In OptimizeAdd, we scan the operand list to see if there are any common factors
between operands that can be factored out to reduce the number of multiplies
(e.g., 'A*A+A*B*C+D' -> 'A*(A+B*C)+D'). For each operand of the operand list, we
only consider unique factors (which is tracked by the Duplicate set). Now if we
find a factor that is a negative constant, we add the negated value as a factor
as well, because we can percolate the negate out. However, we mistakenly don't
add this negated constant to the Duplicates set.
Consider the expression A*2*-2 + B. Obviously, nothing to factor.
For the added value A*2*-2 we over count 2 as a factor without this change,
which causes the assert reported in PR30256. The problem is that this code is
assuming that all the multiply operands of the add are already reassociated.
This change avoids the issue by making OptimizeAdd tolerate multiplies which
haven't been completely optimized; this sort of works, but we're doing wasted
work: we'll end up revisiting the add later anyway.
Another possible approach would be to enforce RPO iteration order more strongly.
If we have RedoInsts, we process them immediately in RPO order, rather than
waiting until we've finished processing the whole function. Intuitively, it
seems like the natural approach: reassociation works on expression trees, so
the optimization only works in one direction. That said, I'm not sure how
practical that is given the current Reassociate; the "optimal" form for an
expression depends on its use list (see all the uses of "user_back()"), so
Reassociate is really an iterative optimization of sorts, so any changes here
would probably get messy.
PR30256
Differential Revision: https://reviews.llvm.org/D30228
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a function's CFG when that CFG is unchanged.
This allows transformation passes to simply claim they preserve the CFG
and analysis passes to check for the CFG being preserved to remove the
fanout of all analyses being listed in all passes.
I've gone through and removed or cleaned up as many of the comments
reminding us to do this as I could.
Differential Revision: https://reviews.llvm.org/D28627
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292054 91177308-0d34-0410-b5e6-96231b3b80d8
We were already testing is the op was not a leaf, so need to then test if it was a leaf (added it to the assert instead).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286817 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
It was detected that the reassociate pass could enter an inifite
loop when analysing dead code. Simply skipping to analyse basic
blocks that are dead avoids such problems (and as a side effect
we avoid spending time on optimising dead code).
The solution is using the same Reverse Post Order ordering of the
basic blocks when doing the optimisations, as when building the
precalculated rank map. A nice side-effect of this solution is
that we now know that we only try to do optimisations for blocks
with ranked instructions.
Fixes https://llvm.org/bugs/show_bug.cgi?id=30818
Reviewers: llvm-commits, davide, eli.friedman, mehdi_amini
Subscribers: dberlin
Differential Revision: https://reviews.llvm.org/D26154
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285793 91177308-0d34-0410-b5e6-96231b3b80d8
Fixes PR 30784. Discussed with Justin, who pointed out that
in the new PassManager infrastructure we can have more fine-grained
control on which analyses we want to preserve, but this is the
best we can do with the current infrastructure.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285380 91177308-0d34-0410-b5e6-96231b3b80d8
pass manager passes' `run` methods.
This removes a bunch of SFINAE goop from the pass manager and just
requires pass authors to accept `AnalysisManager<IRUnitT> &` as a dead
argument. This is a small price to pay for the simplicity of the system
as a whole, despite the noise that changing it causes at this stage.
This will also helpfull allow us to make the signature of the run
methods much more flexible for different kinds af passes to support
things like intelligently updating the pass's progression over IR units.
While this touches many, many, files, the changes are really boring.
Mostly made with the help of my trusty perl one liners.
Thanks to Sean and Hal for bouncing ideas for this with me in IRC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272978 91177308-0d34-0410-b5e6-96231b3b80d8
As suggested by clang-tidy's performance-unnecessary-copy-initialization.
This can easily hit lifetime issues, so I audited every change and ran the
tests under asan, which came back clean.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272126 91177308-0d34-0410-b5e6-96231b3b80d8
This patch implements a optimization bisect feature, which will allow optimizations to be selectively disabled at compile time in order to track down test failures that are caused by incorrect optimizations.
