[llvm] r330947 - [DAGCombiner] refactor FP->int->FP folds; NFC
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 26 08:20:19 PDT 2018
Author: spatel
Date: Thu Apr 26 08:20:18 2018
New Revision: 330947
URL: http://llvm.org/viewvc/llvm-project?rev=330947&view=rev
Log:
[DAGCombiner] refactor FP->int->FP folds; NFC
As discussed in the post-review comments for rL330437,
we need to guard this fold to allow existing code to
keep working with the undefined behavior that they've
come to rely on.
That would mean duplicating more code than we already
have, so let's fix that first.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=330947&r1=330946&r2=330947&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Apr 26 08:20:18 2018
@@ -10902,6 +10902,28 @@ SDValue DAGCombiner::visitFCOPYSIGN(SDNo
return SDValue();
}
+static SDValue foldFPToIntToFP(SDNode *N, SelectionDAG &DAG,
+ const TargetLowering &TLI) {
+ // We only do this if the target has legal ftrunc. Otherwise, we'd likely be
+ // replacing casts with a libcall.
+ EVT VT = N->getValueType(0);
+ if (!TLI.isOperationLegal(ISD::FTRUNC, VT))
+ return SDValue();
+
+ // fptosi/fptoui round towards zero, so converting from FP to integer and
+ // back is the same as an 'ftrunc': [us]itofp (fpto[us]i X) --> ftrunc X
+ SDValue N0 = N->getOperand(0);
+ if (N->getOpcode() == ISD::SINT_TO_FP && N0.getOpcode() == ISD::FP_TO_SINT &&
+ N0.getOperand(0).getValueType() == VT)
+ return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
+
+ if (N->getOpcode() == ISD::UINT_TO_FP && N0.getOpcode() == ISD::FP_TO_UINT &&
+ N0.getOperand(0).getValueType() == VT)
+ return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
+
+ return SDValue();
+}
+
SDValue DAGCombiner::visitSINT_TO_FP(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
@@ -10953,14 +10975,8 @@ SDValue DAGCombiner::visitSINT_TO_FP(SDN
}
}
- // fptosi rounds towards zero, so converting from FP to integer and back is
- // the same as an 'ftrunc': sitofp (fptosi X) --> ftrunc X
- // We only do this if the target has legal ftrunc, otherwise we'd likely be
- // replacing casts with a libcall.
- if (N0.getOpcode() == ISD::FP_TO_SINT &&
- N0.getOperand(0).getValueType() == VT &&
- TLI.isOperationLegal(ISD::FTRUNC, VT))
- return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
+ if (SDValue FTrunc = foldFPToIntToFP(N, DAG, TLI))
+ return FTrunc;
return SDValue();
}
@@ -11001,14 +11017,8 @@ SDValue DAGCombiner::visitUINT_TO_FP(SDN
}
}
- // fptoui rounds towards zero, so converting from FP to integer and back is
- // the same as an 'ftrunc': uitofp (fptoui X) --> ftrunc X
- // We only do this if the target has legal ftrunc, otherwise we'd likely be
- // replacing casts with a libcall.
- if (N0.getOpcode() == ISD::FP_TO_UINT &&
- N0.getOperand(0).getValueType() == VT &&
- TLI.isOperationLegal(ISD::FTRUNC, VT))
- return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
+ if (SDValue FTrunc = foldFPToIntToFP(N, DAG, TLI))
+ return FTrunc;
return SDValue();
}
More information about the llvm-commits
mailing list