Fangrui Song 0db402c5b4 [lld] Buffer writes when composing a single diagnostic ...

llvm::errs() is unbuffered. On a POSIX platform, composing a diagnostic
string may invoke the ::write syscall multiple times, which can be slow.
Buffer writes to a temporary SmallString when composing a single diagnostic to
reduce the number of ::write syscalls to one (also easier to read under
strace/truss).

For an invocation of ld.lld with 62000+ lines of
`ld.lld: warning: symbol ordering file: no such symbol: ` warnings (D87121),
the buffering decreases the write time from 1s to 0.4s (for /dev/tty) and
from 0.4s to 0.1s (for a tmpfs file). This can speed up
`relocation R_X86_64_PC32 out of range` diagnostic printing as well
with `--noinhibit-exec --no-fatal-warnings`.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D87272

2021-09-09 09:27:14 -07:00

..

Args.cpp

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CMakeLists.txt

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DWARF.cpp

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ErrorHandler.cpp

[lld] Buffer writes when composing a single diagnostic

2021-09-09 09:27:14 -07:00

Filesystem.cpp

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Memory.cpp

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Reproduce.cpp

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Strings.cpp

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TargetOptionsCommandFlags.cpp

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Timer.cpp

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Version.cpp

[lld] Remove unused LLD_REPOSITORY

2021-08-04 13:04:10 -07:00