[BPF] Remove exit-on-error flag in test (PR27766)

[rovka]

Summary

The exit-on-error flag on the many_args1.ll test is needed to avoid an unreachable in BPFTargetLowering::LowerCall. We can also avoid it by ignoring any superfluous arguments to the call (i.e. any arguments after the first 5).

[ast]

lgtm
thanks

[rovka]

Thanks for reviewing.

r270419 (forgot to add it to the commit message)

lib/Target/BPF/BPFISelLowering.h

private:
 
   // Lower the result values of a call, copying them out of physregs into vregs
   SDValue LowerCallResult(SDValue Chain, SDValue InFlag,
                           CallingConv::ID CallConv, bool IsVarArg,
                           const SmallVectorImpl<ISD::InputArg> &Ins, SDLoc DL,
                           SelectionDAG &DAG,
                           SmallVectorImpl<SDValue> &InVals) const;
 
+  // Maximum number of arguments to a call
+  static const unsigned long MaxArgs;
+
   // Lower a call into CALLSEQ_START - BPFISD:CALL - CALLSEQ_END chain
   SDValue LowerCall(TargetLowering::CallLoweringInfo &CLI,
                     SmallVectorImpl<SDValue> &InVals) const override;
 
   // Lower incoming arguments, copy physregs into vregs
   SDValue LowerFormalArguments(SDValue Chain, CallingConv::ID CallConv,
                                bool IsVarArg,
                                const SmallVectorImpl<ISD::InputArg> &Ins,

lib/Target/BPF/BPFISelLowering.cpp

SDValue BPFTargetLowering::LowerFormalArguments(
 
   if (IsVarArg || MF.getFunction()->hasStructRetAttr()) {
     fail(DL, DAG, "functions with VarArgs or StructRet are not supported");
   }
 
   return Chain;
 }
 
+const unsigned long BPFTargetLowering::MaxArgs = 5;
+
 SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
                                      SmallVectorImpl<SDValue> &InVals) const {
   SelectionDAG &DAG = CLI.DAG;
   auto &Outs = CLI.Outs;
   auto &OutVals = CLI.OutVals;
   auto &Ins = CLI.Ins;
   SDValue Chain = CLI.Chain;
   SDValue Callee = CLI.Callee;
SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   // Analyze operands of the call, assigning locations to each operand.
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
 
   CCInfo.AnalyzeCallOperands(Outs, CC_BPF64);
 
   unsigned NumBytes = CCInfo.getNextStackOffset();
 
-  if (Outs.size() >= 6) {
+  if (Outs.size() > MaxArgs)
     fail(CLI.DL, DAG, "too many args to ", Callee);
-  }
 
   for (auto &Arg : Outs) {
     ISD::ArgFlagsTy Flags = Arg.Flags;
     if (!Flags.isByVal())
       continue;
 
     fail(CLI.DL, DAG, "pass by value not supported ", Callee);
   }
 
   auto PtrVT = getPointerTy(MF.getDataLayout());
   Chain = DAG.getCALLSEQ_START(
       Chain, DAG.getConstant(NumBytes, CLI.DL, PtrVT, true), CLI.DL);
 
-  SmallVector<std::pair<unsigned, SDValue>, 5> RegsToPass;
+  SmallVector<std::pair<unsigned, SDValue>, MaxArgs> RegsToPass;
 
   // Walk arg assignments
-  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
+  for (unsigned i = 0, e = std::min(ArgLocs.size(), MaxArgs); i != e; ++i) {
     CCValAssign &VA = ArgLocs[i];
     SDValue Arg = OutVals[i];
 
     // Promote the value if needed.
     switch (VA.getLocInfo()) {
     default:
       llvm_unreachable("Unknown loc info");
     case CCValAssign::Full:

test/CodeGen/BPF/many_args1.ll

-; RUN: not llc -march=bpf -exit-on-error < %s 2> %t1
+; RUN: not llc -march=bpf < %s 2> %t1
 ; RUN: FileCheck %s < %t1
 ; CHECK: too many args
 
 ; Function Attrs: nounwind uwtable
 define i32 @foo(i32 %a, i32 %b, i32 %c) #0 {
 entry:
   %call = tail call i32 @bar(i32 %a, i32 %b, i32 %c, i32 1, i32 2, i32 3) #3
   ret i32 %call
 }
 
 declare i32 @bar(i32, i32, i32, i32, i32, i32) #1