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Commit Graph

453 Commits

Author SHA1 Message Date
Matt Arsenault
f8cfaf8c10 OpaquePtr: Bulk update tests to use typed sret 2020-11-20 17:58:26 -05:00
Arthur Eubanks
dd58cefb43 [NPM] Remove -enable-npm-optnone flag
It has been on by default for a couple months without complaint.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D91743
2020-11-18 15:49:16 -08:00
Arthur Eubanks
8a8876f845 [NewPM] Provide method to run all pipeline callbacks, used for -O0
Some targets may add required passes via
TargetMachine::registerPassBuilderCallbacks(). We need to run those even
under -O0. As an example, BPFTargetMachine adds
BPFAbstractMemberAccessPass, a required pass.

This also allows us to clean up BackendUtil.cpp (and out-of-tree Rust
usage of the NPM) by allowing us to share added passes like coroutines
and sanitizers between -O0 and other optimization levels.

Since callbacks may end up not adding passes, we need to check if the
pass managers are empty before adding them, so PassManager now has an
isEmpty() function. For example, polly adds callbacks but doesn't always
add passes in those callbacks, so this is necessary to keep
-debug-pass-manager tests' output from changing depending on if polly is
enabled or not.

Tests are a continuation of those added in
https://reviews.llvm.org/D89083.

Reviewed By: asbirlea, Meinersbur

Differential Revision: https://reviews.llvm.org/D89158
2020-11-11 15:10:27 -08:00
Arthur Eubanks
2e4e41af20 [NewPM] Don't run before pass instrumentation on required passes
This allows those instrumentation to log when they decide to skip a
pass. This provides extra helpful info for optnone functions and also
will help with opt-bisect.

Have OptNoneInstrumentation print when it skips due to seeing optnone.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D90545
2020-11-04 09:45:10 -08:00
Fangrui Song
22ad0ac417 [test] Delete Feature/load_module.ll which is covered by load_extension.ll 2020-10-27 12:50:53 -07:00
sstefan1
34a5b0392e [IR] Make nosync, nofree and willreturn default for intrinsics.
D70365 allows us to make attributes default. This is a follow up to
actually make nosync, nofree and willreturn default. The approach we
chose, for now, is to opt-in to default attributes to avoid introducing
problems to target specific intrinsics. Intrinsics with default
attributes can be created using `DefaultAttrsIntrinsic` class.
2020-10-20 11:57:19 +02:00
Arthur Eubanks
c01a5baad9 [DIE] Remove DeadInstEliminationPass
This pass is like DeadCodeEliminationPass, but only does one pass
through a function instead of iterating on users of eliminated
instructions.

DeadCodeEliminationPass should be used in all cases.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87933
2020-09-21 12:12:25 -07:00
Bryan Chan
a99283db0a [EarlyCSE] Verify hash code in regression tests
As discussed in D86843, -earlycse-debug-hash should be used in more regression
tests to catch inconsistency between the hashing and the equivalence check.

Differential Revision: https://reviews.llvm.org/D86863
2020-09-04 10:40:35 -04:00
Arthur Eubanks
47a36fca7f [NewPM][optnone] Mark various passes as required
This was done by turning on -enable-npm-optnone and fixing failures.
That will be enabled in a follow-up change for ease of reverting.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D85457
2020-08-14 15:51:59 -07:00
Arthur Eubanks
834a6fc438 [NewPM] Print 'Skipping pass' as pass instrumentation
If OptNoneInstrumentation prints it instead, 'Skipping pass' will print for even required passes.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D85493
2020-08-07 15:02:02 -07:00
Yuanfang Chen
377ad5f083 [NewPM] Only verify loop for nonskipped user loop pass
No verification for pass mangers since it is not needed.
No verification for skipped loop pass since the asserted condition is not used.

Add a BeforeNonSkippedPass callback for this. The callback needs more
inputs than its parameters to work so the callback is added on-the-fly.

