Comparing the result of a cmpxchg instruction can be replaced with an
extractvalue of the cmpxchg success indicator.
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FoldOpIntoPhi could create an infinite loop if the PHI could potentially
reach a BB it was considering inserting instructions into. The
instructions it would insert would eventually lead to other combines
firing which would, again, lead to FoldOpIntoPhi firing.
The solution is to handicap FoldOpIntoPhi so that it doesn't attempt to
insert instructions that the PHI might reach.
This fixes PR21377.
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m_ZExt might bind against a ConstantExpr instead of an Instruction.
Assuming this, using cast<Instruction>, results in InstCombine crashing.
Instead, introduce ZExtOperator to bridge both Instruction and
ConstantExpr ZExts.
This fixes PR21445.
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This can happen pretty often in code that looks like:
int foo = bar - 1;
if (foo < 0)
do stuff
In this case, bar < 1 is an equivalent condition.
This transform requires that the add instruction be annotated with nsw.
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If we load from a location with range metadata, we can use information about the ranges of the loaded value for optimization purposes. This helps to remove redundant checks and canonicalize checks for other optimization passes. This particular patch checks whether a value is known to be non-zero from the range metadata.
Currently, these tests are against InstCombine. In theory, all of these should be InstSimplify since we're not inserting any new instructions. Moving the code may follow in a separate change.
Reviewed by: Hal
Differential Revision: http://reviews.llvm.org/D5947
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An icmp may have pointer arguments, it isn't limited to integers or
vectors of integers.
This fixes PR21388.
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This patch removes a chunk of special case logic for folding
(float)sqrt((double)x) -> sqrtf(x)
in InstCombineCasts and handles it in the mainstream path of SimplifyLibCalls.
No functional change intended, but I loosened the restriction on the existing
sqrt testcases to allow for this optimization even without unsafe-fp-math because
that's the existing behavior.
I also added a missing test case for not shrinking the llvm.sqrt.f64 intrinsic
in case the result is used as a double.
Differential Revision: http://reviews.llvm.org/D5919
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When a call to a double-precision libm function has fast-math semantics
(via function attribute for now because there is no IR-level FMF on calls),
we can avoid fpext/fptrunc operations and use the float version of the call
if the input and output are both float.
We already do this optimization using a command-line option; this patch just
adds the ability for fast-math to use the existing functionality.
I moved the cl::opt from InstructionCombining into SimplifyLibCalls because
it's only ever used internally to that class.
Modified the existing test cases to use the unsafe-fp-math attribute rather
than repeating all tests.
This patch should solve: http://llvm.org/bugs/show_bug.cgi?id=17850
Differential Revision: http://reviews.llvm.org/D5893
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These are named following the IEEE-754 names for these
functions, rather than the libm fmin / fmax to avoid
possible ambiguities. Some languages may implement something
resembling fmin / fmax which return NaN if either operand is
to propagate errors. These implement the IEEE-754 semantics
of returning the other operand if either is a NaN representing
missing data.
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This function was complicated by the fact that it tried to perform
canonicalizations that were already preformed by InstSimplify. Remove
this extra code and move the tests over to InstSimplify. Add asserts to
make sure our preconditions hold before we make any assumptions.
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inttoptr or ptrtoint cast provided there is datalayout available.
Eventually, the datalayout can just be required but in practice it will
always be there today.
To go with the ability to expose available values requiring a ptrtoint
or inttoptr cast, helpers are added to perform one of these three casts.
These smarts are necessary to finish canonicalizing loads and stores to
the operational type requirements without regressing fundamental
combines.
I've added some test cases. These should actually improve as the load
combining and store combining improves, but they may fundamentally be
highlighting some missing combines for select in addition to exercising
the specific added logic to load analysis.
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The original code had an implicit assumption that if the test for
allocas or globals was reached, the two pointers were not equal. With my
changes to make the pointer analysis more powerful here, I also had to
guard against circumstances where the results weren't useful. That in
turn violated the assumption and gave rise to a circumstance in which we
could have a store with both the queried pointer and stored pointer
rooted at *the same* alloca. Clearly, we cannot ignore such a store.
There are other things we might do in this code to better handle the
case of both pointers ending up at the same alloca or global, but it
seems best to at least make the test explicit in what it intends to
check.
I've added tests for both the alloca and global case here.
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logic to look through pointer casts, making them trivially stronger in
the face of loads and stores with intervening pointer casts.
I've included a few test cases that demonstrate the kind of folding
instcombine can do without pointer casts and then variations which
obfuscate the logic through bitcasts. Without this patch, the variations
all fail to optimize fully.
This is more important now than it has been in the past as I've started
moving the load canonicialization to more closely follow the value type
requirements rather than the pointer type requirements and thus this
needs to be prepared for more pointer casts. When I made the same change
to stores several test cases regressed without logic along these lines
so I wanted to systematically improve matters first.
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of InstCombine rather than just the bits enabled when datalayout is
optional.
The primary fixes here are because now things are little endian.
In good news, silliness like this seems like it will be going away as
we've got pretty stong consensus on dropping optional datalayout
entirely.
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loads.
This handles many more cases than just the AA metadata, some of them
suggested by Hal in his review of the AA metadata handling patch. I've
tried to test this behavior where tractable to do so.
I'll point out that I have specifically *not* included a test for
debuginfo because it was going to require 2 or 3 times as much work to
craft some input which would survive the "helpful" stripping of debug
info metadata that doesn't match the desired schema. This is another
good example of why the current state of write-ability for our debug
info metadata is unacceptable. I spent over 30 minutes trying to conjure
some test case that would survive, even copying from other debug info
tests, but it always failed to survive with no explanation of why or how
I might fix it. =[
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up to where it actually works as intended. The problem is that
a GlobalAlias isa GlobalValue and so the prior block handled all of the
cases.
