Commit Graph

26926 Commits

Author SHA1 Message Date
Mehdi Amini
6875fa5607 Add a pass to name anonymous/nameless function
Summary:
For correct handling of alias to nameless
function, we need to be able to refer them through a GUID in the summary.
Here we name them using a hash of the non-private global names in the module.

Reviewers: tejohnson

Subscribers: joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D18883

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266132
2016-04-12 21:35:28 +00:00
Mehdi Amini
03a2cdacee Move summary creation out of llvm-as into opt
Summary:
Let keep llvm-as "dumb": it converts textual IR to bitcode. This
commit removes the dependency from llvm-as to libLLVMAnalysis.
We'll add back summary in llvm-as if we get to a textual
representation for it at some point. In the meantime, opt seems
like a better place for that.

Reviewers: tejohnson

Subscribers: joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D19032

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266131
2016-04-12 21:35:18 +00:00
Nicolai Haehnle
30a743add7 AMDGPU: add llvm.amdgcn.buffer.load/store intrinsics
Summary:
They correspond to BUFFER_LOAD/STORE_DWORD[_X2,X3,X4] and mostly behave like
llvm.amdgcn.buffer.load/store.format. They will be used by Mesa for SSBO and
atomic counters at least when robust buffer access behavior is desired.
(These instructions perform no format conversion and do buffer range checking
per component.)

As a side effect of sharing patterns with llvm.amdgcn.buffer.store.format,
it has become trivial to add support for the f32 and v2f32 variants of that
intrinsic, so the patch does so.

Also DAG-ify (and fix) some tests that I noticed intermittent failures in
while developing this patch.

Some tests were (temporarily) adjusted for the required mayLoad/hasSideEffects
changes to the BUFFER_STORE_DWORD* instructions. See also
http://reviews.llvm.org/D18291.

Reviewers: arsenm, tstellarAMD, mareko

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D18292

llvm-svn: 266126
2016-04-12 21:18:10 +00:00
Teresa Johnson
59b10dce61 [ThinLTO] Only compute imports for current module in FunctionImport pass
Summary:
The function import pass was computing all the imports for all the
modules in the index, and only using the imports for the current module.
Change this to instead compute only for the given module. This means
that the exports list can't be populated, but they weren't being used
anyway.

Longer term, the linker can collect all the imports and export lists
and serialize them out for consumption by the distributed backend
processes which use this pass.

Reviewers: joker.eph

Subscribers: llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D18945

llvm-svn: 266125
2016-04-12 21:13:11 +00:00
James Y Knight
a55b68a75e Add __atomic_* lowering to AtomicExpandPass.
(Recommit of r266002, with r266011, r266016, and not accidentally
including an extra unused/uninitialized element in LibcallRoutineNames)

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266115
2016-04-12 20:18:48 +00:00
Matt Arsenault
795072118d APInt: Add overload of isMask
This mimics the version in MathExtras.h which isn't testing for a
specific mask size.

llvm-svn: 266101
2016-04-12 18:17:23 +00:00
Philip Reames
53d0eef093 Introduce an GCRelocateInst class [NFC]
Previously, we were using isGCRelocate predicates.  Using a subclass of IntrinsicInst is far more idiomatic.  The refactoring also enables a couple of minor simplifications and code sharing.

llvm-svn: 266098
2016-04-12 18:05:10 +00:00
Artur Pilipenko
d9a8d9a1af Support arbitrary addrspace pointers in masked load/store intrinsics
This is a resubmittion of 263158 change.

This patch fixes the problem which occurs when loop-vectorize tries to use @llvm.masked.load/store intrinsic for a non-default addrspace pointer. It fails with "Calling a function with a bad signature!" assertion in CallInst constructor because it tries to pass a non-default addrspace pointer to the pointer argument which has default addrspace.

The fix is to add pointer type as another overloaded type to @llvm.masked.load/store intrinsics.

