r253410 - Fix for use-after-free which caused test failure in cuda-detect.cu.

[David Blaikie via cfe-commits]

On Tue, Nov 17, 2015 at 4:37 PM, Artem Belevich via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: tra
> Date: Tue Nov 17 18:37:41 2015
> New Revision: 253410
>
> URL: http://llvm.org/viewvc/llvm-project?rev=253410&view=rev
> Log:
> Fix for use-after-free which caused test failure in cuda-detect.cu.
>
> Return std::string itself instead StringRef to a temporary std::string.
>
> Modified:
>     cfe/trunk/lib/Driver/ToolChains.h
>
> Modified: cfe/trunk/lib/Driver/ToolChains.h
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.h?rev=253410&r1=253409&r2=253410&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Driver/ToolChains.h (original)
> +++ cfe/trunk/lib/Driver/ToolChains.h Tue Nov 17 18:37:41 2015
> @@ -186,7 +186,7 @@ protected:
>      /// \brief Get the detected Cuda device library path.
>      StringRef getLibDevicePath() const { return CudaLibDevicePath; }
>      /// \brief Get libdevice file for given architecture
> -    StringRef getLibDeviceFile(StringRef Gpu) const {
> +    std::string getLibDeviceFile(StringRef Gpu) const {
>        return CudaLibDeviceMap.lookup(Gpu);
>

You could implement this as:

auto I = CudaLibDeviceMap.find(Gpu);
return I != CudaLibDeviceMap.end() ? I->second : "";

returning StringRef

Or, if you know the element will always be in the collection, you could
just assert that and "return CudaLibDeviceMap[Gpu]; - and you could return
const std::string& there, or StringRef, whichever.

(both/any of these options would avoid needing to allocate a new string to
every caller)


>      }
>    };
>
>
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