Use a combination of !associated, comdat, @llvm.compiler.used and
custom sections to allow dead stripping of globals and their asan
metadata. Sometimes.
Currently this works on LLD, which supports SHF_LINK_ORDER with
sh_link pointing to the associated section.
This also works on BFD, which seems to treat comdats as
all-or-nothing with respect to linker GC. There is a weird quirk
where the "first" global in each link is never GC-ed because of the
section symbols.
At this moment it does not work on Gold (as in the globals are never
stripped).
This is a second re-land of r298158. This time, this feature is
limited to -fdata-sections builds.
The only reason not to is global registration, which can be
TU-specific. This is not the case when there are no instrumented
globals. This is also limited to ELF targets, because MachO does
not have comdat, and COFF linkers may GC comdat constructors.
The benefit of this is a lot less __asan_init() calls: one per DSO
instead of one per TU. It's also necessary for the upcoming
gc-sections-for-globals change on Linux, where multiple references to
section start symbols trigger quadratic behaviour in gold linker.
This is a second re-land of r298756. This time with a flag to disable
the whole thing to avoid a bug in the gold linker:
https://sourceware.org/bugzilla/show_bug.cgi?id=19002
This patch dumps the raw bytes of the .rsrc sections that
are present in COFF object and executable files. Subsequent
patches will parse this information and dump in a more human
readable format.
Differential Revision: https://reviews.llvm.org/D32463
Patch By: Eric Beckmann
[PM/LoopUnswitch] Introduce a new, simpler loop unswitch pass.
Currently, this pass only focuses on *trivial* loop unswitching. At that
reduced problem it remains significantly better than the current loop
unswitch:
- Old pass is worse than cubic complexity. New pass is (I think) linear.
- New pass is much simpler in its design by focusing on full unswitching. (See
below for details on this).
- New pass doesn't carry state for thresholds between pass iterations.
- New pass doesn't carry state for correctness (both miscompile and
infloop) between pass iterations.
- New pass produces substantially better code after unswitching.
- New pass can handle more trivial unswitch cases.
- New pass doesn't recompute the dominator tree for the entire function
and instead incrementally updates it.
I've ported all of the trivial unswitching test cases from the old pass
to the new one to make sure that major functionality isn't lost in the
process. For several of the test cases I've worked to improve the
precision and rigor of the CHECKs, but for many I've just updated them
to handle the new IR produced.
My initial motivation was the fact that the old pass carried state in
very unreliable ways between pass iterations, and these mechansims were
incompatible with the new pass manager. However, I discovered many more
improvements to make along the way.
This pass makes two very significant assumptions that enable most of these
improvements:
1) Focus on *full* unswitching -- that is, completely removing whatever
control flow construct is being unswitched from the loop. In the case
of trivial unswitching, this means removing the trivial (exiting)
edge. In non-trivial unswitching, this means removing the branch or
switch itself. This is in opposition to *partial* unswitching where
some part of the unswitched control flow remains in the loop. Partial
unswitching only really applies to switches and to folded branches.
These are very similar to full unrolling and partial unrolling. The
full form is an effective canonicalization, the partial form needs
a complex cost model, cannot be iterated, isn't canonicalizing, and
should be a separate pass that runs very late (much like unrolling).
2) Leverage LLVM's Loop machinery to the fullest. The original unswitch
dates from a time when a great deal of LLVM's loop infrastructure was
missing, ineffective, and/or unreliable. As a consequence, a lot of
complexity was added which we no longer need.
With these two overarching principles, I think we can build a fast and
effective unswitcher that fits in well in the new PM and in the
canonicalization pipeline. Some of the remaining functionality around
partial unswitching may not be relevant today (not many test cases or
benchmarks I can find) but if they are I'd like to add support for them
as a separate layer that runs very late in the pipeline.
Purely to make reviewing and introducing this code more manageable, I've
split this into first a trivial-unswitch-only pass and in the next patch
I'll add support for full non-trivial unswitching against a *fixed*
threshold, exactly like full unrolling. I even plan to re-use the
unrolling thresholds, as these are incredibly similar cost tradeoffs:
we're cloning a loop body in order to end up with simplified control
flow. We should only do that when the total growth is reasonably small.
