306 Commits

Author SHA1 Message Date
Sam Parker
7df94e8bbc [CodeGen] Generic Hardware Loop Support
Patch which introduces a target-independent framework for generating
hardware loops at the IR level. Most of the code has been taken from
PowerPC CTRLoops and PowerPC has been ported over to use this generic
pass. The target dependent parts have been moved into
TargetTransformInfo, via isHardwareLoopProfitable, with
HardwareLoopInfo introduced to transfer information from the backend.
    
Three generic intrinsics have been introduced:
- void @llvm.set_loop_iterations
  Takes as a single operand, the number of iterations to be executed.
- i1 @llvm.loop_decrement(anyint)
  Takes the maximum number of elements processed in an iteration of
  the loop body and subtracts this from the total count. Returns
  false when the loop should exit.
- anyint @llvm.loop_decrement_reg(anyint, anyint)
  Takes the number of elements remaining to be processed as well as
  the maximum numbe of elements processed in an iteration of the loop
  body. Returns the updated number of elements remaining.

llvm-svn: 362774
2019-06-07 07:35:30 +00:00
Sjoerd Meijer
27556576bb [TargetMachine] error message unsupported code model
When the tiny code model is requested for a target machine that does not
support this, we get an error message (which is nice) but also this diagnostic
and request to submit a bug report:

    fatal error: error in backend: Target does not support the tiny CodeModel
    [Inferior 2 (process 31509) exited with code 0106]
    clang-9: error: clang frontend command failed with exit code 70 (use -v to see invocation)
    (gdb) clang version 9.0.0 (http://llvm.org/git/clang.git 29994b0c63a40f9c97c664170244a7bba5ecc15e) (http://llvm.org/git/llvm.git 95606fdf91c2d63a931e865f4b78b2e9828ddc74)
    Target: arm-arm-none-eabi
    Thread model: posix
    clang-9: note: diagnostic msg: PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
    clang-9: note: diagnostic msg:
    ********************
    PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
    Preprocessed source(s) and associated run script(s) are located at:
    clang-9: note: diagnostic msg: /tmp/tiny-dfe1a2.c
    clang-9: note: diagnostic msg: /tmp/tiny-dfe1a2.sh
    clang-9: note: diagnostic msg:

But this is not a bug, this is a feature. :-) Not only is this not a bug, this
is also pretty confusing. This patch causes just to print the fatal error and
not the diagnostic:

fatal error: error in backend: Target does not support the tiny CodeModel

Differential Revision: https://reviews.llvm.org/D62236

llvm-svn: 361370
2019-05-22 10:40:26 +00:00
Fangrui Song
6bc5ef5612 [PPC64] Parse -elfv1 -elfv2 when specified on target triple
Summary:
For big-endian powerpc64, the default ABI is ELFv1. OpenPower ABI ELFv2 is supported when -mabi=elfv2 is specified. FreeBSD support for PowerPC64 ELFv2 ABI with LLVM is in progress[1]. This patch adds an alternative way to specify ELFv2 ABI on target triple [2].

The following results are expected:

ELFv1 when using:
-target powerpc64-unknown-freebsd12.0
-target powerpc64-unknown-freebsd12.0 -mabi=elfv1
-target powerpc64-unknown-freebsd12.0-elfv1

ELFv2 when using:
-target powerpc64-unknown-freebsd12.0 -mabi=elfv2
-target powerpc64-unknown-freebsd12.0-elfv2

[1] https://wiki.freebsd.org/powerpc/llvm-elfv2
[2] https://clang.llvm.org/docs/CrossCompilation.html

Patch by Alfredo Dal'Ava Júnior!

