Commit Graph

1411 Commits

Author SHA1 Message Date
Rumeet Dhindsa 57a2eaf3c1 Revert "[modules] Do not cache invalid state for modules that we attempted to load."
As per comment on https://reviews.llvm.org/D72860, it is suggested to
revert this change in the meantime, since it has introduced regression.

This reverts commit 83f4c3af02.
2020-03-10 10:59:26 -07:00
Michael Spencer 27a3ecee45 [clang][Modules] Add -fsystem-module flag
The -fsystem-module flag is used when explicitly building a module. It
forces the module to be treated as a system module. This is used when
converting an implicit build to an explicit build to match the
systemness the implicit build would have had for a given module.

Differential Revision: https://reviews.llvm.org/D75395
2020-03-03 14:14:24 -08:00
Volodymyr Sapsai 4069dd1412 [modules] Allow frameworks to have only a private module without a public one.
Support only preferred spelling 'Modules/module.private.modulemap' and
not the deprecated 'module_private.map'.

rdar://problem/57715533

Reviewed By: bruno

Differential Revision: https://reviews.llvm.org/D75311
2020-02-28 15:40:24 -08:00
Hans Wennborg 7ea9a6e022 Revert "make -fmodules-codegen and -fmodules-debuginfo work also with PCHs"
This caused PR44953. See also the discussion on D74846.

This reverts commit cbc9d22e49.
2020-02-27 14:33:43 +01:00
John McCall 77b2ffc498 Fix a reentrance bug with deserializing ObjC type parameters.
This is a longstanding bug that seems to have been hidden by
a combination of (1) the normal flow being to deserialize the
interface before deserializing its parameter and (2) a precise
ordering of work that was apparently recently disturbed,
perhaps by my abstract-serialization work or Bruno's ObjC
module merging work.

Fixes rdar://59153545.
2020-02-12 18:44:19 -05:00
Jordan Rupprecht 60a8a504f1 [llvm-objdump] Print file format in lowercase to match GNU output.
Summary:
GNU objdump prints the file format in lowercase, e.g. `elf64-x86-64`. llvm-objdump prints `ELF64-x86-64` right now, even though piping that into llvm-objcopy refuses that as a valid arch to use.

As an example of a problem this causes, see: https://github.com/ClangBuiltLinux/linux/issues/779

Reviewers: MaskRay, jhenderson, alexshap

Reviewed By: MaskRay

Subscribers: tpimh, sbc100, grimar, jvesely, nhaehnle, kerbowa, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74433
2020-02-12 08:17:01 -08:00
Richard Smith 7ae1b4a0ce Implement P1766R1: diagnose giving non-C-compatible classes a typedef name for linkage purposes.
Summary:
Due to a recent (but retroactive) C++ rule change, only sufficiently
C-compatible classes are permitted to be given a typedef name for
linkage purposes. Add an enabled-by-default warning for these cases, and
rephrase our existing error for the case where we encounter the typedef
name for linkage after we've already computed and used a wrong linkage
in terms of the new rule.

Reviewers: rjmccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D74103
2020-02-07 11:47:37 -08:00
Fangrui Song dbc96b518b Revert "[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition"
This reverts commit 789a46f2d7.

Accidentally committed.
2020-02-03 10:09:39 -08:00
Fangrui Song 789a46f2d7 [CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition
Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.

Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.

Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert

Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73865
2020-02-03 09:52:48 -08:00
Nico Weber 49532137d0 Make AST reading work better with LLVM_APPEND_VC_REV=NO
With LLVM_APPEND_VC_REV=NO, Modules/merge-lifetime-extended-temporary.cpp
would fail if it ran before a0f50d7316 (which changed
the serialization format) and then after, for these reasons:

1. With LLVM_APPEND_VC_REV=NO, the module hash before and after the
   change was the same.

2. Modules/merge-lifetime-extended-temporary.cpp is the only test
   we have that uses -fmodule-cache-path=%t that
   a) actually writes to the cache path
   b) doesn't do `rm -rf %t` at the top of the test

So the old run would write a module file, and then the new run would
try to load it, but the serialized format changed.