This allows us to constant fold based on the actual constant expression
in the global alias. As an example, see the last function in the newly
added test case which explicitly aligns an unaligned pointer using
constant expression math. Without this change, we fail to see that and
fold an alignment test to zero.
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The following implements the optimization for sequences of the form:
icmp eq/ne (shl Const2, A), Const1
Such sequences can be transformed to:
icmp eq/ne A, (TrailingZeros(Const1) - TrailingZeros(Const2))
This handles only the equality operators for now. Other operators need
to be handled.
Patch by Ankur Garg!
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by my refactoring of this code.
The method isSafeToLoadUnconditionally assumes that the load will
proceed with the preferred type alignment. Given that, it has to ensure
that the alloca or global is at least that aligned. It has always done
this historically when a datalayout is present, but has never checked it
when the datalayout is absent. When I refactored the code in r220156,
I exposed this path when datalayout was present and that turned the
latent bug into a patent bug.
This fixes the issue by just removing the special case which allows
folding things without datalayout. This isn't worth the complexity of
trying to tease apart when it is or isn't safe without actually knowing
the preferred alignment.
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...)) and (load (cast ...)): canonicalize toward the former.
Historically, we've tried to load using the type of the *pointer*, and
tried to match that type as closely as possible removing as many pointer
casts as we could and trading them for bitcasts of the loaded value.
This is deeply and fundamentally wrong.
Repeat after me: memory does not have a type! This was a hard lesson for
me to learn working on SROA.
There is only one thing that should actually drive the type used for
a pointer, and that is the type which we need to use to load from that
pointer. Matching up pointer types to the loaded value types is very
useful because it minimizes the physical size of the IR required for
no-op casts. Similarly, the only thing that should drive the type used
for a loaded value is *how that value is used*! Again, this minimizes
casts. And in fact, the *only* thing motivating types in any part of
LLVM's IR are the types used by the operations in the IR. We should
match them as closely as possible.
I've ended up removing some tests here as they were testing bugs or
behavior that is no longer present. Mostly though, this is just cleanup
to let the tests continue to function as intended.
The only fallout I've found so far from this change was SROA and I have
fixed it to not be impeded by the different type of load. If you find
more places where this change causes optimizations not to fire, those
too are likely bugs where we are assuming that the type of pointers is
"significant" for optimization purposes.
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This test is pretty awesome. It is claiming to test devirtualization.
However, the code in question is not in fact devirtualized by LLVM. If
you take the original C++ test case and run it through Clang at -O3 we
fail to devirtualize it completely. It also isn't a sufficiently focused
test case.
The *reason* we fail to devirtualize it isn't because of any missing
instcombine though. Instead, it is because we fail to emit an available
externally vtable and thus the vtable is just an external and completely
opaque. If I cause the vtable to be emitted, we successfully
devirtualize things.
Anyways, I'm just removing it because it is providing negative value at
this point: it isn't representative of the output of Clang really, LLVM
isn't doing the transform it claims to be testing, LLVM's failure to do
the transform isn't actually an LLVM bug at all and we shouldn't be
testing for it here, and finally the test is written in such a way that
it will trivially pass even when the point of the test is failing.
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If a square root call has an FP multiplication argument that can be reassociated,
then we can hoist a repeated factor out of the square root call and into a fabs().
In the simplest case, this:
y = sqrt(x * x);
becomes this:
y = fabs(x);
This patch relies on an earlier optimization in instcombine or reassociate to put the
multiplication tree into a canonical form, so we don't have to search over
every permutation of the multiplication tree.
Because there are no IR-level FastMathFlags for intrinsics (PR21290), we have to
use function-level attributes to do this optimization. This needs to be fixed
for both the intrinsics and in the backend.
Differential Revision: http://reviews.llvm.org/D5787
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The code committed in r219832 asserted when it attempted to shrink a switch
statement whose type was larger than 64-bit.
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Truncate the operands of a switch instruction to a narrower type if the upper
bits are known to be all ones or zeros.
rdar://problem/17720004
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Eliminate library calls and intrinsic calls to fabs when the input
is a squared value.
Note that no unsafe-math / fast-math assumptions are needed for
this optimization.
Differential Revision: http://reviews.llvm.org/D5777
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We assumed that A must be greater than B because the right hand side of
a remainder operator must be nonzero.
However, it is possible for A to be less than B if Pow2 is a power of
two greater than 1.
Take for example:
i32 %A = 0
i32 %B = 31
i32 Pow2 = 2147483648
((Pow2 << 0) >>u 31) is non-zero but A is less than B.
This fixes PR21274.
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We assumed that negation operations of the form (0 - %Z) resulted in a
negative number. This isn't true if %Z was originally negative.
Substituting the negative number into the remainder operation may result
in undefined behavior because the dividend might be INT_MIN.
This fixes PR21256.
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We have a transform that changes:
(x lshr C1) udiv C2
into:
x udiv (C2 << C1)
However, it is unsafe to do so if C2 << C1 discards any of C2's bits.
This fixes PR21255.
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Consider the case where X is 2. (2 <<s 31)/s-2147483648 is zero but we
would fold to X. Note that this is valid when we are in the unsigned
domain because we require NUW: 2 <<u 31 results in poison.
This fixes PR21245.
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consider:
C1 = INT_MIN
C2 = -1
C1 * C2 overflows without a doubt but consider the following:
%x = i32 INT_MIN
This means that (%X /s C1) is 1 and (%X /s C1) /s C2 is -1.
N. B. Move the unsigned version of this transform to InstSimplify, it
doesn't create any new instructions.
This fixes PR21243.
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consider:
mul i32 nsw %x, -2147483648
this instruction will not result in poison if %x is 1
however, if we transform this into:
shl i32 nsw %x, 31
then we will be generating poison because we just shifted into the sign
bit.
This fixes PR21242.
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The LLVM Lang Ref states for signed/unsigned int to float conversions:
"If the value cannot fit in the floating point value, the results are undefined."
