If the block being cloned contains a PHI node, in general, we need to
clone that PHI node, even though it's trivial. If the operand of the PHI
is an instruction in the block being cloned, the correct value for the
operand doesn't exist until SSAUpdater constructs it.
We usually don't hit this issue because we try to avoid threading across
loop headers, but it's possible to hit this in some cases involving
irreducible CFGs. I added a flag to allow threading across loop headers
to make the testcase easier to understand.
Thanks to Brian Rzycki for reducing the testcase.
Fixes https://bugs.llvm.org/show_bug.cgi?id=42085.
Differential Revision: https://reviews.llvm.org/D63913
llvm-svn: 365094
As noted in the test change, this is not trivially NFC, but all of the changes in output are cases where the SCEVExpander form is more canonical/optimal than the hand generation.
llvm-svn: 365075
The motivation for this is two fold:
1) Make the output (and thus tests) a bit more readable to a human trying to understand the result of the transform
2) Reduce spurious diffs in a potential future change to restructure all of this logic to use SCEVExpander (which hoists by default)
llvm-svn: 365066
On some occasions ReuseOrCreateCast may convert previously
expanded value to undefined. That value may be passed by
SCEVExpander as an argument to InsertBinop making IV chain
undefined.
Differential revision: https://reviews.llvm.org/D63928
llvm-svn: 365009
This reverts r364422 (git commit 1a3dc76186)
The inlining cost calculation is incorrect, leading to stack overflow due to large stack frames from heavy inlining.
llvm-svn: 365000
Summary: This patch introduces a new heuristic for guiding operand reordering. The new "look-ahead" heuristic can look beyond the immediate predecessors. This helps break ties when the immediate predecessors have identical opcodes (see lit test for an example).
Reviewers: RKSimon, ABataev, dtemirbulatov, Ayal, hfinkel, rnk
Reviewed By: RKSimon, dtemirbulatov
Subscribers: hiraditya, phosek, rnk, rcorcs, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60897
llvm-svn: 364964
I was actually wondering if there was some nicer way than m_Value()+cast,
but apparently what i was really "subconsciously" thinking about
was correctness issue.
hasNoUnsignedWrap()/hasNoUnsignedWrap() exist for Instruction,
not for BinaryOperator, so let's just use m_Instruction(),
thus both avoiding a cast, and a crash.
Fixes https://bugs.llvm.org/show_bug.cgi?id=42484,
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15587
llvm-svn: 364915
Use both one bit and signbit shifting to check for one bit merge.
Reviewers: lebedev.ri, spatel, efriedma, craig.topper
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63903
llvm-svn: 364857
Extends the transform from:
rL364341
...to include another (more common?) pattern that tests whether a
value is a power-of-2 (including or excluding zero).
llvm-svn: 364856
Summary:
To be noted, this pattern is not unhandled by instcombine per-se,
it is somehow does end up being folded when one runs opt -O3,
but not if it's just -instcombine. Regardless, that fold is
indirect, depends on some other folds, and is thus blind
when there are extra uses.
This does address the regression being exposed in D63992.
https://godbolt.org/z/7DGltUhttps://rise4fun.com/Alive/EPO0
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42459 | PR42459 ]]
Reviewers: spatel, nikic, huihuiz
Reviewed By: spatel
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63993
llvm-svn: 364792
Summary:
Given pattern:
`icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0`
we should move shifts to the same hand of 'and', i.e. rewrite as
`icmp eq/ne (and (x shift (Q+K)), y), 0` iff `(Q+K) u< bitwidth(x)`
It might be tempting to not restrict this to situations where we know
we'd fold two shifts together, but i'm not sure what rules should there be
to avoid endless combine loops.
We pick the same shift that was originally used to shift the variable we picked to shift:
https://rise4fun.com/Alive/6x1v
Should fix [[ https://bugs.llvm.org/show_bug.cgi?id=42399 | PR42399]].