Do several things to fix this:

1. Include clang::serialization::VERSION_MAJOR/VERSION_MINOR in
   the module hash, so that when the AST format changes (...and
   we remember to bump these), we use a different module cache dir.
2. Bump VERSION_MAJOR, since a0f50d7316 changed the
   on-disk format in a way that a gch file written before that change
   can't be read after that change.
3. Add `rm -rf %t` to all tests that pass -fmodule-cache-path=%t.
   This is unnecessary from a correctness PoV after 1 and 2,
   but makes it so that we don't amass many cache dirs over time.
   (Arguably, it also makes it so that the test suite doesn't catch
   when we change the serialization format but don't bump
   clang::serialization::VERSION_MAJOR/VERSION_MINOR; oh well.)

Differential Revision: https://reviews.llvm.org/D73202
2020-01-27 22:08:37 -05:00
Adrian Prantl 7b30370e5b Move the sysroot attribute from DIModule to DICompileUnit
[this re-applies c0176916a4
 with the correct commit message and phabricator link]

This addresses point 1 of PR44213.
https://bugs.llvm.org/show_bug.cgi?id=44213

The DW_AT_LLVM_sysroot attribute is used for Clang module debug info,
to allow LLDB to import a Clang module from source. Currently it is
part of each DW_TAG_module, however, it is the same for all modules in
a compile unit. It is more efficient and less ambiguous to store it
once in the DW_TAG_compile_unit.

This should have no effect on DWARF consumers other than LLDB.

Differential Revision: https://reviews.llvm.org/D71732
2020-01-17 12:55:40 -08:00
Adrian Prantl c17aee67f1 Revert "Rename DW_AT_LLVM_isysroot to DW_AT_LLVM_sysroot"
This reverts commit 12e479475a.

I accidentally landed this patch with the wrong commit message ...
2020-01-17 12:52:36 -08:00
Adrian Prantl 12e479475a Rename DW_AT_LLVM_isysroot to DW_AT_LLVM_sysroot
This is a purely cosmetic change that is NFC in terms of the binary
output. I bugs me that I called the attribute DW_AT_LLVM_isysroot
since the "i" is an artifact of GCC command line option syntax
(-isysroot is in the category of -i options) and doesn't carry any
useful information otherwise.

This attribute only appears in Clang module debug info.

Differential Revision: https://reviews.llvm.org/D71722
2020-01-17 09:36:48 -08:00
Volodymyr Sapsai 83f4c3af02 [modules] Do not cache invalid state for modules that we attempted to load.
Partially reverts 0a2be46cfd as it turned
out to cause redundant module rebuilds in multi-process incremental builds.
When a module was getting out of date, all compilation processes started at the
same time were marking it as `ToBuild`. So each process was building the same
module instead of checking if it was built by someone else and using that
result. In addition to the work duplication, contention on the same .pcm file
wasn't making builds faster.

Note that for a single-process build this change would cause redundant module
reads and validations. But reading a module is faster than building it and
multi-process builds are more common than single-process. So I'm willing to
make such a trade-off.

rdar://problem/54395127

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D72860
2020-01-16 17:12:41 -08:00
Weverything a60e892729 [ODRHash] Fix wrong error message with bitfields and mutable.
Add a check to bitfield mismatches that may have caused Clang to
give an error about the bitfield instead of being mutable.
2020-01-14 21:12:15 -08:00
Luboš Luňák cbc9d22e49 make -fmodules-codegen and -fmodules-debuginfo work also with PCHs
Allow to build PCH's (with -building-pch-with-obj and the extra .o file)
with -fmodules-codegen -fmodules-debuginfo to allow emitting shared code
into the extra .o file, similarly to how it works with modules. A bit of
a misnomer, but the underlying functionality is the same. This saves up
to 20% of build time here.