One of the biggest changes with this pass compared to the previous one
is that previously, each individual trivial exiting edge from a switch
was unswitched separately as a branch. Now, we unswitch the entire
switch at once, with cases going to the various destinations. This lets
us unswitch multiple exiting edges in a single operation and also avoids
numerous extremely bad behaviors, where we would introduce 1000s of
branches to test for thousands of possible values, all of which would
take the exact same exit path bypassing the loop. Now we will use
a switch with 1000s of cases that can be efficiently lowered into
a jumptable. This avoids relying on somehow forming a switch out of the
branches or getting horrible code if that fails for any reason.
Another significant change is that this pass actively updates the CFG
based on unswitching. For trivial unswitching, this is actually very
easy because of the definition of loop simplified form. Doing this makes
the code coming out of loop unswitch dramatically more friendly. We
still should run loop-simplifycfg (at the least) after this to clean up,
but it will have to do a lot less work.
Finally, this pass makes much fewer attempts to simplify instructions
based on the unswitch. Something like loop-instsimplify, instcombine, or
GVN can be used to do increasingly powerful simplifications based on the
now dominating predicate. The old simplifications are things that
something like loop-instsimplify should get today or a very, very basic
loop-instcombine could get. Keeping that logic separate is a big
simplifying technique.
Most of the code in this pass that isn't in the old one has to do with
achieving specific goals:
- Updating the dominator tree as we go
- Unswitching all cases in a switch in a single step.
I think it is still shorter than just the trivial unswitching code in
the old pass despite having this functionality.
Sanjoy Das [Thu, 27 Apr 2017 17:17:16 +0000 (17:17 +0000)]
Use a pointer type for target frame indices during statepoint lowering
Summary:
The type of the target frame index is intptr, not the type of the value we're
going to store into it. Without this change we crash in the attached test case
when trying to type-legalize a TargetFrameIndex.
Patchpoint lowering types the target frame index as intptr as well.
Refactor DynamicLibrary so searching for a symbol will have a defined order and
libraries are properly unloaded when llvm_shutdown is called.
Summary:
This was mostly affecting usage of the JIT, where storing the library handles in
a set made iteration unordered/undefined. This lead to disagreement between the
JIT and native code as to what the address and implementation of particularly on
Windows with stdlib functions:
JIT: putenv_s("TEST", "VALUE") // called msvcrt.dll, putenv_s
JIT: getenv("TEST") -> "VALUE" // called msvcrt.dll, getenv
Native: getenv("TEST") -> NULL // called ucrt.dll, getenv
Also fixed is the issue of DynamicLibrary::getPermanentLibrary(0,0) on Windows
not giving priority to the process' symbols as it did on Unix.
[CodeView] Isolate Debug Info Fragments into standalone classes.
Previously parsing of these were all grouped together into a
single master class that could parse any type of debug info
fragment.
With writing forthcoming, the complexity of each individual
fragment is enough to warrant them having their own classes so
that reading and writing of each fragment type can be grouped
together, but isolated from the code for reading and writing
other fragment types.
In doing so, I found a place where parsing code was duplicated
for the FileChecksums fragment, across llvm-readobj and the
CodeView library, and one of the implementations had a bug.
Now that the codepaths are merged, the bug is resolved.
We have a lot of very similarly named classes related to
dealing with module debug info. This patch has NFC, it just
renames some classes to be more descriptive (albeit slightly
more to type). The mapping from old to new class names is as
follows:
Old | New
ModInfo | DbiModuleDescriptor
ModuleSubstream | ModuleDebugFragment
ModStream | ModuleDebugStream
With the corresponding Builder classes renamed accordingly.
[mips][microMIPS] Adding code size reduction pass for MicroMIPS
Author: milena.vujosevic.janicic
Reviewers: sdardis
The code implements size reduction pass for MicroMIPS.
Load and store instructions are examined and transformed, if possible.
lw32 instruction is transformed into 16-bit instruction lwsp
sw32 instruction is transformed into 16-bit instruction swsp
Arithmetic instrcutions are examined and transformed, if possible.
addu32 instruction is transformed into 16-bit instruction addu16
subu32 instruction is transformed into 16-bit instruction subu16
Differential Revision: https://reviews.llvm.org/D15144
Jonas Paulsson [Thu, 27 Apr 2017 11:01:18 +0000 (11:01 +0000)]
[SystemZ] Remove incorrect assert in SystemZTTIImpl
In getCmpSelInstrCost(), CondTy may actually be scalar while ValTy is a
vector when LoopVectorizer is the caller. Therefore the assert that CondTy
must be a vector type if ValTy is was wrong and is now removed.
