[llvm] fabe52a - Fix uninitialized variable warning. NFC.

[David Blaikie via llvm-commits]

Which compiler warned about this? It looks like this would be a bad
compiler warning we maybe shuold disable, because the variable is
initialized before being used in the code that follows & it's best not to
add an unneeded initialization like that - since it thwarts the warning (or
msan, etc) from catching real bugs that might be introduced later (if
another arg mode was added & wasn't fully handled in the code that came
after)

The other thing might be worth doing is changing those unreachables to
assertions...

assert(ArgVT != MVT::f80 && "Not yet implemented");
if (is floating point && size <= 16)
  Mode = 2;
else
  assert(is integer && size <= 32)
  Mode = 1

That might be easier for a compiler to see that it's always initialized
before use.

On Thu, Feb 27, 2020 at 6:29 AM Simon Pilgrim via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

>
> Author: Simon Pilgrim
> Date: 2020-02-27T14:20:43Z
> New Revision: fabe52a7412d850bf06e006db1d53de0500a1853
>
> URL:
> https://github.com/llvm/llvm-project/commit/fabe52a7412d850bf06e006db1d53de0500a1853
> DIFF:
> https://github.com/llvm/llvm-project/commit/fabe52a7412d850bf06e006db1d53de0500a1853.diff
>
> LOG: Fix uninitialized variable warning. NFC.
>
> Added:
>
>
> Modified:
>     llvm/lib/Target/X86/X86ISelLowering.cpp
>
> Removed:
>
>
>
>
> ################################################################################
> diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp
> b/llvm/lib/Target/X86/X86ISelLowering.cpp
> index 1cc9c7b16d78..c2d18e21d07d 100644
> --- a/llvm/lib/Target/X86/X86ISelLowering.cpp
> +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
> @@ -23423,7 +23423,7 @@ SDValue X86TargetLowering::LowerVAARG(SDValue Op,
> SelectionDAG &DAG) const {
>    EVT ArgVT = Op.getNode()->getValueType(0);
>    Type *ArgTy = ArgVT.getTypeForEVT(*DAG.getContext());
>    uint32_t ArgSize = DAG.getDataLayout().getTypeAllocSize(ArgTy);
> -  uint8_t ArgMode;
> +  uint8_t ArgMode = 0;
>
>    // Decide which area this value should be read from.
>    // TODO: Implement the AMD64 ABI in its entirety. This simple
>
>
>
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