tree 229a5bf9966dbcf3bd3c98d2569fa9037d33c21d
parent 50b4f7f5164cb4a24404ffd32e0684a466e23be2
author Sam McCall <sam.mccall@gmail.com> 1556196702 +0000
committer Sam McCall <sam.mccall@gmail.com> 1556196702 +0000

[Support] Add JSON streaming output API, faster where the heavy value types aren't needed.

Summary:
There's still a little bit of constant factor that could be trimmed (e.g.
more overloads to avoid round-tripping primitives through json::Value).
But this solves the memory scaling problem, and greatly improves the performance
constant factor, and the API should leave room for optimization if needed.

Adapt TimeProfiler to use it, eliminating almost all the performance regression
from r358476.

Performance test on my machine:
perf stat -r 5 ~/llvmbuild-opt/bin/clang++ -w -S -ftime-trace -mllvm -time-trace-granularity=0 spirit.cpp

Handcrafted JSON (HEAD=r358532 with r358476 reverted): 2480ms
json::Value (HEAD): 2757ms (+11%)
After this patch: 2520 ms (+1.6%)

Reviewers: anton-afanasyev, lebedev.ri

Subscribers: kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60804

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359186 91177308-0d34-0410-b5e6-96231b3b80d8