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17270

llvm-svn: 266086
2016-04-12 15:58:04 +00:00
Matt Arsenault
f100af354c AMDGPU: Add atomic_inc + atomic_dec intrinsics
These are different than atomicrmw add 1 because they have
an additional input value to clamp the result.

llvm-svn: 266074
2016-04-12 14:05:04 +00:00
Rafael Espindola
b04bc032f0 This reverts commit r266002, r266011 and r266016.
They broke the msan bot.

Original message:

Add __atomic_* lowering to AtomicExpandPass.

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw,and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266062
2016-04-12 12:30:25 +00:00
Mehdi Amini
f1caa14180 Refactor the Internalize stage of libLTO in a separate file (NFC)
This is intended to be shared by the ThinLTOCodeGenerator.

Note that there is a change in the way the verifier is run, previously
it was ran as a Pass on the merged module during internalization.
While now the verifier is called explicitely on the merged module
outside of the internalize "pass pipeline".

What remains strange in the API is the fact that `DisableVerify` in
the API does not disable this initial verifier.

Differential Revision: http://reviews.llvm.org/D19000

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266047
2016-04-12 06:34:10 +00:00
Mehdi Amini
97f744e831 Use StringSet instead of StringMap where it makes sense to in LTOCodeGenerator (NFC)
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266046
2016-04-12 06:33:44 +00:00
Matthias Braun
ca2eebf587 TargetLowering: Add missing doxygen group end.
The missing end was also confusing the '{', '}' matching heuristics in
vim.

llvm-svn: 266036
2016-04-12 02:16:15 +00:00
George Burgess IV
4e2d8dca99 Add the allocsize attribute to LLVM.
`allocsize` is a function attribute that allows users to request that
LLVM treat arbitrary functions as allocation functions.

This patch makes LLVM accept the `allocsize` attribute, and makes
`@llvm.objectsize` recognize said attribute.

The review for this was split into two patches for ease of reviewing:
D18974 and D14933. As promised on the revisions, I'm landing both
patches as a single commit.

Differential Revision: http://reviews.llvm.org/D14933

llvm-svn: 266032
2016-04-12 01:05:35 +00:00
Quentin Colombet
312261ffb2 [RegBankSelect] Teach how to repair definitions.
Although repairing definitions is not mandatory for correctness (only
phis would be impacted because of the RPO traversal), not repairing
might go against the cost model. Therefore, just repair when it is
possible.

llvm-svn: 266025
2016-04-12 00:12:59 +00:00
Quentin Colombet
afceaae11d [MachineIRBuilder] Expose the insertion point in the public API.
It may be convenient to know where we are about to insert some code, for
instance to save and then restore this insertion.

llvm-svn: 266024
2016-04-12 00:07:14 +00:00
Derek Schuff
bf676249bc Replace MachineRegisterInfo::TracksLiveness with a MachineFunctionProperty
Use the MachineFunctionProperty mechanism to indicate whether the
liveness info is accurate instead of a bool flag on MRI.
Keeps the MRI accessor function for convenience. NFC

Differential Revision: http://reviews.llvm.org/D18767

llvm-svn: 266020
2016-04-11 23:32:13 +00:00
Mehdi Amini
bf78d0ed58 ThinLTO renaming: use module hash instead of position in the summary
This is more robust to changes in the link ordering.

Differential Revision: http://reviews.llvm.org/D18946

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266018
2016-04-11 23:26:46 +00:00
James Y Knight
003ee915ba Add __atomic_* lowering to AtomicExpandPass.
AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266002
2016-04-11 22:22:33 +00:00
Reid Kleckner
4c1925e12c Use member initializers for all scalar fields of MachineFrameInfo to save boilerplate
No functionality change.

llvm-svn: 265972
2016-04-11 17:54:16 +00:00
Reid Kleckner
20a4aff741 Combine redundant stack realignment booleans in MachineFrameInfo
MachineFrameInfo does not need to be able to distinguish between the
user asking us not to realign the stack and the target telling us it
doesn't support stack realignment. Either way, fixed stack objects have
their alignment clamped.

llvm-svn: 265971
2016-04-11 17:54:03 +00:00
Tom Stellard
d52acda33e TargetRegisterInfo: Add getRegAsmName()
Summary:
The motivation for this new function is to move an invalid assumption
about the relationship between the names of register definitions in
tablegen files and their assembly names into TargetRegisterInfo, so that
we can begin working on fixing this assumption.