Reviewed By: aeubanks, asbirlea

Differential Revision: https://reviews.llvm.org/D84977
2020-08-07 11:00:31 -07:00
Arthur Eubanks
8a584da153 [FunctionAttrs] Rename functionattrs -> function-attrs
To match NewPM pass name, and also for readability.
Also rename rpo-functionattrs -> rpo-function-attrs while we're here.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D84694
2020-07-28 09:09:13 -07:00
Arthur Eubanks
c136b2bbc8 [NewPM] Support optnone under new pass manager
OptNoneInstrumentation is part of StandardInstrumentations. It skips
functions (or loops) that are marked optnone.

The feature of skipping optional passes for optnone functions under NPM
is gated on a -enable-npm-optnone flag. Currently it is by default
false. That is because we still need to mark all required passes to be
required. Otherwise optnone functions will start having incorrect
semantics.  After that is done in following changes, we can remove the
flag and always enable this.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D83519
2020-07-21 09:53:43 -07:00
Fangrui Song
ae62035cf0 [BasicAA] Rename deprecated -basicaa to -basic-aa
Follow-up to D82607
Revert an accidental change (empty.ll) of D82683
2020-06-26 20:41:37 -07:00
Eli Friedman
ffa26401ac StoreInst should store Align, not MaybeAlign
This is D77454, except for stores.  All the infrastructure work was done
for loads, so the remaining changes necessary are relatively small.

Differential Revision: https://reviews.llvm.org/D79968
2020-05-15 12:26:58 -07:00
Eli Friedman
f5d3346387 Infer alignment of unmarked loads in IR/bitcode parsing.
For IR generated by a compiler, this is really simple: you just take the
datalayout from the beginning of the file, and apply it to all the IR
later in the file. For optimization testcases that don't care about the
datalayout, this is also really simple: we just use the default
datalayout.

The complexity here comes from the fact that some LLVM tools allow
overriding the datalayout: some tools have an explicit flag for this,
some tools will infer a datalayout based on the code generation target.
Supporting this properly required plumbing through a bunch of new
machinery: we want to allow overriding the datalayout after the
datalayout is parsed from the file, but before we use any information
from it. Therefore, IR/bitcode parsing now has a callback to allow tools
to compute the datalayout at the appropriate time.

Not sure if I covered all the LLVM tools that want to use the callback.
(clang? lli? Misc IR manipulation tools like llvm-link?). But this is at
least enough for all the LLVM regression tests, and IR without a
datalayout is not something frontends should generate.

This change had some sort of weird effects for certain CodeGen
regression tests: if the datalayout is overridden with a datalayout with
a different program or stack address space, we now parse IR based on the
overridden datalayout, instead of the one written in the file (or the
default one, if none is specified). This broke a few AVR tests, and one
AMDGPU test.

Outside the CodeGen tests I mentioned, the test changes are all just
fixing CHECK lines and moving around datalayout lines in weird places.

Differential Revision: https://reviews.llvm.org/D78403
2020-05-14 13:03:50 -07:00
Martin Storsjö
f96eecf20b [examples] Skip building the Bye pass plugin on windows
Windows doesn't properly support pass plugins (as a shared library
can't have undefined references, which pass plugins assume, being
loaded into a host process that contains provides them), thus
disable building it and the corresponding test.

This matches what was done for the passes unit test in
bc8e44218810c0db6328b9809c959ceb7d43e3f5.

Differential Revision: https://reviews.llvm.org/D79771
2020-05-13 13:40:56 +03:00
Eli Friedman
82b54aea79 Enable new passmanager plugin support for LTO.
This should make both static and dynamic NewPM plugins work with LTO.
And as a bonus, it makes static linking of OldPM plugins more reliable
for plugins with both an OldPM and NewPM interface.

I only implemented the command-line flag to specify NewPM plugins in
llvm-lto2, to show it works. Support can be added for other tools later.

