[llvm] [BPF] Allow libcalls behind a feature gate (PR #168442)

[Matt Arsenault via llvm-commits]

================
@@ -1196,3 +1198,18 @@ bool BPFTargetLowering::isLegalAddressingMode(const DataLayout &DL,
 
   return true;
 }
+
+bool BPFTargetLowering::shouldSignExtendTypeInLibCall(Type *Ty,
+                                                      bool IsSigned) const {
+  return IsSigned || Ty->isIntegerTy(32);
+}
+
+bool BPFTargetLowering::CanLowerReturn(
+    CallingConv::ID CallConv, MachineFunction &MF, bool IsVarArg,
+    const SmallVectorImpl<ISD::OutputArg> &Outs, LLVMContext &Context,
+    const Type *RetTy) const {
+  // At minimal return Outs.size() <= 1, or check valid types in CC.
+  SmallVector<CCValAssign, 16> RVLocs;
+  CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, Context);
+  return CCInfo.CheckReturn(Outs, getHasAlu32() ? RetCC_BPF32 : RetCC_BPF64);
+}
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arsenm wrote:

End of file whitespace error 

https://github.com/llvm/llvm-project/pull/168442