| Commit message (Collapse) | Author | Age | Files | Lines |
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Something like this is requested by:
https://bugs.llvm.org/show_bug.cgi?id=40265
...and it seems like a common enough case that we should acknowledge it.
Differential Revision: https://reviews.llvm.org/D56551
llvm-svn: 351010
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Summary:
Records in the module summary index whether the bitcode was compiled
with the option necessary to enable splitting the LTO unit
(e.g. -fsanitize=cfi, -fwhole-program-vtables, or -fsplit-lto-unit).
The information is passed down to the ModuleSummaryIndex builder via a
new module flag "EnableSplitLTOUnit", which is propagated onto a flag
on the summary index.
This is then used during the LTO link to check whether all linked
summaries were built with the same value of this flag. If not, an error
is issued when we detect a situation requiring whole program visibility
of the class hierarchy. This is the case when both of the following
conditions are met:
1) We are performing LowerTypeTests or Whole Program Devirtualization.
2) There are type tests or type checked loads in the code.
Note I have also changed the ThinLTOBitcodeWriter to also gate the
module splitting on the value of this flag.
Reviewers: pcc
Subscribers: ormris, mehdi_amini, Prazek, inglorion, eraman, steven_wu, dexonsmith, arphaman, dang, llvm-commits
Differential Revision: https://reviews.llvm.org/D53890
llvm-svn: 350948
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MergeFunc only deletes unused duplicate functions if they have local
linkage, but it should be safe to relax this to any "discardable if
unused" linkage type.
Differential Revision: https://reviews.llvm.org/D56574
llvm-svn: 350939
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llvm-svn: 350938
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Currently when a select has a constant value in one branch and the select feeds
a conditional branch (via a compare/ phi and compare) we unfold the select
statement. This results in threading the conditional branch later on. Similar
opportunity exists when a select (with a constant in one branch) feeds a
switch (via a phi node). The patch unfolds select under this condition.
A testcase is provided.
llvm-svn: 350931
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Summary:
The original patch addressed the use of BlockRPONumber by forcing a sequence point when accessing that map in a conditional. In short we found cases where that map was being accessed with blocks that had not yet been added to that structure. For context, I've kept the wall of text below, to what we are trying to fix, by always ensuring a updated BlockRPONumber.
== Backstory ==
I was investigating an ICE (segfault accessing a DenseMap item). This failure happened non-deterministically, with no apparent reason and only on a Windows build of LLVM (from October 2018).
After looking into the crashes (multiple core files) and running DynamoRio, the cores and DynamoRio (DR) log pointed to the same code in `GVN::performScalarPRE()`. The values in the map are unsigned integers, the keys are `llvm::BasicBlock*`. Our test case that triggered this warning and periodic crash is rather involved. But the problematic line looks to be:
GVN.cpp: Line 2197
```
if (BlockRPONumber[P] >= BlockRPONumber[CurrentBlock] &&
```
To test things out, I cooked up a patch that accessed the items in the map outside of the condition, by forcing a sequence point between accesses. DynamoRio stopped warning of the issue, and the test didn't seem to crash after 1000+ runs.
My investigation was on an older version of LLVM, (source from October this year). What it looks like was occurring is the following, and the assembly from the latest pull of llvm in December seems to confirm this might still be an issue; however, I have not witnessed the crash on more recent builds. Of course the asm in question is generated from the host compiler on that Windows box (not clang), but it hints that we might want to consider how we access the BlockRPONumber map in this conditional (line 2197, listed above). In any case, I don't think the host compiler is wrong, rather I think it is pointing out a possibly latent bug in llvm.
1) There is no sequence point for the `>=` operation.
2) A call to a `DenseMapBase::operator[]` can have the side effect of the map reallocating a larger store (more Buckets, via a call to `DenseMap::grow`).
3) It seems perfectly legal for a host compiler to generate assembly that stores the result of a call to `operator[]` on the stack (that's what my host compile of GVN.cpp is doing) . A second call to `operator[]` //might// encourage the map to 'grow' thus making any pointers to the map's store invalid. The `>=` compares the first and second values. If the first happens to be a pointer produced from operator[], it could be invalid when dereferenced at the time of comparison.