The current problem is that if you have a register definition in
TableGen like:

def MYReg0 : Register<"r0", 0>;

The function TargetLowering::getRegForInlineAsmConstraint() derives the
assembly name from the tablegen name: "MyReg0" rather than the given
assembly name "r0".  This is working, because on most targets the
tablegen name and the assembly names are case insensitive matches for
each other (e.g. def EAX : X86Reg<"eax", ...>

getRegAsmName() will allow targets to override this default assumption and
return the correct assembly name.

Reviewers: echristo, hfinkel

Subscribers: SamWot, echristo, hfinkel, llvm-commits

Differential Revision: http://reviews.llvm.org/D15614

llvm-svn: 265955
2016-04-11 16:21:12 +00:00
Sanjoy Das
23c7d74ce2 This reverts commit r265913 and r265912
See PR27315

r265913: "[IndVars] Eliminate op.with.overflow when possible"

r265912: "[SCEV] See through op.with.overflow intrinsics"
llvm-svn: 265950
2016-04-11 15:26:18 +00:00
Teresa Johnson
d7c9485243 [ThinLTO] Move summary computation from BitcodeWriter to new pass
Summary:
This is the first step in also serializing the index out to LLVM
assembly.

The per-module summary written to bitcode is moved out of the bitcode
writer and to a new analysis pass (ModuleSummaryIndexWrapperPass).
The pass itself uses a new builder class to compute index, and the
builder class is used directly in places where we don't have a pass
manager (e.g. llvm-as).

Because we are computing summaries outside of the bitcode writer, we no
longer can use value ids created by the bitcode writer's
ValueEnumerator. This required changing the reference graph edge type
to use a new ValueInfo class holding a union between a GUID (combined
index) and Value* (permodule index). The Value* are converted to the
appropriate value ID during bitcode writing.

Also, this enables removal of the BitWriter library's dependence on the
Analysis library that was previously required for the summary computation.

Reviewers: joker.eph

Subscribers: joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D18763

llvm-svn: 265941
2016-04-11 13:58:45 +00:00
Sanjoy Das
e72674dde8 [SCEV] See through op.with.overflow intrinsics
Summary:
This change teaches SCEV to see reduce `(extractvalue
0 (op.with.overflow X Y))` into `op X Y` (with a no-wrap tag if
possible).

Reviewers: atrick, regehr

Subscribers: mcrosier, mzolotukhin, llvm-commits

Differential Revision: http://reviews.llvm.org/D18684

llvm-svn: 265912
2016-04-10 22:50:26 +00:00
Mehdi Amini
6ed54cb0ed Plumb the option to emit the ModuleHash in the bitcode through the bitcode writer APIs
From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265907
2016-04-10 21:07:19 +00:00
Charles Davis
9f6526358e [CodeGen] Don't assume that fixed stack objects are aligned in a stack-realigned function.
Summary:
After we make the adjustment, we can assume that for local allocas, but
not for stack parameters, the return address, or any other fixed stack
object (which has a negative offset and therefore lies prior to the
adjusted SP).

Fixes PR26662.

Reviewers: hfinkel, qcolombet, rnk

Subscribers: rnk, llvm-commits

Differential Revision: http://reviews.llvm.org/D18471

llvm-svn: 265886
2016-04-09 23:34:42 +00:00
JF Bastien
16f8e8748e Fix hash_integer_value
Broken in D18938 because underlying_type only works for enums and not all stdlibs are sad when given a non-enum. Bots error out with 'only enumeration types have underlying types'.

There's probably a clever enable_if-ism that I can do with underlying_type and the actual integer value, but is_integral_or_enum also accepts implicit conversion so I need to ponder my life choices a bit before committing to template magic. A quick fix for now.

llvm-svn: 265880
2016-04-09 20:25:02 +00:00
JF Bastien
fd71b93500 is_integral_or_enum ❥ enum class ⇒ hashable enum class
Summary:
As discussed in D18775 making AtomicOrdering an enum class makes it non-hashable, which shouldn't be the case. Hashing.h defines hash_value for all is_integral_or_enum, but type_traits.h's definition of is_integral_or_enum only checks for *inplicit* conversion to integral types which leaves enum classes out and is very confusing because is_enum is true for enum classes.