And for FP to signed/unsigned int:
"If the value cannot fit in ty2, the results are undefined."
This matches the C definitions.
The existing behavior pins to infinity or a max int value, but that may just
lead to more confusion as seen in:
http://llvm.org/bugs/show_bug.cgi?id=21130
Returning undef will hopefully lead to a less silent failure.
Differential Revision: http://reviews.llvm.org/D5603
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This patch fixes a bug in method InstCombiner::FoldCmpCstShrCst where we
wrongly computed the distance between the highest bits set of two negative
values.
This fixes PR21222.
Differential Revision: http://reviews.llvm.org/D5700
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The icmp-select-icmp optimization targets select-icmp.eq
only. This is now ensured by testing the branch predicate
explictly. This commit also includes the test case for pr21199.
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Takes care of the assert that caused build fails.
Rather than asserting the code checks now that the definition
and use are in the same block, and does not attempt
to optimize when that is not the case.
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For any @llvm.assume intrinsic, if there is another which dominates it and uses
the same condition, then it is redundant and can be removed. While this does
not alter the semantics of the @llvm.assume intrinsics, it makes subsequent
handling more efficient (and the resulting IR easier to read).
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C++14 adds new builtin signatures for 'operator delete'. This change allows
new/delete pairs to be removed in C++14 onwards, as they were in C++11 and
before.
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This reverts commit r218918, effectively reapplying r218914 after fixing
an Ocaml bindings test and an Asan crash. The root cause of the latter
was a tightened-up check in `DILexicalBlock::Verify()`, so I'll file a
PR to investigate who requires the loose check (and why).
Original commit message follows.
--
This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString. Integers are stringified and
a `\0` character is used as a separator.
Part of PR17891.
Note: I've attached my testcases upgrade scripts to the PR. If I've
just broken your out-of-tree testcases, they might help.
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This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString. Integers are stringified and
a `\0` character is used as a separator.
Part of PR17891.
Note: I've attached my testcases upgrade scripts to the PR. If I've
just broken your out-of-tree testcases, they might help.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218914 91177308-0d34-0410-b5e6-96231b3b80d8
When unsafe-fp-math is enabled, we can turn sqrt(X) * sqrt(X) into X.
This can happen in the real world when calculating x ** 3/2. This occurs
in test-suite/SingleSource/Benchmarks/BenchmarkGame/n-body.c.
Differential Revision: http://reviews.llvm.org/D5584
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As discussed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140609/220598.html
And again here:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-September/077168.html
The sqrt of a negative number when using the llvm intrinsic is undefined.
We should return undef rather than 0.0 to match the definition in the LLVM IR lang ref.
This change should not affect any code that isn't using "no-nans-fp-math";
ie, no-nans is a requirement for generating the llvm intrinsic in place of a sqrt function call.
Unfortunately, the behavior introduced by this patch will not match current gcc, xlc, icc, and
possibly other compilers. The current clang/llvm behavior of returning 0.0 doesn't either.
We knowingly approve of this difference with the other compilers in an attempt to flag code
that is invoking undefined behavior.
A front-end warning should also try to convince the user that the program will fail:
http://llvm.org/bugs/show_bug.cgi?id=21093
Differential Revision: http://reviews.llvm.org/D5527
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argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
Note: I accidentally committed a bogus older version of this patch previously.
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argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
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In special cases select instructions can be eliminated by
replacing them with a cheaper bitwise operation even when the
select result is used outside its home block. The instances implemented
are patterns like
%x=icmp.eq
%y=select %x,%r, null
%z=icmp.eq|neq %y, null
br %z,true, false
==> %x=icmp.ne
%y=icmp.eq %r,null
%z=or %x,%y
br %z,true,false
The optimization is integrated into the instruction
combiner and performed only when all uses of the select result can
be replaced by the select operand proper. For this dominator information
is used and dominance is now a required analysis pass in the combiner.
The optimization itself is iterative. The critical step is to replace the
select result with the non-constant select operand. So the select becomes
local and the combiner iteratively works out simpler code pattern and
eventually eliminates the select.
rdar://17853760
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Example:
define i1 @foo(i32 %a) {
%shr = ashr i32 -9, %a
%cmp = icmp ne i32 %shr, -5
ret i1 %cmp
}
Before this fix, the instruction combiner wrongly thought that %shr
could have never been equal to -5. Therefore, %cmp was always folded to 'true'.
However, when %a is equal to 1, then %cmp evaluates to 'false'. Therefore,
in this example, it is not valid to fold %cmp to 'true'.
The problem was only affecting the case where the comparison was between
negative quantities where one of the quantities was obtained from arithmetic
shift of a negative constant.
This patch fixes the problem with the wrong folding (fixes PR20945).
With this patch, the 'icmp' from the example is now simplified to a
comparison between %a and 1. This still allows us to get rid of the arithmetic
shift (%shr).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217950 91177308-0d34-0410-b5e6-96231b3b80d8
From a combination of @llvm.assume calls (and perhaps through other means, such
as range metadata), it is possible that all bits of a return value might be
known. Previously, InstCombine did not check for this (which is understandable
given assumptions of constant propagation), but means that we'd miss simple
cases where assumptions are involved.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217346 91177308-0d34-0410-b5e6-96231b3b80d8
This builds on r217342, which added the infrastructure to compute known bits
using assumptions (@llvm.assume calls). That original commit added only a few
patterns (to catch common cases related to determining pointer alignment); this
change adds several other patterns for simple cases.
r217342 contained that, for assume(v & b = a), bits in the mask
that are known to be one, we can propagate known bits from the a to v. It also
had a known-bits transfer for assume(a = b). This patch adds:
assume(~(v & b) = a) : For those bits in the mask that are known to be one, we
can propagate inverted known bits from the a to v.
assume(v | b = a) : For those bits in b that are known to be zero, we can
propagate known bits from the a to v.
