The algorithm in allLoopPathsLeadToBlock() does not handle the case
where the loop latch is part of the predecessor set correctly: In
this case, we may take the backedge (escaping to a different loop
iteration) and not execute other latch successors. This can happen
if the latch is part of an inner cycle.
Fixes https://github.com/llvm/llvm-project/issues/57780.
Differential Revision: https://reviews.llvm.org/D134279
If the single-thread model is used, or the
-licm-force-thread-model-single flag is specified, skip checks
related to thread-safety. This means that store promotion for
conditionally executed stores only requires proof of
dereferenceability and writability, but not of thread-safety. For
example, this enables promotion of stores to (non-constant) globals,
as well as captured allocas.
Fixes https://github.com/llvm/llvm-project/issues/50537.
Differential Revision: https://reviews.llvm.org/D130466
This is the first patch in a series intended for removing flag
-enable-new-pm=0 from lit tests. This is part of a bigger
effort of completely removing legacy code related to legacy
pass manager in favor of currently default new pass manager.
In this patch flag has been removed only from tests where no significant
change has been required because checks has been duplicated for
both PMs.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D134150
If there are non-load/store users of the promoted pointer, we
currently abort promotion. However, having such users isn't really
relevant to the transform. We already separately check that a)
there are no instructions that modref the promoted pointer and
b) that a pointer capture disables store promotion.
In the affected @test_captured_in_loop test case we have a readnone
capture of the promoted pointer, which means that load promotion
can be performed (while store promotion cannot).
Differential Revision: https://reviews.llvm.org/D133485
Currently, we bail out of scalar promotion if the loop may unwind
and the memory may be visible on unwind. This is because we can't
insert stores of the promoted value on unwind edges.
However, nowadays scalar promotion also has support for only
promoting loads, while leaving stores in place. This kind of
promotion is safe even in the presence of unwinding.
Differential Revision: https://reviews.llvm.org/D133111
This code was relying on a very subtle contract: The expectation
was that for non-allocas, the unwind safety check would already
perform a capture check, so we don't need to perform it later.
This held true when this unwind safety was only handled for allocas
and noalias calls, but became incorrect when byval support was
added.
To avoid this kind of issue, just remove the dependency between the
unwind and thread-safety checks entirely. At worst, this means we
perform a redundant capture check. If this should turn out to be
problematic for compile-time, we can cache that query in a more
explicit way.
Following some recent discussions, this changes the representation
of callbrs in IR. The current blockaddress arguments are replaced
with `!` label constraints that refer directly to callbr indirect
destinations:
; Before:
%res = callbr i8* asm "", "=r,r,i"(i8* %x, i8* blockaddress(@test8, %foo))
to label %asm.fallthrough [label %foo]
; After:
%res = callbr i8* asm "", "=r,r,!i"(i8* %x)
to label %asm.fallthrough [label %foo]
The benefit of this is that we can easily update the successors of
a callbr, without having to worry about also updating blockaddress
references. This should allow us to remove some limitations:
* Allow unrolling/peeling/rotation of callbr, or any other
clone-based optimizations
(https://github.com/llvm/llvm-project/issues/41834)
* Allow duplicate successors
(https://github.com/llvm/llvm-project/issues/45248)
This is just the IR representation change though, I will follow up
with patches to remove limtations in various transformation passes
that are no longer needed.
Differential Revision: https://reviews.llvm.org/D129288
Pre-commit the test cases (for D128302) to show that more accurate cost
estimation of extract-element could generate better code.
Differential Revision: https://reviews.llvm.org/D128945
SplitBlockPredecessors currently asserts if one of the predecessor
terminators is a callbr. This limitation was originally necessary,
because just like with indirectbr, it was not possible to replace
successors of a callbr. However, this is no longer the case since
D67252. As the requirement nowadays is that callbr must reference
all blockaddrs directly in the call arguments, and these get
automatically updated when setSuccessor() is called, we no longer
need this limitation.
The only thing we need to do here is use replaceSuccessorWith()
instead of replaceUsesOfWith(), because only the former does the
necessary blockaddr updating magic.
I believe there's other similar limitations that can be removed,
e.g. related to critical edge splitting.
Differential Revision: https://reviews.llvm.org/D129205
This function is well-defined for an instruction that doesn't access
memory (and thus trivially doesn't alias anything in the AST), so
drop the assert. We can end up with a readnone call here if we
originally created a MemoryDef for an indirect call, which was
later replaced with a direct readnone call.
Fixes https://github.com/llvm/llvm-project/issues/51333.
Differential Revision: https://reviews.llvm.org/D127947
This test demonstrates how sinking down gc.relocate may lead to breach
of LCSSA form by tokens and, consecutively, end up with SSA breach by
LoopSimplifyCFG which creates fake edges and is unable to update missing
LCSSA phis for tokens used outside of the loop.
This is another attempt to land this patch.
The patch proposed to use a new cost model for loop interchange,
which is obtained from loop cache analysis.
Given a loopnest, what loop cache analysis returns is a vector of
loops [loop0, loop1, loop2, ...] where loop0 should be replaced as
the outermost loop, loop1 should be placed one more level inside, and
loop2 one more level inside, etc. What loop cache analysis does is not
only more comprehensive than the current cost model, it is also a "one-shot"
query which means that we only need to query it once during the entire
loop interchange pass, which is better than the current cost model where
we query it every time we check whether it is profitable to interchange
two loops. Thus complexity is reduced, especially after D120386 where we
do more interchanges to get the globally optimal loop access pattern.