This patch:
  - Adds a check for is_enum when determining is_integral_or_enum.
  - Explicitly converts the value parameter in hash_value to handle enum class hashing.

Note that the warning at the top of Hashing.h still applies: each execution of the program has a high probability of producing a different hash_code for a given input. Thus their values are not stable to save or persist, and should only be used during the execution for the construction of hashing datastructures.

Reviewers: dberlin, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18938

llvm-svn: 265879
2016-04-09 20:04:34 +00:00
Sanjay Patel
ea5cc7e72d [x86] use BMI 'andn' for logic + compare ops
With BMI, we can use 'andn' to save an instruction when the result is only used in a compare.
This is related to one of the potential sequences to check 'isfinite' in:
https://llvm.org/bugs/show_bug.cgi?id=27164

Differential Revision: http://reviews.llvm.org/D18910

llvm-svn: 265875
2016-04-09 16:02:52 +00:00
Adrian Prantl
4300f8a4c5 Support the Nodebug emission kind for DICompileUnits.
Sample-based profiling and optimization remarks currently remove
DICompileUnits from llvm.dbg.cu to suppress the emission of debug info
from them. This is somewhat of a hack and only borderline legal IR.

This patch uses the recently introduced NoDebug emission kind in
DICompileUnit to achieve the same result without breaking the Verifier.
A nice side-effect of this change is that it is now possible to combine
NoDebug and regular compile units under LTO.

http://reviews.llvm.org/D18808
<rdar://problem/25427165>

llvm-svn: 265861
2016-04-08 22:43:03 +00:00
Sanjay Patel
744e3da853 fix documentation comments; NFC
llvm-svn: 265855
2016-04-08 21:42:43 +00:00
Tim Shen
8cac1d5c28 [SSP] Remove llvm.stackprotectorcheck.
This is a cleanup patch for SSP support in LLVM. There is no functional change.
llvm.stackprotectorcheck is not needed, because SelectionDAG isn't
actually lowering it in SelectBasicBlock; rather, it adds check code in
FinishBasicBlock, ignoring the position where the intrinsic is inserted
(See FindSplitPointForStackProtector()).

llvm-svn: 265851
2016-04-08 21:26:31 +00:00
Kyle Butt
0a6f26fc08 Codegen: Factor tail duplication into a utility class. NFC
This is in preparation for tail duplication during block placement. See D18226.
This needs to be a utility class for 2 reasons. No passes may run after block
placement, and also, tail-duplication affects subsequent layout decisions, so
it must be interleaved with placement, and can't be separated out into its own
pass. The original pass is still useful, and now runs by delegating to the
utility class.

llvm-svn: 265842
2016-04-08 20:35:01 +00:00
Duncan P. N. Exon Smith
436cc1b92b ValueMapper: Extract llvm::RemapFunction from IRMover.cpp, NFC
Strip out the remapping parts of IRLinker::linkFunctionBody and put them
in ValueMapper.cpp under the name Mapper::remapFunction (with a
top-level entry-point llvm::RemapFunction).

This is a nice cleanup on its own since it puts the remapping code
together and shares a single Mapper context for the entire
IRLinker::linkFunctionBody Call.  Besides that, this will make it easier
to break the co-recursion between IRMover.cpp and ValueMapper.cpp in
follow ups.

llvm-svn: 265835
2016-04-08 19:26:32 +00:00
Duncan P. N. Exon Smith
61b07b7af9 ValueMapper: Roll RemapInstruction into Mapper, NFC
Add Mapper::remapInstruction, move the guts of llvm::RemapInstruction
into it, and use the same Mapper for most of the calls to MapValue and
MapMetadata.  There should be no functionality change here.

