Summary:
While walking defs of pointer operands we were assuming that the pointer
size would remain constant. This is not true, because addresspacecast
instructions may cast the pointer to an address space with a different
pointer width.
This partial reverts r282612, which was a more conservative solution
to this problem.
Reviewers: reames, sanjoy, apilipenko
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D24772
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283557 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The computeKnownBits and ComputeNumSignBits functions in ValueTracking can now do a simple look-through of ExtractElement.
Reviewers: majnemer, spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24955
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283434 91177308-0d34-0410-b5e6-96231b3b80d8
Pointers in different addrspaces can have different sizes, so it's not valid to look through addrspace cast calculating base and offset for a value.
This is similar to D13008.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D24729
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282612 91177308-0d34-0410-b5e6-96231b3b80d8
There is no benefit in looking through assumptions on UndefValue to
guess known bits. Return early to avoid walking their use-lists, and
assert that all instances of ConstantData are handled here for similar
reasons (UndefValue was the only integer/pointer holdout).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282337 91177308-0d34-0410-b5e6-96231b3b80d8
Check and return early for ConstantPointerNull and UndefValue
specifically in isKnownNonNullAt, and assert that ConstantData never
make it to isKnownNonNullFromDominatingCondition.
This confirms that isKnownNonNullFromDominatingCondition never walks
through the use-list of an instance of ConstantData. Given that such
use-lists cross module boundaries, it never really made sense to do so,
and was potentially very expensive.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282333 91177308-0d34-0410-b5e6-96231b3b80d8
computeKnownBits() already works for integer vectors, so allow vector types when calling that from InstCombine.
I don't think the change to use m_APInt in computeKnownBits is strictly necessary because we do check for
ConstantVector later, but it's more efficient to handle the splat case without needing to loop on vector elements.
This should work with InstSimplify, but doesn't yet, so I made that a FIXME comment on the test for PR24942:
https://llvm.org/bugs/show_bug.cgi?id=24942
Differential Revision: https://reviews.llvm.org/D24677
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281777 91177308-0d34-0410-b5e6-96231b3b80d8
Almost all of the method here are only analysing Value's as opposed to
mutating them. Mark all of the easy ones as const.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278585 91177308-0d34-0410-b5e6-96231b3b80d8
This method had some duplicate code when we did or did not have a dom tree. Refactor
it to remove the duplication, but also clean up the control flow to have less duplication.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278450 91177308-0d34-0410-b5e6-96231b3b80d8
There were 2 versions of this method. A public one which takes a
const Instruction* and a private implementation which takes a mutable
Value* and casts to an Instruction*.
There was no need for the 2 versions as all callers pass a const Instruction*
and there was no need for a mutable pointer as we only do analysis here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278434 91177308-0d34-0410-b5e6-96231b3b80d8
Motivated by the work on the llvm.noalias intrinsic, teach BasicAA to look
through returned-argument functions when answering queries. This is essential
so that we don't loose all other AA information when supplementing with
llvm.noalias.
Differential Revision: http://reviews.llvm.org/D9383
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275035 91177308-0d34-0410-b5e6-96231b3b80d8
This actually uncovered a surprisingly large chain of ultimately unused
TLI args.
From what I can gather, this argument is a remnant of when
isKnownNonNull would look at the TLI directly.
The current approach seems to be that InferFunctionAttrs runs early in
the pipeline and uses TLI to annotate the TLI-dependent non-null
information as return attributes.
This also removes the dependence of functionattrs on TLI altogether.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274455 91177308-0d34-0410-b5e6-96231b3b80d8
This is breaking an optimizaton remark test in clang. I've identified a couple fixes for that, but want to understand it better before I commit to anything.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274102 91177308-0d34-0410-b5e6-96231b3b80d8
If a operation for a recurrence is an addition with no signed wrap and both input sign bits are 0, then the result sign bit must also be 0. Similar for the negative case.
I found this deficiency while playing around with a loop in the x86 backend that contained a signed division that could be optimized into an unsigned division if we could prove both inputs were positive. One of them being the loop induction variable. With this patch we can perform the conversion for this case. One of the test cases here is a contrived variation of the loop I was looking at.
