[clang] [flang] [llvm] add -floop-fuse to clang and flang (PR #142686)

[Tarun Prabhu via llvm-commits]

================
@@ -1991,6 +1996,7 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
                    (Opts.OptimizationLevel > 1));
   Opts.InterchangeLoops =
       Args.hasFlag(OPT_floop_interchange, OPT_fno_loop_interchange, false);
+  Opts.FuseLoops = Args.hasFlag(OPT_fexperimental_loop_fuse, OPT_fno_experimental_loop_fuse, false);
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tarunprabhu wrote:

NIT:
```suggestion
  Opts.FuseLoops = Args.hasFlag(OPT_fexperimental_loop_fusion, OPT_fno_experimental_loop_fusion, false);
```

https://github.com/llvm/llvm-project/pull/142686