assume(~(v | b) = a): For those bits in b that are known to be zero, we can
propagate inverted known bits from the a to v.
assume(v ^ b = a) : For those bits in b that are known to be zero, we can
propagate known bits from the a to v. For those bits in
b that are known to be one, we can propagate inverted
known bits from the a to v.
assume(~(v ^ b) = a) : For those bits in b that are known to be zero, we can
propagate inverted known bits from the a to v. For those
bits in b that are known to be one, we can propagate
known bits from the a to v.
assume(v << c = a) : For those bits in a that are known, we can propagate them
to known bits in v shifted to the right by c.
assume(~(v << c) = a) : For those bits in a that are known, we can propagate
them inverted to known bits in v shifted to the right by c.
assume(v >> c = a) : For those bits in a that are known, we can propagate them
to known bits in v shifted to the right by c.
assume(~(v >> c) = a) : For those bits in a that are known, we can propagate
them inverted to known bits in v shifted to the right by c.
assume(v >=_s c) where c is non-negative: The sign bit of v is zero
assume(v >_s c) where c is at least -1: The sign bit of v is zero
assume(v <=_s c) where c is negative: The sign bit of v is one
assume(v <_s c) where c is non-positive: The sign bit of v is one
assume(v <=_u c): Transfer the known high zero bits
assume(v <_u c): Transfer the known high zero bits (if c is know to be a power
of 2, transfer one more)
A small addition to InstCombine was necessary for some of the test cases. The
problem is that when InstCombine was simplifying and, or, etc. it would fail to
check the 'do I know all of the bits' condition before checking less specific
conditions and would not fully constant-fold the result. I'm not sure how to
trigger this aside from using assumptions, so I've just included the change
here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217343 91177308-0d34-0410-b5e6-96231b3b80d8
This change, which allows @llvm.assume to be used from within computeKnownBits
(and other associated functions in ValueTracking), adds some (optional)
parameters to computeKnownBits and friends. These functions now (optionally)
take a "context" instruction pointer, an AssumptionTracker pointer, and also a
DomTree pointer, and most of the changes are just to pass this new information
when it is easily available from InstSimplify, InstCombine, etc.
As explained below, the significant conceptual change is that known properties
of a value might depend on the control-flow location of the use (because we
care that the @llvm.assume dominates the use because assumptions have
control-flow dependencies). This means that, when we ask if bits are known in a
value, we might get different answers for different uses.
The significant changes are all in ValueTracking. Two main changes: First, as
with the rest of the code, new parameters need to be passed around. To make
this easier, I grouped them into a structure, and I made internal static
versions of the relevant functions that take this structure as a parameter. The
new code does as you might expect, it looks for @llvm.assume calls that make
use of the value we're trying to learn something about (often indirectly),
attempts to pattern match that expression, and uses the result if successful.
By making use of the AssumptionTracker, the process of finding @llvm.assume
calls is not expensive.
Part of the structure being passed around inside ValueTracking is a set of
already-considered @llvm.assume calls. This is to prevent a query using, for
example, the assume(a == b), to recurse on itself. The context and DT params
are used to find applicable assumptions. An assumption needs to dominate the
context instruction, or come after it deterministically. In this latter case we
only handle the specific case where both the assumption and the context
instruction are in the same block, and we need to exclude assumptions from
being used to simplify their own ephemeral values (those which contribute only
to the assumption) because otherwise the assumption would prove its feeding
comparison trivial and would be removed.
This commit adds the plumbing and the logic for a simple masked-bit propagation
(just enough to write a regression test). Future commits add more patterns
(and, correspondingly, more regression tests).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217342 91177308-0d34-0410-b5e6-96231b3b80d8
The special case did not work when run under -reassociate and can easily
be expressed by a further generalization of an existing pattern.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217227 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r216698 which reverted r216523 and r216598.
We would attempt to perform the transformation even if the match()
failed because, as a side effect, it would set V. This would trick us
into believing that we correctly found a place to correctly apply the
transform.
An additional test case was added to getelementptr.ll so that we might
not regress in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216890 91177308-0d34-0410-b5e6-96231b3b80d8
consider: (and (icmp X, Y), (and Z, (icmp A, B)))
It may be possible to combine (icmp X, Y) with (icmp A, B).
If we successfully combine, create an 'and' instruction with Z.
This fixes PR20814.
N.B. There is room for improvement after this change but I'm not
convinced it's worth chasing yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216814 91177308-0d34-0410-b5e6-96231b3b80d8
Several combines involving icmp (shl C2, %X) C1 can be simplified
without introducing any new instructions. Move them to InstSimplify;
while we are at it, make them more powerful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216642 91177308-0d34-0410-b5e6-96231b3b80d8
We try to perform this transform in InstSimplify but we aren't always
able to. Sometimes, we need to insert a bitcast if X and Y don't have
the same time.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216598 91177308-0d34-0410-b5e6-96231b3b80d8
We supported transforming:
(gep i8* X, -(ptrtoint Y))
to:
(inttoptr (sub (ptrtoint X), (ptrtoint Y)))
However, this only fired if 'X' had type i8*. Generalize this to
support various types of different sizes. This results in much better
CodeGen, especially for pointers to packed structs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216523 91177308-0d34-0410-b5e6-96231b3b80d8
CFE, with -03, would turn:
bool f(unsigned x) {
bool a = x & 1;
bool b = x & 2;
return a | b;
}
into:
%1 = lshr i32 %x, 1
%2 = or i32 %1, %x
%3 = and i32 %2, 1
%4 = icmp ne i32 %3, 0
This sort of thing exposes a nasty pathology in GCC, ICC and LLVM.