I left off the call to MapValue that wasn't passing in a Materializer
argument (for basic blocks of PHINodes).  It shouldn't change
functionality either, but I'm suspicious enough to commit separately.

llvm-svn: 265832
2016-04-08 19:09:34 +00:00
Duncan P. N. Exon Smith
695a2ff629 ValueMapper: Don't memoize metadata when RF_NoModuleLevelChanges
Prevent the Metadata side-table in ValueMap from growing unnecessarily
when RF_NoModuleLevelChanges.  As a drive-by, make ValueMap::hasMD,
which apparently had no users until I used it here for testing, actually
compile.

llvm-svn: 265828
2016-04-08 18:49:36 +00:00
Hans Wennborg
8c75bb0137 Revert r265547 "Recommit r265309 after fixed an invalid memory reference bug happened"
It caused PR27275: "ARM: Bad machine code: Using an undefined physical register"

Also reverting the following commits that were landed on top:
r265610 "Fix the compare-clang diff error introduced by r265547."
r265639 "Fix the sanitizer bootstrap error in r265547."
r265657 "InlineSpiller.cpp: Escap \@ in r265547. [-Wdocumentation]"

llvm-svn: 265790
2016-04-08 15:17:43 +00:00
Silviu Baranga
a0999051a2 Re-commit [SCEV] Introduce a guarded backedge taken count and use it in LAA and LV
This re-commits r265535 which was reverted in r265541 because it
broke the windows bots. The problem was that we had a PointerIntPair
which took a pointer to a struct allocated with new. The problem
was that new doesn't provide sufficient alignment guarantees.
This pattern was already present before r265535 and it just happened
to work. To fix this, we now separate the PointerToIntPair from the
ExitNotTakenInfo struct into a pointer and a bool.

Original commit message:

Summary:
When the backedge taken codition is computed from an icmp, SCEV can
deduce the backedge taken count only if one of the sides of the icmp
is an AddRecExpr. However, due to sign/zero extensions, we sometimes
end up with something that is not an AddRecExpr.

However, we can use SCEV predicates to produce a 'guarded' expression.
This change adds a method to SCEV to get this expression, and the
SCEV predicate associated with it.

In HowManyGreaterThans and HowManyLessThans we will now add a SCEV
predicate associated with the guarded backedge taken count when the
analyzed SCEV expression is not an AddRecExpr. Note that we only do
this as an alternative to returning a 'CouldNotCompute'.

We use new feature in Loop Access Analysis and LoopVectorize to analyze
and transform more loops.

Reviewers: anemet, mzolotukhin, hfinkel, sanjoy

Subscribers: flyingforyou, mcrosier, atrick, mssimpso, sanjoy, mzolotukhin, llvm-commits

Differential Revision: http://reviews.llvm.org/D17201

llvm-svn: 265786
2016-04-08 14:29:09 +00:00
Jeroen Ketema
04e6411373 [llvm-c] Expose LLVMContextGetDiagnostic{Handler,Context}
Differential Revision: http://reviews.llvm.org/D18820

llvm-svn: 265773
2016-04-08 09:19:02 +00:00
Duncan P. N. Exon Smith
89c4487fee Reapply "ValueMapper: Treat LocalAsMetadata more like function-local Values"
This reverts commit r265765, reapplying r265759 after changing a call from
LocalAsMetadata::get to ValueAsMetadata::get (and adding a unit test).  When a
local value is mapped to a constant (like "i32 %a" => "i32 7"), the new debug
intrinsic operand may no longer be pointing at a local.

    http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA_build/19020/

The previous coommit message follows:

--

This is a partial re-commit -- maybe more of a re-implementation -- of
r265631 (reverted in r265637).

This makes RF_IgnoreMissingLocals behave (almost) consistently between
the Value and the Metadata hierarchy.  In particular:

  - MapValue returns nullptr or "metadata !{}" for missing locals in
    MetadataAsValue/LocalAsMetadata bridging paris, depending on
    the RF_IgnoreMissingLocals flag.

  - MapValue doesn't memoize LocalAsMetadata-related results.

