I think we can use here same logic as for nonnull.
strlen(X) - X must be noundef => valid pointer.
for libcalls with size arg, we add noundef only if size is known and greater than 0 - so pointers must be noundef (valid ones)
Reviewed By: jdoerfert, aqjune
Differential Revision: https://reviews.llvm.org/D95122
MemorySSA currently treats lifetime.end intrinsics as not aliasing
anything. This breaks MemorySSA-based MemCpyOpt, because we'll happily
move a read of a pointer below a lifetime.end intrinsic, as no clobber
is reported.
I think the MemorySSA modelling here isn't correct: lifetime.end(p)
has approximately the same effect as doing a memcpy(p, undef), and
should be treated as a clobber.
This patch removes the special handling of lifetime.end, leaving
alias analysis to handle it appropriately.
Differential Revision: https://reviews.llvm.org/D95763
With the addition of the `willreturn` attribute, functions that may
not return (e.g. due to an infinite loop) are well defined, if they are
not marked as `willreturn`.
This patch updates `wouldInstructionBeTriviallyDead` to not consider
calls that may not return as dead.
This patch still provides an escape hatch for intrinsics, which are
still assumed as willreturn unconditionally. It will be removed once
all intrinsics definitions have been reviewed and updated.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D94106
D91936 placed the tracking for the assumptions into BasicAA.
However, when recursing over phis, we may use fresh AAQI instances.
In this case AssumptionBasedResults from an inner AAQI can reesult
in a removal of an element from the outer AAQI.
To avoid this, move the tracking into AAQI. This generally makes
more sense, as the NoAlias assumptions themselves are also stored
in AAQI.
The test case only produces an assertion failure with D90094
reapplied. I think the issue exists independently of that change
as well, but I wasn't able to come up with a reproducer.
Explicitly opt-out llvm/test/Transforms/Attributor.
Verified by flipping the default value of allow-unused-prefixes and
observing that none of the failures were under llvm/test/Transforms.
Differential Revision: https://reviews.llvm.org/D92404
When MemCpyOpt performs call slot optimization it will concatenate the `alias.scope` metadata between the function call and the memcpy. However, scoped AA relies on the domains in metadata to be maintained in a caller-callee relationship. Naive concatenation breaks this assumption leading to bad AA results.
The fix is to take the intersection of domains then union the scopes within those domains.
The original bug came from a case of rust bad codegen which uses this bad aliasing to perform additional memcpy optimizations. As show in the added test case `%src` got forwarded past its lifetime leading to a dereference of garbage data.
Testing
ninja check-llvm
Reviewed By: jeroen.dobbelaere
Differential Revision: https://reviews.llvm.org/D91576
This is a straightforward port of MemCpyOpt to MemorySSA following
the approach of D26739. MemDep queries are replaced with MSSA queries
without changing the overall structure of the pass. Some care has
to be taken to account for differences between these APIs
(MemDep also returns reads, MSSA doesn't).
Differential Revision: https://reviews.llvm.org/D89207
CapturesBefore tracker has an overly restrictive dominates check when
the `BeforeHere` and the capture point are in different basic blocks.
All we need to check is that there is no path from the capture point
to `BeforeHere` (which is less stricter than the dominates check).
See added testcase in one of the users of CapturesBefore.
Reviewed-By: jdoerfert
Differential Revision: https://reviews.llvm.org/D90688
When performing a call slot optimization to a GEP destination, it
will currently usually fail, because the GEP is directly before the
memcpy and as such does not dominate the call. We should move it
above the call if that satisfies the domination requirement.
I think that a constant-index GEP is the only useful thing to move
here, as otherwise isDereferenceablePointer couldn't look through
it anyway. As such I'm not trying to generalize this further.
Differential Revision: https://reviews.llvm.org/D89623
D70365 allows us to make attributes default. This is a follow up to
actually make nosync, nofree and willreturn default. The approach we
chose, for now, is to opt-in to default attributes to avoid introducing
problems to target specific intrinsics. Intrinsics with default
attributes can be created using `DefaultAttrsIntrinsic` class.
After investigation by @asbirlea, the issue that caused the
revert appears to be an issue in the original source, rather
than a problem with the compiler.
This patch enables MemorySSA DSE again.
This reverts commit 915310bf14.