Instead, we would rather want:
%1 = and i32 %x, 3
%2 = icmp ne i32 %1, 0
Things get a bit more interesting in the following case:
%1 = lshr i32 %x, %y
%2 = or i32 %1, %x
%3 = and i32 %2, 1
%4 = icmp ne i32 %3, 0
Replacing it with the following sequence is better:
%1 = shl nuw i32 1, %y
%2 = or i32 %1, 1
%3 = and i32 %2, %x
%4 = icmp ne i32 %3, 0
This sequence is preferable because %1 doesn't involve %x and could
potentially be hoisted out of loops if it is invariant; only perform
this transform in the non-constant case if we know we won't increase
register pressure.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216343 91177308-0d34-0410-b5e6-96231b3b80d8
Consider:
%add = add nuw i32 %a, -16777216
%and = and i32 %add, 255
Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nuw' from the
instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216273 91177308-0d34-0410-b5e6-96231b3b80d8
Consider:
%add = add nsw i32 %a, -16777216
%and = and i32 %add, 255
Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nsw' from the
instruction.
This fixes PR20377.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216261 91177308-0d34-0410-b5e6-96231b3b80d8
We can prove that a 'sub' can be a 'sub nuw' if the left-hand side is
negative and the right-hand side is non-negative.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216045 91177308-0d34-0410-b5e6-96231b3b80d8
We can prove that a 'sub' can be a 'sub nsw' under certain conditions:
- The sign bits of the operands is the same.
- Both operands have more than 1 sign bit.
The subtraction cannot be a signed overflow in either case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216037 91177308-0d34-0410-b5e6-96231b3b80d8
While this might seem like an obvious canonicalization, there is one subtle problem with it. The result of the original expression
is undef when x is NaN (remember, fast math flags), but the result of the select is always defined when x is NaN. This means that the
new expression is strictly more defined than the original one. One unfortunate consequence of this is that the transform is not reversible!
It's always legal to make increase the defined-ness of an expression, but it's not legal to reduce it. Thus, targets that prefer the original
form of the expression cannot reverse the transform to recover it. Another way to think of it is that the transform has lost source-level
information (the fast math flags), which is undesirable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215825 91177308-0d34-0410-b5e6-96231b3b80d8
We can combne a mul with a div if one of the operands is a multiple of
the other:
%mul = mul nsw nuw %a, C1
%ret = udiv %mul, C2
=>
%ret = mul nsw %a, (C1 / C2)
This can expose further optimization opportunities if we end up
multiplying or dividing by a power of 2.
Consider this small example:
define i32 @f(i32 %a) {
%mul = mul nuw i32 %a, 14
%div = udiv exact i32 %mul, 7
ret i32 %div
}
which gets CodeGen'd to:
imull $14, %edi, %eax
imulq $613566757, %rax, %rcx
shrq $32, %rcx
subl %ecx, %eax
shrl %eax
addl %ecx, %eax
shrl $2, %eax
retq
We can now transform this into:
define i32 @f(i32 %a) {
%shl = shl nuw i32 %a, 1
ret i32 %shl
}
which gets CodeGen'd to:
leal (%rdi,%rdi), %eax
retq
This fixes PR20681.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215815 91177308-0d34-0410-b5e6-96231b3b80d8
What follows bellow is a correctness proof of the transform using CVC3.
$ < t.cvc
A, B : BITVECTOR(32);
QUERY BVPLUS(32, A & B, A | B) = BVPLUS(32, A, B);
$ cvc3 < t.cvc
Valid.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215400 91177308-0d34-0410-b5e6-96231b3b80d8
We can only propagate the nsw bits if both subtraction instructions are
marked with the appropriate bit.
N.B. We only propagate the nsw bit in InstCombine because the nuw case
is already handled in InstSimplify.
This fixes PR20189.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214385 91177308-0d34-0410-b5e6-96231b3b80d8
Before this patch we had
@a = weak global ...
but
@b = alias weak ...
The patch changes aliases to look more like global variables.
Looking at some really old code suggests that the reason was that the old
bison based parser had a reduction for alias linkages and another one for
global variable linkages. Putting the alias first avoided the reduce/reduce
conflict.
The days of the old .ll parser are long gone. The new one parses just "linkage"
and a later check is responsible for deciding if a linkage is valid in a
given context.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214355 91177308-0d34-0410-b5e6-96231b3b80d8
While we can already transform A | (A ^ B) into A | B, things get bad
once we have (A ^ B) | (A ^ B ^ Cst) because reassociation will morph
this into (A ^ B) | ((A ^ Cst) ^ B). Our existing patterns fail once
this happens.
To fix this, we add a new pattern which looks through the tree of xor
binary operators to see that, in fact, there exists a redundant xor
operation.
What follows bellow is a correctness proof of the transform using CVC3.
$ cat t.cvc
A, B, C : BITVECTOR(64);
QUERY BVXOR(A, B) | BVXOR(BVXOR(B, C), A) = BVXOR(A, B) | C;
QUERY BVXOR(BVXOR(A, C), B) | BVXOR(A, B) = BVXOR(A, B) | C;
QUERY BVXOR(A, B) & BVXOR(BVXOR(B, C), A) = BVXOR(A, B) & ~C;
QUERY BVXOR(BVXOR(A, C), B) & BVXOR(A, B) = BVXOR(A, B) & ~C;
$ cvc3 < t.cvc
Valid.
Valid.
Valid.
Valid.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214342 91177308-0d34-0410-b5e6-96231b3b80d8
It handles the errors which were seen in PR19958 where wrong code was being emitted due to earlier patch.
Added code for lshr as well as non-exact right shifts.
It implements :
(icmp eq/ne (ashr/lshr const2, A), const1)" ->
(icmp eq/ne A, Log2(const2/const1)) ->
(icmp eq/ne A, Log2(const2) - Log2(const1))
Differential Revision: http://reviews.llvm.org/D4068
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213678 91177308-0d34-0410-b5e6-96231b3b80d8
We previously supported the align attribute on all (pointer) parameters, but we
only used it for byval parameters. However, it is completely consistent at the
IR level to treat 'align n' on all pointer parameters as an alignment
assumption on the pointer, and now we wll. Specifically, this causes
computeKnownBits to use the align attribute on all pointer parameters, not just
byval parameters. I've also added an explicit parameter attribute test for this
to test/Bitcode/attributes.ll.