Differential Revision: https://reviews.llvm.org/D69778
2020-01-15 00:01:08 +01:00
Luboš Luňák b5b2cf7af4 fix recent -fmodules-codegen fix test 2020-01-14 23:51:07 +01:00
Luboš Luňák 729530f68f -fmodules-codegen should not emit extern templates
If a header contains 'extern template', then the template should be provided
somewhere by an explicit instantiation, so it is not necessary to generate
a copy. Worse, this can lead to an unresolved symbol, because the codegen's
object file will not actually contain functions from such a template
because of the GVA_AvailableExternally, but the object file for the explicit
instantiation will not contain them either because it will be blocked
by the information provided by the module.

Differential Revision: https://reviews.llvm.org/D69779
2020-01-14 23:39:50 +01:00
Adrian Prantl 44b4b833ad Rename DW_AT_LLVM_isysroot to DW_AT_LLVM_sysroot
This is a purely cosmetic change that is NFC in terms of the binary
output. I bugs me that I called the attribute DW_AT_LLVM_isysroot
since the "i" is an artifact of GCC command line option syntax
(-isysroot is in the category of -i options) and doesn't carry any
useful information otherwise.

This attribute only appears in Clang module debug info.

Differential Revision: https://reviews.llvm.org/D71722
2019-12-20 13:11:17 -08:00
Daniel Sanders 327894859c Fix `sed -e s@FOO@%/S@` and similar when there's @'s in the working directory
Jenkins sometimes starts a new working directory by appending @2 (or
incrementing the number if the @n suffix is already there). This causes
several clang tests to fail as:
  s@INPUT_DIR@%/S/Inputs@g
gets expanded to the invalid:
  s@INPUT_DIR@/path/to/workdir@2/Inputs@g
                               ~~~~~~~~~~
where the part marked with ~'s is interpreted as the flags. These are
invalid and the test fails.

Previous fixes simply exchanged the @ character for another like | but
that's just moving the problem. Address it by adding an expansion that
escapes the @ character we're using as a delimiter as well as other magic
characters in the replacement of sed's s@@@.

There's still room for expansions to cause trouble though. One I ran into
while testing this was that having a directory called foo@bar causes lots
of `CHECK-NOT: foo` directives to match. There's also things like
directories containing `\1`
2019-12-03 15:44:01 -08:00
Tyker 9ec6d71211 [clang][modules] Add support for merging lifetime-extended temporaries
Summary: Add support for merging lifetime-extended temporaries

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: xbolva00, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70190
2019-12-02 19:55:13 +01:00
Tyker ae5484540f Revert "[clang][modules] Add support for merging lifetime-extended temporaries"
This reverts commit a3cbe1a202.
2019-12-01 22:38:31 +01:00
Tyker a3cbe1a202 [clang][modules] Add support for merging lifetime-extended temporaries
Summary: Add support for merging lifetime-extended temporaries

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: xbolva00, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70190
2019-12-01 21:28:48 +01:00
Tyker 486d1a5358 Revert "[clang][modules] Add support for merging lifetime-extended temporaries"
This reverts commit 85c7438477.
2019-12-01 11:58:14 +01:00
Tyker 85c7438477 [clang][modules] Add support for merging lifetime-extended temporaries
Summary: Add support for merging lifetime-extended temporaries

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: xbolva00, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70190
2019-11-30 23:09:11 +01:00
Tyker 3f4b70c79e Revert "[clang][modules] Add support for merging lifetime-extended temporaries"
This reverts commit 3c7f6b4396.
2019-11-30 17:52:26 +01:00
Tyker 3c7f6b4396 [clang][modules] Add support for merging lifetime-extended temporaries
Summary: Add support for merging lifetime-extended temporaries

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: xbolva00, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70190
2019-11-30 16:42:33 +01:00
Sylvestre Ledru 9b40a7f3bf Remove +x permission on some files 2019-11-16 14:47:20 +01:00
Bruno Cardoso Lopes 3466cebe94 Add a test to cover structural match for recursive data types
This didn't use to work prior to r370639, now that this is supported
add a testcase to prevent regressions.

rdar://problem/53602368
2019-11-14 18:32:27 -08:00
Adrian McCarthy 1275ab1620 Improve VFS compatibility on Windows
Keys in a virtual file system can be in Posix or Windows form or even
a combination of the two.  Many VFS tests (and a few Clang tests) were
XFAILed on Windows because of false negatives when comparing paths.