This adds an -enable-memcpyopt-memoryssa option that currently does
nothing apart from requiring MSSA as a dependency. The tests are
split to run both with the option disabled and enabled. I went with
this rather than the separate directory DSE uses, as I found it
convenient to have a direct side-by-side comparison of differences.
Differential Revision: https://reviews.llvm.org/D89206
moveUp() moves instructions, so we should move the corresponding
memory accesses as well. We should also move the store instruction
itself: Even though we'll end up removing it later, this gives us
a correct MemoryDef to replace.
The implementation is somewhat more complicated than it should be,
because we also handle the case where P does not have a memory
access due to a degnerate AA pipeline. Hopefully, the need for this
will go away in the future, when the rest of the pass is based on
MSSA.
Differential Revision: https://reviews.llvm.org/D88778
If the memcpy operands are the same (which is allowed since D86815)
then the memcpy is effectively a no-op and the partially overlapping
memset is not dead.
Differential Revision: https://reviews.llvm.org/D89192
MemCpyOpt can shorten a memset if it is later partially overwritten
by a memcpy. It checks that the destination is not read in between,
but we also need to make sure that the destination cannot be observed
via unwinding.
Differential Revision: https://reviews.llvm.org/D89190
MemCpyOpt can hoist stores while load+store pairs into memcpy.
This hoisting can currently result in stores being executed that
weren't guaranteed to execute in the original problem.
Differential Revision: https://reviews.llvm.org/D89154
The call slot optimization has some home-grown code for checking
whether the destination is dereferenceable. Replace this with the
generic isDereferenceableAndAlignedPointer() helper.
I'm not checking alignment here, because that is currently handled
separately and may be an enforced alignment for allocas. The clean
way of integrating that part would probably be to accept a callback
in isDereferenceableAndAlignedPointer() for the actual isAligned check,
which would then have a chance to use an enforced alignment instead.
This allows the destination to be a GEP (among other things), though
the two open TODOs may prevent it from working in practice.
Differential Revision: https://reviews.llvm.org/D88805
When performing call slot optimization for a non-local destination,
we need to check whether there may be throwing calls between the
call and the copy. Otherwise, the early write to the destination
may be observable by the caller.
This was already done for call slot optimization of load/store,
but not for memcpys. For the sake of clarity, I'm moving this check
into the common optimization function, even if that does need an
additional instruction scan for the load/store case.
As efriedma pointed out, this check is not sufficient due to
potential accesses from another thread. This case is left as a TODO.
Differential Revision: https://reviews.llvm.org/D88799
Apparently querying dereferenceability of array allocations is
being intentionally penalized (https://reviews.llvm.org/D41398),
so avoid using them in tests.
The case of a destination read between call and memcpy was not
covered anywhere (but is handled correctly).
However, a potentially throwing call between the call and the
memcpy appears to be miscompiled.
If we allow the non-integral pointers to become memset and memcpy, we loose the ability to reason about pointer propagation. This patch is modeled on changes we've carried downstream for a long time, figured it was worth being equally conservative for other users. There is room to refine the semantics and handling here if anyone is motivated.
There appears to be a mis-compile with MemorySSA-backed DSE in
combination with llvm.lifetime.end. It currently appears like
DSE is doing the right thing and the llvm.lifetime.end markers
are incorrect. The reverted patch uncovers the mis-compile.
This patch temporarily switches back to the legacy DSE
implementation, while we investigate.
This reverts commit 9d172c8e9c.
This switches to using DSE + MemorySSA by default again, after
fixing the issues reported after the first commit.
Notable fixes fc82006331, a0017c2bc2.
This reverts commit 3a59628f3c.
The tests have been updated and I plan to move them from the MSSA
directory up.
Some end-to-end tests needed small adjustments. One difference to the
legacy DSE is that legacy DSE also deletes trivially dead instructions
that are unrelated to memory operations. Because MemorySSA-backed DSE
just walks the MemorySSA, we only visit/check memory instructions. But
removing unrelated dead instructions is not really DSE's job and other
passes will clean up.
One noteworthy change is in llvm/test/Transforms/Coroutines/ArgAddr.ll,
but I think this comes down to legacy DSE not handling instructions that
may throw correctly in that case. To cover this with MemorySSA-backed
DSE, we need an update to llvm.coro.begin to treat it's return value to
belong to the same underlying object as the passed pointer.
