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Commit Graph

1415 Commits

Author SHA1 Message Date
Nico Weber
217c395e5b Remove HAVE_REALPATH from config.h
Its last use was removed in r352916.
No behavior change.

Differential Revision: https://reviews.llvm.org/D59601

llvm-svn: 356579
2019-03-20 17:26:11 +00:00
Alex Langford
111f016973 [CMake] Correct CMake message mode
Summary:
This wasn't actually printing out a CMake warning, it was prepending
"WARN" to the message.

Reviewers: zturner

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59432

llvm-svn: 356297
2019-03-15 20:43:53 +00:00
Jason Liu
59e6264189 [AIX][CMake] Changes for building on AIX with XL and GCC
Summary:
In support of IBM's efforts to produce a viable C and C++ LLVM compiler for AIX
(ref: RFC at http://lists.llvm.org/pipermail/llvm-dev/2019-February/130175.html),
this patch adds customizations to the CMake files in order to properly
invoke the host toolchain for the build on AIX.
Additional changes to enable a successful build will follow.

Patch by Xing Xue

Reviewers: hubert.reinterpretcast, jasonliu, sfertile

Reviewed by: hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D58250

llvm-svn: 356104
2019-03-13 21:50:25 +00:00
Louis Dionne
638bfc7d2a [NFC][CMake] Improve Status message in the iOS toolchain file
llvm-svn: 356056
2019-03-13 15:35:21 +00:00
Hubert Tong
6a41f396a5 Use AIX version detection at LLVM run-time
Summary:
AIX compilers define macros based on the version of the operating
system.

This patch implements updating of versionless AIX triples to include the
host AIX version. Also, the host triple detection in the build system is
adjusted to strip the AIX version information so that the run-time
detection is preferred.

Reviewers: xingxue, stefanp, nemanjai, jasonliu

Reviewed By: xingxue

Subscribers: mgorny, kristina, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58798

llvm-svn: 355995
2019-03-13 00:12:43 +00:00
Petr Hosek
d80d14c5a9 [CMake] Support stripping and linking output to .build-id directory
When installing runtimes with install-runtimes-stripped, we don't want
to just strip them, we also want to preserve the debugging information
for potential debugging. To make it possible to later find the stripped
debugging information, we want to use the .build-id layout:

https://fedoraproject.org/wiki/RolandMcGrath/BuildID#Find_files_by_build_ID

That is, for libfoo.so with build ID abcdef1234, the debugging information
will be installed into lib/debug/.build-id/ab/cdef1234. llvm-objcopy
already has support for stripping files and linking the debugging
stripped output into the right location. However, CMake doesn't support
customizing strip invocation for the *-stripped targets. So instead, we
replace CMAKE_STRIP with a custom script that invokes llvm-objcopy with
the right command line flags.

Differential Revision: https://reviews.llvm.org/D59127

llvm-svn: 355765
2019-03-09 01:26:55 +00:00
Hubert Tong
55192374db Add secondary libstdc++ 4.8 and 5.1 detection mechanisms
Summary:
The date-based approach to detecting unsupported versions of libstdc++
does not handle bug fix releases of older versions. As an example, the
`__GLIBCXX__` value associated with version 5.1, `20150422`, is less
than the values associated with versions 4.8.5 and 4.9.3.

This patch adds secondary checks based on certain properties in
sufficiently new versions of libstdc++.

Reviewers: jfb, tstellar, rnk, sfertile, nemanjai

Reviewed By: jfb

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58682

llvm-svn: 355638
2019-03-07 21:28:33 +00:00
Rong Xu
36a2adc1b6 [PGO] Context sensitive PGO (part 4)
Part 4 of CSPGO changes:
(1) add support in cmake for cspgo build.
(2) fix an issue in big endian.
(3) test cases.