  - MapMetadata no longer deals with LocalAsMetadata or
    RF_IgnoreMissingLocals at all.  (This wasn't in r265631 at all, but
    I realized during testing it would make the patch simpler with no
    loss of generality.)

r265631 went too far, making both functions universally ignore
RF_IgnoreMissingLocals.  This broke building (e.g.) compiler-rt.
Reassociate (and possibly other passes) don't currently maintain
dominates-use invariants for metadata operands, resulting in IR like
this:

    define void @foo(i32 %arg) {
      call void @llvm.some.intrinsic(metadata i32 %x)
      %x = add i32 1, i32 %arg
    }

If the inliner chooses to inline @foo into another function, then
RemapInstruction will call `MapValue(metadata i32 %x)` and assert that
the return is not nullptr.

I've filed PR27273 to add a Verifier check and fix the underlying
problem in the optimization passes.

As a workaround, return `!{}` instead of nullptr for unmapped
LocalAsMetadata when RF_IgnoreMissingLocals is unset.  Otherwise, match
the behaviour of r265631.

Original commit message:

    ValueMapper: Make LocalAsMetadata match function-local Values

    Start treating LocalAsMetadata similarly to function-local members of
    the Value hierarchy in MapValue and MapMetadata.

      - Don't memoize them.
      - Return nullptr if they are missing.

    This also cleans up ConstantAsMetadata to stop listening to the
    RF_IgnoreMissingLocals flag.

llvm-svn: 265768
2016-04-08 03:13:22 +00:00
Duncan P. N. Exon Smith
957a52adbf Revert "ValueMapper: Treat LocalAsMetadata more like function-local Values"
This reverts commit r265759, since even this limited version breaks some
bots:
  http://lab.llvm.org:8011/builders/clang-ppc64be-linux/builds/3311
  http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-autoconf/builds/17696

This also reverts r265761 "ValueMapper: Unduplicate
RF_NoModuleLevelChanges check, NFC", since I had trouble separating it
from r265759.

llvm-svn: 265765
2016-04-08 00:56:21 +00:00
Quentin Colombet
f126967795 [TargetRegisterInfo] Fix BitMaskClassIterator::moveToNextID implementation.
Make sure we do not read past the size of the mask. Although we were not using
the value read, this is bad and makes ASan complain.

llvm-svn: 265763
2016-04-08 00:50:58 +00:00
Sanjoy Das
b20d278ebd Don't IPO over functions that can be de-refined
Summary:
Fixes PR26774.

If you're aware of the issue, feel free to skip the "Motivation"
section and jump directly to "This patch".

Motivation:

I define "refinement" as discarding behaviors from a program that the
optimizer has license to discard.  So transforming:

```
void f(unsigned x) {
  unsigned t = 5 / x;
  (void)t;
}
```

to

```
void f(unsigned x) { }
```

is refinement, since the behavior went from "if x == 0 then undefined
else nothing" to "nothing" (the optimizer has license to discard
undefined behavior).

Refinement is a fundamental aspect of many mid-level optimizations done
by LLVM.  For instance, transforming `x == (x + 1)` to `false` also
involves refinement since the expression's value went from "if x is
`undef` then { `true` or `false` } else { `false` }" to "`false`" (by
definition, the optimizer has license to fold `undef` to any non-`undef`
value).

Unfortunately, refinement implies that the optimizer cannot assume
that the implementation of a function it can see has all of the
behavior an unoptimized or a differently optimized version of the same
function can have.  This is a problem for functions with comdat
linkage, where a function can be replaced by an unoptimized or a
differently optimized version of the same source level function.

For instance, FunctionAttrs cannot assume a comdat function is
actually `readnone` even if it does not have any loads or stores in
it; since there may have been loads and stores in the "original
function" that were refined out in the currently visible variant, and
at the link step the linker may in fact choose an implementation with
a load or a store.  As an example, consider a function that does two
atomic loads from the same memory location, and writes to memory only
if the two values are not equal.  The optimizer is allowed to refine
this function by first CSE'ing the two loads, and the folding the
comparision to always report that the two values are equal.  Such a
refined variant will look like it is `readonly`.  However, the
unoptimized version of the function can still write to memory (since
the two loads //can// result in different values), and selecting the
unoptimized version at link time will retroactively invalidate
transforms we may have done under the assumption that the function
does not write to memory.