There are some minor cases MemorySSA-backed DSE currently misses, e.g. related
to atomic operations, but I think those can be implemented after the switch.
This has been discussed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2020-August/144417.html
For the MultiSource/SPEC2000/SPEC2006 the number of eliminated stores
goes from ~17500 (legayc DSE) to ~26300 (MemorySSA-backed). More numbers
and details in the thread on llvm-dev.
Impact on CTMark:
```
Legacy Pass Manager
exec instrs size-text
O3 + 0.60% - 0.27%
ReleaseThinLTO + 1.00% - 0.42%
ReleaseLTO-g. + 0.77% - 0.33%
RelThinLTO (link only) + 0.87% - 0.42%
RelLO-g (link only) + 0.78% - 0.33%
```
http://llvm-compile-time-tracker.com/compare.php?from=3f22e96d95c71ded906c67067d75278efb0a2525&to=ae8be4642533ff03803967ee9d7017c0d73b0ee0&stat=instructions
```
New Pass Manager
exec instrs. size-text
O3 + 0.95% - 0.25%
ReleaseThinLTO + 1.34% - 0.41%
ReleaseLTO-g. + 1.71% - 0.35%
RelThinLTO (link only) + 0.96% - 0.41%
RelLO-g (link only) + 2.21% - 0.35%
```
http://195.201.131.214:8000/compare.php?from=3f22e96d95c71ded906c67067d75278efb0a2525&to=ae8be4642533ff03803967ee9d7017c0d73b0ee0&stat=instructions
Reviewed By: asbirlea, xbolva00, nikic
Differential Revision: https://reviews.llvm.org/D87163
This patch updates MemCpyOpt to preserve MemorySSA. It uses the
MemoryDef at the insertion point of the builder and inserts the new def
after that def.
In some cases, we just modify a memory instruction. In that case, get
the defining access, then remove the memory access and add a new one.
If the defining access is in a different block, insert a new def at the
beginning of the current block, otherwise after the defining access.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D86651
Summary: To match NewPM name. Also the new name is clearer and more consistent.
Subscribers: jvesely, nhaehnle, hiraditya, asbirlea, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D84542
For IR generated by a compiler, this is really simple: you just take the
datalayout from the beginning of the file, and apply it to all the IR
later in the file. For optimization testcases that don't care about the
datalayout, this is also really simple: we just use the default
datalayout.
The complexity here comes from the fact that some LLVM tools allow
overriding the datalayout: some tools have an explicit flag for this,
some tools will infer a datalayout based on the code generation target.
Supporting this properly required plumbing through a bunch of new
machinery: we want to allow overriding the datalayout after the
datalayout is parsed from the file, but before we use any information
from it. Therefore, IR/bitcode parsing now has a callback to allow tools
to compute the datalayout at the appropriate time.
Not sure if I covered all the LLVM tools that want to use the callback.
(clang? lli? Misc IR manipulation tools like llvm-link?). But this is at
least enough for all the LLVM regression tests, and IR without a
datalayout is not something frontends should generate.
This change had some sort of weird effects for certain CodeGen
regression tests: if the datalayout is overridden with a datalayout with
a different program or stack address space, we now parse IR based on the
overridden datalayout, instead of the one written in the file (or the
default one, if none is specified). This broke a few AVR tests, and one
AMDGPU test.
Outside the CodeGen tests I mentioned, the test changes are all just
fixing CHECK lines and moving around datalayout lines in weird places.
Differential Revision: https://reviews.llvm.org/D78403
Summary:
DataLayout::getTypeStoreSize() returns TypeSize.
For cases where it can not be scalable vector (e.g., GlobalVariable),
explicitly call TypeSize::getFixedSize().
For cases where scalable property doesn't matter, (e.g., check for
zero-sized type), use TypeSize::isNonZero().
Reviewers: sdesmalen, efriedma, apazos, reames
Reviewed By: efriedma
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76454
Summary:
Return None if GEP index type is scalable vector. Size of scalable vectors
are multiplied by a runtime constant.
