[llvm] [RegAllocEvictAdvisor] Add minimum weight ratio heuristic. (PR #98109)

[Quentin Colombet via llvm-commits]

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@@ -44,6 +44,12 @@ static cl::opt<bool> EnableLocalReassignment(
              "may be compile time intensive"),
     cl::init(false));
 
+static cl::opt<float> MinWeightRatioNeededToEvictHint(
+    "min-weight-ratio-needed-to-evict-hint", cl::Hidden,
+    cl::desc("The minimum ration of weights needed in order for the live range with bigger weight to evict the other live range which"
+    "satisfies a hint),
+    cl::init(7.5));
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qcolombet wrote:

To add on what @mtrofin said, could you explain the rationale for `7.5`?

It feels random to me.

https://github.com/llvm/llvm-project/pull/98109