Differential Revision: https://reviews.llvm.org/D76866
2020-04-14 15:07:07 -07:00
serge-sans-paille
9479b0618c Remove no un-necessary require for load_extension.ll
Local testing on OSX no longer exhibit the linking error mentioned in
https://reviews.llvm.org/D71959#1860286
2020-02-26 08:29:09 +01:00
Ehud Katz
f6fd87fc2b [LoopExtractor] Convert LoopExtractor from LoopPass to ModulePass
The LoopExtractor created new functions (by definition), which violates
the restrictions of a LoopPass.
The correct implementation of this pass should be as a ModulePass.
Includes reverting rL82990 implications on the LoopExtractor.

Fixes PR3082 and PR8929.

Differential Revision: https://reviews.llvm.org/D69069
2020-02-09 12:25:21 +02:00
Jan Korous
4a2256fd57 Revert "Activate extension loading test on Darwin now that the underlying fix has landed"
This reverts commit 058070893428a480b76a137f647ae6b9c89ac2d4.
2020-02-05 11:04:38 -08:00
serge-sans-paille
f308ea9212 Activate extension loading test on Darwin now that the underlying fix has landed
Original bug fixed by ab2300bc154f7bed43f85f74fd3fe31be71d90e0
2020-01-30 14:04:27 +01:00
Reid Kleckner
85e933eefe [IR] Keep a double break between functions when printing a module
This behavior appears to have changed unintentionally in
b0e979724f2679e4e6f5b824144ea89289bd6d56.

Instead of printing the leading newline in printFunction, print it when
printing a module. This ensures that `OS << *Func` starts printing
immediately on the current line, but whole modules are printed nicely.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D73505
2020-01-27 15:31:09 -08:00
Amara Emerson
7eb435b9b8 Mark the test/Feature/load_extension.ll test as unsupported on Darwin.
With plugins and examples enabled, this XPASSes. Mark it as unsupported until
the owner investigates what's going on.
2020-01-10 20:18:36 -08:00
Serge Guelton
2a61810810 XFAIL load_extension.ll test on macOS only
Other setup have been fixed by 346de9b67228f42eb9b55fa3b426b5dedfdb1d40
2020-01-10 05:03:33 -05:00
Eric Christopher
c61e6c8784 XFAIL load_extension.ll for all targets currently - it's failing on
additional platforms than just darwin.
2020-01-07 17:00:55 -08:00
Florian Hahn
2ba3f87ddb [Pass Registration] XFAIL load_extension.ll test on macOS.
This test fails  on macOS, causing the following bots to fail

http://green.lab.llvm.org/green/job/clang-stage1-cmake-RA-incremental/7438/
http://green.lab.llvm.org/green/job/clang-stage1-RA/5034/

Error:
Error opening 'build/./lib/libBye.dylib': dlopen(build/./lib/libBye.dylib, 9): image not found
  -load request ignored.
2020-01-04 17:37:08 +00:00
serge-sans-paille
d731f0fb50 Fix compiler extension testing
Correctly declare example dependency. Pipe stderr through FileCheck.

Differential Revision: https://reviews.llvm.org/D72130
2020-01-03 15:42:35 +01:00
serge_sans_paille
d4f51b5c4f Generalize the pass registration mechanism used by Polly to any third-party tool
There's quite a lot of references to Polly in the LLVM CMake codebase. However
the registration pattern used by Polly could be useful to other external
projects: thanks to that mechanism it would be possible to develop LLVM
extension without touching the LLVM code base.

This patch has two effects:

1. Remove all code specific to Polly in the llvm/clang codebase, replaicing it
   with a generic mechanism

2. Provide a generic mechanism to register compiler extensions.

A compiler extension is similar to a pass plugin, with the notable difference
that the compiler extension can be configured to be built dynamically (like
plugins) or statically (like regular passes).

As a result, people willing to add extra passes to clang/opt can do it using a
separate code repo, but still have their pass be linked in clang/opt as built-in
passes.

Differential Revision: https://reviews.llvm.org/D61446
2020-01-02 16:45:31 +01:00
Kevin P. Neal
ad46a5663d This adds constrained intrinsics for the signed and unsigned conversions
of integers to floating point.

This includes some of Craig Topper's changes for promotion support from
D71130.