Updates made to test cases are mostly minor changes and some
corrections. One change that applies to all tests is that we added an option
`-cache-line-size=64` to the RUN lines. This is ensure that loop
cache analysis receives a valid number of cache line size for correct
analysis. Test coverage for loop interchange is not reduced.
Currently we did not completely remove the legacy cost model, but
keep it as fall-back in case the new cost model did not run successfully.
This is because currently we have some limitations in delinearization, which
sometimes makes loop cache analysis bail out. The longer term goal is to
enhance delinearization and eventually remove the legacy cost model
compeletely.
Reviewed By: bmahjour, #loopoptwg
Differential Revision: https://reviews.llvm.org/D124926
llvm/lib/Analysis/LoopCacheAnalysis.cpp:702:30: runtime error: signed
integer overflow: 6148914691236517209 * 100 cannot be represented in
type 'long'
https://lab.llvm.org/buildbot/#/builders/5/builds/25185
This reverts commit 1b24fe34b06cd9f2337313f513a8b19f9a37c5de.
This is the second attempt to land this patch.
The patch proposed to use a new cost model for loop interchange,
which is obtained from loop cache analysis.
Given a loopnest, what loop cache analysis returns is a vector of
loops [loop0, loop1, loop2, ...] where loop0 should be replaced as the
outermost loop, loop1 should be placed one more level inside, and loop2
one more level inside, etc. What loop cache analysis does is not only more
comprehensive than the current cost model, it is also a "one-shot" query
which means that we only need to query it once during the entire loop
interchange pass, which is better than the current cost model where we
query it every time we check whether it is profitable to interchange two
loops. Thus complexity is reduced, especially after D120386 where we do
more interchanges to get the globally optimal loop access pattern.
Updates made to test cases are mostly minor changes and some corrections.
One change that applies to all tests is that we added an option
`-cache-line-size=64` to the RUN lines. This is ensure that loop cache
analysis receives a valid number of cache line size for correct analysis.
Test coverage for loop interchange is not reduced.
Currently we did not completely remove the legacy cost model, but keep it
as fall-back in case the new cost model did not run successfully. This is
because currently we have some limitations in delinearization, which sometimes
makes loop cache analysis bail out. The longer term goal is to enhance
delinearization and eventually remove the legacy cost model compeletely.
Reviewed By: bmahjour, #loopoptwg
Differential Revision: https://reviews.llvm.org/D124926
If all available vals to basic block are the same - do not build new phi node and
just use this value.
Reviewed By: sameerds
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D126525
This patch proposed to use a new cost model for loop interchange, which
is obtained from loop cache analysis.
Given a loopnest, what loop cache analysis returns is a vector of loops
[loop0, loop1, loop2, ...] where loop0 should be replaced as the outermost
loop, loop1 should be placed one more level inside, and loop2 one more level
inside, etc. What loop cache analysis does is not only more comprehensive than
the current cost model, it is also a "one-shot" query which means that we only
need to query it once during the entire loop interchange pass, which is better
than the current cost model where we query it every time we check whether it is
profitable to interchange two loops. Thus complexity is reduced, especially after
D120386 where we do more interchanges to get the globally optimal loop access pattern.
Updates made to test cases are mostly minor changes and some corrections.
Test coverage for loop interchange is not reduced.
Currently we did not completely remove the legacy cost model, but keep it as
fall-back in case the new cost model did not run successfully. This is because
currently we have some limitations in delinearization, which sometimes makes
loop cache analysis bail out. The longer term goal is to enhance delinearization
and eventually remove the legacy cost model compeletely.
Reviewed By: bmahjour, #loopoptwg
Differential Revision: https://reviews.llvm.org/D124926
This reverts the revert commit ad95255b9215a.
The updated version also creates a load when the store may not execute.
In those cases, we still need to introduce a load in a function where
there may not have been one before, so this doesn't completely resolve
issue #51248.
Original message:
When only a store is sunk, there is no need to create a load in the
pre-header, as the result of the load will never get used.
The dead load can can introduce UB, if the function is marked as
writeonly.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D123473
This reverts the revert commit 1ddc719680c21f3.
This version of the patch sets the initial available value to poison,
which resolves an issue with the SSAUpdater breaking LCSSA form.
When only a store is sunk, there is no need to create a load in the
pre-header, as the result of the load will never get used.
The dead load can can introduce UB, if the function is marked as
writeonly.
Fixes#51248.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D123473
This makes MemorySSA in LoopSink required, and removes the AST-based
implementation, as well as the related support code in LICM.
Differential Revision: https://reviews.llvm.org/D123288
Rather than iterating over users and comparing operands, iterate
over uses and check operand number. Otherwise, we'll end up
promoting a store twice if it has two equal operands.
This can only happen with opaque pointers, as otherwise both
operands differ by a level of indirection, so a bitcast would have
to be involved.
Fixes https://github.com/llvm/llvm-project/issues/54495.
This adds a new option to control AllowSpeculation added in D119965 when
using `-passes=...`.
This allows reproducing #54023 using opt.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D121944
Skip phi nodes in the preheader. They may not be considered loop
invariant by the assertion below.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D121010
