Summary:
Avoid blind cast from Operator to ExtractElementInst in
computeKnownBitsFromOperator. This resulted in some crashes
in downstream fuzzy testing. Instead we use getOperand directly
on the Operator when accessing the vector/index operands.
Haven't seen any problems with InsertElement and ShuffleVector,
but I believe those could be used in constant expressions as well.
So the same kind of fix as for ExtractElement was also applied for
InsertElement.
When it comes to ShuffleVector we now simply bail out if a dynamic
cast of the Operator to ShuffleVectorInst fails. I've got no
reproducer indicating problems for ShuffleVector, and a fix would be
slightly more complicated as getShuffleDemandedElts is involved.
Reviewers: RKSimon, nikic, spatel, efriedma
Reviewed By: RKSimon
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76564
If one operand is unknown (and we don't have nowrap), don't compute
the second operand.
Also don't create an unnecessary extra KnownBits variable, it's
okay to reuse KnownOut.
This reduces instructions on libclamav_md5.c by 40%.
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
The sll/srl/sra scalar vector shifts can be replaced with generic shifts if the shift amount is known to be in range.
This also required public DemandedElts variants of llvm::computeKnownBits to be exposed (PR36319).
Summary:
DataLayout::getTypeAllocSize() return TypeSize. For cases where the
scalable property doesn't matter, we should explicitly call getKnownMinSize()
to avoid implicit type conversion to uint64_t, which is not valid for scalable
vector type.
Reviewers: sdesmalen, efriedma, apazos, reames
Reviewed By: efriedma
Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76260
Because we have to use a ConstantExpr at some point, the canonical form
isn't set in stone, but this seems reasonable.
The pretty sizeof(<vscale x 4 x i32>) dumping is a relic of ancient
LLVM; I didn't have to touch that code. :)
Differential Revision: https://reviews.llvm.org/D75887
Summary:
```
br i1 c, BB1, BB2:
BB1:
use1(c)
BB2:
use2(c)
```
In BB1 and BB2, c is never undef or poison because otherwise the branch would have triggered UB.
This is a resubmission of 952ad47 with crash fix of llvm/test/Transforms/LoopRotate/freeze-crash.ll.
Checked with Alive2
Reviewers: xbolva00, spatel, lebedev.ri, reames, jdoerfert, nlopes, sanjoy
Reviewed By: reames
Subscribers: jdoerfert, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75401
Summary:
```
br i1 c, BB1, BB2:
BB1:
use1(c)
BB2:
use2(c)
```
In BB1 and BB2, c is never undef or poison because otherwise the branch would have triggered UB.
Checked with Alive2
Reviewers: xbolva00, spatel, lebedev.ri, reames, jdoerfert, nlopes, sanjoy
Reviewed By: reames
Subscribers: jdoerfert, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75401
Summary:
This patch helps getGuaranteedNonFullPoisonOp handle llvm.assume call.
Also, a comment about the semantics of branch is removed to prevent confusion.
As llvm.assume does, branching on poison directly raises UB (as LangRef says), and this allows transformations such as introduction of llvm.assume on branch condition at each successor, or freely replacing values after conditional branch (such as at loop exit).
Handling br is not addressed in this patch. It makes SCEV more accurate, causing existing LoopVectorize/IndVar/etc tests to fail.
Reviewers: spatel, lebedev.ri, nlopes
Reviewed By: nlopes
Subscribers: hiraditya, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75397
Summary:
This patch helps isGuaranteedNotToBeUndefOrPoison return true if the value
makes the program always undefined.
According to value tracking functions' comments, it is not still in consensus
whether a poison value can be bitwise or not, so conservatively only the case with
i1 is considered.
Reviewers: spatel, lebedev.ri, reames, nlopes, regehr
Reviewed By: nlopes
Subscribers: uenoku, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75396
isKnownNonNaN() could not recognize a zero splat because that is a
ConstantAggregateZero which is-a ConstantData but not a ConstantDataVector.
Patch makes a ConstantAggregateZero return true.
Review: Thomas Lively
Differential Revision: https://reviews.llvm.org/D74263
Summary:
This was a very odd API, where you had to pass a flag into a zext
function to say whether the extended bits really were zero or not. All
callers passed in a literal true or false.
I think it's much clearer to make the function name reflect the
operation being performed on the value we're tracking (rather than on
the KnownBits Zero and One fields), so zext means the value is being
zero extended and new function anyext means the value is being extended
with unknown bits.
NFC.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74482
If we know that a >= b (unsigned), usub.with.overflow(a, b) cannot
overflow. Similarly, if b > a, the same expression overflows.
Reviewers: nikic, RKSimon, lebedev.ri, spatel
Reviewed By: nikic, Gerolf
Differential Revision: https://reviews.llvm.org/D74066
This patch adds versions of isImpliedCondition and
isImpliedByDomCondition that take a predicate, LHS and RHS operands as
instead of a Value representing the condition.
This allows using those functions to check conditions without having a
concrete ICmp instruction.
Reviewers: nikic, RKSimon, lebedev.ri, spatel
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D74065
This patch adds initial support for a DemandedElts mask to the internal computeKnownBits/ComputeNumSignBits methods, matching the SelectionDAG and GlobalISel equivalents.
So far only a couple of instructions have been setup to handle the DemandedElts, the remainder still using the existing 'all elements' default. The plan is to extend support as we have test coverage.
Differential Revision: https://reviews.llvm.org/D73435
This addresses https://bugs.llvm.org/show_bug.cgi?id=42801.
The m_c_ICmp() matcher is changed to provide the swapped predicate
if the operands are swapped.
Existing uses of m_c_ICmp() fall in one of two categories: Working
on equality predicates only, where swapping is irrelevant.