Avoid transforming:
%a = bitcast i8* %p to <vscale x 16 x i8>*
%tmp0 = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* %a, i64 0
store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* %tmp0
%tmp1 = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* %a, i64 1
store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* %tmp1
into:
%a = bitcast i8* %p to <vscale x 16 x i8>*
%tmp0 = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* %a, i64 0
%1 = bitcast <vscale x 16 x i8>* %tmp0 to i8*
call void @llvm.memset.p0i8.i64(i8* align 16 %1, i8 0, i64 32, i1 false)
Reviewers: sdesmalen, efriedma, apazos, reames
Reviewed By: sdesmalen
Subscribers: tschuett, hiraditya, rkruppe, arphaman, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76464
Summary: This patch fixes https://bugs.llvm.org/show_bug.cgi?id=44388 which incorrectly assigns an ABI alignment to memset when there was no explicit alignment given.
Reviewers: gchatelet, lenary, nikic
Reviewed By: nikic
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74083
This reapplies: 8ff85ed905
Original commit message:
As a follow-up to my initial mail to llvm-dev here's a first pass at the O1 described there.
This change doesn't include any change to move from selection dag to fast isel
and that will come with other numbers that should help inform that decision.
There also haven't been any real debuggability studies with this pipeline yet,
this is just the initial start done so that people could see it and we could start
tweaking after.
Test updates: Outside of the newpm tests most of the updates are coming from either
optimization passes not run anymore (and without a compelling argument at the moment)
that were largely used for canonicalization in clang.
Original post:
http://lists.llvm.org/pipermail/llvm-dev/2019-April/131494.html
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410
This reverts commit c9ddb02659.
This change doesn't include any change to move from selection dag to fast isel
and that will come with other numbers that should help inform that decision.
There also haven't been any real debuggability studies with this pipeline yet,
this is just the initial start done so that people could see it and we could start
tweaking after.
Test updates: Outside of the newpm tests most of the updates are coming from either
optimization passes not run anymore (and without a compelling argument at the moment)
that were largely used for canonicalization in clang.
Original post:
http://lists.llvm.org/pipermail/llvm-dev/2019-April/131494.html
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65410
Summary:
When MemCpyOpt is handling aggregate type values, if an instruction (let's call it P) between the targeting load (L) and store (S) clobbers the source pointer of L, it will try to hoist S before P. This process will also hoist S's data dependency instructions.
However, the current implementation has a bug that if one of S's dependency instructions is //also// a user of P, MemCpyOpt will not prevent it from being hoisted above P and cause a use-before-define error. For example, in the newly added test file (i.e. `aggregate-type-crash.ll`), it will try to hoist both `store %my_struct %1, %my_struct* %3` and its dependent, `%3 = bitcast i8* %2 to %my_struct*`, above `%2 = call i8* @my_malloc(%my_struct* %0)`. Creating the following BB:
```
entry:
%1 = bitcast i8* %4 to %my_struct*
%2 = bitcast %my_struct* %1 to i8*
%3 = bitcast %my_struct* %0 to i8*
call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %2, i8* align 4 %3, i64 8, i1 false)
%4 = call i8* @my_malloc(%my_struct* %0)
ret void
```
Where there is a use-before-define error between `%1` and `%4`.
Update: The compiler for the Pony Programming Language [also encounter the same bug](https://github.com/ponylang/ponyc/issues/3140)
Patch by Min-Yih Hsu (myhsu)
Reviewers: eugenis, pcc, dblaikie, dneilson, t.p.northover, lattner
Reviewed By: eugenis
Subscribers: lenary, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66060
llvm-svn: 375403
This patch improves the handling of pointer offset in GEP expressions where
one argument is the base pointer. isPointerOffset() is being used by memcpyopt
where current code synthesizes consecutive 32 bytes stores to one store and
two memset intrinsic calls. With this patch, we convert the stores to one
memset intrinsic.
Differential Revision: https://reviews.llvm.org/D67989
llvm-svn: 374454
Summary:
In D62801, new function attribute `willreturn` was introduced. In short, a function with `willreturn` is guaranteed to come back to the call site(more precise definition is in LangRef).
In this patch, willreturn is annotated for LLVM intrinsics.
Reviewers: jdoerfert
Reviewed By: jdoerfert
Subscribers: jvesely, nhaehnle, sstefan1, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64904
llvm-svn: 367184
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
Bitcast and certain Ptr2Int/Int2Ptr instructions will not alter the
value of their operand and can therefore be looked through when we
determine non-nullness.
