[mips] Fix incorrect sign extension for fpowi libcall

PR36061 showed that during the expansion of ISD::FPOWI, that there
was an incorrect zero extension of the integer argument which for
MIPS64 would then give incorrect results. Address this with the
existing mechanism for correcting sign extensions.

This resolves PR36061.

Thanks to James Cowgill for reporting the issue!

Reviewers: atanasyan, hfinkel

Differential Revision: https://reviews.llvm.org/D42537

llvm-svn: 323781

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index b69c362db67..76aedfec2f8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1996,14 +1996,15 @@ SDValue SelectionDAGLegalize::ExpandLibCall(RTLIB::Libcall LC, SDNode *Node,
     Type *ArgTy = ArgVT.getTypeForEVT(*DAG.getContext());
     Entry.Node = Op;
     Entry.Ty = ArgTy;
-    Entry.IsSExt = isSigned;
-    Entry.IsZExt = !isSigned;
+    Entry.IsSExt = TLI.shouldSignExtendTypeInLibCall(ArgVT, isSigned);
+    Entry.IsZExt = !TLI.shouldSignExtendTypeInLibCall(ArgVT, isSigned);
     Args.push_back(Entry);
   }
   SDValue Callee = DAG.getExternalSymbol(TLI.getLibcallName(LC),
                                          TLI.getPointerTy(DAG.getDataLayout()));
 
-  Type *RetTy = Node->getValueType(0).getTypeForEVT(*DAG.getContext());
+  EVT RetVT = Node->getValueType(0);
+  Type *RetTy = RetVT.getTypeForEVT(*DAG.getContext());
 
   // By default, the input chain to this libcall is the entry node of the
   // function. If the libcall is going to be emitted as a tail call then
@@ -2022,13 +2023,14 @@ SDValue SelectionDAGLegalize::ExpandLibCall(RTLIB::Libcall LC, SDNode *Node,
     InChain = TCChain;
 
   TargetLowering::CallLoweringInfo CLI(DAG);
+  bool signExtend = TLI.shouldSignExtendTypeInLibCall(RetVT, isSigned);
   CLI.setDebugLoc(SDLoc(Node))
       .setChain(InChain)
       .setLibCallee(TLI.getLibcallCallingConv(LC), RetTy, Callee,
                     std::move(Args))
       .setTailCall(isTailCall)
-      .setSExtResult(isSigned)
-      .setZExtResult(!isSigned)
+      .setSExtResult(signExtend)
+      .setZExtResult(!signExtend)
       .setIsPostTypeLegalization(true);
 
   std::pair<SDValue, SDValue> CallInfo = TLI.LowerCallTo(CLI);