And I've updated the LangRef to document the align parameter attribute (as it
turns out, it was not documented at all previously, although the byval
documentation mentioned that it could be used).
There are (at least) two benefits to doing this:
- It allows enhancing alignment based on the pointer alignment after inlining callees.
- It allows simplification of pointer arithmetic.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213670 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a crash in `InstCombiner::Descale()` when a multiply-by-zero gets
created as an argument to a GEP partway through an iteration, causing
-instcombine to optimize the GEP before the multiply.
rdar://problem/17615671
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212742 91177308-0d34-0410-b5e6-96231b3b80d8
In PR20059 ( http://llvm.org/pr20059 ), instcombine eliminates shuffles that are necessary before performing an operation that can trap (srem).
This patch calls isSafeToSpeculativelyExecute() and bails out of the optimization in SimplifyVectorOp() if needed.
Differential Revision: http://reviews.llvm.org/D4424
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212629 91177308-0d34-0410-b5e6-96231b3b80d8
It is not safe to negate the smallest signed integer, doing so yields
the same number back.
This fixes PR20186.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212164 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
With this patch, range metadata can be added to call/invoke including
IntrinsicInst. Previously, it could only be added to load.
Rename computeKnownBitsLoad to computeKnownBitsFromRangeMetadata because
range metadata is not only used by load.
Update the language reference to reflect this change.
Test Plan:
Add several tests in range-2.ll to confirm the verifier is happy with
having range metadata on call/invoke.
Add two tests in AddOverFlow.ll to confirm annotating range metadata to
call/invoke can benefit InstCombine.
Reviewers: meheff, nlewycky, reames, hfinkel, eliben
Reviewed By: eliben
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4187
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211281 91177308-0d34-0410-b5e6-96231b3b80d8
* Find factorization opportunities using identity values.
* Find factorization opportunities by treating shl(X, C) as mul (X, shl(C))
* Keep NSW flag while simplifying instruction using factorization.
This fixes PR19263.
Differential Revision: http://reviews.llvm.org/D3799
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211261 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombineMulDivRem has:
// Canonicalize (X+C1)*CI -> X*CI+C1*CI.
InstCombineAddSub has:
// W*X + Y*Z --> W * (X+Z) iff W == Y
These two transforms could fight with each other if C1*CI would not fold
away to something simpler than a ConstantExpr mul.
The InstCombineMulDivRem transform only acted on ConstantInts until
r199602 when it was changed to operate on all Constants in order to
let it fire on ConstantVectors.
To fix this, make this transform more careful by checking to see if we
actually folded away C1*CI.
This fixes PR20079.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211258 91177308-0d34-0410-b5e6-96231b3b80d8
These will be used for custom lowering and for library
implementations of various math functions, so it's useful
to expose these as builtins.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211247 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
As a starting step, we only use one simple heuristic: if the sign bits
of both a and b are zero, we can prove "add a, b" do not unsigned
overflow, and thus convert it to "add nuw a, b".
Updated all affected tests and added two new tests (@zero_sign_bit and
@zero_sign_bit2) in AddOverflow.ll
Test Plan: make check-all
Reviewers: eliben, rafael, meheff, chandlerc
Reviewed By: chandlerc
Subscribers: chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D4144
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211084 91177308-0d34-0410-b5e6-96231b3b80d8
As a follow-up to r210375 which canonicalizes addrspacecast
instructions, this patch canonicalizes addrspacecast constant
expressions.
Given clang uses ConstantExpr::getAddrSpaceCast to emit addrspacecast
cosntant expressions, this patch is also a step towards having the
frontend emit canonicalized addrspacecasts.
Piggyback a minor refactor in InstCombineCasts.cpp
Update three affected tests in addrspacecast-alias.ll,
access-non-generic.ll and constant-fold-gep.ll and added one new test in
constant-fold-address-space-pointer.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211004 91177308-0d34-0410-b5e6-96231b3b80d8
The messages were
"PR19753: Optimize comparisons with "ashr exact" of a constanst."
"Added support to optimize comparisons with "lshr exact" of a constant."
They were not correctly handling signed/unsigned operation differences,
causing pr19958.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210393 91177308-0d34-0410-b5e6-96231b3b80d8
addrspacecast X addrspace(M)* to Y addrspace(N)*
-->
bitcast X addrspace(M)* to Y addrspace(M)*
addrspacecast Y addrspace(M)* to Y addrspace(N)*
Updat all affected tests and add several new tests in addrspacecast.ll.
This patch is based on http://reviews.llvm.org/D2186 (authored by Matt
Arsenault) with fixes and more tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210375 91177308-0d34-0410-b5e6-96231b3b80d8
Alias with unnamed_addr were in a strange state. It is stored in GlobalValue,
the language reference talks about "unnamed_addr aliases" but the verifier
was rejecting them.
It seems natural to allow unnamed_addr in aliases:
* It is a property of how it is accessed, not of the data itself.
* It is perfectly possible to write code that depends on the address
of an alias.
This patch then makes unname_addr legal for aliases. One side effect is that
the syntax changes for a corner case: In globals, unnamed_addr is now printed
before the address space.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210302 91177308-0d34-0410-b5e6-96231b3b80d8
This patch implements two things:
1. If we know one number is positive and another is negative, we return true as
signed addition of two opposite signed numbers will never overflow.
2. Implemented TODO : If one of the operands only has one non-zero bit, and if
the other operand has a known-zero bit in a more significant place than it
(not including the sign bit) the ripple may go up to and fill the zero, but
won't change the sign. e.x - (x & ~4) + 1
We make sure that we are ignoring 0 at MSB.