Differential Revision: https://reviews.llvm.org/D54956
llvm-svn: 352293
Summary:
BasicAA has special logic for unescaped allocas, which normally applies
equally well to dynamic and static allocas. However, llvm.stackrestore
has the power to end the lifetime of dynamic allocas, without referring
to them directly.
stackrestore is already marked with the most conservative memory
modification attributes, but because the alloca is not escaped, the
normal logic produces incorrect results. I think BasicAA needs a special
case here to teach it about the relationship between dynamic allocas and
stackrestore.
Fixes PR40118
Reviewers: gbiv, efriedma, george.burgess.iv
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D55969
llvm-svn: 349945
Currently memcpyopt optimizes cases like
memset(a, byte, N);
memcpy(b, a, M);
to
memset(a, byte, N);
memset(b, byte, M);
if M <= N. Often this allows further simplifications down the line,
which drop the first memset entirely.
This patch extends this optimization for the case where M > N, but we
know that the bytes a[N..M] are undef due to alloca/lifetime.start.
This situation arises relatively often for Rust code, because Rust does
not initialize trailing structure padding and loves to insert redundant
memcpys. This also fixes https://bugs.llvm.org/show_bug.cgi?id=39844.
The previous version of this patch did not perform dependency checking
properly: While the dependency is checked at the position of the memset,
the used size must be that of the memcpy. Previously the size of the
memset was used, which missed modification in the region
MemSetSize..CopySize, resulting in miscompiles. The added tests cover
variations of this issue.
Differential Revision: https://reviews.llvm.org/D55120
llvm-svn: 349078
Currently memcpyopt optimizes cases like
memset(a, byte, N);
memcpy(b, a, M);
to
memset(a, byte, N);
memset(b, byte, M);
if M <= N. Often this allows further simplifications down the line,
which drop the first memset entirely.
This patch extends this optimization for the case where M > N, but we
know that the bytes a[N..M] are undef due to alloca/lifetime.start.
This situation arises relatively often for Rust code, because Rust does
not initialize trailing structure padding and loves to insert redundant
memcpys. This also fixes https://bugs.llvm.org/show_bug.cgi?id=39844.
For the implementation, I'm reusing a bit of code for a similar existing
optimization (direct memcpy of undef). I've also added memset support to
MemDepAnalysis GetLocation -- Instead, getPointerDependencyFrom could be
used, but it seems to make more sense to add this to GetLocation and thus
make the computation cachable.
Differential Revision: https://reviews.llvm.org/D55120
llvm-svn: 348645
Summary:
his code was in CGDecl.cpp and really belongs in LLVM's isBytewiseValue. Teach isBytewiseValue the tricks clang's isRepeatedBytePattern had, including merging undef properly, and recursing on more types.
clang part of this patch: D51752
Subscribers: dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51751
llvm-svn: 342709
Summary:
Skip basic blocks not reachable from the entry node
in MemCpyOptPass::iterateOnFunction.
Code that is unreachable may have properties that do not exist
for reachable code (an instruction in a basic block can for
example be dominated by a later instruction in the same basic
block, for example if there is a single block loop).
MemCpyOptPass::processStore is only safe to use for reachable
basic blocks, since it may iterate past the basic block
beginning when used for unreachable blocks. By simply skipping
to optimize unreachable basic blocks we can avoid asserts such
as "Assertion `!NodePtr->isKnownSentinel()' failed."
in MemCpyOptPass::processStore.
The problem was detected by fuzz tests.
Reviewers: eli.friedman, dneilson, efriedma
Reviewed By: efriedma
Subscribers: efriedma, llvm-commits
Differential Revision: https://reviews.llvm.org/D45889
llvm-svn: 330635
Summary:
This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
MemCpyOpt pass to cease using:
1) The old getAlignment() API of MemoryIntrinsic in favour of getting source & dest specific
alignments through the new API.
2) The old IRBuilder CreateMemCpy/CreateMemMove single-alignment APIs in favour of the new
API that allows setting source and destination alignments independently.
We also add a few tests to fill gaps in the testing of this pass.
Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886, rL323891, rL324148, rL324273, rL324278,
rL324384, rL324395, rL324402, rL324626, rL324642, rL324653, rL324654, rL324773, rL324774,
rL324781, rL324784, rL324955, rL324960, rL325816, rL327398, rL327421 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.