Differential Revision: https://reviews.llvm.org/D54175

llvm-svn: 355541
2019-03-06 19:31:37 +00:00
Francis Visoiu Mistrih
7f77ac0406 [OptRemarks] Make OptRemarks more generic: rename OptRemarks to Remarks
Getting rid of the name "optimization remarks" for anything that
involves handling remarks on the client side.

It's safer to do this now, before we get stuck with that name in all the
APIs and public interfaces we decide to export to users in the future.

This renames llvm/tools/opt-remarks to llvm/tools/remarks-shlib, and now
generates `libRemarks.dylib` instead of `libOptRemarks.dylib`.

Differential Revision: https://reviews.llvm.org/D58535

llvm-svn: 355439
2019-03-05 20:45:17 +00:00
Shoaib Meenai
25c7018595 [cmake] Create exports for umbrella library targets
When using the umbrella llvm-libraries and clang-libraries targets, we
should export all library targets, otherwise they'll be part of our
distribution but not usable from the CMake package.

Differential Revision: https://reviews.llvm.org/D58862

llvm-svn: 355354
2019-03-05 00:38:32 +00:00
Kamil Rytarowski
93c23f7519 Revert duplicate check for DragonFly BSD
Summary: Revert duplicate check for DragonFly BSD

Submitted by tuxillo.

Reviewers: krytarowski

Reviewed By: krytarowski

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58907

llvm-svn: 355319
2019-03-04 15:51:02 +00:00
Kamil Rytarowski
2e2558b1bf Unbreak shared library linkage on DragonFlyBSD.
Patch submitted by rimvydas.

Reviewers: llvm-commits, krytarowski, mgorny

Reviewed By: krytarowski, mgorny

Subscribers: mgorny

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D35125

llvm-svn: 355315
2019-03-04 14:36:43 +00:00
Tom Stellard
f3333c1bc5 CMake: Fix stand-alone clang builds since r353268
Summary:
Handle the case where LLVM_MAIN_SRC_DIR is not set and also use
LLVM_CMAKE_DIR for locating installed cmake files rather than
LLVM_CMAKE_PATH.

Reviewers: phosek, andrewrk, smeenai

Reviewed By: phosek, andrewrk, smeenai

Subscribers: mgorny, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D58204

llvm-svn: 354417
2019-02-20 01:11:05 +00:00
Daniel Sanders
c51d219e2f Fix builds with llvm/runtimes/compiler-rt after r354365
Compiler-rt doesn't include config-ix which was providing CheckSymbolExists to
the LLVM build. Add it to HandleLLVMOptions to fix this

llvm-svn: 354389
2019-02-19 22:02:38 +00:00
Daniel Sanders
d5b0d52a8c Fix builds for older macOS deployment targets after r354365
Surprisingly, check_symbol_exists is not sufficient. The macOS linker checks the
called functions against a compatibility list for the given deployment target
and check_symbol_exists doesn't trigger this check as it never calls the
function.

This fixes the GreenDragon bots where the deployment target is 10.9

llvm-svn: 354374
2019-02-19 19:45:03 +00:00
Daniel Sanders
6542491095 Annotate timeline in Instruments with passes and other timed regions.
Summary:
Instruments is a useful tool for finding performance issues in LLVM but it can
be difficult to identify regions of interest on the timeline that we can use
to filter the profiler or allocations instrument. Xcode 10 and the latest
macOS/iOS/etc. added support for the os_signpost() API which allows us to
annotate the timeline with information that's meaningful to LLVM.

This patch causes timer start and end events to emit signposts. When used with
-time-passes, this causes the passes to be annotated on the Instruments timeline.
In addition to visually showing the duration of passes on the timeline, it also
allows us to filter the profile and allocations instrument down to an individual
pass allowing us to find the issues within that pass without being drowned out
by the noise from other parts of the compiler.