Patch by Suyog Sarda.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210186 91177308-0d34-0410-b5e6-96231b3b80d8
This patch changes GlobalAlias to point to an arbitrary ConstantExpr and it is
up to MC (or the system assembler) to decide if that expression is valid or not.
This reduces our ability to diagnose invalid uses and how early we can spot
them, but it also lets us do things like
@test5 = alias inttoptr(i32 sub (i32 ptrtoint (i32* @test2 to i32),
i32 ptrtoint (i32* @bar to i32)) to i32*)
An important implication of this patch is that the notion of aliased global
doesn't exist any more. The alias has to encode the information needed to
access it in its metadata (linkage, visibility, type, etc).
Another consequence to notice is that getSection has to return a "const char *".
It could return a NullTerminatedStringRef if there was such a thing, but when
that was proposed the decision was to just uses "const char*" for that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210062 91177308-0d34-0410-b5e6-96231b3b80d8
The code was actually correct. Sorry for the confusion. I have expanded the
comment saying why the analysis is valid to avoid me misunderstaning it
again in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210052 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r210029.
It was not correctly handling cases where LHS and RHS had multiple but different
sign bits.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210048 91177308-0d34-0410-b5e6-96231b3b80d8
if ((x & C) == 0) x |= C becomes x |= C
if ((x & C) != 0) x ^= C becomes x &= ~C
if ((x & C) == 0) x ^= C becomes x |= C
if ((x & C) != 0) x &= ~C becomes x &= ~C
if ((x & C) == 0) x &= ~C becomes nothing
Differential Revision: http://reviews.llvm.org/D3777
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210006 91177308-0d34-0410-b5e6-96231b3b80d8
Currently LLVM will generally merge GEPs. This allows backends to use more
complex addressing modes. In some cases this is not happening because there
is PHI inbetween the two GEPs:
GEP1--\
|-->PHI1-->GEP3
GEP2--/
This patch checks to see if GEP1 and GEP2 are similiar enough that they can be
cloned (GEP12) in GEP3's BB, allowing GEP->GEP merging (GEP123):
GEP1--\ --\ --\
|-->PHI1-->GEP3 ==> |-->PHI2->GEP12->GEP3 == > |-->PHI2->GEP123
GEP2--/ --/ --/
This also breaks certain use chains that are preventing GEP->GEP merges that the
the existing instcombine would merge otherwise.
Tests included.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209843 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r209762, bringing back r209746. It was not responsible for the libc++ build failure
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209776 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r209746.
It looks it is causing a crash while building libcxx. I am trying to get a
reduced testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209762 91177308-0d34-0410-b5e6-96231b3b80d8
Currently LLVM will generally merge GEPs. This allows backends to use more
complex addressing modes. In some cases this is not happening because there
is PHI inbetween the two GEPs:
GEP1--\
|-->PHI1-->GEP3
GEP2--/
This patch checks to see if GEP1 and GEP2 are similiar enough that they can be
cloned (GEP12) in GEP3's BB, allowing GEP->GEP merging (GEP123):
GEP1--\ --\ --\
|-->PHI1-->GEP3 ==> |-->PHI2->GEP12->GEP3 == > |-->PHI2->GEP123
GEP2--/ --/ --/
This also breaks certain use chains that are preventing GEP->GEP merges that the
the existing instcombine would merge otherwise.
Tests included.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209755 91177308-0d34-0410-b5e6-96231b3b80d8
This patch implements two things:
1. If we know one number is positive and another is negative, we return true as
signed addition of two opposite signed numbers will never overflow.
2. Implemented TODO : If one of the operands only has one non-zero bit, and if
the other operand has a known-zero bit in a more significant place than it
(not including the sign bit) the ripple may go up to and fill the zero, but
won't change the sign. e.x - (x & ~4) + 1
We make sure that we are ignoring 0 at MSB.
Patch by Suyog Sarda.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209746 91177308-0d34-0410-b5e6-96231b3b80d8
Detected by Daniel Jasper, Ilia Filippov, and Andrea Di Biagio
Fixed the argument order to select (the mask semantics to blendv* are the
inverse of select) and fixed the tests
Added parenthesis to the assert condition
Ran clang-format
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209667 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Implemented an InstCombine transformation that takes a blendv* intrinsic
call and translates it into an IR select, if the mask is constant.
This will eventually get lowered into blends with immediates if possible,
or pblendvb (with an option to further optimize if we can transform the
pblendvb into a blend+immediate instruction, depending on the selector).
It will also enable optimizations by the IR passes, which give up on
sight of the intrinsic.
Both the transformation and the lowering of its result to asm got shiny
new tests.
The transformation is a bit convoluted because of blendvp[sd]'s
definition:
Its mask is a floating point value! This forces us to convert it and get
the highest bit. I suppose this happened because the mask has type
__m128 in Intel's intrinsic and v4sf (for blendps) in gcc's builtin.
I will send an email to llvm-dev to discuss if we want to change this or
not.
Reviewers: grosbach, delena, nadav
Differential Revision: http://reviews.llvm.org/D3859
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209643 91177308-0d34-0410-b5e6-96231b3b80d8
This commit starts with a "git mv ARM64 AArch64" and continues out
from there, renaming the C++ classes, intrinsics, and other
target-local objects for consistency.
"ARM64" test directories are also moved, and tests that began their
life in ARM64 use an arm64 triple, those from AArch64 use an aarch64
triple. Both should be equivalent though.
This finishes the AArch64 merge, and everyone should feel free to
continue committing as normal now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209577 91177308-0d34-0410-b5e6-96231b3b80d8
Currently LLVM will generally merge GEPs. This allows backends to use more
complex addressing modes. In some cases this is not happening because there
is PHI inbetween the two GEPs:
GEP1--\
|-->PHI1-->GEP3
GEP2--/
This patch checks to see if GEP1 and GEP2 are similiar enough that they can be
cloned (GEP12) in GEP3's BB, allowing GEP->GEP merging (GEP123):
GEP1--\ --\ --\
|-->PHI1-->GEP3 ==> |-->PHI2->GEP12->GEP3 == > |-->PHI2->GEP123
GEP2--/ --/ --/
This also breaks certain use chains that are preventing GEP->GEP merges that the
the existing instcombine would merge otherwise.
