[llvm] r333363 - [Tablegen] Avoid generating empty switch statements. NFC

[Aaron Ballman via llvm-commits]

On Sun, May 27, 2018 at 3:08 PM, Andrea Di Biagio via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: adibiagio
> Date: Sun May 27 12:08:12 2018
> New Revision: 333363
>
> URL: http://llvm.org/viewvc/llvm-project?rev=333363&view=rev
> Log:
> [Tablegen] Avoid generating empty switch statements. NFC
>
> This fixes an MSVC warning (warning C4065: switch statement contains 'default'
> but no 'case' labels) introduced with revision 333293.

Thank you!

~Aaron

>
> Modified:
>     llvm/trunk/utils/TableGen/SubtargetEmitter.cpp
>
> Modified: llvm/trunk/utils/TableGen/SubtargetEmitter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/SubtargetEmitter.cpp?rev=333363&r1=333362&r2=333363&view=diff
> ==============================================================================
> --- llvm/trunk/utils/TableGen/SubtargetEmitter.cpp (original)
> +++ llvm/trunk/utils/TableGen/SubtargetEmitter.cpp Sun May 27 12:08:12 2018
> @@ -1506,7 +1506,7 @@ void SubtargetEmitter::emitSchedModelHel
>    }
>
>    if (!VariantClasses.empty()) {
> -    OS << "  switch (SchedClass) {\n";
> +    bool FoundPredicates = false;
>      for (unsigned VC : VariantClasses) {
>        // Emit code for each variant scheduling class.
>        const CodeGenSchedClass &SC = SchedModels.getSchedClass(VC);
> @@ -1527,6 +1527,12 @@ void SubtargetEmitter::emitSchedModelHel
>        if (ProcIndices.empty())
>          continue;
>
> +      // Emit a switch statement only if there are predicates to expand.
> +      if (!FoundPredicates) {
> +        OS << "  switch (SchedClass) {\n";
> +        FoundPredicates = true;
> +      }
> +
>        OS << "  case " << VC << ": // " << SC.Name << '\n';
>        PredicateExpander PE;
>        PE.setByRef(false);
> @@ -1556,9 +1562,9 @@ void SubtargetEmitter::emitSchedModelHel
>          OS << "    return " << SC.Index << ";\n";
>        OS << "    break;\n";
>      }
> -    // Add a default case to avoid generating a potentially empty switch.
> -    OS << "  default : break;\n"
> -       << "  };\n";
> +
> +    if (FoundPredicates)
> +     OS << "  };\n";
>    }
>
>    if (OnlyExpandMCInstPredicates) {
>
>
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