Using this in conjunction with the Time Profiler (in high frequency mode) and
the Allocations instrument is how I found the SparseBitVector that should have
been a BitVector and the DenseMap that could be replaced by a sorted vector a
couple months ago. I added NamedRegionTimers to TableGen and used the resulting
annotations to identify the slow portions of the Register Info Emitter. Some of
these were placed according to educated guesses while others were placed
according to hot functions from a previous profile. From there I filtered the
profile to a slow portion and the aforementioned issues stood out in the
profile.

To use this feature enable LLVM_SUPPORT_XCODE_SIGNPOSTS in CMake and run the
compiler under Instruments with -time-passes like so:
  instruments -t 'Time Profiler' bin/llc -time-passes -o - input.ll'
Then open the resulting trace in Instruments.

There was a talk at WWDC 2018 that explained the feature which can be found at
https://developer.apple.com/videos/play/wwdc2018/405/ if you'd like to know
more about it.

Reviewers: bogner

Reviewed By: bogner

Subscribers: jdoerfert, mgorny, kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D52954

llvm-svn: 354365
2019-02-19 18:18:31 +00:00
Michal Gorny
ef8b9cdabe [llvm] [cmake] Provide split include paths in LLVMConfig
Modify LLVMConfig to provide split variables for in-source and generated
include paths.  Currently, it uses a single value for both
LLVM_INCLUDE_DIRS and LLVM_INCLUDE_DIR which works for install tree but
fails hard at build tree (where LLVM_INCLUDE_DIR incorrectly contains
multiple values).

Instead, put the generated directory in LLVM_INCLUDE_DIR, and the source
tree in LLVM_MAIN_INCLUDE_DIR which is consistent with in-LLVM builds.
For install tree, both variables will have the same value.

Differential Revision: https://reviews.llvm.org/D58109

llvm-svn: 353924
2019-02-13 08:34:40 +00:00
Michal Gorny
5d3d16669d [llvm] [cmake] Use current directory in GenerateVersionFromVCS
Find dependent scripts of GenerateVersionFromVCS in current directory
rather than ../../cmake/modules.  I do not see any reason why the former
would not work and The latter is incorrect when GenerateVersionFromVCS
is used from install directory (i.e. in stand-alone builds).

Differential Revision: https://reviews.llvm.org/D57996

llvm-svn: 353674
2019-02-11 09:07:07 +00:00
Mikhail R. Gadelha
7db7f7f32f This reverts commit 1440a848a635849b97f7a5cfa0ecc40d37451f5b.
and commit a1853e834c65751f92521f7481b15cf0365e796b.

They broke arm and aarch64

llvm-svn: 353590
2019-02-09 00:46:12 +00:00
Rong Xu
10486b5c91 [Cmake] Add an option to build LLVM using the experimental new pass manager
Add LLVM_USE_NEWPM to build LLVM using the experimental new pass manager.

Differential Revision: http://reviews.llvm.org/D57068

llvm-svn: 353550
2019-02-08 19:31:03 +00:00
Shoaib Meenai
b5d55878f8 [cmake] Pass LLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN to NATIVE configure
We should propagate this down to host builds so that e.g. people using
an optimized tablegen can do the sub-configure successfully.

llvm-svn: 353463
2019-02-07 20:58:04 +00:00
JF Bastien
406b84702a Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 353374
2019-02-07 05:20:00 +00:00
Mikhail R. Gadelha
dd981b7599 Move the SMT API to LLVM
Moved everything SMT-related to LLVM and updated the cmake scripts.

Differential Revision: https://reviews.llvm.org/D54978

llvm-svn: 353373
2019-02-07 03:19:45 +00:00
Peter Collingbourne
20a57ab952 build: Remove the cmake check for malloc.h.
As far as I can tell, malloc.h is only being used here to provide
a definition of mallinfo (malloc itself is declared in stdlib.h via
cstdlib). We already have a macro for whether mallinfo is available,
so switch to using that instead.