Fix a crash when trying to extend a value passed as a sign- or
zero-extended stack parameter. The cause of the crash was that we were
setting the size of the loaded value to 32 bits, and then tyring to
extend again to 32 bits.
This patch addresses the issue by also introducing a G_TRUNC after the
load. This will leave the unused bits to their original values set by
the caller, while being consistent about the types. For values that are
not extended, we just use a smaller load.
George Rimar [Thu, 27 Apr 2017 10:00:13 +0000 (10:00 +0000)]
[llvm-dwarfdump] - Change format for .gdb_index dump.
It is useful to output size of ranges when address ranges
section of .gdb_index is dumped.
It helps to compare outputs produced by different linkers,
for example. In that case address ranges can look very different,
when they are the same at fact. Difference comes from different
low address because of different address of .text.
Sanjoy Das [Thu, 27 Apr 2017 06:02:18 +0000 (06:02 +0000)]
Use accessors for ValueHandleBase::V; NFC
This changes code that touches ValueHandleBase::V to go through
getValPtr and (newly added) setValPtr. This functionality will be
used later, but also seemed like a generally good cleanup.
I also renamed the field to Val, but that's just to make it obvious
that I fixed all the uses.
Previously, an expression such as Saver.save(std::string("foo") + "bar")
didn't compile because there is an ambiguity as to whether the argument
is of const Twine& or StringRef.
Adrian Prantl [Wed, 26 Apr 2017 23:59:52 +0000 (23:59 +0000)]
Turn DISubprogram into a variable-length node.
DISubprogram currently has 10 pointer operands, several of which are
often nullptr. This patch reduces the amount of memory allocated by
DISubprogram by rearranging the operands such that containing type,
template params, and thrown types come last, and are only allocated
when they are non-null (or followed by non-null operands).
This patch also eliminates the entirely unused DisplayName operand.
This saves up to 4 pointer operands per DISubprogram. (I tried
measuring the effect on peak memory usage on an LTO link of an X86
llc, but the results were very noisy).
This reapplies r301498 with an attempted workaround for g++.
Adrian Prantl [Wed, 26 Apr 2017 23:44:54 +0000 (23:44 +0000)]
Turn DISubprogram into a variable-length node.
DISubprogram currently has 10 pointer operands, several of which are
often nullptr. This patch reduces the amount of memory allocated by
DISubprogram by rearranging the operands such that containing type,
template params, and thrown types come last, and are only allocated
when they are non-null (or followed by non-null operands).
This patch also eliminates the entirely unused DisplayName operand.
This saves up to 4 pointer operands per DISubprogram. (I tried
measuring the effect on peak memory usage on an LTO link of an X86
llc, but the results were very noisy).
It was doing the same as the base implementation and was irritating me
when I was searching for backends that have custom behavior for
canRealignStack.
Adrian Prantl [Wed, 26 Apr 2017 22:56:44 +0000 (22:56 +0000)]
Add support for DW_TAG_thrown_type.
For Swift we would like to be able to encode the error types that a
function may throw, so the debugger can display them alongside the
function's return value when finish-ing a function.
DWARF defines DW_TAG_thrown_type (intended to be used for C++ throw()
declarations) that is a perfect fit for this purpose. This patch wires
up support for DW_TAG_thrown_type in LLVM by adding a list of thrown
types to DISubprogram.
To offset the cost of the extra pointer, there is a follow-up patch
that turns DISubprogram into a variable-length node.
The previous algorithm processed one character at a time, which is very
painful on a modern CPU. Replace it with xxHash64, which both already
exists in the codebase and is fairly fast.
Besides better codegen, the motivation is to be able to canonicalize this pattern
in IR (currently we don't) knowing that the backend is prepared for that.
This may also allow removing code for special constant cases in
DAGCombiner::foldSelectOfConstants() that was added in D30180.
Marking them as used causes them to be considered visible outside of LTO. This
prevents the symbols from being internalized or discarded, either by GlobalDCE
or by summary-based dead stripping in ThinLTO.