Reference
http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.htmlhttp://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
llvm-svn: 328097
This reverts r321138. It seems there are still underlying issues with
memdep. PR35519 seems to still be present if debug info is enabled. We
end up losing a memcpy. Somehow during store to memset merging, we
insert the memset after the memcpy or fail to update the memdep analysis
to account for the newly inserted memset of a pair.
Reduced test case:
#include <assert.h>
#include <stdio.h>
#include <string>
#include <utility>
#include <vector>
void do_push_back(
std::vector<std::pair<std::string, std::vector<std::string>>>* crls) {
crls->push_back(std::make_pair(std::string(), std::vector<std::string>()));
}
int __attribute__((optnone)) main() {
// Put some data in the vector and then remove it so we take the push_back
// fast path.
std::vector<std::pair<std::string, std::vector<std::string>>> crl_set;
crl_set.push_back({"asdf", {}});
crl_set.pop_back();
printf("first word in vector storage: %p\n", *(void**)crl_set.data());
// Do the push_back which may fail to initialize the data.
do_push_back(&crl_set);
auto* first = &crl_set.back().first;
printf("first word in vector storage (should be zero): %p\n",
*(void**)crl_set.data());
assert(first->empty());
puts("ok");
}
Compile with libc++, enable optimizations, and enable debug info:
$ clang++ -stdlib=libc++ -g -O2 t.cpp -o t.exe -Wl,-rpath=llvm/build/lib
This program will assert with this change.
llvm-svn: 321510
This teaches memcpyopt to make a non-local memdep query when a local query
indicates that the dependency is non-local. This notably allows it to
eliminate many more llvm.memcpy calls in common Rust code, often by 20-30%.
This is r319482 and r319483, along with fixes for PR35519: fix the
optimization that merges stores into memsets to preserve cached memdep
info, and fix memdep's non-local caching strategy to not assume that larger
queries are always more conservative than smaller ones.
Fixes PR28958 and PR35519.
Differential Revision: https://reviews.llvm.org/D40802
llvm-svn: 321138
This caused PR35519.
> [memcpyopt] Teach memcpyopt to optimize across basic blocks
>
> This teaches memcpyopt to make a non-local memdep query when a local query
> indicates that the dependency is non-local. This notably allows it to
> eliminate many more llvm.memcpy calls in common Rust code, often by 20-30%.
>
> Fixes PR28958.
>
> Differential Revision: https://reviews.llvm.org/D38374
>
> [memcpyopt] Commit file missed in r319482.
>
> This change was meant to be included with r319482 but was accidentally
> omitted.
llvm-svn: 319873
This teaches memcpyopt to make a non-local memdep query when a local query
indicates that the dependency is non-local. This notably allows it to
eliminate many more llvm.memcpy calls in common Rust code, often by 20-30%.
Fixes PR28958.
Differential Revision: https://reviews.llvm.org/D38374
llvm-svn: 319482
Argument evaluation order is one of the edge cases where Clang differs
from GCC, yielding different IR depending on which compiler LLVM was
built with. Make the order deterministic and tune the test to actually
verify the order instead of trying to hide it.
llvm-svn: 286126
Summary:
This fixes pr29105. The reason is that lifetime marks creates new
aliasing pointers the original ones, but before this patch aliases
were not checked in performMemCpyToMemSetOptzn.
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23846
llvm-svn: 279769
Summary:
We teach alias analysis that invariant.start is readonly.
This helps with GVN and memcopy optimizations that currently treat.
invariant.start as a clobber.
We need to treat this as readonly, so that DSE does not incorrectly
remove stores prior to the invariant.start
Reviewers: sanjoy, reames, majnemer, dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23214
llvm-svn: 278138
The need for all these Lookup* functions is just because of calls to
getAnalysis inside methods (i.e. not at the top level) of the
runOnFunction method. They should be straightforward to clean up when
the old PM is gone.
llvm-svn: 272615
An exception could prevent a store from occurring but MemCpyOpt's
callslot optimization would fire anyway, causing the store to occur.
This fixes PR27849.
llvm-svn: 270892
Summary: This change fix the bug in isProfitableToUseMemset() where MaxIntSize shoule be in byte, not bit.
Reviewers: arsenm, joker.eph, mcrosier
Subscribers: mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D20176
llvm-svn: 269433
Sort of the BB-local equivalent to idiom-recognizer: if we have a basic-block
that really implements a memcpy operation, backends can benefit from seeing
this.
llvm-svn: 269125
Summary: This now try to reorder instructions in order to help create the optimizable pattern.