Differential Revision: https://reviews.llvm.org/D57807

llvm-svn: 353329
2019-02-06 19:20:47 +00:00
Petr Hosek
ec05af2652 [CMake] Unify scripts for generating VCS headers
Previously, there were two different scripts for generating VCS headers:
one used by LLVM and one used by Clang and lldb. They were both similar,
but different. They were both broken in their own ways, for example the
one used by Clang didn't properly handle monorepo resulting in an
incorrect version information reported by Clang.

This change unifies two the scripts by introducing a new script that's
used from both LLVM, Clang and lldb, ensures that the new script
supports both monorepo and standalone SVN and Git setups, and removes
the old scripts.

Differential Revision: https://reviews.llvm.org/D57063

llvm-svn: 353268
2019-02-06 03:51:00 +00:00
JF Bastien
495652a992 Revert "Bump minimum toolchain version"
Reverting D57264 again, it looks like we're down to two bots that need fixing:

polly-amd64-linux
polly-arm-linux

They both have old versions of libstdc++ and recent clang.

llvm-svn: 352954
2019-02-02 06:01:12 +00:00
JF Bastien
5b2eb5b50c Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352951
2019-02-02 05:15:34 +00:00
Stefan Granitz
817d11d6b8 [CMake] Add install targets for utilities to LLVM exports if LLVM_INSTALL_UTILS=ON
Summary: D56606 was only appending target names to the `LLVM_EXPORTS`/`LLVM_EXPORTS_BUILDTREE_ONLY` properties. Targets showed up correctly in the build-tree `LLVMExports.cmake`, but they were missing in the installed one (as we found in https://bugs.llvm.org/show_bug.cgi?id=40443), because install did not register them explicitly.

Reviewers: mgorny, smeenai, beanz, gottesmm, dschuff, tstellar, serge-sans-paille

Reviewed By: smeenai

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D57383

llvm-svn: 352869
2019-02-01 13:08:09 +00:00
JF Bastien
d34b028451 Revert "Bump minimum toolchain version"
Looks like we still have a few bots that are sad. Let try to get them fixed!

llvm-svn: 352835
2019-02-01 04:44:39 +00:00
JF Bastien
0621177282 Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352834
2019-02-01 04:33:21 +00:00
JF Bastien
d979e38527 Revert "Bump minimum toolchain version"
A handful of bots are still breaking, either because I missed them in my audit,
they were offline, or something else. I'm contacting their authors, but I'll
revert for now and re-commit later.

llvm-svn: 352814
2019-01-31 23:29:39 +00:00
JF Bastien
023da30e96 Bump minimum toolchain version
Summary:
The RFC on moving past C++11 got good traction:
  http://lists.llvm.org/pipermail/llvm-dev/2019-January/129452.html

This patch therefore bumps the toolchain versions according to our policy:
  llvm.org/docs/DeveloperPolicy.html#toolchain

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits, mehdi_amini, jyknight, rsmith, chandlerc, smeenai, hans, reames, lattner, lhames, erichkeane

Differential Revision: https://reviews.llvm.org/D57264

llvm-svn: 352811
2019-01-31 23:13:10 +00:00
Shoaib Meenai
95e2e63b36 [cmake] Note future cleanup in comment. NFC
CMake 3.6 introduced CMAKE_TRY_COMPILE_PLATFORM_VARIABLES, which solves
precisely the problem that necessitated init_user_prop, so we can switch
over whenever we bump our minimum CMake requirement.

llvm-svn: 352790
2019-01-31 20:32:45 +00:00
Petr Hosek
be96a2d9e7 Revert "[CMake] Unify scripts for generating VCS headers"
This reverts commits r352729 and r352731: this broke Sanitizer Windows bots

llvm-svn: 352733
2019-01-31 07:12:43 +00:00
Petr Hosek
874d1380a0 [CMake] Unify scripts for generating VCS headers
Previously, there were two different scripts for generating VCS headers:
one used by LLVM and one used by Clang. They were both similar, but
different. They were both broken in their own ways, for example the one
used by Clang didn't properly handle monorepo resulting in an incorrect
version information reported by Clang.