This change makes it unnecessary to add these symbols to llvm.compiler.used
in the backend, as the symbols are kept alive by virtue of being external,
so remove the backend code that handles that.
[ValueTracking] Introduce a KnownBits struct to wrap the two APInts for computeKnownBits
This patch introduces a new KnownBits struct that wraps the two APInt used by computeKnownBits. This allows us to treat them as more of a unit.
Initially I've just altered the signatures of computeKnownBits and InstCombine's simplifyDemandedBits to pass a KnownBits reference instead of two separate APInt references. I'll do similar to the SelectionDAG version of computeKnownBits/simplifyDemandedBits as a separate patch.
I've added a constructor that allows initializing both APInts to the same bit width with a starting value of 0. This reduces the repeated pattern of initializing both APInts. Once place default constructed the APInts so I added a default constructor for those cases.
Going forward I would like to add more methods that will work on the pairs. For example trunc, zext, and sext occur on both APInts together in several places. We should probably add a clear method that can be used to clear both pieces. Maybe a method to check for conflicting information. A method to return (Zero|One) so we don't write it out everywhere. Maybe a method for (Zero|One).isAllOnesValue() to determine if all bits are known. I'm sure there are many other methods we can come up with.
Sanjoy Das [Wed, 26 Apr 2017 16:21:02 +0000 (16:21 +0000)]
Use WeakVH instead of WeakTrackingVH in AliasSetTracker's UnkownInsts
Summary:
In cases where an instruction (a call site, say) is RAUW'ed with some
other value (this is possible via the `returned` attribute, amongst
other things), we want the slot in UnknownInsts to point to the
original Instruction we wanted to track, not the value it got replaced
by.
[sampleprof] Drop test dependency on the string hash func (NFC)
The SampleProfWriter emits function information in an order determined
by the string hash function. The situation is a bit brittle, because
changing the hash function can break the tests.
Instead of sorting the function samples to get a relaible ordering (that
might be too expensive), make the tests not depend on a particular
ordering of function samples.
For targets that don't have ISD::MULHS or ISD::SMUL_LOHI for the type
and the double width type is illegal, then the two operands are
sign extended to twice their size then multiplied to check for overflow.
The extended upper halves were mismatched causing an incorrect result.
This fixes the mismatch.
A test was added for ARM V6-M where the bug was detected.
[mips] Fix test mips64fpldst.ll with machine verifier enabled
Removed micro mips register classes for gp initialization because gp initialization uses pure mips64 instruction. Even when compiling for micro mips, gp initialization can be done with pure mips64 instructions.
Simon Dardis [Wed, 26 Apr 2017 11:10:38 +0000 (11:10 +0000)]
[mips] Rework a portion of MipsCC interface. (NFC)
r299766 contained a "conditional move or jump depends on uninitialized value"
fault, identified by valgrind. This occurred as MipsFastISel::finishCall(..)
used CCState over MipsCCState. The latter is required for the TableGen'd calling
convention logic due to reliance on pre-analyzing type information to lower call
results/returns of vectors correctly.
This change modifies the MipsCC AnalyzeCallResult to be useful with both the
SelectionDAG and FastISel lowering logic.
Daniel Berlin [Wed, 26 Apr 2017 04:09:56 +0000 (04:09 +0000)]
InstructionSimplify: End our long national nightmare of ever-growing Simplify* arguments.
Summary:
Expose the internal query structure, start using it.
Note: This is the most minimal change possible i could create. I have
trivial followups, like fixing the one use of const FastMathFlags &,
the renaming of CtxI to be consistent, etc.
[MSP430] Fix PR32769: Select8 and Select16 need to have SR in Uses.
If Select pseudo instruction doesn't have use SR, then
CMP instructions are being marked as dead and later can be
removed by MachineCSE pass. This leads to incorrect code
generation.
The order in which GCOV file info is printed depends on the string hash
function. This makes some GCOV tests brittle, because the tests must be
updated whenever the hash function changes.
Sort the filenames before printing out the file info to solve the
problem. This should be relatively cheap.
Sam Clegg [Wed, 26 Apr 2017 00:02:31 +0000 (00:02 +0000)]
[WebAssembly] Allow for signed relocation addends
Summary:
Addends are used as offsets to addresses of globals
and can be both positive and negative. This change
prints libObject in line with the spec and the MC
layer.
projects / llvm / log