The assembly generated from the Window's host compiler does show the result of the first access to the map via `operator[]` produces a pointer to an unsigned int. And that pointer is being stored on the stack. If a second call to the map (which does occur) causes the map to grow, that address (on the stack) is now invalid.
Reviewers: t.p.northover, efriedma
Reviewed By: efriedma
Subscribers: efriedma, llvm-commits
Differential Revision: https://reviews.llvm.org/D55974
llvm-svn: 350880
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Summary:
Step 2 in using MemorySSA in LICM:
Use MemorySSA in LICM to do sinking and hoisting, all under "EnableMSSALoopDependency" flag.
Promotion is disabled.
Enable flag in LICM sink/hoist tests to test correctness of this change. Moved one test which
relied on promotion, in order to test all sinking tests.
Reviewers: sanjoy, davide, gberry, george.burgess.iv
Subscribers: llvm-commits, Prazek
Differential Revision: https://reviews.llvm.org/D40375
llvm-svn: 350879
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That is, remove many of the calls to Type::getNumContainedTypes(),
Type::subtypes(), and Type::getContainedType(N).
I'm not intending to remove these accessors -- they are
useful/necessary in some cases. However, removing the pointee type
from pointers would potentially break some uses, and reducing the
number of calls makes it easier to audit.
llvm-svn: 350835
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The C standard says "The memchr function locates the first
occurrence of c (converted to an unsigned char)[...]". The expansion
was missing the conversion to unsigned char.
Fixes https://bugs.llvm.org/show_bug.cgi?id=39041 .
Differential Revision: https://reviews.llvm.org/D55947
llvm-svn: 350775
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Summary:
Instead of using two separate callbacks to return the entry count and the
relative block frequency, use a single callback to return callsite
count. This would allow better supporting hybrid mode in the future as
the count of callsite need not always be derived from entry count (as in
sample PGO).
Reviewers: davidxl
Subscribers: mehdi_amini, steven_wu, dexonsmith, dang, llvm-commits
Differential Revision: https://reviews.llvm.org/D56464
llvm-svn: 350755
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This patch breaks thread sanitizer on some macOS builders, e.g.
http://green.lab.llvm.org/green/job/clang-stage1-configure-RA/52725/
llvm-svn: 350719
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Current strategy of dropping `InstructionPrecedenceTracking` cache is to
invalidate the entire basic block whenever we change its contents. In fact,
`InstructionPrecedenceTracking` has 2 internal strictures: `OrderedInstructions`
that is needed to be invalidated whenever the contents changes, and the map
with first special instructions in block. This second map does not need an
update if we add/remove a non-special instuction because it cannot
affect the contents of this map.
This patch changes API of `InstructionPrecedenceTracking` so that it now
accounts for reasons under which we invalidate blocks. This should lead
to much less recalculations of the map and should save us some compile time
because in practice we don't typically add/remove special instructions.
Differential Revision: https://reviews.llvm.org/D54462
Reviewed By: efriedma
llvm-svn: 350694
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This is matching the equivalent of the DAG expansion,
so it should never end up with worse perf than the
original code even if the target doesn't have a rotate
instruction.
llvm-svn: 350672
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A straightforward port of tsan to the new PM, following the same path
as D55647.
Differential Revision: https://reviews.llvm.org/D56433
llvm-svn: 350647
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Summary:
This fixes the IDom for exit blocks and all blocks reachable from the exit blocks, when runtime unrolling under multiexit/exiting case.
We initially had a restrictive check that the IDom is only updated when
it is the header of the loop.
However, we also need to update the IDom to the correct one when the
IDom is any block within the original loop. See added test cases (which
fail dom tree verification without the patch).
Reviewers: reames, mzolotukhin, mkazantsev, hfinkel
Reviewed by: brzycki, kuhar
Subscribers: zzheng, dmgreen, llvm-commits
Differential Revision: https://reviews.llvm.org/D56284
llvm-svn: 350640
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update client code.
Also rename it to use the more generic term `call` instead of something
that could be confused with a praticular type.
Differential Revision: https://reviews.llvm.org/D56183
llvm-svn: 350508
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minted `CallBase` class instead of the `CallSite` wrapper.