First, we default CaseSenstive to false on Windows.  This allows
drive letters like "D:" to match "d:".  Windows filesystems are, by
default, case insensitive, so this makes sense even beyond the drive
letter.

Second, we allow slashes to match backslashes when they're used as the
root component of a path.

Both of these changes are limited to RedirectingFileSystems, so there's
little chance of affecting other path handling.

These changes allow eleven of the VFS tests to pass on Windows as well
as three other Clang tests, so they have re-enabled.

This solves the majority of PR43272.  Additional VFS test failures will
be fixed in separate patches.

Differential Revision: https://reviews.llvm.org/D69958
2019-11-14 08:48:47 -08:00
Dávid Bolvanský 1da13237a4 [Diagnostics] Try to improve warning message for -Wreturn-type
Summary: I agree with https://easyaspi314.github.io/gcc-vs-clang.html?fbclid=IwAR1VA0qxiWVUusOQUv5z7JESS7ZpeJy-UqAI5mnJscofGLqXcqeErIUB2gU, current warning message is not very good. We should try to improve it..

Reviewers: rsmith, aaron.ballman, easyaspi314

Reviewed By: aaron.ballman

Subscribers: arphaman, Quuxplusone, mehdi_amini, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D69762
2019-11-09 17:54:58 +01:00
Michael J. Spencer 8896d073b1 [Implicit Modules] Add -cc1 option -fmodules-strict-context-hash which includes search paths and diagnostics.
This is a recommit of r375322 and r375327 with a fix for the Windows test breakage.

llvm-svn: 375466
2019-10-21 22:51:13 +00:00
Michael J. Spencer 81a01e73fa Revert "[Implicit Modules] Add -cc1 option -fmodules-strict-context-hash which includes search paths and diagnostics." and "[Docs] Fix header level."
The test doesn't work on Windows. I'll fix it and recommit later.

llvm-svn: 375338
2019-10-19 09:45:28 +00:00
Michael J. Spencer 14a3f77ba1 [Implicit Modules] Add -cc1 option -fmodules-strict-context-hash which includes search paths and diagnostics.
Differential Revision: https://reviews.llvm.org/D68528

llvm-svn: 375322
2019-10-19 01:36:37 +00:00
Bruno Cardoso Lopes 1731fc88d1 Reapply: [Modules][PCH] Hash input files content
Summary:
When files often get touched during builds, the mtime based validation
leads to different problems in implicit modules builds, even when the
content doesn't actually change:

- Modules only: module invalidation due to out of date files. Usually causing rebuild traffic.
- Modules + PCH: build failures because clang cannot rebuild a module if it comes from building a PCH.
- PCH: build failures because clang cannot rebuild a PCH in case one of the input headers has different mtime.

This patch proposes hashing the content of input files (headers and
module maps), which is performed during serialization time. When looking
at input files for validation, clang only computes the hash in case
there's a mtime mismatch.

I've tested a couple of different hash algorithms availble in LLVM in
face of building modules+pch for `#import <Cocoa/Cocoa.h>`:
- `hash_code`: performace diff within the noise, total module cache increased by 0.07%.
- `SHA1`: 5% slowdown. Haven't done real size measurements, but it'd be BLOCK_ID+20 bytes per input file, instead of BLOCK_ID+8 bytes from `hash_code`.
- `MD5`: 3% slowdown. Like above, but BLOCK_ID+16 bytes per input file.

