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653c1099b4
Emit the number of bytes in a `.debug_loc` entry directly. The old code created temp labels (expensive), emitted the difference between them, and then emitted one on each side of the relevant bytes. (I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc` (the optimized version of ld64's `-save-temps` when linking the `verify-uselistorder` executable in an LTO bootstrap). I've hacked `MCContext::Allocate()` to just call `malloc()` instead of using the `BumpPtrAllocator` so that the heap profile is easier to read. As far as peak memory is concerned, `MCContext::Allocate()` is equivalent to a leak, since it only gets freed at process teardown. In my heap profile, this patch drops memory usage of `DwarfDebug::emitDebugLoc()` from 132.56 MB (11.4%) down to 29.86 MB (2.7%) at peak memory. Some of that must be noise from `SmallVector` (or other) allocations -- peak memory only dropped from 1160 MB down to 1100 MB -- but this nevertheless shaves 5% off the top.) llvm-svn: 236629