This change unifies two the scripts by introducing a new script that's
used from both LLVM and Clang, ensures that the new script supports both
monorepo and standalone SVN and Git setups, and removes the old scripts.

Differential Revision: https://reviews.llvm.org/D57063

llvm-svn: 352729
2019-01-31 06:21:01 +00:00
Stefan Granitz
f4a52b4401 [CMake] Accept ENTITLEMENTS in llvm_add_library()
Summary: We added support for code signing entitlements in add_llvm_executable() with D54443. In the future it would be useful to have this functionality available also for libraries.

Reviewers: beanz, bogner

Reviewed By: bogner

Subscribers: mgorny, llvm-commits, lldb-commits, #lldb

Differential Revision: https://reviews.llvm.org/D57334

llvm-svn: 352628
2019-01-30 15:10:08 +00:00
Michal Gorny
af50a668bf [cmake] Fix get_llvm_lit_path() to respect LLVM_EXTERNAL_LIT always
Refactor the get_llvm_lit_path() logic to respect LLVM_EXTERNAL_LIT,
and require the fallback to be defined explicitly
as LLVM_DEFAULT_EXTERNAL_LIT. This fixes building libcxx standalone
after r346888.

The old logic was using LLVM_EXTERNAL_LIT both as user-defined cache
variable and an optional pre-definition of default value from caller
(e.g. libcxx). It included a hack to make this work by assigning
the value back and forth but it was fragile and stopped working
in libcxx.

The new logic is simpler and more transparent. Default value is
provided in a separate variable, and used only when user-specified
variable is empty (i.e. not overriden).

Differential Revision: https://reviews.llvm.org/D57282

llvm-svn: 352374
2019-01-28 15:16:03 +00:00
Serge Guelton
1e000b2c69 Fix llvm::is_trivially_copyable portability issues
llvm::is_trivially_copyable portability is verified at compile time using
std::is_trivially_copyable as the reference implementation.

Unfortunately, the latter is not available on all platforms, so introduce
a proper configure check to detect if it is available on the target platform.

In a similar manner, std::is_copy_assignable is not fully supported for gcc4.9.
Provide a portable (?) implementation instead.

Differential Revision: https://reviews.llvm.org/D57018

llvm-svn: 351820
2019-01-22 13:48:55 +00:00
JF Bastien
dec3ae0936 Document toolchain update policy
Summary:
Capture the current agreed-upon toolchain update policy based on the following
discussions:

  - LLVM dev meeting 2018 BoF "Migrating to C++14, and beyond!"
    llvm.org/devmtg/2018-10/talk-abstracts.html#bof3
  - A Short Policy Proposal Regarding Host Compilers
    lists.llvm.org/pipermail/llvm-dev/2018-May/123238.html
  - Using C++14 code in LLVM (2018)
    lists.llvm.org/pipermail/llvm-dev/2018-May/123182.html
  - Using C++14 code in LLVM (2017)
    lists.llvm.org/pipermail/llvm-dev/2017-October/118673.html
  - Using C++14 code in LLVM (2016)
    lists.llvm.org/pipermail/llvm-dev/2016-October/105483.html
  - Document and Enforce new Host Compiler Policy
    llvm.org/D47073
  - Require GCC 5.1 and LLVM 3.5 at a minimum
    llvm.org/D46723

Subscribers: jkorous, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D56819

llvm-svn: 351765
2019-01-21 23:53:52 +00:00
Dylan McKay
cafb601214 [AVR] Allow AVR to be explicitly set as the default target triple
This extends the CMake cross compilation logic so that AVR can be set as
the default target triple, and thus the generic codegen tests can be
run.

This used to be possible on AVR; the CMake configuration files have
since been changed.