Differential Revision: https://reviews.llvm.org/D61950

llvm-svn: 361355
2019-05-22 07:29:59 +00:00
Richard Trieu
35115b7a82 [PowerPC] Create a TargetInfo header. NFC
Move the declarations of getThe<Name>Target() functions into a new header in
TargetInfo and make users of these functions include this new header.
This fixes a layering problem.

llvm-svn: 360731
2019-05-15 00:09:58 +00:00
Kang Zhang
c6dbd0cc22 [PowerPC] Add initialization for some ppc passes
Summary:

Some llc debug options need pass-name as the parameters.
But if we use the pass-name ppc-early-ret, we will get below error:
llc test.ll -stop-after ppc-early-ret
LLVM ERROR: "ppc-early-ret" pass is not registered.
Below pass-names have the pass is not registered error:
ppc-ctr-loops
ppc-ctr-loops-verify
ppc-loop-preinc-prep
ppc-toc-reg-deps
ppc-vsx-copy
ppc-early-ret
ppc-vsx-fma-mutate
ppc-vsx-swaps
ppc-reduce-cr-ops
ppc-qpx-load-splat
ppc-branch-coalescing
ppc-branch-select

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D60248

llvm-svn: 358271
2019-04-12 09:59:40 +00:00
Eric Christopher
e1ecb61f36 Revert "[PowerPC] Add initialization for some ppc passes"
This reverts commit 6f8f98ce8de7c0e4ebd7fa2e1fd9507fe8d1c317 as it
is breaking nearly every bot.

llvm-svn: 358260
2019-04-12 07:16:58 +00:00
Kang Zhang
240e768ef4 [PowerPC] Add initialization for some ppc passes
Summary:

Some llc debug options need pass-name as the parameters.
But if we use the pass-name ppc-early-ret, we will get below error:
llc test.ll -stop-after ppc-early-ret
LLVM ERROR: "ppc-early-ret" pass is not registered.
Below pass-names have the pass is not registered error:
ppc-ctr-loops
ppc-ctr-loops-verify
ppc-loop-preinc-prep
ppc-toc-reg-deps
ppc-vsx-copy
ppc-early-ret
ppc-vsx-fma-mutate
ppc-vsx-swaps
ppc-reduce-cr-ops
ppc-qpx-load-splat
ppc-branch-coalescing
ppc-branch-select

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D60248

llvm-svn: 358256
2019-04-12 06:35:15 +00:00
QingShan Zhang
562ec4991a [NFC][PowerPC] Custom PowerPC specific machine-scheduler
This patch lays the groundwork for extending the generic machine scheduler by providing a PPC-specific implementation.
There are no functional changes as this is an incremental patch that simply provides the necessary overrides which just
encapsulate the behavior of the generic scheduler. Subsequent patches will add specific behavior.

Differential Revision: https://reviews.llvm.org/D59284

llvm-svn: 357047
2019-03-27 03:50:16 +00:00
Chandler Carruth
ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
David Green
76448ad394 [Targets] Add errors for tiny and kernel codemodel on targets that don't support them
Adds fatal errors for any target that does not support the Tiny or Kernel
codemodels by rejigging the getEffectiveCodeModel calls.

Differential Revision: https://reviews.llvm.org/D50141

llvm-svn: 348585
2018-12-07 12:10:23 +00:00
Stefan Pintilie
edd36f6e4c [PowerPC] Make no-PIC default to match GCC - LLVM
Change the default for PowerPC LE to -fno-PIC.

Differential Revision: https://reviews.llvm.org/D53383

llvm-svn: 348298
2018-12-04 20:14:57 +00:00
Stefan Pintilie
36931cd8d0 Revert "[PowerPC] Make no-PIC default to match GCC - LLVM"
This reverts commit r347069

llvm-svn: 347076
2018-11-16 19:24:23 +00:00
Stefan Pintilie
e3d9879744 [PowerPC] Make no-PIC default to match GCC - LLVM
Set -fno-PIC as the default option.

Differential Revision: https://reviews.llvm.org/D53383

llvm-svn: 347069
2018-11-16 18:36:21 +00:00
Kit Barton
5fe828ca5e [PPC] Remove Darwin support from POWER backend.
This patch issues an error message if Darwin ABI is attempted with the PPC
backend. It also cleans up existing test cases, either converting the test to
use an alternative triple or removing the test if the coverage is no longer
needed.

Updated Tests
-------------
The majority of test cases were updated to use a different triple that does not
include the Darwin ABI. Many tests were also updated to use FileCheck, in place
of grep.

Deleted Tests
-------------
llvm/test/tools/dsymutil/PowerPC/sibling.test was originally added to test
specific functionality of dsymutil using an object file created with an old
version of llvm-gcc for a Powerbook G4. After a discussion with @JDevlieghere he
suggested removing the test.

llvm/test/CodeGen/PowerPC/combine_loads_from_build_pair.ll was converted from a
PPC test to a SystemZ test, as the behavior is also reproducible there.

