[PATCH] D65304: [MC] Don't recreate a label if it's already used

[Nick Desaulniers via Phabricator via llvm-commits]

nickdesaulniers added inline comments.


================
Comment at: lib/MC/MCContext.cpp:64
       Symbols(Allocator), UsedNames(Allocator),
+      InlineAsmUsedLabelNames(Allocator),
       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
----------------
I think we may want to be invoking the `StringMap` constructor that additionally takes an `InitialSize`, which we'd set to `0U`, as it's highly unlikely that the `%l` modifier is used at all for any given piece of code.

IIUC, `StringMap`'s constructor that simply accepts an allocator will allocate room for 1 instance.  See the definition of `StringMapImpl::StringMapImpl(unsigned InitSize, unsigned itemSize)`.

I think that micro optimization would save many small allocations for the general case.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65304/new/

https://reviews.llvm.org/D65304