Differential Revision: https://reviews.llvm.org/D69275
2019-12-17 10:06:51 -05:00
Carey Williams
0f73b0ec78 Revert "[ARM] Allocatable Global Register Variables for ARM"
This reverts commit 2d739f98d8a53e38bf9faa88cdb6b0c2a363fb77.
2019-11-29 17:01:05 +00:00
Carey Williams
85671c3fae Revert "[NFC] Fix test reserve_global_reg.ll after 2d739f9"
This reverts commit aea7578fade2563cb5ea60548914667b515c457a.
2019-11-29 17:00:55 +00:00
Eric Christopher
9d2281caf5 Revert "Revert "As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there.""
This reapplies: 8ff85ed905a7306977d07a5cd67ab4d5a56fafb4

Original commit message:

As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there.

This change doesn't include any change to move from selection dag to fast isel
and that will come with other numbers that should help inform that decision.
There also haven't been any real debuggability studies with this pipeline yet,
this is just the initial start done so that people could see it and we could start
tweaking after.

Test updates: Outside of the newpm tests most of the updates are coming from either
optimization passes not run anymore (and without a compelling argument at the moment)
that were largely used for canonicalization in clang.

Original post:

http://lists.llvm.org/pipermail/llvm-dev/2019-April/131494.html

Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410

This reverts commit c9ddb02659e3ece7a0d9d6b4dac7ceea4ae46e6d.
2019-11-26 20:28:52 -08:00
Muhammad Omair Javaid
2cf4a29dd2 Revert "As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there."
This reverts commit 8ff85ed905a7306977d07a5cd67ab4d5a56fafb4.

This commit introduced 9 new failures on lldb buildbot host at http://lab.llvm.org:8014/builders/lldb-aarch64-ubuntu

Following tests were failing:
    lldb-api :: functionalities/tail_call_frames/ambiguous_tail_call_seq1/TestAmbiguousTailCallSeq1.py
    lldb-api :: functionalities/tail_call_frames/ambiguous_tail_call_seq2/TestAmbiguousTailCallSeq2.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_call_site/TestDisambiguateCallSite.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_paths_to_common_sink/TestDisambiguatePathsToCommonSink.py
    lldb-api :: functionalities/tail_call_frames/disambiguate_tail_call_seq/TestDisambiguateTailCallSeq.py
    lldb-api :: functionalities/tail_call_frames/inlining_and_tail_calls/TestInliningAndTailCalls.py
    lldb-api :: functionalities/tail_call_frames/sbapi_support/TestTailCallFrameSBAPI.py
    lldb-api :: functionalities/tail_call_frames/thread_step_out_message/TestArtificialFrameStepOutMessage.py
    lldb-api :: functionalities/tail_call_frames/thread_step_out_or_return/TestSteppingOutWithArtificialFrames.py
    lldb-api :: functionalities/tail_call_frames/unambiguous_sequence/TestUnambiguousTailCalls.py

Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410
2019-11-26 09:32:13 +05:00
Eric Christopher
5675044024 As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there.
This change doesn't include any change to move from selection dag to fast isel
and that will come with other numbers that should help inform that decision.
There also haven't been any real debuggability studies with this pipeline yet,
this is just the initial start done so that people could see it and we could start
tweaking after.

Test updates: Outside of the newpm tests most of the updates are coming from either
optimization passes not run anymore (and without a compelling argument at the moment)
that were largely used for canonicalization in clang.

Original post:

http://lists.llvm.org/pipermail/llvm-dev/2019-April/131494.html

Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410
2019-11-25 17:16:46 -08:00
Eric Christopher
7b534b3c55 Temporarily Revert "[SLP] allow forming 2-way reduction patterns" and update testcases.
After speaking with Sanjay - seeing a number of miscompiles and working
on tracking down a testcase. None of the follow on patches seem to
have helped so far.

This reverts commit 8a0aa5310bccbb42d16d11db090419fcefdd1376.
2019-11-20 16:00:53 -08:00
Eric Christopher
6d982d0bf7 Temporarily Revert "Temporarily Revert "[SLP] allow forming 2-way reduction patterns""
as there were testcase changes after that need to also be reverted.