All other tests that were deleted were specific to the darwin/ppc ABI and no
longer necessary.

Phabricator Review: https://reviews.llvm.org/D50988

llvm-svn: 340795
2018-08-28 01:18:29 +00:00
Stefan Pintilie
f220e7cb76 [PowerPC] Replace the Post RA List Scheduler with the Machine Scheduler
We want to run the Machine Scheduler instead of the List Scheduler after RA.
  Checked with a performance run on a Power 9 machine with SPEC 2006 and while
  some benchmarks improved and others degraded the geomean was slightly improved
  with the Machine Scheduler.

  Differential Revision: https://reviews.llvm.org/D45265

llvm-svn: 336295
2018-07-04 18:54:25 +00:00
David Blaikie
3154efa401 Plumb useAA through TargetTransformInfo to remove Transforms->CodeGen header dependency
Thanks to echristo for the pointers on direction.

llvm-svn: 328737
2018-03-28 22:28:50 +00:00
David Blaikie
0bf763875a Move TargetLoweringObjectFile from CodeGen to Target to fix layering
It's implemented in Target & include from other Target headers, so the
header should be in Target.

llvm-svn: 328392
2018-03-23 23:58:19 +00:00
Sanjoy Das
df40ece177 (Re-landing) Expose a TargetMachine::getTargetTransformInfo function
Re-land r321234.  It had to be reverted because it broke the shared
library build.  The shared library build broke because there was a
missing LLVMBuild dependency from lib/Passes (which calls
TargetMachine::getTargetIRAnalysis) to lib/Target.  As far as I can
tell, this problem was always there but was somehow masked
before (perhaps because TargetMachine::getTargetIRAnalysis was a
virtual function).

Original commit message:

This makes the TargetMachine interface a bit simpler.  We still need
the std::function in TargetIRAnalysis to avoid having to add a
dependency from Analysis to Target.

See discussion:
http://lists.llvm.org/pipermail/llvm-dev/2017-December/119749.html

I avoided adding all of the backend owners to this review since the
change is simple, but let me know if you feel differently about this.

Reviewers: echristo, MatzeB, hfinkel

Reviewed By: hfinkel

Subscribers: jholewinski, jfb, arsenm, dschuff, mcrosier, sdardis, nemanjai, nhaehnle, javed.absar, sbc100, jgravelle-google, aheejin, kbarton, llvm-commits

Differential Revision: https://reviews.llvm.org/D41464

llvm-svn: 321375
2017-12-22 18:21:59 +00:00
Sanjoy Das
259bcf37bc Revert "Expose a TargetMachine::getTargetTransformInfo function"
This reverts commit r321234.  It breaks the -DBUILD_SHARED_LIBS=ON build.

llvm-svn: 321243
2017-12-21 02:34:39 +00:00
Sanjoy Das
90359bc4d6 Expose a TargetMachine::getTargetTransformInfo function
Summary:
This makes the TargetMachine interface a bit simpler.  We still need
the std::function in TargetIRAnalysis to avoid having to add a
dependency from Analysis to Target.

See discussion:
http://lists.llvm.org/pipermail/llvm-dev/2017-December/119749.html

I avoided adding all of the backend owners to this review since the
change is simple, but let me know if you feel differently about this.

Reviewers: echristo, MatzeB, hfinkel

Reviewed By: hfinkel

Subscribers: jholewinski, jfb, arsenm, dschuff, mcrosier, sdardis, nemanjai, nhaehnle, javed.absar, sbc100, jgravelle-google, aheejin, kbarton, llvm-commits

Differential Revision: https://reviews.llvm.org/D41464

llvm-svn: 321234
2017-12-21 01:06:58 +00:00
Nemanja Ivanovic
b8102d2cc0 [PowerPC] Convert r+r instructions to r+i (pre and post RA)
This patch adds the necessary infrastructure to convert instructions that
take two register operands to those that take a register and immediate if
the necessary operand is produced by a load-immediate. Furthermore, it uses
this infrastructure to perform such conversions twice - first at MachineSSA
and then pre-emit.

