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750f1d0625
In some places, like InstCombine, we resize a DenseMap to fit the elements we intend to put in it, then insert those elements (to avoid continual reallocations as it grows). But .resize(foo) doesn't actually do what people think; it resizes to foo buckets (which is really an implementation detail the user of DenseMap probably shouldn't care about), not the space required to fit foo elements. DenseMap grows if 3/4 of its buckets are full, so this actually causes one forced reallocation every time instead of avoiding a reallocation. This patch makes .resize(foo) do the intuitive thing: it grows to the size necessary to fit foo elements without new allocations. Also include a test to verify that .resize() actually does what we think it does. llvm-svn: 263522