This reverts commit cd8748a15f2d18861b3548eb26ed2b52e5ee50b4.
2019-11-20 15:39:47 -08:00
Eric Christopher
fd20022682 Temporarily Revert "[SLP] allow forming 2-way reduction patterns"
After speaking with Sanjay - seeing a number of miscompiles and working
on tracking down a testcase. None of the follow on patches seem to
have helped so far.

This reverts commit 7ff57705ba196ce649d6034614b3b9df57e1f84f.
2019-11-20 15:19:31 -08:00
Russell Gallop
dfb9b0fb32 [NFC] Fix test reserve_global_reg.ll after 2d739f9 2019-11-18 15:04:32 +00:00
Anna Welker
82ebd4fde8 [ARM] Allocatable Global Register Variables for ARM
Provides support for using r6-r11 as globally scoped
      register variables. This requires a -ffixed-rN flag
      in order to reserve rN against general allocation.

      If for a given GRV declaration the corresponding flag
      is not found, or the the register in question is the
      target's FP, we fail with a diagnostic.

      Differential Revision: https://reviews.llvm.org/D68862
2019-11-18 10:07:37 +00:00
Sanjay Patel
fd4fb656a1 [SLP] allow forming 2-way reduction patterns
We have a vector compare reduction problem seen in PR39665 comment 2:
https://bugs.llvm.org/show_bug.cgi?id=39665#c2

Or slightly reduced here:

define i1 @cmp2(<2 x double> %a0) {
  %a = fcmp ogt <2 x double> %a0, <double 1.0, double 1.0>
  %b = extractelement <2 x i1> %a, i32 0
  %c = extractelement <2 x i1> %a, i32 1
  %d = and i1 %b, %c
  ret i1 %d
}

SLP would not attempt to turn this into a vector reduction because there is an
artificial lower limit on that transform. We can not completely remove that limit
without inducing regressions though, so this patch just hacks an extra attempt at
creating a 2-way reduction to the end of the analysis.

As shown in the test file, we are still not getting some of the motivating cases,
so follow-on patches will be needed to solve those cases.

Differential Revision: https://reviews.llvm.org/D59710
2019-11-07 06:08:42 -05:00
Kevin P. Neal
02f26957db [FPEnv] Add constrained intrinsics for lrint and lround
Earlier in the year intrinsics for lrint, llrint, lround and llround were
added to llvm. The constrained versions are now implemented here.

Reviewed by:	andrew.w.kaylor, craig.topper, cameron.mcinally
Approved by:	craig.topper
Differential Revision:	https://reviews.llvm.org/D64746

llvm-svn: 373900
2019-10-07 13:20:00 +00:00
Kevin P. Neal
a24a01e0c1 [FPEnv] Strict FP tests should use the requisite function attributes.
A set of function attributes is required in any function that uses constrained
floating point intrinsics. None of our tests use these attributes.

This patch fixes this.

These tests have been tested against the IR verifier changes in D68233.

Reviewed by:	andrew.w.kaylor, cameron.mcinally, uweigand
Approved by:	andrew.w.kaylor
Differential Revision:	https://reviews.llvm.org/D67925

llvm-svn: 373761
2019-10-04 17:03:46 +00:00
Kevin P. Neal
d20252fbdf [FPEnv] Add fptosi and fptoui constrained intrinsics.
This implements constrained floating point intrinsics for FP to signed and
unsigned integers.

Quoting from D32319:
The purpose of the constrained intrinsics is to force the optimizer to
respect the restrictions that will be necessary to support things like the
STDC FENV_ACCESS ON pragma without interfering with optimizations when
these restrictions are not needed.

Reviewed by:	Andrew Kaylor, Craig Topper, Hal Finkel, Cameron McInally, Roman Lebedev, Kit Barton
Approved by:	Craig Topper
Differential Revision:	http://reviews.llvm.org/D63782

llvm-svn: 370228
2019-08-28 16:33:36 +00:00
Tim Northover
e5745c32fd IR: print value numbers for unnamed function arguments
For consistency with normal instructions and clarity when reading IR,
it's best to print the %0, %1, ... names of function arguments in
definitions.

