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

[Tarun Prabhu via llvm-commits]

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@@ -43,6 +43,7 @@ CODEGENOPT(StackArrays, 1, 0) ///< -fstack-arrays (enable the stack-arrays pass)
 CODEGENOPT(VectorizeLoop, 1, 0) ///< Enable loop vectorization.
 CODEGENOPT(VectorizeSLP, 1, 0) ///< Enable SLP vectorization.
 CODEGENOPT(InterchangeLoops, 1, 0) ///< Enable loop interchange.
+CODEGENOPT(FuseLoops, 1, 0)        ///< Enable loop fuse.
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tarunprabhu wrote:

NIT:
```suggestion
CODEGENOPT(FuseLoops, 1, 0)        ///< Enable loop fusion.
```

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