Added API for copy vs. alias and added benchmarks to test both.
Benchmark output:
$ bazel-bin/benchmarks/benchmark '--benchmark_filter=BM_Parse'
2020-11-11 15:39:04
Running bazel-bin/benchmarks/benchmark
Run on (72 X 3700 MHz CPU s)
CPU Caches:
L1 Data 32K (x36)
L1 Instruction 32K (x36)
L2 Unified 1024K (x36)
L3 Unified 25344K (x2)
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Benchmark Time CPU Iterations
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BM_Parse_Upb_FileDesc<UseArena, Copy> 4134 ns 4134 ns 168714 1.69152GB/s
BM_Parse_Upb_FileDesc<UseArena, Alias> 3487 ns 3487 ns 199509 2.00526GB/s
BM_Parse_Upb_FileDesc<InitBlock, Copy> 3727 ns 3726 ns 187581 1.87643GB/s
BM_Parse_Upb_FileDesc<InitBlock, Alias> 3110 ns 3110 ns 224970 2.24866GB/s
BM_Parse_Proto2<FileDesc, NoArena, Copy> 31132 ns 31132 ns 22437 229.995MB/s
BM_Parse_Proto2<FileDesc, UseArena, Copy> 21011 ns 21009 ns 33922 340.812MB/s
BM_Parse_Proto2<FileDesc, InitBlock, Copy> 17976 ns 17975 ns 38808 398.337MB/s
BM_Parse_Proto2<FileDescSV, InitBlock, Alias> 17357 ns 17356 ns 40244 412.539MB/s
Joshua Haberman
65d166a6ba