The bisection is enabled using a new command line option (-opt-bisect-limit). Individual passes that may be skipped call the OptBisect object (via an LLVMContext) to see if they should be skipped based on the bisect limit. A finer level of control (disabling individual transformations) can be managed through an addition OptBisect method, but this is not yet used.
The skip checking in this implementation is based on (and replaces) the skipOptnoneFunction check. Where that check was being called, a new call has been inserted in its place which checks the bisect limit and the optnone attribute. A new function call has been added for module and SCC passes that behaves in a similar way.
Differential Revision: http://reviews.llvm.org/D19172
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I missed == and != when I removed implicit conversions between iterators
and pointers in r252380 since they were defined outside ilist_iterator.
Since they depend on getNodePtrUnchecked(), they indirectly rely on UB.
This commit removes all uses of these operators. (I'll delete the
operators themselves in a separate commit so that it can be easily
reverted if necessary.)
There should be NFC here.
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Previously the RedoInsts was processed at the end of the block.
However it was possible that it left behind some instructions that
were not canonicalized.
This should guarantee that any previous instruction in the basic
block is canonicalized before we process a new instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258830 91177308-0d34-0410-b5e6-96231b3b80d8
Before reevaluating instructions, iterate over all instructions
to be reevaluated and remove trivially dead instructions and if
any of it's operands become trivially dead, mark it for deletion
until all trivially dead instructions have been removed
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256773 91177308-0d34-0410-b5e6-96231b3b80d8
While we have successfully implemented a funclet-oriented EH scheme on
top of LLVM IR, our scheme has some notable deficiencies:
- catchendpad and cleanupendpad are necessary in the current design
but they are difficult to explain to others, even to seasoned LLVM
experts.
- catchendpad and cleanupendpad are optimization barriers. They cannot
be split and force all potentially throwing call-sites to be invokes.
This has a noticable effect on the quality of our code generation.
- catchpad, while similar in some aspects to invoke, is fairly awkward.
It is unsplittable, starts a funclet, and has control flow to other
funclets.
- The nesting relationship between funclets is currently a property of
control flow edges. Because of this, we are forced to carefully
analyze the flow graph to see if there might potentially exist illegal
nesting among funclets. While we have logic to clone funclets when
they are illegally nested, it would be nicer if we had a
representation which forbade them upfront.
Let's clean this up a bit by doing the following:
- Instead, make catchpad more like cleanuppad and landingpad: no control
flow, just a bunch of simple operands; catchpad would be splittable.
- Introduce catchswitch, a control flow instruction designed to model
the constraints of funclet oriented EH.
- Make funclet scoping explicit by having funclet instructions consume
the token produced by the funclet which contains them.
- Remove catchendpad and cleanupendpad. Their presence can be inferred
implicitly using coloring information.
N.B. The state numbering code for the CLR has been updated but the
veracity of it's output cannot be spoken for. An expert should take a
look to make sure the results are reasonable.
Reviewers: rnk, JosephTremoulet, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D15139
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Terrifyingly, one of them is a mishandling of floating point vectors
in Constant::isZero(). How exactly this issue survived this long
is beyond me.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253655 91177308-0d34-0410-b5e6-96231b3b80d8
We sometimes create intermediate subtract instructions during
reassociation. Adding these to the worklist to revisit exposes many
additional reassociation opportunities.
Patch by Aditya Nandakumar.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253240 91177308-0d34-0410-b5e6-96231b3b80d8
Remove remaining `ilist_iterator` implicit conversions from
LLVMScalarOpts.