There are a number of reasons we may end up with opportunities for this
transformation, including but not limited to:
- X-Form instructions chosen since the exact offset isn't available at ISEL time
- Atomic instructions with constant operands (we will add patterns for this
  in the future)
- Tail duplication may duplicate code where one block contains this redundancy
- When emitting compare-free code in PPCDAGToDAGISel, we don't handle constant
  comparands specially

Furthermore, this patch moves the initialization of PPCMIPeepholePass so that
it can be used for MIR tests.

llvm-svn: 320791
2017-12-15 07:27:53 +00:00
Nemanja Ivanovic
98599706d1 [PowerPC] MachineSSA pass to reduce the number of CR-logical operations
The initial implementation of an MI SSA pass to reduce cr-logical operations.
Currently, the only operations handled by the pass are binary operations where
both CR-inputs come from the same block and the single use is a conditional
branch (also in the same block).

Committing this off by default to allow for a period of field testing. Will
enable it by default in a follow-up patch soon.

Differential Revision: https://reviews.llvm.org/D30431

llvm-svn: 320584
2017-12-13 14:47:35 +00:00
David Blaikie
e01dc73ad2 Fix a bunch more layering of CodeGen headers that are in Target
All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, not the
other way around).

llvm-svn: 318490
2017-11-17 01:07:10 +00:00
Matthias Braun
6cdc04a20c Revert "TargetMachine: Merge TargetMachine and LLVMTargetMachine"
Reverting to investigate layering effects of MCJIT not linking
libCodeGen but using TargetMachine::getNameWithPrefix() breaking the
lldb bots.

This reverts commit r315633.

llvm-svn: 315637
2017-10-12 22:57:28 +00:00
Matthias Braun
e1c491ab05 TargetMachine: Merge TargetMachine and LLVMTargetMachine
Merge LLVMTargetMachine into TargetMachine.

- There is no in-tree target anymore that just implements TargetMachine
  but not LLVMTargetMachine.
- It should still be possible to stub out all the various functions in
  case a target does not want to use lib/CodeGen
- This simplifies the code and avoids methods ending up in the wrong
  interface.

Differential Revision: https://reviews.llvm.org/D38489

llvm-svn: 315633
2017-10-12 22:28:54 +00:00
Lei Huang
ffe49cfc41 Update branch coalescing to be a PowerPC specific pass
Implementing this pass as a PowerPC specific pass.  Branch coalescing utilizes
the analyzeBranch method which currently does not include any implicit operands.
This is not an issue on PPC but must be handled on other targets.

Pass is currently off by default. Enabled via -enable-ppc-branch-coalesce.

Differential Revision : https: // reviews.llvm.org/D32776

llvm-svn: 313061
2017-09-12 18:39:11 +00:00
Eric Christopher
63c50e9047 Temporarily revert "Update branch coalescing to be a PowerPC specific pass"
From comments and code review it wasn't intended to be enabled by default yet.

This reverts commit r311588.

llvm-svn: 312214
2017-08-31 05:56:16 +00:00
Lei Huang
b2307c41ea Update branch coalescing to be a PowerPC specific pass
Implementing this pass as a PowerPC specific pass.  Branch coalescing utilizes
the analyzeBranch method which currently does not include any implicit operands.
This is not an issue on PPC but must be handled on other targets.

Differential Revision : https: // reviews.llvm.org/D32776

llvm-svn: 311588
2017-08-23 19:25:04 +00:00
Rafael Espindola
2b2c232b43 Fix the ppc jit tests.
llvm-svn: 309921
2017-08-03 04:52:45 +00:00
Rafael Espindola
f2011a3ae7 Delete Default and JITDefault code models
IMHO it is an antipattern to have a enum value that is Default.

At any given piece of code it is not clear if we have to handle
Default or if has already been mapped to a concrete value. In this
case in particular, only the target can do the mapping and it is nice
to make sure it is always done.