Given the numbers above, the patch uses `hash_code`. The patch also
improves invalidation error msgs to point out which type of problem the
user is facing: "mtime", "size" or "content".

rdar://problem/29320105

Reviewers: dexonsmith, arphaman, rsmith, aprantl

Subscribers: jkorous, cfe-commits, ributzka

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67249

> llvm-svn: 374841

llvm-svn: 374895
2019-10-15 14:23:55 +00:00
Eric Christopher 3be9169caa Temporarily Revert [Modules][PCH] Hash input files content
as it's breaking a few bots.

This reverts r374841 (git commit 2a1386c81d)

llvm-svn: 374842
2019-10-14 23:14:24 +00:00
Bruno Cardoso Lopes 2a1386c81d [Modules][PCH] Hash input files content
Summary:
When files often get touched during builds, the mtime based validation
leads to different problems in implicit modules builds, even when the
content doesn't actually change:

- Modules only: module invalidation due to out of date files. Usually causing rebuild traffic.
- Modules + PCH: build failures because clang cannot rebuild a module if it comes from building a PCH.
- PCH: build failures because clang cannot rebuild a PCH in case one of the input headers has different mtime.

This patch proposes hashing the content of input files (headers and
module maps), which is performed during serialization time. When looking
at input files for validation, clang only computes the hash in case
there's a mtime mismatch.

I've tested a couple of different hash algorithms availble in LLVM in
face of building modules+pch for `#import <Cocoa/Cocoa.h>`:
- `hash_code`: performace diff within the noise, total module cache increased by 0.07%.
- `SHA1`: 5% slowdown. Haven't done real size measurements, but it'd be BLOCK_ID+20 bytes per input file, instead of BLOCK_ID+8 bytes from `hash_code`.
- `MD5`: 3% slowdown. Like above, but BLOCK_ID+16 bytes per input file.

Given the numbers above, the patch uses `hash_code`. The patch also
improves invalidation error msgs to point out which type of problem the
user is facing: "mtime", "size" or "content".

rdar://problem/29320105

Reviewers: dexonsmith, arphaman, rsmith, aprantl

Subscribers: jkorous, cfe-commits, ributzka

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67249

llvm-svn: 374841
2019-10-14 23:02:03 +00:00
Nico Weber 1f1703f5c7 Prefer 'env not' over 'not env' in tests.
That way, lit's builtin 'env' command can be used for the 'env' bit.

Also it's clearer that way that the 'not' shouldn't cover 'env'
failures.

llvm-svn: 374749
2019-10-14 01:41:56 +00:00
Fangrui Song e6d423fe03 [test] Use %clang_cc1 instead of %clang -cc1
llvm-svn: 373043
2019-09-27 05:37:06 +00:00
Adrian Prantl 350de4f05d Support for DWARF-5 C++ language tags.
This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

Reapplies r372663 after adapting a failing test in the LLDB testsuite.

llvm-svn: 372681
2019-09-24 00:38:49 +00:00
Jonas Devlieghere 5c49c26714 Revert "Support for DWARF-5 C++ language tags."
This reverts commit bf9c8ffb54.

llvm-svn: 372672
2019-09-23 23:49:36 +00:00
Adrian Prantl bf9c8ffb54 Support for DWARF-5 C++ language tags.
This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

llvm-svn: 372663
2019-09-23 22:01:49 +00:00
Lubos Lunak 533434fc72 make -frewrite-includes also rewrite conditions in #if/#elif
Those conditions may use __has_include, which needs to be rewritten.
The existing code has already tried to rewrite just __has_include,
but it didn't work with macro expansion, so e.g. Qt's
"#define QT_HAS_INCLUDE(x) __has_include(x)" didn't get handled
properly. Since the preprocessor run knows what each condition evaluates
to, just rewrite the entire condition. This of course requires that
the -frewrite-include pass has the same setup as the following
compilation, but that has always been the requirement.

Differential Revision: https://reviews.llvm.org/D63508

llvm-svn: 372248
2019-09-18 19:09:41 +00:00
Bruno Cardoso Lopes 919fc50034 [Modules][Objective-C] Use complete decl from module when diagnosing missing import
Summary:
Otherwise the definition (first found) for ObjCInterfaceDecl's might
precede the module one, which will eventually lead to crash, since
diagnoseMissingImport needs one coming from a module.