Differential revision: http://reviews.llvm.org/D21493
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274098 91177308-0d34-0410-b5e6-96231b3b80d8
This is similar to the computeKnownBits improvement in rL268479.
There's probably more we can do for vector logic instructions, but
this should let us see non-splat constant masking ops that can
become vector selects instead of and/andn/or sequences.
Differential Revision: http://reviews.llvm.org/D21610
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273459 91177308-0d34-0410-b5e6-96231b3b80d8
This change teaches llvm::isGuaranteedToTransferExecutionToSuccessor
that calls to @llvm.assume always terminate. Most other relevant
intrinsics should be covered by the "CS.onlyReadsMemory() ||
CS.onlyAccessesArgMemory()" bit but we were missing @llvm.assumes
because we state that it clobbers memory.
Added an LICM test case, but this change is not specific to LICM.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272703 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Make isGuaranteedToExecute use the
isGuaranteedToTransferExecutionToSuccessor helper, and make that helper
a bit more accurate.
There's a potential performance impact here from assuming that arbitrary
calls might not return. This probably has little impact on loads and
stores to a pointer because most things alias analysis can reason about
are dereferenceable anyway. The other impacts, like less aggressive
hoisting of sdiv by a variable and less aggressive hoisting around
volatile memory operations, are unlikely to matter for real code.
This also impacts SCEV, which uses the same helper. It's a minor
improvement there because we can tell that, for example, memcpy always
returns normally. Strictly speaking, it's also introducing
a bug, but it's not any worse than everywhere else we assume readonly
functions terminate.
Fixes http://llvm.org/PR27857.
Reviewers: hfinkel, reames, chandlerc, sanjoy
Subscribers: broune, llvm-commits
Differential Revision: http://reviews.llvm.org/D21167
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272489 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
Summary:
This change teaches SCEV to see reduce `(extractvalue
0 (op.with.overflow X Y))` into `op X Y` (with a no-wrap tag if
possible).
This was first checked in at r265912 but reverted in r265950 because it
exposed some issues around how SCEV handled post-inc add recurrences.
Those issues have now been fixed.
Reviewers: atrick, regehr
Subscribers: mcrosier, mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D18684
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271152 91177308-0d34-0410-b5e6-96231b3b80d8
This is a stripped down version of D19211, leaving out the questionable
"branching in poison is UB" bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271150 91177308-0d34-0410-b5e6-96231b3b80d8
Similar in spirit to D20497 :
If all elements of a constant vector are known non-zero, then we can say that the
whole vector is known non-zero.
It seems like we could extend this to FP scalar/vector too, but isKnownNonZero()
says it only works for integers and pointers for now.
Differential Revision: http://reviews.llvm.org/D20544
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270562 91177308-0d34-0410-b5e6-96231b3b80d8
We could try harder to handle non-splat vector constants too,
but that seems much rarer to me.
Note that the div test isn't resolved because there's a check
for isIntegerTy() guarding that transform.
Differential Revision: http://reviews.llvm.org/D20497
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270369 91177308-0d34-0410-b5e6-96231b3b80d8
We assumed that ConstantVectors would be rather uninteresting from the
perspective of analysis. However, this is not the case due to a quirk
of how LLVM handles vectors of i1. Vectors of i1 are not
ConstantDataVectors like vectors of i8, i16, i32 or i64 because i1's
SizeInBits differs from it's StoreSizeInBytes. This leads to it being
categorized as a ConstantVector instead of a ConstantDataVector.
Instead, treat ConstantVector more uniformly.
This fixes PR27591.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268479 91177308-0d34-0410-b5e6-96231b3b80d8
matchSelectPattern attempts to see through casts which mask min/max
patterns from being more obvious. Under certain circumstances, it would
misidentify a sequence of instructions as a min/max because it assumed
that folding casts would preserve the result. This is not the case for
floating point <-> integer casts.
This fixes PR27575.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268086 91177308-0d34-0410-b5e6-96231b3b80d8