This deletes the two default enum values of CodeModel and uses an
explicit Optional<CodeModel> when it is possible that it is
unspecified.

llvm-svn: 309911
2017-08-03 02:16:21 +00:00
Eric Christopher
d3300ec378 Make the PPCCTRLoops pass depend on being able to access the TargetMachine and clean up accordingly.
llvm-svn: 306761
2017-06-29 23:28:45 +00:00
Hiroshi Inoue
50f0371528 [PowerPC] fix potential verification error on __tls_get_addr
This patch fixes a verification error with -verify-machineinstrs while expanding __tls_get_addr by not creating ADJCALLSTACKUP and ADJCALLSTACKDOWN if there is another ADJCALLSTACKUP in this basic block since nesting ADJCALLSTACKUP/ADJCALLSTACKDOWN is not allowed.

Here, ADJCALLSTACKUP and ADJCALLSTACKDOWN are created as a fence for instruction scheduling to avoid _tls_get_addr is scheduled before mflr in the prologue (https://bugs.llvm.org//show_bug.cgi?id=25839). So if another ADJCALLSTACKUP exists before _tls_get_addr, we do not need to create a new ADJCALLSTACKUP.

Differential Revision: https://reviews.llvm.org/D34347

llvm-svn: 306678
2017-06-29 14:13:38 +00:00
Hiroshi Inoue
69391ac868 [PowerPC] set optimization level in SelectionDAGISel
PowerPC backend does not pass the current optimization level to SelectionDAGISel and so SelectionDAGISel works with the default optimization level regardless of the current optimization level.
This patch makes the PowerPC backend set the optimization level correctly.

Differential Revision: https://reviews.llvm.org/D34615

llvm-svn: 306367
2017-06-27 04:52:17 +00:00
Hiroshi Inoue
aa8d2c3186 [PowerPC] fix trivial typos in comment, NFC
llvm-svn: 305813
2017-06-20 17:53:33 +00:00
Eric Christopher
7db18ea118 Rework logic and comment out the default relocation models for PPC.
llvm-svn: 305630
2017-06-17 02:25:56 +00:00
Eric Christopher
6321be89df Turn a large if block into a smaller early return for clarity.
llvm-svn: 305629
2017-06-17 02:25:55 +00:00
Eric Christopher
16d1a522c8 Remove the old and unused PPC32 and PPC64TargetMachine classes.
llvm-svn: 305628
2017-06-17 02:25:53 +00:00
Chandler Carruth
eb66b33867 Sort the remaining #include lines in include/... and lib/....
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.

I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.

This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.

Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).

llvm-svn: 304787
2017-06-06 11:49:48 +00:00
Matthias Braun
7b8d690af1 TargetPassConfig: Keep a reference to an LLVMTargetMachine; NFC
TargetPassConfig is not useful for targets that do not use the CodeGen
library, so we may just as well store a pointer to an
LLVMTargetMachine instead of just to a TargetMachine.

While at it, also change the constructor to take a reference instead of a
pointer as the TM must not be nullptr.

llvm-svn: 304247
2017-05-30 21:36:41 +00:00
Francis Visoiu Mistrih
5f6c901f02 [LegacyPassManager] Remove TargetMachine constructors
This provides a new way to access the TargetMachine through
TargetPassConfig, as a dependency.

The patterns replaced here are:

* Passes handling a null TargetMachine call
  `getAnalysisIfAvailable<TargetPassConfig>`.

* Passes not handling a null TargetMachine
  `addRequired<TargetPassConfig>` and call
  `getAnalysis<TargetPassConfig>`.

* MachineFunctionPasses now use MF.getTarget().

* Remove all the TargetMachine constructors.
* Remove INITIALIZE_TM_PASS.

This fixes a crash when running `llc -start-before prologepilog`.

PEI needs StackProtector, which gets constructed without a TargetMachine
by the pass manager. The StackProtector pass doesn't handle the case
where there is no TargetMachine, so it segfaults.

Related to PR30324.

Differential Revision: https://reviews.llvm.org/D33222

llvm-svn: 303360
2017-05-18 17:21:13 +00:00
Eric Christopher
268838043d Remove the default subtarget from the Power port. It's unnecessary and harmful if used.
llvm-svn: 299726
2017-04-06 23:01:30 +00:00
Eric Christopher
5e49ef02c7 Temporarily revert "[PPC] In PPCBoolRetToInt change the bool value to i64 if the target is ppc64" as it's causing test failures, I've given Carrot a testcase offline.
This reverts commit r298955.

llvm-svn: 299153
2017-03-31 02:16:54 +00:00
Guozhi Wei
299bb34210 [PPC] In PPCBoolRetToInt change the bool value to i64 if the target is ppc64
In PPCBoolRetToInt bool value is changed to i32 type. On ppc64 it may introduce an extra zero extension for the return value. This patch changes the integer type to i64 to avoid the zero extension on ppc64.