This moves the largest interwoven collection of APIs that traffic in
`CallSite`s. While a handful of these could have been migrated with
a minorly more shallow migration by converting from a `CallSite` to
a `CallBase`, it hardly seemed worth it. Most of the APIs needed to
migrate together because of the complex interplay of AA APIs and the
fact that converting from a `CallBase` to a `CallSite` isn't free in its
current implementation.
Out of tree users of these APIs can fairly reliably migrate with some
combination of `.getInstruction()` on the `CallSite` instance and
casting the resulting pointer. The most generic form will look like `CS`
-> `cast_or_null<CallBase>(CS.getInstruction())` but in most cases there
is a more elegant migration. Hopefully, this migrates enough APIs for
users to fully move from `CallSite` to the base class. All of the
in-tree users were easily migrated in that fashion.
Thanks for the review from Saleem!
Differential Revision: https://reviews.llvm.org/D55641
llvm-svn: 350503
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The cttz/ctlz intrinsics have a parameter specifying whether the
result is undefined for zero. cttz(x, false) can be relaxed to
cttz(x, true) if x is known non-zero, and in fact such an optimization
is already performed. However, this currently doesn't work if x is
non-zero as a result of a select rather than an explicit branch.
This patch adds handling for this case, thus allowing
x != 0 ? cttz(x, false) : y to simplify to x != 0 ? cttz(x, true) : y.
Differential Revision: https://reviews.llvm.org/D55786
llvm-svn: 350463
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This has some minor optimizations to shouldBeDeferred. This is not
strictly NFC because the early exit inside the loop assumes
TotalSecondaryCost is monotonically non-decreasing, which is not true if
the threshold used by CostAnalyzer is negative. AFAICT the thresholds do
not go below 0 for the default values of the various options we use.
llvm-svn: 350456
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TLS_SLOT_SANITIZER(6)""
This reapplies commit r348983.
llvm-svn: 350448
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In addition to finding dead uses of instructions, also find dead uses
of function arguments, and replace them with zero as well.
I'm changing the way the known bits are computed here to remove the
coupling between the transfer function and the algorithm. It previously
relied on the first op being visited first and computing known bits --
unless the first op is not an instruction, in which case they're computed
on the second op. I could have adjusted this to check for "instruction
or argument", but I think it's better to avoid the repeated calculation
with an explicit flag.
Differential Revision: https://reviews.llvm.org/D56247
llvm-svn: 350435
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The problem is similar to D55986 but for threads: a process with the
interceptor hwasan library loaded might have some threads started by
instrumented libraries and some by uninstrumented libraries, and we
need to be able to run instrumented code on the latter.
The solution is to perform per-thread initialization lazily. If a
function needs to access shadow memory or add itself to the per-thread
ring buffer its prologue checks to see whether the value in the
sanitizer TLS slot is null, and if so it calls __hwasan_thread_enter
and reloads from the TLS slot. The runtime does the same thing if it
needs to access this data structure.
This change means that the code generator needs to know whether we
are targeting the interceptor runtime, since we don't want to pay
the cost of lazy initialization when targeting a platform with native
hwasan support. A flag -fsanitize-hwaddress-abi={interceptor,platform}
has been introduced for selecting the runtime ABI to target. The
default ABI is set to interceptor since it's assumed that it will
be more common that users will be compiling application code than
platform code.
Because we can no longer assume that the TLS slot is initialized,
the pthread_create interceptor is no longer necessary, so it has
been removed.
Ideally, lazy initialization should only cost one instruction in the
hot path, but at present the call may cause us to spill arguments
to the stack, which means more instructions in the hot path (or
theoretically in the cold path if the spills are moved with shrink
wrapping). With an appropriately chosen calling convention for
the per-thread initialization function (TODO) the hot path should
always need just one instruction and the cold path should need two
instructions with no spilling required.
Differential Revision: https://reviews.llvm.org/D56038
llvm-svn: 350429
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At -O0, globalopt is not run during the compile step, and we can have a
chain of an alias having an immediate aliasee of another alias. The
summaries are constructed assuming aliases in a canonical form
(flattened chains), and as a result only the base object but no
intermediate aliases were preserved.
Fix by adding a pass that canonicalize aliases, which ensures each
alias is a direct alias of the base object.