Or performing a manual swap, in which case this patch removes it.
The only exception is the foldICmpWithLowBitMaskedVal() fold, which
does not swap the predicate, and instead reasons about whether
a swap occurred or not for each predicate. Getting the swapped
predicate allows us to merge the logic for pairs of predicates,
instead of duplicating it.
Differential Revision: https://reviews.llvm.org/D72976
Summary:
It is pretty common to assume that something is not zero.
Even optimizer itself sometimes emits such assumptions
(e.g. `addAssumeNonNull()` in `PromoteMemoryToRegister.cpp`).
But we currently don't deal with such assumptions :)
The only way `isKnownNonZero()` handles assumptions is
by calling `computeKnownBits()` which calls `computeKnownBitsFromAssume()`.
But `x != 0` does not tell us anything about set bits,
it only says that there are *some* set bits.
So naturally, `KnownBits` does not get populated,
and we fail to make use of this assumption.
I propose to deal with this special case by special-casing it
via adding a `isKnownNonZeroFromAssume()` that returns boolean
when there is an applicable assumption.
While there, we also deal with other predicates,
mainly if the comparison is with constant.
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=43267 | PR43267 ]].
Differential Revision: https://reviews.llvm.org/D71660
This is a pretty rare case, when CxtI and assume are
in the same basic block, with assume being located later.
We were already checking that assumption was guaranteed to be
executed, but we omitted CxtI itself from consideration,
and as the test (miscompile) shows, that is incorrect.
As noted in D71660 review by @nikic.
GEP index size can be specified in the DataLayout, introduced in D42123. However, there were still places
in which getIndexSizeInBits was used interchangeably with getPointerSizeInBits. This notably caused issues
with Instcombine's visitPtrToInt; but the unit tests was incorrect, so this remained undiscovered.
This fixes the buildbot failures.
Differential Revision: https://reviews.llvm.org/D68328
Patch by Joseph Faulls!
GEP index size can be specified in the DataLayout, introduced in D42123. However, there were still places
in which getIndexSizeInBits was used interchangeably with getPointerSizeInBits. This notably caused issues
with Instcombine's visitPtrToInt; but the unit tests was incorrect, so this remained undiscovered.
Differential Revision: https://reviews.llvm.org/D68328
Patch by Joseph Faulls!
This has two main effects:
- Optimizes debug info size by saving 221.86 MB of obj file size in a
Windows optimized+debug build of 'all'. This is 3.03% of 7,332.7MB of
object file size.
- Incremental step towards decoupling target intrinsics.
The enums are still compact, so adding and removing a single
target-specific intrinsic will trigger a rebuild of all of LLVM.
Assigning distinct target id spaces is potential future work.
Part of PR34259
Reviewers: efriedma, echristo, MaskRay
Reviewed By: echristo, MaskRay
Differential Revision: https://reviews.llvm.org/D71320
If the pointer was loaded/stored before the null check, the check
is redundant and can be removed. For now the optimizers do not
remove the nullptr check, see https://gcc.godbolt.org/z/H2r5GG.
The patch allows to use more nonnull constraints. Also, it found
one more optimization in some PowerPC test. This is my first llvm
review, I am free to any comments.
Differential Revision: https://reviews.llvm.org/D71177
Summary:
Same as D60846 and D69571 but with a fix for the problem encountered
after them. Both times it was a missing context adjustment in the
handling of PHI nodes.
The reproducers created from the bugs that caused the old commits to be
reverted are included.
Reviewers: nikic, nlopes, mkazantsev, spatel, dlrobertson, uabelho, hakzsam, hans
Subscribers: hiraditya, bollu, asbirlea, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71181
As it can be seen from accompanying cleanup, it is not unheard of
to write `~Known.Zero` meaning "what maximal value can this KnownBits
produce". But i think `~Known.Zero` isn't *that* self-explanatory,
as compared to a method with a name.
Note that not all `~Known.Zero` places were cleaned up,
only those where this arguably improves things.
This caused miscompiles of Chromium (https://crbug.com/1023818). The reduced
repro is small enough to fit here:
$ cat /tmp/a.c
unsigned char f(unsigned char *p) {
unsigned char result = 0;
for (int shift = 0; shift < 1; ++shift)
result |= p[0] << (shift * 8);
return result;
}
$ bin/clang -O2 -S -o - /tmp/a.c | grep -A4 f:
f: # @f
.cfi_startproc
# %bb.0: # %entry
xorl %eax, %eax
retq
That's nicely optimized, but I don't think it's the right result :-)
> Same as D60846 but with a fix for the problem encountered there which
> was a missing context adjustment in the handling of PHI nodes.
>
> The test that caused D60846 to be reverted was added in e15ab8f277.
>
> Reviewers: nikic, nlopes, mkazantsev,spatel, dlrobertson, uabelho, hakzsam
>
> Subscribers: hiraditya, bollu, llvm-commits
>
> Tags: #llvm
>
> Differential Revision: https://reviews.llvm.org/D69571
This reverts commit 57dd4b03e4.
Same as D60846 but with a fix for the problem encountered there which
was a missing context adjustment in the handling of PHI nodes.
The test that caused D60846 to be reverted was added in e15ab8f277.
Reviewers: nikic, nlopes, mkazantsev,spatel, dlrobertson, uabelho, hakzsam
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69571
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
The static analyzer is warning about a potential null dereferences, but since the pointer is only used in a switch statement for Operator::getOpcode() (with an empty default) then its easiest just to wrap this in a null test as the dyn_cast might return null here.
llvm-svn: 372962
Static analyzer complains about const_cast uninitialized variables, we should explicitly set these to null.
Ideally that const wrapper would go away though.......
llvm-svn: 372603
Sanjay Patel