R600: Factor i64 UDIVREM lowering into its own fuction

This is so it could potentially be used by SI.  However, the current
implementation does not always produce correct results, so the
IntegerDivisionPass is being used instead.

llvm-svn: 222072

1 files changed, 81 insertions, 0 deletions

diff --git a/llvm/lib/Target/R600/AMDGPUISelLowering.cpp b/llvm/lib/Target/R600/AMDGPUISelLowering.cpp
index 83083786fe8..78e6a5230f9 100644
--- a/llvm/lib/Target/R600/AMDGPUISelLowering.cpp
+++ b/llvm/lib/Target/R600/AMDGPUISelLowering.cpp
@@ -1562,11 +1562,92 @@ SDValue AMDGPUTargetLowering::LowerDIVREM24(SDValue Op, SelectionDAG &DAG, bool
   return DAG.getMergeValues(Res, DL);
 }
 
+void AMDGPUTargetLowering::LowerUDIVREM64(SDValue Op,
+                                      SelectionDAG &DAG,
+                                      SmallVectorImpl<SDValue> &Results) const {
+  assert(Op.getValueType() == MVT::i64);
+
+  SDLoc DL(Op);
+  EVT VT = Op.getValueType();
+  EVT HalfVT = VT.getHalfSizedIntegerVT(*DAG.getContext());
+
+  SDValue one = DAG.getConstant(1, HalfVT);
+  SDValue zero = DAG.getConstant(0, HalfVT);
+
+  //HiLo split
+  SDValue LHS = Op.getOperand(0);
+  SDValue LHS_Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, LHS, zero);
+  SDValue LHS_Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, LHS, one);
+
+  SDValue RHS = Op.getOperand(1);
+  SDValue RHS_Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, RHS, zero);
+  SDValue RHS_Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, RHS, one);
+
+  // Get Speculative values
+  SDValue DIV_Part = DAG.getNode(ISD::UDIV, DL, HalfVT, LHS_Hi, RHS_Lo);
+  SDValue REM_Part = DAG.getNode(ISD::UREM, DL, HalfVT, LHS_Hi, RHS_Lo);
+
+  SDValue REM_Hi = zero;
+  SDValue REM_Lo = DAG.getSelectCC(DL, RHS_Hi, zero, REM_Part, LHS_Hi, ISD::SETEQ);
+
+  SDValue DIV_Hi = DAG.getSelectCC(DL, RHS_Hi, zero, DIV_Part, zero, ISD::SETEQ);
+  SDValue DIV_Lo = zero;
+
+  const unsigned halfBitWidth = HalfVT.getSizeInBits();
+
+  for (unsigned i = 0; i < halfBitWidth; ++i) {
+    SDValue POS = DAG.getConstant(halfBitWidth - i - 1, HalfVT);
+    // Get Value of high bit
+    SDValue HBit;
+    if (halfBitWidth == 32 && Subtarget->hasBFE()) {
+      HBit = DAG.getNode(AMDGPUISD::BFE_U32, DL, HalfVT, LHS_Lo, POS, one);
+    } else {
+      HBit = DAG.getNode(ISD::SRL, DL, HalfVT, LHS_Lo, POS);
+      HBit = DAG.getNode(ISD::AND, DL, HalfVT, HBit, one);
+    }
+
+    SDValue Carry = DAG.getNode(ISD::SRL, DL, HalfVT, REM_Lo,
+      DAG.getConstant(halfBitWidth - 1, HalfVT));
+    REM_Hi = DAG.getNode(ISD::SHL, DL, HalfVT, REM_Hi, one);
+    REM_Hi = DAG.getNode(ISD::OR, DL, HalfVT, REM_Hi, Carry);
+
+    REM_Lo = DAG.getNode(ISD::SHL, DL, HalfVT, REM_Lo, one);
+    REM_Lo = DAG.getNode(ISD::OR, DL, HalfVT, REM_Lo, HBit);
+
+
+    SDValue REM = DAG.getNode(ISD::BUILD_PAIR, DL, VT, REM_Lo, REM_Hi);
+
+    SDValue BIT = DAG.getConstant(1 << (halfBitWidth - i - 1), HalfVT);
+    SDValue realBIT = DAG.getSelectCC(DL, REM, RHS, BIT, zero, ISD::SETGE);
+
+    DIV_Lo = DAG.getNode(ISD::OR, DL, HalfVT, DIV_Lo, realBIT);
+
+    // Update REM
+
+    SDValue REM_sub = DAG.getNode(ISD::SUB, DL, VT, REM, RHS);
+
+    REM = DAG.getSelectCC(DL, REM, RHS, REM_sub, REM, ISD::SETGE);
+    REM_Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, REM, zero);
+    REM_Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT, REM, one);
+  }
+
+  SDValue REM = DAG.getNode(ISD::BUILD_PAIR, DL, VT, REM_Lo, REM_Hi);
+  SDValue DIV = DAG.getNode(ISD::BUILD_PAIR, DL, VT, DIV_Lo, DIV_Hi);
+  Results.push_back(DIV);
+  Results.push_back(REM);
+}
+
 SDValue AMDGPUTargetLowering::LowerUDIVREM(SDValue Op,
                                            SelectionDAG &DAG) const {
   SDLoc DL(Op);
   EVT VT = Op.getValueType();
 
+  if (VT == MVT::i64) {
+    SmallVector<SDValue, 2> Results;
+    LowerUDIVREM64(Op, DAG, Results);
+    return DAG.getMergeValues(Results, DL);
+  }
+
   SDValue Num = Op.getOperand(0);
   SDValue Den = Op.getOperand(1);