Teach the DAG combiner to turn sitofp/uitofp from i1 into a conditional move, since there are only two possible values.

Previously, this would become an integer extension operation, followed by a real integer->float conversion.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159957 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 36 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 28c3be9eb6..02877862b4 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5974,6 +5974,30 @@ SDValue DAGCombiner::visitSINT_TO_FP(SDNode *N) {
       return DAG.getNode(ISD::UINT_TO_FP, N->getDebugLoc(), VT, N0);
   }
 
+  // fold (sint_to_fp (setcc x, y, cc)) -> (select_cc x, y, -1.0, 0.0,, cc)
+  if (N0.getOpcode() == ISD::SETCC && !VT.isVector() &&
+      (!LegalOperations ||
+       TLI.isOperationLegalOrCustom(llvm::ISD::ConstantFP, VT))) {
+    SDValue Ops[] =
+      { N0.getOperand(0), N0.getOperand(1),
+        DAG.getConstantFP(-1.0, VT) , DAG.getConstantFP(0.0, VT),
+        N0.getOperand(2) };
+    return DAG.getNode(ISD::SELECT_CC, N->getDebugLoc(), VT, Ops, 5);
+  }
+
+  // fold (sint_to_fp (zext (setcc x, y, cc))) ->
+  //      (select_cc x, y, 1.0, 0.0,, cc)
+  if (N0.getOpcode() == ISD::ZERO_EXTEND &&
+      N0.getOperand(0).getOpcode() == ISD::SETCC &&!VT.isVector() &&
+      (!LegalOperations ||
+       TLI.isOperationLegalOrCustom(llvm::ISD::ConstantFP, VT))) {
+    SDValue Ops[] =
+      { N0.getOperand(0).getOperand(0), N0.getOperand(0).getOperand(1),
+        DAG.getConstantFP(1.0, VT) , DAG.getConstantFP(0.0, VT),
+        N0.getOperand(0).getOperand(2) };
+    return DAG.getNode(ISD::SELECT_CC, N->getDebugLoc(), VT, Ops, 5);
+  }
+
   return SDValue();
 }
 
@@ -5999,6 +6023,18 @@ SDValue DAGCombiner::visitUINT_TO_FP(SDNode *N) {
       return DAG.getNode(ISD::SINT_TO_FP, N->getDebugLoc(), VT, N0);
   }
 
+  // fold (uint_to_fp (setcc x, y, cc)) -> (select_cc x, y, -1.0, 0.0,, cc)
+  if (N0.getOpcode() == ISD::SETCC && !VT.isVector() &&
+      (!LegalOperations ||
+       TLI.isOperationLegalOrCustom(llvm::ISD::ConstantFP, VT))) {
+    SDValue Ops[] =
+      { N0.getOperand(0), N0.getOperand(1),
+        DAG.getConstantFP(1.0, VT),  DAG.getConstantFP(0.0, VT),
+        N0.getOperand(2) };
+    return DAG.getNode(ISD::SELECT_CC, N->getDebugLoc(), VT, Ops, 5);
+  }
+
+
   return SDValue();
 }