[SDAG] move FP constant folding to helper function; NFC

llvm-svn: 355411

1 files changed, 72 insertions, 67 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index fb03b4198c1..e8bdc05b888 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4734,6 +4734,76 @@ SDValue SelectionDAG::FoldConstantVectorArithmetic(unsigned Opcode,
   return V;
 }
 
+SDValue SelectionDAG::foldConstantFPMath(unsigned Opcode, const SDLoc &DL,
+                                         EVT VT, SDValue N1, SDValue N2) {
+  auto *N1CFP = dyn_cast<ConstantFPSDNode>(N1.getNode());
+  auto *N2CFP = dyn_cast<ConstantFPSDNode>(N2.getNode());
+  bool HasFPExceptions = TLI->hasFloatingPointExceptions();
+  if (N1CFP && N2CFP) {
+    APFloat C1 = N1CFP->getValueAPF(), C2 = N2CFP->getValueAPF();
+    APFloat::opStatus Status;
+    switch (Opcode) {
+    case ISD::FADD:
+      Status = C1.add(C2, APFloat::rmNearestTiesToEven);
+      if (!HasFPExceptions || Status != APFloat::opInvalidOp)
+        return getConstantFP(C1, DL, VT);
+      break;
+    case ISD::FSUB:
+      Status = C1.subtract(C2, APFloat::rmNearestTiesToEven);
+      if (!HasFPExceptions || Status != APFloat::opInvalidOp)
+        return getConstantFP(C1, DL, VT);
+      break;
+    case ISD::FMUL:
+      Status = C1.multiply(C2, APFloat::rmNearestTiesToEven);
+      if (!HasFPExceptions || Status != APFloat::opInvalidOp)
+        return getConstantFP(C1, DL, VT);
+      break;
+    case ISD::FDIV:
+      Status = C1.divide(C2, APFloat::rmNearestTiesToEven);
+      if (!HasFPExceptions || (Status != APFloat::opInvalidOp &&
+                               Status != APFloat::opDivByZero)) {
+        return getConstantFP(C1, DL, VT);
+      }
+      break;
+    case ISD::FREM:
+      Status = C1.mod(C2);
+      if (!HasFPExceptions || (Status != APFloat::opInvalidOp &&
+                               Status != APFloat::opDivByZero)) {
+        return getConstantFP(C1, DL, VT);
+      }
+      break;
+    case ISD::FCOPYSIGN:
+      C1.copySign(C2);
+      return getConstantFP(C1, DL, VT);
+    default: break;
+    }
+  }
+  if (N1CFP && Opcode == ISD::FP_ROUND) {
+    APFloat C1 = N1CFP->getValueAPF();    // make copy
+    bool Unused;
+    // This can return overflow, underflow, or inexact; we don't care.
+    // FIXME need to be more flexible about rounding mode.
+    (void) C1.convert(EVTToAPFloatSemantics(VT), APFloat::rmNearestTiesToEven,
+                     &Unused);
+    return getConstantFP(C1, DL, VT);
+  }
+
+  switch (Opcode) {
+  case ISD::FADD:
+  case ISD::FSUB:
+  case ISD::FMUL:
+  case ISD::FDIV:
+  case ISD::FREM:
+    // If both operands are undef, the result is undef. If 1 operand is undef,
+    // the result is NaN. This should match the behavior of the IR optimizer.
+    if (N1.isUndef() && N2.isUndef())
+      return getUNDEF(VT);
+    if (N1.isUndef() || N2.isUndef())
+      return getConstantFP(APFloat::getNaN(EVTToAPFloatSemantics(VT)), DL, VT);
+  }
+  return SDValue();
+}
+
 SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
                               SDValue N1, SDValue N2, const SDNodeFlags Flags) {
   ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
@@ -5079,73 +5149,8 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
           FoldConstantArithmetic(Opcode, DL, VT, N1.getNode(), N2.getNode()))
     return SV;
 
-  // Constant fold FP operations.
-  bool HasFPExceptions = TLI->hasFloatingPointExceptions();
-  if (N1CFP) {
-    if (N2CFP) {
-      APFloat V1 = N1CFP->getValueAPF(), V2 = N2CFP->getValueAPF();
-      APFloat::opStatus s;
-      switch (Opcode) {
-      case ISD::FADD:
-        s = V1.add(V2, APFloat::rmNearestTiesToEven);
-        if (!HasFPExceptions || s != APFloat::opInvalidOp)
-          return getConstantFP(V1, DL, VT);
-        break;
-      case ISD::FSUB:
-        s = V1.subtract(V2, APFloat::rmNearestTiesToEven);
-        if (!HasFPExceptions || s!=APFloat::opInvalidOp)
-          return getConstantFP(V1, DL, VT);
-        break;
-      case ISD::FMUL:
-        s = V1.multiply(V2, APFloat::rmNearestTiesToEven);
-        if (!HasFPExceptions || s!=APFloat::opInvalidOp)
-          return getConstantFP(V1, DL, VT);
-        break;
-      case ISD::FDIV:
-        s = V1.divide(V2, APFloat::rmNearestTiesToEven);
-        if (!HasFPExceptions || (s!=APFloat::opInvalidOp &&
-                                 s!=APFloat::opDivByZero)) {
-          return getConstantFP(V1, DL, VT);
-        }
-        break;
-      case ISD::FREM :
-        s = V1.mod(V2);
-        if (!HasFPExceptions || (s!=APFloat::opInvalidOp &&
-                                 s!=APFloat::opDivByZero)) {
-          return getConstantFP(V1, DL, VT);
-        }
-        break;
-      case ISD::FCOPYSIGN:
-        V1.copySign(V2);
-        return getConstantFP(V1, DL, VT);
-      default: break;
-      }
-    }
-
-    if (Opcode == ISD::FP_ROUND) {
-      APFloat V = N1CFP->getValueAPF();    // make copy
-      bool ignored;
-      // This can return overflow, underflow, or inexact; we don't care.
-      // FIXME need to be more flexible about rounding mode.
-      (void)V.convert(EVTToAPFloatSemantics(VT),
-                      APFloat::rmNearestTiesToEven, &ignored);
-      return getConstantFP(V, DL, VT);
-    }
-  }
-
-  switch (Opcode) {
-  case ISD::FADD:
-  case ISD::FSUB:
-  case ISD::FMUL:
-  case ISD::FDIV:
-  case ISD::FREM:
-    // If both operands are undef, the result is undef. If 1 operand is undef,
-    // the result is NaN. This should match the behavior of the IR optimizer.
-    if (N1.isUndef() && N2.isUndef())
-      return getUNDEF(VT);
-    if (N1.isUndef() || N2.isUndef())
-      return getConstantFP(APFloat::getNaN(EVTToAPFloatSemantics(VT)), DL, VT);
-  }
+  if (SDValue V = foldConstantFPMath(Opcode, DL, VT, N1, N2))
+    return V;
 
   // Canonicalize an UNDEF to the RHS, even over a constant.
   if (N1.isUndef()) {