Reviewers: craig.topper, spatel, dexonsmith, Prazek, chandlerc, joker.eph, majnemer
Differential Revision: http://reviews.llvm.org/D16523
llvm-svn: 263503
Summary: As per title. This will allow the optimizer to pick up on it.
Reviewers: craig.topper, spatel, dexonsmith, Prazek, chandlerc, joker.eph, majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15923
llvm-svn: 256969
Summary: It turns out that if we don't try to do it at the store location, we can do it before any operation that alias the load, as long as no operation alias the store.
Reviewers: craig.topper, spatel, dexonsmith, Prazek, chandlerc, joker.eph
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15903
llvm-svn: 256923
Summary:
Most of the tool chain is able to optimize scalar and memcpy like operation effisciently while it isn't that good with aggregates. In order to improve the support of aggregate, we try to change aggregate manipulation into either scalar or memcpy like ones whenever possible without loosing informations.
This is one such opportunity.
Reviewers: craig.topper, spatel, dexonsmith, Prazek, chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15894
llvm-svn: 256868
Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
These intrinsics currently have an explicit alignment argument which is
required to be a constant integer. It represents the alignment of the
source and dest, and so must be the minimum of those.
This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments. The alignment
argument itself is removed.
There are a few places in the code for which the code needs to be
checked by an expert as to whether using only src/dest alignment is
safe. For those places, they currently take the minimum of src/dest
alignments which matches the current behaviour.
For example, code which used to read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 500, i32 8, i1 false)
will now read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 500, i1 false)
For out of tree owners, I was able to strip alignment from calls using sed by replacing:
(call.*llvm\.memset.*)i32\ [0-9]*\,\ i1 false\)
with:
$1i1 false)
and similarly for memmove and memcpy.
I then added back in alignment to test cases which needed it.
A similar commit will be made to clang which actually has many differences in alignment as now
IRBuilder can generate different source/dest alignments on calls.
In IRBuilder itself, a new argument was added. Instead of calling:
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, /* isVolatile */ false)
you now call
CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, SrcAlign, /* isVolatile */ false)
There is a temporary class (IntegerAlignment) which takes the source alignment and rejects
implicit conversion from bool. This is to prevent isVolatile here from passing its default
parameter to the source alignment.
Note, changes in future can now be made to codegen. I didn't change anything here, but this
change should enable better memcpy code sequences.
Reviewed by Hal Finkel.
llvm-svn: 253511
Pass MemCpyOpt doesn't check if a store instruction is nontemporal.
As a consequence, adjacent nontemporal stores are always merged into a
memset call.
Example:
;;;
define void @foo(<4 x float>* nocapture %p) {
entry:
store <4 x float> zeroinitializer, <4 x float>* %p, align 16, !nontemporal !0
%p1 = getelementptr inbounds <4 x float>, <4 x float>* %dst, i64 1
store <4 x float> zeroinitializer, <4 x float>* %p1, align 16, !nontemporal !0
ret void
}
!0 = !{i32 1}
;;;
In this example, the two nontemporal stores are combined to a memset of zero
which does not preserve the nontemporal hint. Later on the backend (tested on a
x86-64 corei7) expands that memset call into a sequence of two normal 16-byte
aligned vector stores.
opt -memcpyopt example.ll -S -o - | llc -mcpu=corei7 -o -
Before:
xorps %xmm0, %xmm0
movaps %xmm0, 16(%rdi)
movaps %xmm0, (%rdi)
With this patch, we no longer merge nontemporal stores into calls to memset.
In this example, llc correctly expands the two stores into two movntps:
xorps %xmm0, %xmm0
movntps %xmm0, 16(%rdi)
movntps %xmm0, (%rdi)
In theory, we could extend the usage of !nontemporal metadata to memcpy/memset
calls. However a change like that would only have the effect of forcing the
backend to expand !nontemporal memsets back to sequences of store instructions.
A memset library call would not have exactly the same semantic of a builtin
!nontemporal memset call. So, SelectionDAG will have to conservatively expand
it back to a sequence of !nontemporal stores (effectively undoing the merging).
Differential Revision: http://reviews.llvm.org/D13519
llvm-svn: 249820
Dávid Bolvanský