Reviewers: pcc, davidxl
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D54507
llvm-svn: 350423
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Lifetime markers which reference inputs to the extraction region are not
safe to extract. Example ('rhs' will be extracted):
```
entry:
+------------+
| x = alloca |
| y = alloca |
+------------+
/ \
lhs: rhs:
+-------------------+ +-------------------+
| lifetime_start(x) | | lifetime_start(x) |
| use(x) | | lifetime_start(y) |
| lifetime_end(x) | | use(x, y) |
| lifetime_start(y) | | lifetime_end(y) |
| use(y) | | lifetime_end(x) |
| lifetime_end(y) | +-------------------+
+-------------------+
```
Prior to extraction, the stack coloring pass sees that the slots for 'x'
and 'y' are in-use at the same time. After extraction, the coloring pass
infers that 'x' and 'y' are *not* in-use concurrently, because markers
from 'rhs' are no longer available to help decide otherwise.
This leads to a miscompile, because the stack slots actually are in-use
concurrently in the extracted function.
Fix this by moving lifetime start/end markers for memory regions defined
in the calling function around the call to the extracted function.
Fixes llvm.org/PR39671 (rdar://45939472).
Differential Revision: https://reviews.llvm.org/D55967
llvm-svn: 350420
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Similar to rL350199 - there are no known analysis/codegen holes for
funnel shift intrinsics now, so we can canonicalize the 6+ regular
instructions to funnel shift to improve vectorization, inlining,
unrolling, etc.
llvm-svn: 350419
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In some cases the order that we hoist instructions in means that when rehoisting
(which uses the same order as hoisting) we can rehoist to a block A, then a
block B, then block A again. This currently causes an assertion failure as it
expects that when changing the hoist point it only ever moves to a block that
dominates the hoist point being moved from.
Fix this by moving the re-hoist point when it doesn't dominate the dominator of
hoisted instruction, or in other words when it wouldn't dominate the uses of
the instruction being rehoisted.
Differential Revision: https://reviews.llvm.org/D55266
llvm-svn: 350408
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We already checked for isSimple() on the store.
llvm-svn: 350378
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Suggested by Hal as done in r349871.
llvm-svn: 350349
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NFC: This adds the dom tree verification under debug mode at a point
just before we start unrolling the loop. This allows us to verify dom
tree at a state where it is much smaller and before the unrolling
actually happens.
This also implies we do not need to run -verify-dom-info everytime to
see if the DT is in a valid state when we transform the loop for runtime
unrolling.
llvm-svn: 350334
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Summary:
Keeping msan a function pass requires replacing the module level initialization:
That means, don't define a ctor function which calls __msan_init, instead just
declare the init function at the first access, and add that to the global ctors
list.
Changes:
- Pull the actual sanitizer and the wrapper pass apart.
- Add a newpm msan pass. The function pass inserts calls to runtime
library functions, for which it inserts declarations as necessary.
- Update tests.
Caveats:
- There is one test that I dropped, because it specifically tested the
definition of the ctor.
Reviewers: chandlerc, fedor.sergeev, leonardchan, vitalybuka
Subscribers: sdardis, nemanjai, javed.absar, hiraditya, kbarton, bollu, atanasyan, jsji
Differential Revision: https://reviews.llvm.org/D55647
llvm-svn: 350305
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autoreleaseRV/retainRV pairs
OptimizeAutoreleaseRVCall skips optimizing llvm.objc.autoreleaseReturnValue if it
sees a user which is llvm.objc.retainAutoreleasedReturnValue, and if they have
equivalent arguments (either identical or equivalent PHIs). It then assumes that
ObjCARCOpt::OptimizeRetainRVCall will optimize the pair instead.
Trouble is, ObjCARCOpt::OptimizeRetainRVCall doesn't know about equivalent PHIs
so optimizes in a different way and we are left with an unoptimized llvm.objc.autoreleaseReturnValue.
This teaches ObjCARCOpt::OptimizeRetainRVCall to also understand PHI equivalence.
rdar://problem/47005143
Reviewed By: ahatanak
Differential Revision: https://reviews.llvm.org/D56235
llvm-svn: 350284
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Summary:
Alias can make one (but not all) live, we still need to scan all others if this symbol is reachable
from somewhere else.
