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

[Pengcheng Wang via llvm-commits]

================
@@ -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));
----------------
wangpc-pp wrote:

I was thinking why we can't just use `RISCVSubtarget::getMaxBuildIntsCost() - 1` (minus 1 because we need a conversion from int to float)?

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