[llvm] [RISCV] Set riscv-fpimm-cost threshold to 3 by default (PR #159352)

[Alex Bradbury via llvm-commits]

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@@ -79,7 +79,7 @@ static cl::opt<int>
     FPImmCost(DEBUG_TYPE "-fpimm-cost", cl::Hidden,
               cl::desc("Give the maximum number of instructions that we will "
                        "use for creating a floating-point immediate value"),
-              cl::init(2));
+              cl::init(3));
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asb wrote:

We'd need to account for Zfinx/Zdinx as well which doesn't need the conversion. I see this as a good suggestion for what a more "principled" constant to use might be, which might be worth exploring as a followup.

https://github.com/llvm/llvm-project/pull/159352