Reviewers: spatel, nikic, RKSimon
Reviewed By: spatel
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63829
llvm-svn: 364791
As discussed in https://reviews.llvm.org/D63829
*if* *both* shifts are one-use, we'd most likely want to produce `lshr`,
and not rely on ordering.
Also, there should likely be a *separate* fold to do this reordering.
llvm-svn: 364772
To be noted, this pattern is not unhandled by instcombine per-se,
it is somehow does end up being folded when one runs opt -O3,
but not if it's just -instcombine. Regardless, that fold is
indirect, depends on some other folds, and is thus blind
when there are extra uses.
https://bugs.llvm.org/show_bug.cgi?id=42459https://rise4fun.com/Alive/EPO0
llvm-svn: 364749
Backend changes to enable WLS/LE low-overhead loops for armv8.1-m:
1) Use TTI to communicate to the HardwareLoop pass that we should try
to generate intrinsics that guard the loop entry, as well as setting
the loop trip count.
2) Lower the BRCOND that uses said intrinsic to an Arm specific node:
ARMWLS.
3) ISelDAGToDAG the node to a new pseudo instruction:
t2WhileLoopStart.
4) Add support in ArmLowOverheadLoops to handle the new pseudo
instruction.
Differential Revision: https://reviews.llvm.org/D63816
llvm-svn: 364733
This is the opposite direction of D62158 (we have to choose 1 form or the other).
Now that we have FMF on the select, this becomes more palatable. And the benefits
of having a single IR instruction for this operation (less chances of missing folds
based on extra uses, etc) overcome my previous comments about the potential advantage
of larger pattern matching/analysis.
Differential Revision: https://reviews.llvm.org/D62414
llvm-svn: 364721
This transform came up in D62414, but we should deal with it first.
We have LLVM intrinsics that correspond exactly to libm calls (unlike
most libm calls, these libm calls never set errno).
This holds without any fast-math-flags, so we should always canonicalize
to those intrinsics directly for better optimization.
Currently, we convert to fcmp+select only when we have FMF (nnan) because
fcmp+select does not preserve the semantics of the call in the general case.
Differential Revision: https://reviews.llvm.org/D63214
llvm-svn: 364714
Fixes https://bugs.llvm.org/show_bug.cgi?id=41998. Usually when we
have a truncated exit count we'll truncate the IV when comparing
against the limit, in which case exit count overflow in post-inc
form doesn't matter. However, for pointer IVs we don't do that, so
we have to be careful about incrementing the IV in the wide type.
I'm fixing this by removing the IVCount variable (which was
ExitCount or ExitCount+1) and replacing it with a UsePostInc flag,
and then moving the actual limit adjustment to the individual cases
(which are: pointer IV where we add to the wide type, integer IV
where we add to the narrow type, and constant integer IV where we
add to the wide type).
Differential Revision: https://reviews.llvm.org/D63686
llvm-svn: 364709
Introduce llvm.test.set.loop.iterations which sets the loop counter
and also produces an i1 after testing that the count is not zero.
Differential Revision: https://reviews.llvm.org/D63809
llvm-svn: 364628
This patch introduces a new function attribute, willreturn, to indicate
that a call of this function will either exhibit undefined behavior or
comes back and continues execution at a point in the existing call stack
that includes the current invocation.
This attribute guarantees that the function does not have any endless
loops, endless recursion, or terminating functions like abort or exit.
Patch by Hideto Ueno (@uenoku)
Reviewers: jdoerfert
Subscribers: mehdi_amini, hiraditya, steven_wu, dexonsmith, lebedev.ri, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D62801
llvm-svn: 364555
FunctionComparator attempts to produce a stable comparison of two Function
instances by looking at all available properties. Since ByVal attributes now
contain a Type pointer, they are not trivially ordered and FunctionComparator
should use its own Type comparison logic to sort them.
llvm-svn: 364523
Chen Zheng