Note: this is not just a problem with atomics or with linking
differently optimized object files.  See PR26774 for more realistic
examples that involved neither.

This patch:

This change introduces a new set of linkage types, predicated as
`GlobalValue::mayBeDerefined` that returns true if the linkage type
allows a function to be replaced by a differently optimized variant at
link time.  It then changes a set of IPO passes to bail out if they see
such a function.

Reviewers: chandlerc, hfinkel, dexonsmith, joker.eph, rnk

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D18634

llvm-svn: 265762
2016-04-08 00:48:30 +00:00
Duncan P. N. Exon Smith
1f42c70b4f ValueMapper: Treat LocalAsMetadata more like function-local Values
This is a partial re-commit -- maybe more of a re-implementation -- of
r265631 (reverted in r265637).

This makes RF_IgnoreMissingLocals behave (almost) consistently between
the Value and the Metadata hierarchy.  In particular:

  - MapValue returns nullptr or "metadata !{}" for missing locals in
    MetadataAsValue/LocalAsMetadata bridging paris, depending on
    the RF_IgnoreMissingLocals flag.

  - MapValue doesn't memoize LocalAsMetadata-related results.

  - MapMetadata no longer deals with LocalAsMetadata or
    RF_IgnoreMissingLocals at all.  (This wasn't in r265631 at all, but
    I realized during testing it would make the patch simpler with no
    loss of generality.)

r265631 went too far, making both functions universally ignore
RF_IgnoreMissingLocals.  This broke building (e.g.) compiler-rt.
Reassociate (and possibly other passes) don't currently maintain
dominates-use invariants for metadata operands, resulting in IR like
this:

    define void @foo(i32 %arg) {
      call void @llvm.some.intrinsic(metadata i32 %x)
      %x = add i32 1, i32 %arg
    }

If the inliner chooses to inline @foo into another function, then
RemapInstruction will call `MapValue(metadata i32 %x)` and assert that
the return is not nullptr.

I've filed PR27273 to add a Verifier check and fix the underlying
problem in the optimization passes.

As a workaround, return `!{}` instead of nullptr for unmapped
LocalAsMetadata when RF_IgnoreMissingLocals is unset.  Otherwise, match
the behaviour of r265631.

Original commit message:

    ValueMapper: Make LocalAsMetadata match function-local Values

    Start treating LocalAsMetadata similarly to function-local members of
    the Value hierarchy in MapValue and MapMetadata.

      - Don't memoize them.
      - Return nullptr if they are missing.

    This also cleans up ConstantAsMetadata to stop listening to the
    RF_IgnoreMissingLocals flag.

llvm-svn: 265759
2016-04-08 00:33:44 +00:00
Quentin Colombet
d8b8e21c6f [RegisterBankInfo] Add print and dump method to the InstructionMapping
helper class.

llvm-svn: 265747
2016-04-07 23:31:58 +00:00
Quentin Colombet
980ab75040 [RegisterBankInfo] Add print and dump method to the ValueMapping helper
class.

llvm-svn: 265746
2016-04-07 23:25:43 +00:00
Quentin Colombet
8a8671e8bb [RegisterBankInfo] Escap \@ in r265741. [-Wdocumentation]
llvm-svn: 265742
2016-04-07 23:08:52 +00:00
Quentin Colombet
c7b62134f9 [RegisterBankInfo] Change the semantic of recordRegBankForType.
Now, recordRegBankForType records only the first register bank that
covers a type instead of the last. This behavior can, nevertheless, be
override with the additional Force parameter to force the update.

llvm-svn: 265741
2016-04-07 23:02:00 +00:00
David Blaikie
841beedad7 llvm-dwarfdump: Use deque rather than vector to preserve object reference/pointer identity
TUs in each unit refer to the unit they are in, if the unit is moved
this reference is invalidated & things break.

No test case because UB isn't testable - ASan would likely catch this on
a large enough test case (just needs to have enough TUs that a
reallocation of the vector would occur) but didn't seem worthwhile. Up
for debate/revisiting if anyone feels strongly.

llvm-svn: 265740
2016-04-07 22:59:58 +00:00