With this patch, 'cmake -DLLVM_DEFAULT_TARGET_TRIPLE=avr-unknown-unknown' can
be passed on the command line, making the `-mcpu` argument redundant to
'llc' and friends.

llvm-svn: 351678
2019-01-20 11:12:39 +00:00
JF Bastien
36109c9464 [NFC] Factor out + document build requirements
Summary: This change factors out compiler checking / warning, and documents LLVM_FORCE_USE_OLD_TOOLCHAIN. It doesn't introduce any functional changes nor policy changes, these will come late.

Subscribers: mgorny, jkorous, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D56799

llvm-svn: 351387
2019-01-16 22:22:38 +00:00
Stefan Granitz
5993f667ea [CMake] Export utility targets to the build/install tree depending on LLVM_BUILD/INSTALL_UTILS
Summary:
Allow external projects to import test-related targets like FileCheck, count, not etc. and query binary paths, properties, etc.
This would be useful for LLDB, because it reduces the difference between in-tree vs. standalone builds and simplifies CMake logic.

Reviewers: chapuni, gottesmm, beanz

Reviewed By: beanz

Subscribers: mgorny, lldb-commits, llvm-commits, #lldb

Differential Revision: https://reviews.llvm.org/D56606

llvm-svn: 350959
2019-01-11 19:34:34 +00:00
Stefan Granitz
8c5f738610 [CMake] Use XCODE_ATTRIBUTE properties for code signing and entitlements in Xcode
Summary: A post-commit comment to D55116 amended that this was the correct way for code signing in Xcode.

Reviewers: beanz

Reviewed By: beanz

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D55816

llvm-svn: 350383
2019-01-04 09:22:32 +00:00
Tom Stellard
ab11edc4b3 Fix mingw build failures caused by r349839
Reviewers: mstorsjo

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D56004

llvm-svn: 349990
2018-12-22 03:43:08 +00:00
Tom Stellard
e84d87abe0 Fix Windows build failures caused by r349839
llvm-svn: 349846
2018-12-20 22:36:02 +00:00
Tom Stellard
c1b672534d cmake: Remove add_llvm_loadable_module()
Summary:
This function is very similar to add_llvm_library(),  so this patch merges it
into add_llvm_library() and replaces all calls to add_llvm_loadable_module(lib ...)
with add_llvm_library(lib MODULE ...)

Reviewers: philip.pfaffe, beanz, chandlerc

Reviewed By: philip.pfaffe

Subscribers: chapuni, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D51748

llvm-svn: 349839
2018-12-20 22:04:08 +00:00
Alexandre Ganea
f107767821 Re-land "Fix MSVC dependency issue between Clang-tablegen and LLVM-tablegen"
(was reverted by mistake)

llvm-svn: 349672
2018-12-19 19:42:21 +00:00
Alexandre Ganea
d4b6310f63 Revert r349517 "[CMake] Default options for faster executables on MSVC"
llvm-svn: 349656
2018-12-19 18:01:42 +00:00
Alexandre Ganea
028b8bbe8e Revert r349517 "[CMake] Default options for faster executables on MSVC"
llvm-svn: 349654
2018-12-19 17:57:31 +00:00
Nico Weber
60a32e805a Let TableGen write output only if it changed, instead of doing so in cmake, attempt 2
This relands r330742:
"""
Let TableGen write output only if it changed, instead of doing so in cmake.

Removes one subprocess and one temp file from the build for each tablegen
invocation.

No intended behavior change.
"""

In particular, if you see rebuilds after this change that you didn't see
before this change, that's unintended and it's fine to revert this change
again (but let me know).

r330742 got reverted because some people reported that llvm-tblgen ran on every
build after it.  This could happen if the depfile output got deleted without
deleting the main .inc output. To fix, make TableGen always write the depfile,
but keep writing the main .inc output only if it has changed. This matches what
we did in cmake before.

Differential Revision: https://reviews.llvm.org/D55842

llvm-svn: 349624
2018-12-19 13:35:53 +00:00