Commit Graph

18 Commits

Author SHA1 Message Date
Teresa Johnson a344fd3db6 [LTO] Remove unused Path parameter to AddBufferFn
Summary:
With D43396, no clients use the Path parameter anymore.

Depends on D43396.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D43400

llvm-svn: 325619
2018-02-20 20:21:53 +00:00
Bob Haarman 847a77ffb3 LTO: clarify why we need to gracefully handle sys::fs::rename failures
Reviewers: pcc, rafael

Reviewed By: pcc

Subscribers: mehdi_amini, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D40094

llvm-svn: 318362
2017-11-16 01:16:52 +00:00
Rafael Espindola a17fca06ee Use TempFile in lto caching.
This requires a small change to TempFile: allowing a discard after a
failed keep.

With this the cache now handles signals and reuses a fd instead of
reopening the file.

llvm-svn: 318322
2017-11-15 19:09:22 +00:00
Bob Haarman a17bd12185 LTO: don't fatal when value for cache key already exists
Summary:
LTO/Caching.cpp uses file rename to atomically set the value for a
cache key. On Windows, this fails when the destination file already
exists. Previously, LLVM would report_fatal_error in such
cases. However, because the old and the new value for the cache key
are supposed to be equivalent, it actually doesn't matter which one we
keep. This change makes it so that failing the rename when an openable
file with the desired name already exists causes us to report success
instead of fataling.

Reviewers: pcc, hans

Subscribers: mehdi_amini, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D39874

llvm-svn: 317899
2017-11-10 17:08:21 +00:00
Peter Collingbourne d5fc37cc88 LTO: Improve error reporting when adding a cache entry.
Move error handling code next to the code that returns the error,
and change the error message in order to distinguish it from a similar
error message elsewhere in this file.

llvm-svn: 314745
2017-10-03 00:44:21 +00:00
Peter Collingbourne 264d7c9021 LTO: Remove unnecessary Windows support code.
I empirically verified that open files can in fact be renamed on
Windows with sys::fs::rename, so remove the incorrect code and comment.

llvm-svn: 312683
2017-09-07 00:55:00 +00:00
Peter Collingbourne d0e9c167d8 LTO: Try to open cache files before renaming them.
It appears that a potential race between the cache client and the cache
pruner that I thought was unlikely actually happened in practice [1].
Try to avoid the race condition by opening the temporary file before
renaming it. Do this only on non-Windows platforms because we cannot
rename open files on Windows using the sys::fs::rename function.

[1] https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Fchromium.memory%2FLinux_CFI%2F1610%2F%2B%2Frecipes%2Fsteps%2Fcompile%2F0%2Fstdout

Differential Revision: https://reviews.llvm.org/D37410

llvm-svn: 312567
2017-09-05 19:51:38 +00:00
Peter Collingbourne d786047583 Try using llvm::errc, should hopefully fix version mismatch problem on clang-s390x-linux bot.
llvm-svn: 298285
2017-03-20 18:19:41 +00:00
Peter Collingbourne 25a17ba4c7 Support, LTO: When pruning a directory, ignore files matching a prefix.
This is a safeguard against data loss if the user specifies a directory
that is not a cache directory. Teach the existing cache pruning clients
to create files with appropriate names.

Differential Revision: https://reviews.llvm.org/D31109

llvm-svn: 298271
2017-03-20 16:41:57 +00:00
Peter Collingbourne 6bfe4d369b LTO: Work around libstdc++ version mismatch bug, see D31063 review thread.
llvm-svn: 298127
2017-03-17 21:49:09 +00:00
Peter Collingbourne 128423f99b LTO: Fix a potential race condition in the caching API.
After the call to sys::fs::exists succeeds, indicating a cache hit, we call
AddFile and the client will open the file using the supplied path. If the
client is using cache pruning, there is a potential race between the pruner
and the client. To avoid this, change the caching API so that it provides
a MemoryBuffer to the client, and have clients use that MemoryBuffer where
possible.

This scheme won't work with the gold plugin because the plugin API expects a
file path. So we have the gold plugin use the buffer identifier as a path and
live with the race for now. (Note that the gold plugin isn't actually affected
by the problem at the moment because it doesn't support cache pruning.)

This effectively reverts r279883 modulo the change to use the existing path
in the gold plugin.

Differential Revision: https://reviews.llvm.org/D31063

llvm-svn: 298020
2017-03-17 00:34:07 +00:00
Peter Collingbourne cb46a6baf7 LTO: Create temporary cache files in the cache directory instead of $TMPDIR.
This fixes a race condition where another linker process can observe a
partially written file if we copy it from another file system, and allows
the link to be independent of the amount of free disk space in $TMPDIR.

Differential Revision: https://reviews.llvm.org/D31045

llvm-svn: 297970
2017-03-16 18:20:06 +00:00
Peter Collingbourne ab76a19afb LTO: When creating a local cache, create the cache directory if it does not already exist.
Differential Revision: https://reviews.llvm.org/D30519

llvm-svn: 296726
2017-03-02 02:02:38 +00:00
Benjamin Kramer 061f4a5fe6 Apply clang-tidy's performance-unnecessary-value-param to LLVM.
With some minor manual fixes for using function_ref instead of
std::function. No functional change intended.

llvm-svn: 291904
2017-01-13 14:39:03 +00:00
Peter Collingbourne a638fe057c Add qualification to fix MSVC build.
llvm-svn: 282313
2016-09-23 23:23:23 +00:00
Peter Collingbourne 80186a57d6 LTO: Simplify caching interface.
The NativeObjectOutput class has a design problem: it mixes up the caching
policy with the interface for output streams, which makes the client-side
code hard to follow and would for example make it harder to replace the
cache implementation in an arbitrary client.

This change separates the two aspects by moving the caching policy
to a separate field in Config, replacing NativeObjectOutput with a
NativeObjectStream class which only deals with streams and does not need to
be overridden by most clients and introducing an AddFile callback for adding
files (e.g. from the cache) to the link.

Differential Revision: https://reviews.llvm.org/D24622

llvm-svn: 282299
2016-09-23 21:33:43 +00:00
Teresa Johnson 26a462877b [ThinLTO] Move loading of cache entry to client
Summary:
Have the cache pass back the path to the cache entry when it
is ready to be loaded, instead of a buffer.

For gold-plugin we can simply pass this file back to gold directly,
which avoids expensive writing of a separate tmp file. Ensure
the cache entry is not deleted on cleanup by adjusting the setting
of the IsTemporary flags.

Moved the loading of the buffer into llvm-lto2 to maintain current
behavior.

Reviewers: mehdi_amini

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23946

llvm-svn: 279883
2016-08-26 23:29:14 +00:00
Mehdi Amini adc0e26bef [ThinLTO] Add caching to the new LTO API
Add the ability to plug a cache on the LTO API.
I tried to write such that a linker implementation can
control the cache backend. This is intrusive and I'm
not totally happy with it, but I can't figure out a
better design right now.

Differential Revision: https://reviews.llvm.org/D23599

llvm-svn: 279576
2016-08-23 21:30:12 +00:00