This change exposed some scary behaviour in
lib/Transforms/Scalar/SCCP.cpp around line 1770. This patch changes a
call from `Function::begin()` to `&Function::front()`, since the return
was immediately being passed into another function that takes a
`Function*`. `Function::front()` started to assert, since the function
was empty. Note that `Function::end()` does not point at a legal
`Function*` -- it points at an `ilist_half_node` -- so the other
function was getting garbage before. (I added the missing check for
`Function::isDeclaration()`.)
Otherwise, no functionality change intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250211 91177308-0d34-0410-b5e6-96231b3b80d8
GlobalsAA must by definition be preserved in function passes, but the passmanager doesn't know that. Make each pass explicitly preserve GlobalsAA.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247263 91177308-0d34-0410-b5e6-96231b3b80d8
Some personality routines require funclet exit points to be clearly
marked, this is done by producing a token at the funclet pad and
consuming it at the corresponding ret instruction. CleanupReturnInst
already had a spot for this operand but CatchReturnInst did not.
Other personality routines don't need to use this which is why it has
been made optional.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245149 91177308-0d34-0410-b5e6-96231b3b80d8
iisUnmovableInstruction() had a list of instructions hardcoded which are
considered unmovable. The list lacked (at least) an entry for the va_arg
and cmpxchg instructions.
Fix this by introducing a new Instruction::mayBeMemoryDependent()
instead of maintaining another instruction list.
Patch by Matthias Braun <matze@braunis.de>.
Differential Revision: http://reviews.llvm.org/D11577
rdar://problem/22118647
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Reassociate mutated existing instructions in order to form negations
which would create additional reassociate opportunities.
This fixes PR23926.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240593 91177308-0d34-0410-b5e6-96231b3b80d8
The patch is generated using this command:
tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
llvm/lib/
Thanks to Eugene Kosov for the original patch!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240137 91177308-0d34-0410-b5e6-96231b3b80d8
If the type isn't trivially moveable emplace can skip a potentially
expensive move. It also saves a couple of characters.
Call sites were found with the ASTMatcher + some semi-automated cleanup.
memberCallExpr(
argumentCountIs(1), callee(methodDecl(hasName("push_back"))),
on(hasType(recordDecl(has(namedDecl(hasName("emplace_back")))))),
hasArgument(0, bindTemporaryExpr(
hasType(recordDecl(hasNonTrivialDestructor())),
has(constructExpr()))),
unless(isInTemplateInstantiation()))
No functional change intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238602 91177308-0d34-0410-b5e6-96231b3b80d8
Canonicalizing 'x [+-] (-Constant * y)' is not a win if we don't *know*
we will open up CSE opportunities.
If the multiply was 'nsw', then negating 'y' requires us to clear the
'nsw' flag. If this is actually worth pursuing, it is probably more
appropriate to do so in GVN or EarlyCSE.
This fixes PR23675.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238397 91177308-0d34-0410-b5e6-96231b3b80d8
This reapplies the patch previously committed at revision 232190. This was
reverted at revision 232196 as it caused test failures in tests that did not
expect operands to be commuted. I have made the tests more resilient to
reassociation in revision 232206.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232209 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts revision 232190 due to buildbot failure reported on clang-hexagon-elf
for test arm64_vtst.c. To be investigated.
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This patch adds initial support for vector instructions to the reassociation
pass. It enables most parts of the pass to work with vectors but to keep the
size of the patch small, optimization of Xor trees, canonicalization of
negative constants and converting shifts to muls, etc., have been left out.
This will be handled in later patches.
The patch is based on an initial patch by Chad Rosier.
Differential Revision: http://reviews.llvm.org/D7566
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232190 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
When trying to canonicalize negative constants out of
multiplication expressions, we need to check that the
constant is not INT_MIN which cannot be negated.
Reviewers: mcrosier
Reviewed By: mcrosier
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D7286
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228872 91177308-0d34-0410-b5e6-96231b3b80d8
The alloca's type is irrelevant, only those types which are used in a
load or store of the exact size of the slice should be considered.
This manifested as an assertion failure when we compared the various
types: we had a size mismatch.
This fixes PR21480.
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