[clang] [flang] [flang] Add -fcomplex-arithmetic= option and select complex division algorithm (PR #146641)

[Shunsuke Watanabe via cfe-commits]

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@@ -1023,12 +1023,12 @@ defm offload_uniform_block : BoolFOption<"offload-uniform-block",
   BothFlags<[], [ClangOption], " that kernels are launched with uniform block sizes (default true for CUDA/HIP and false otherwise)">>;
 
 def fcomplex_arithmetic_EQ : Joined<["-"], "fcomplex-arithmetic=">, Group<f_Group>,
-  Visibility<[ClangOption, CC1Option]>,
+  Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
   Values<"full,improved,promoted,basic">, NormalizedValuesScope<"LangOptions">,
   NormalizedValues<["CX_Full", "CX_Improved", "CX_Promoted", "CX_Basic"]>;
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s-watanabe314 wrote:

I added content to `ComplexOperations.md` based on the clang documentation. Because I'm not a native English speaker, I would appreciate it if you could review it.

https://github.com/llvm/llvm-project/pull/146641