);
+ // Select special operations if node forms integer ABS pattern
+ SDNode *SelectABSOp(SDNode *N);
+
SDNode *SelectConcatVector(SDNode *N);
SDNode *SelectAtomic64(SDNode *Node, unsigned Opc);
@@ -2295,6 +2303,56 @@
return CurDAG->SelectNodeTo(N, Opc, VT, Ops, 5);
}
+/// Target-specific DAG combining for ISD::XOR.
+/// Target-independent combining lowers SELECT_CC nodes of the form
+/// select_cc setg[ge] X, 0, X, -X
+/// select_cc setgt X, -1, X, -X
+/// select_cc setl[te] X, 0, -X, X
+/// select_cc setlt X, 1, -X, X
+/// which represent Integer ABS into:
+/// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
+/// ARM instruction selection detects the latter and matches it to
+/// ARM::ABS or ARM::t2ABS machine node.
+SDNode *ARMDAGToDAGISel::SelectABSOp(SDNode *N){
+ SDValue XORSrc0 = N->getOperand(0);
+ SDValue XORSrc1 = N->getOperand(1);
+ DebugLoc DL = N->getDebugLoc();
+ EVT VT = N->getValueType(0);
+
+ if (DisableARMIntABS)
+ return NULL;
+
+ if (Subtarget->isThumb1Only())
+ return NULL;
+
+ if (XORSrc0.getOpcode() != ISD::ADD ||
+ XORSrc1.getOpcode() != ISD::SRA)
+ return NULL;
+
+ SDValue ADDSrc0 = XORSrc0.getOperand(0);
+ SDValue ADDSrc1 = XORSrc0.getOperand(1);
+ SDValue SRASrc0 = XORSrc1.getOperand(0);
+ SDValue SRASrc1 = XORSrc1.getOperand(1);
+ ConstantSDNode *SRAConstant = dyn_cast<ConstantSDNode>(SRASrc1);
+ EVT XType = SRASrc0.getValueType();
+ unsigned Size = XType.getSizeInBits() - 1;
+
+ if (ADDSrc1 == XORSrc1 &&
+ ADDSrc0 == SRASrc0 &&
+ XType.isInteger() &&
+ SRAConstant != NULL &&
+ Size == SRAConstant->getZExtValue()) {
+
+ unsigned Opcode = ARM::ABS;
+ if (Subtarget->isThumb2())
+ Opcode = ARM::t2ABS;
+
+ return CurDAG->SelectNodeTo(N, Opcode, VT, ADDSrc0);
+ }
+
+ return NULL;
+}
+
SDNode *ARMDAGToDAGISel::SelectConcatVector(SDNode *N) {
// The only time a CONCAT_VECTORS operation can have legal types is when
// two 64-bit vectors are concatenated to a 128-bit vector.
@@ -2331,6 +2389,14 @@
switch (N->getOpcode()) {
default: break;
+ case ISD::XOR: {
+ // Select special operations if XOR node forms integer ABS pattern
+ SDNode *ResNode = SelectABSOp(N);
+ if (ResNode)
+ return ResNode;
+ // Other cases are autogenerated.
+ break;
+ }
case ISD::Constant: {
unsigned Val = cast<ConstantSDNode>(N)->getZExtValue();
bool UseCP = true;