This behavior changed after Richard's r342018, which started to look
into the definition of ObjCInterfaceDecls.

rdar://problem/49237144

Reviewers: rsmith, arphaman

Subscribers: jkorous, dexonsmith, ributzka, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66982

llvm-svn: 372039
2019-09-16 22:00:29 +00:00
Jeremy Morse 0c1e0d52c2 Switch "windows" to "system-windows" in some XFAILs
The test failure mode appears to be due to the host machine rather than the
target. The PS4 buildbots are windows-hosted targeting x86_64-scei-ps4,
and are currently reporting these as unexpected failures:

  http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast/builds/28114

llvm-svn: 371726
2019-09-12 11:19:12 +00:00
Reid Kleckner a685f5161d Start porting ivfsoverlay tests to Windows
Part of PR43272, the changes are:

1. Use @ as the sed pattern delimiter instead of : so that the drive
letter in lit substitutions isn't an issue.

2. Use the %/t and %/S substitutions to get paths with forward slashes
to work around string quoting issues in the yaml file.

3. Replace REQUIRES:shell with XFAIL:windows. These tests should pass on
Windows, but do not for reasons that are not yet understood. We would
like to know if they pass unexpectedly.

I was able to remove the XFAILs from two tests, since they already pass
with my sed fix:
  clang/test/VFS/module_missing_vfs.m
  clang/test/VFS/test_nonmodular.c

Reviewers: amccarth

Differential Revision: https://reviews.llvm.org/D67454

llvm-svn: 371663
2019-09-11 20:56:25 +00:00
Reid Kleckner 38e033bf33 Re-land Remove REQUIRES:shell from tests that pass for me on Windows
This reverts r371497 (git commit 3d7e9ab7b9)

Reorder `not` with `env` in these two tests so they pass:
  Driver/rewrite-map-in-diagnostics.c
  Index/crash-recovery-modules.m.

This will not be necessary after D66531 lands.

llvm-svn: 371552
2019-09-10 20:15:45 +00:00
James Henderson 3d7e9ab7b9 Revert Remove REQUIRES:shell from tests that pass for me on Windows
This reverts r371478 (git commit a9980f60ce)

llvm-svn: 371497
2019-09-10 08:48:33 +00:00
Reid Kleckner a9980f60ce Remove REQUIRES:shell from tests that pass for me on Windows
I see in the history for some of these tests REQUIRES:shell was used as
a way to disable tests on Windows because they are flaky there. I tried
not to re-enable such tests, but it's possible that I missed some and
this will re-enable flaky tests on Windows. If so, we should disable
them with UNSUPPORTED:system-windows and add a comment that they are
flaky there. So far as I can tell, the lit internal shell is capable of
running all of these tests, and we shouldn't use REQUIRES:shell as a
proxy for Windows.

llvm-svn: 371478
2019-09-10 00:50:32 +00:00
Volodymyr Sapsai f91b6f8159 [Modules] Fix rebuilding an updated module for each of its consumers.
Marking a module for a rebuild when its signature differs from the
expected one causes redundant module rebuilds for incremental builds.
When a module is updated, its signature changes. But its consumers still
have the old signature and loading them will result in signature
mismatches. It will correctly cause the rebuilds for the consumers but
we don't need to rebuild the common module for each of them as it is
already up to date.

In practice this bug causes longer build times. We are doing more work
than required and only a single process can build a module, so parallel
builds degrade to a single-process mode where extra processes are just
waiting on a file lock.

Fix by not marking a module dependency for a rebuild on signature
mismatch. We'll check if it is up to date when we load it.

rdar://problem/50212358

Reviewers: dexonsmith, bruno, rsmith

Reviewed By: dexonsmith, bruno

Subscribers: jkorous, ributzka, cfe-commits, aprantl

Differential Revision: https://reviews.llvm.org/D66907

llvm-svn: 370274
2019-08-28 23:31:32 +00:00