This patch fixed PR32442.

Differential Revision: https://reviews.llvm.org/D31407

llvm-svn: 298955
2017-03-28 22:55:01 +00:00
Eric Christopher
b256ef8c46 Temporarily revert "For X86-64 linux and PPC64 linux align int128 to 16 bytes."
until we can get better TargetMachine::isCompatibleDataLayout to compare - otherwise
we can't code generate existing bitcode without a string equality data layout.

This reverts commit r294702.

llvm-svn: 294709
2017-02-10 04:35:32 +00:00
Eric Christopher
e864dd4497 For X86-64 linux and PPC64 linux align int128 to 16 bytes.
For other platforms we should find out what they need and likely
make the same change, however, a smaller additional change is easier
for platforms we know have it specified	in the ABI. As part of this
rewrite some of the handling in the backends for data layout and update
a bunch of testcases.

Based on a patch by Simonas Kazlauskas!

llvm-svn: 294702
2017-02-10 03:32:21 +00:00
Tony Jiang
7cd663b80c [PowerPC] Expand ISEL instruction into if-then-else sequence.
Generally, the ISEL is expanded into if-then-else sequence, in some
cases (like when the destination register is the same with the true
or false value register), it may just be expanded into just the if
or else sequence.

llvm-svn: 292154
2017-01-16 20:12:26 +00:00
Tony Jiang
126ab16f24 Revert "[PowerPC] Expand ISEL instruction into if-then-else sequence."
This reverts commit 1d0e0374438ca6e153844c683826ba9b82486bb1.

llvm-svn: 292131
2017-01-16 15:01:07 +00:00
Tony Jiang
dc6e042270 [PowerPC] Expand ISEL instruction into if-then-else sequence.
Generally, the ISEL is expanded into if-then-else sequence, in some
cases (like when the destination register is the same with the true
or false value register), it may just be expanded into just the if
or else sequence.

llvm-svn: 292128
2017-01-16 14:43:12 +00:00
Eugene Zelenko
94f3a7bd66 [PowerPC] Fix some Clang-tidy modernize and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 291872
2017-01-13 00:58:58 +00:00
Joerg Sonnenberger
5ece3a7510 Use PIC relocation model as default for PowerPC64 ELF.
Most of the PowerPC64 code generation for the ELF ABI is already PIC.
There are four main exceptions:
(1) Constant pointer arrays etc. should in writeable sections.
(2) The TOC restoration NOP after a call is needed for all global
symbols. While GNU ld has a workaround for questionable GCC self-calls,
we trigger the checks for calls from COMDAT sections as they cross input
sections and are therefore not considered self-calls. The current
decision is questionable and suboptimal, but outside the scope of the
change.
(3) TLS access can not use the initial-exec model.
(4) Jump tables should use relative addresses. Note that the current
encoding doesn't work for the large code model, but it is more compact
than the default for any non-trivial jump table. Improving this is again
beyond the scope of this change.

At least (1) and (3) are assumptions made in target-independent code and
introducing additional hooks is a bit messy. Testing with clang shows
that a -fPIC binary is 600KB smaller than the corresponding -fno-pic
build. Separate testing from improved jump table encodings would explain
only about 100KB or so. The rest is expected to be a result of more
aggressive immediate forming for -fno-pic, where the -fPIC binary just
uses TOC entries.

This change brings the LLVM output in line with the GCC output, other
PPC64 compilers like XLC on AIX are known to produce PIC by default
as well. The relocation model can still be provided explicitly, i.e.
when using MCJIT.

One test case for case (1) is included, other test cases with relocation
mode sensitive behavior are wired to static for now. They will be
reviewed and adjusted separately.

Differential Revision: https://reviews.llvm.org/D26566

llvm-svn: 289743
2016-12-15 00:01:53 +00:00