Also modifies the parser to accept IR in that form for obvious reasons.

llvm-svn: 367755
2019-08-03 14:28:34 +00:00
Hideto Ueno
97957b2f53 [FunctionAttrs] Annotate "willreturn" for intrinsics
Summary:
In D62801, new function attribute `willreturn` was introduced. In short, a function with `willreturn` is guaranteed to come back to the call site(more precise definition is in LangRef).

In this patch, willreturn is annotated for LLVM intrinsics.

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: jvesely, nhaehnle, sstefan1, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64904

llvm-svn: 367184
2019-07-28 06:09:56 +00:00
Brian Homerding
ed0ab9dc76 Add, and infer, a nofree function attribute
This patch adds a function attribute, nofree, to indicate that a function does
not, directly or indirectly, call a memory-deallocation function (e.g., free,
C++'s operator delete).

Reviewers: jdoerfert

Differential Revision: https://reviews.llvm.org/D49165

llvm-svn: 365336
2019-07-08 15:57:56 +00:00
Petr Hosek
ac0fd59c9c [Bugpoint] Only run plugins tests if plugins are enabled
This is a followup to r360991 which applies the same logic to LLVM.

Differential Revision: https://reviews.llvm.org/D62050

llvm-svn: 360993
2019-05-17 06:41:04 +00:00
Ben Dunbobbin
2aa2767ebe [ELF] Implement Dependent Libraries Feature
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.

Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.

The design goals were to provide:

- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
  environments (MSVC in particular).

Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.

In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:

1. There are no competing defined symbols in a given set of libraries, or
   if they exist, the program owner doesn't care which is linked to their
   program.
2. There may be circular dependencies between libraries.

The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:

.section ".deplibs","MS",@llvm_dependent_libraries,1
         .asciz "foo"

For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.

LLD processes the dependent library specifiers in the following way:

1. Dependent libraries which are found from the specifiers in .deplibs sections
   of relocatable object files are added when the linker decides to include that
   file (which could itself be in a library) in the link. Dependent libraries
   behave as if they were appended to the command line after all other options. As
   a consequence the set of dependent libraries are searched last to resolve
   symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
   to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
   strings in a .deplibs section by; first, handling the string as if it was
   specified on the command line; second, by looking for the string in each of the
   library search paths in turn; third, by looking for a lib<string>.a or
   lib<string>.so (depending on the current mode of the linker) in each of the
   library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
   dependent libraries.

Rationale for the above points:

1. Adding the dependent libraries last makes the process simple to understand
   from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
   failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
   will affect all of the dependent libraries. There is a potential problem of
   surprise for developers, who might not realize that these options would apply
   to these "invisible" input files; however, despite the potential for surprise,
   this is easy for developers to reason about and gives developers the control
   that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
   find input files. The different search methods are tried by the linker in most
   obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
   ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
   is not necessary: if finer control is required developers can fall back to using
   the command line directly.

RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.

Differential Revision: https://reviews.llvm.org/D60274

llvm-svn: 360984
2019-05-17 03:44:15 +00:00
Fangrui Song
7cb7bfede4 [IR] Disallow llvm.global_ctors and llvm.global_dtors of the 2-field form in textual format
The 3-field form was introduced by D3499 in 2014 and the legacy 2-field
form was planned to be removed in LLVM 4.0

For the textual format, this patch migrates the existing 2-field form to
use the 3-field form and deletes the compatibility code.
test/Verifier/global-ctors-2.ll checks we have a friendly error message.

For bitcode, lib/IR/AutoUpgrade UpgradeGlobalVariables will upgrade the
2-field form (add i8* null as the third field).

Reviewed By: rnk, dexonsmith

Differential Revision: https://reviews.llvm.org/D61547

llvm-svn: 360742
2019-05-15 02:35:32 +00:00