4000c9ee18
Measure amount of high-level or fixed-cost operations performed during building/loading modules and during header search. High-level operations like building a module or processing a .pcm file are motivated by previous issues where clang was re-building modules or re-reading .pcm files unnecessarily. Fixed-cost operations like `stat` calls are tracked because clang cannot change how long each operation takes but it can perform fewer of such operations to improve the compile time. Also tracking such stats over time can help us detect compile-time regressions. Added stats are more stable than the actual measured compilation time, so expect the detected regressions to be less noisy. On relanding drop stats in MemoryBuffer.cpp as their value is pretty low but affects a lot of clients and many of those aren't interested in modules and header search. rdar://problem/55715134 Reviewed By: aprantl, bruno Differential Revision: https://reviews.llvm.org/D86895
llvm/lib/Support/Unix README =========================== This directory provides implementations of the lib/System classes that are common to two or more variants of UNIX. For example, the directory structure underneath this directory could look like this: Unix - only code that is truly generic to all UNIX platforms Posix - code that is specific to Posix variants of UNIX SUS - code that is specific to the Single Unix Specification SysV - code that is specific to System V variants of UNIX As a rule, only those directories actually needing to be created should be created. Also, further subdirectories could be created to reflect versions of the various standards. For example, under SUS there could be v1, v2, and v3 subdirectories to reflect the three major versions of SUS.