Reviewers: tejohnson, grimar
Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D56117
llvm-svn: 350269
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The caller to EraseInstruction had this conditional:
// ARC calls with null are no-ops. Delete them.
if (IsNullOrUndef(Arg))
but the assert inside EraseInstruction only allowed ConstantPointerNull and not
undef or bitcasts.
This adds support for both of these cases.
rdar://problem/47003805
llvm-svn: 350261
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If an instruction has no demanded bits, remove it directly during BDCE,
instead of leaving it for something else to clean up.
Differential Revision: https://reviews.llvm.org/D56185
llvm-svn: 350257
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llvm-svn: 350255
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The final piece of IR-level analysis to allow this was committed with:
rL350188
Using the intrinsics should improve transforms based on cost models
like vectorization and inlining.
The backend should be prepared too, so we can now canonicalize more
sequences of shift/logic to the intrinsics and know that the end
result should be equal or better to the original code even if the
target does not have an actual rotate instruction.
llvm-svn: 350199
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This (mostly) fixes https://bugs.llvm.org/show_bug.cgi?id=39771.
BDCE currently detects instructions that don't have any demanded bits
and replaces their uses with zero. However, if an instruction has
multiple uses, then some of the uses may be dead (have no demanded bits)
even though the instruction itself is still live. This patch extends
DemandedBits/BDCE to detect such uses and replace them with zero.
While this will not immediately render any instructions dead, it may
lead to simplifications (in the motivating case, by converting a rotate
into a simple shift), break dependencies, etc.
The implementation tries to strike a balance between analysis power and
complexity/memory usage. Originally I wanted to track demanded bits on
a per-use level, but ultimately we're only really interested in whether
a use is entirely dead or not. I'm using an extra set to track which uses
are dead. However, as initially all uses are dead, I'm not storing uses
those user is also dead. This case is checked separately instead.
The previous attempt to land this lead to miscompiles, because cases
where uses were initially dead but were later found to be live during
further analysis were not always correctly removed from the DeadUses
set. This is fixed now and the added test case demanstrates such an
instance.
Differential Revision: https://reviews.llvm.org/D55563
llvm-svn: 350188
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-X * Y --> -(X * Y)
X * -Y --> -(X * Y)
Differential Revision: https://reviews.llvm.org/D55961
llvm-svn: 350185
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MSan used to report false positives in the case the argument of
llvm.is.constant intrinsic was uninitialized.
In fact checking this argument is unnecessary, as the intrinsic is only
used at compile time, and its value doesn't depend on the value of the
argument.
llvm-svn: 350173
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llvm-svn: 350145
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Added -verify-loop-lcssa to test cases.
Updated comments in ConnectProlog.
llvm-svn: 350131
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llvm-svn: 350117
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Deletion of dead blocks in arbitrary order may lead to failure
of assertion in `DeleteDeadBlock` that requires that we have
deleted all predecessors before we can delete the current block.
We should instead delete them in RPO order.
llvm-svn: 350116
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Summary:
Existing LIR recognizes CTLZ where shifting input variable right until it is zero. (Shift-Until-Zero idiom)
This commit:
1. Augments Shift-Until-Zero idiom to recognize CTTZ where input variable is shifted left.
2. Prepare for BitScan idiom recognition.
Patch by Yuanfang Chen (tabloid.adroit)
Reviewers: craig.topper, evstupac
Reviewed By: craig.topper
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D55876
llvm-svn: 350074
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llvm-svn: 350064
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llvm-svn: 350062
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Differential revision: https://reviews.llvm.org/D55926
llvm-svn: 350055
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This patch teaches LoopSimplifyCFG to remove dead exiting edges
from loops.
Differential Revision: https://reviews.llvm.org/D54025
Reviewed By: fedor.sergeev
llvm-svn: 350049
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The underlying bug that caused the revert should be fixed by rL348567.
Differential Revision: https://reviews.llvm.org/D54023
llvm-svn: 350045
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Both of these places reference memset-like loops. Memset is precise.
Trying to keep these patches super small so they're easily post-commit
verifiable, as requested in D44748.
llvm-svn: 350044
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