[llvm] r345878 - Annotate possibly unintended fallthroughs in Hexagon MC code, NFC

[Krzysztof Parzyszek via llvm-commits]

Yeah, those should be breaks. This doesn't fail because the values of Ga 
and Gb always hit some "case", but the intent is that those are breaks, 
not fall-throughs.

Thanks for finding this!

-Krzysztof


On 11/1/2018 2:32 PM, Reid Kleckner via llvm-commits wrote:
> Author: rnk
> Date: Thu Nov  1 12:32:04 2018
> New Revision: 345878
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=345878&view=rev
> Log:
> Annotate possibly unintended fallthroughs in Hexagon MC code, NFC
> 
> Clang's -Wimplicit-fallthrough check fires on these switch cases. GCC
> does not warn when a case body that ends in a switch falls through to a
> case label of an outer switch.
> 
> It's not clear if these fall throughs are truly intended.  The Hexagon
> tests pass regardless of whether these case blocks fall through or
> break.
> 
> For now, I have applied the intended fallthrough annotation macro with a
> FIXME comment to unblock enabling the warning. I will send a follow-up
> patch that converts them to breaks to the Hexagon maintainers.
> 
> Modified:
>      llvm/trunk/lib/Target/Hexagon/MCTargetDesc/HexagonMCDuplexInfo.cpp
> 
> Modified: llvm/trunk/lib/Target/Hexagon/MCTargetDesc/HexagonMCDuplexInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/MCTargetDesc/HexagonMCDuplexInfo.cpp?rev=345878&r1=345877&r2=345878&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/Hexagon/MCTargetDesc/HexagonMCDuplexInfo.cpp (original)
> +++ llvm/trunk/lib/Target/Hexagon/MCTargetDesc/HexagonMCDuplexInfo.cpp Thu Nov  1 12:32:04 2018
> @@ -127,6 +127,7 @@ unsigned HexagonMCInstrInfo::iClassOfDup
>       case HexagonII::HSIG_A:
>         return 0x4;
>       }
> +    LLVM_FALLTHROUGH; // FIXME: Intentional?
>     case HexagonII::HSIG_L2:
>       switch (Gb) {
>       default:
> @@ -138,6 +139,7 @@ unsigned HexagonMCInstrInfo::iClassOfDup
>       case HexagonII::HSIG_A:
>         return 0x5;
>       }
> +    LLVM_FALLTHROUGH; // FIXME: Intentional?
>     case HexagonII::HSIG_S1:
>       switch (Gb) {
>       default:
> @@ -151,6 +153,7 @@ unsigned HexagonMCInstrInfo::iClassOfDup
>       case HexagonII::HSIG_A:
>         return 0x6;
>       }
> +    LLVM_FALLTHROUGH; // FIXME: Intentional?
>     case HexagonII::HSIG_S2:
>       switch (Gb) {
>       default:
> @@ -166,6 +169,7 @@ unsigned HexagonMCInstrInfo::iClassOfDup
>       case HexagonII::HSIG_A:
>         return 0x7;
>       }
> +    LLVM_FALLTHROUGH; // FIXME: Intentional?
>     case HexagonII::HSIG_A:
>       switch (Gb) {
>       default:
> @@ -173,11 +177,13 @@ unsigned HexagonMCInstrInfo::iClassOfDup
>       case HexagonII::HSIG_A:
>         return 0x3;
>       }
> +    LLVM_FALLTHROUGH; // FIXME: Intentional?
>     case HexagonII::HSIG_Compound:
>       switch (Gb) {
>       case HexagonII::HSIG_Compound:
>         return 0xFFFFFFFF;
>       }
> +    break;
>     }
>     return 0xFFFFFFFF;
>   }
> 
> 
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