Tests included.
rdar://15547484
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209049 91177308-0d34-0410-b5e6-96231b3b80d8
This patch changes the design of GlobalAlias so that it doesn't take a
ConstantExpr anymore. It now points directly to a GlobalObject, but its type is
independent of the aliasee type.
To avoid changing all alias related tests in this patches, I kept the common
syntax
@foo = alias i32* @bar
to mean the same as now. The cases that used to use cast now use the more
general syntax
@foo = alias i16, i32* @bar.
Note that GlobalAlias now behaves a bit more like GlobalVariable. We
know that its type is always a pointer, so we omit the '*'.
For the bitcode, a nice surprise is that we were writing both identical types
already, so the format change is minimal. Auto upgrade is handled by looking
through the casts and no new fields are needed for now. New bitcode will
simply have different types for Alias and Aliasee.
One last interesting point in the patch is that replaceAllUsesWith becomes
smart enough to avoid putting a ConstantExpr in the aliasee. This seems better
than checking and updating every caller.
A followup patch will delete getAliasedGlobal now that it is redundant. Another
patch will add support for an explicit offset.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209007 91177308-0d34-0410-b5e6-96231b3b80d8
if ((x & C) == 0) x |= C becomes x |= C
if ((x & C) != 0) x ^= C becomes x &= ~C
if ((x & C) == 0) x ^= C becomes x |= C
if ((x & C) != 0) x &= ~C becomes x &= ~C
if ((x & C) == 0) x &= ~C becomes nothing
Z3 Verifications code for above transform
http://rise4fun.com/Z3/Pmsh
Differential Revision: http://reviews.llvm.org/D3717
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208848 91177308-0d34-0410-b5e6-96231b3b80d8
In transformation:
BinOp(shuffle(v1,undef), shuffle(v2,undef)) -> shuffle(BinOp(v1, v2),undef)
type of the undef argument must be same as type of BinOp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208531 91177308-0d34-0410-b5e6-96231b3b80d8
Do not apply transformation:
BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))
if operands v1 and v2 are of different size.
This change fixes PR19717, which was caused by r208488.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208518 91177308-0d34-0410-b5e6-96231b3b80d8
This patch enables transformations:
BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))
BinOp(shuffle(v1), const1) -> shuffle(BinOp, const2)
They allow to eliminate extra shuffles in some cases.
Differential Revision: http://reviews.llvm.org/D3525
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208488 91177308-0d34-0410-b5e6-96231b3b80d8
The instcomine logic to handle vpermilvar's pd and 256 variants was incorrect.
The _256 variants have indexes into the individual 128 bit lanes and in all
cases it also has to mask out unused bits.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207577 91177308-0d34-0410-b5e6-96231b3b80d8
right intrinsics.
A packed logical shift right with a shift count bigger than or equal to the
element size always produces a zero vector. In all other cases, it can be
safely replaced by a 'lshr' instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207299 91177308-0d34-0410-b5e6-96231b3b80d8
This excludes avx512 as I don't have hardware to verify. It excludes _dq
variants because they are represented in the IR as <{2,4} x i64> when it's
actually a byte shift of the entire i{128,265}.
This also excludes _dq_bs as they aren't at all supported by the backend.
There are also no corresponding instructions in the ISA. I have no idea why
they exist...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207058 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Since the upper 64 bits of the destination register are undefined when
performing this operation, we can substitute it and let the optimizer
figure out that only a copy is needed.
Also added range merging, if an instruction copies a range that can be
merged with a previous copied range.
Added test cases for both optimizations.
Reviewers: grosbach, nadav
CC: llvm-commits
Differential Revision: http://reviews.llvm.org/D3357
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207055 91177308-0d34-0410-b5e6-96231b3b80d8
With a constant mask a vpermil* is just a shufflevector. This patch implements
that simplification. This allows us to produce denser code. It should also
allow more folding down the line.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206801 91177308-0d34-0410-b5e6-96231b3b80d8
If multiplication involves zero-extended arguments and the result is
compared as in the patterns:
%mul32 = trunc i64 %mul64 to i32
%zext = zext i32 %mul32 to i64
%overflow = icmp ne i64 %mul64, %zext
or
%overflow = icmp ugt i64 %mul64 , 0xffffffff
then the multiplication may be replaced by call to umul.with.overflow.
This change fixes PR4917 and PR4918.
Differential Revision: http://llvm-reviews.chandlerc.com/D2814
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206137 91177308-0d34-0410-b5e6-96231b3b80d8
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.
Everything will be easier with the target in-tree though, hence this
commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205090 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r204912, and follow-up commit r204948.
This introduced a performance regression, and the fix is not completely
clear yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205010 91177308-0d34-0410-b5e6-96231b3b80d8
Fixes a miscompile introduced in r204912. It would miscompile code like
(unsigned)(a + -49) <= 5U. The transform would turn this into
(unsigned)a < 55U, which would return true for values in [0, 49], when
it should not.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204948 91177308-0d34-0410-b5e6-96231b3b80d8
Transform:
icmp X+Cst2, Cst
into:
icmp X, Cst-Cst2
when Cst-Cst2 does not overflow, and the add has nsw.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204912 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Previously the code didn't check if the before and after types for the
store were pointers to different address spaces. This resulted in
instcombine using a bitcast to convert between pointers to different
address spaces, causing an assertion due to the invalid cast.
It is not be appropriate to use addrspacecast this case because it is
not guaranteed to be a no-op cast. Instead bail out and do not do the
transformation.
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D3117
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204733 91177308-0d34-0410-b5e6-96231b3b80d8
bitcast between pointers of two different address spaces if they happened to have
the same pointer size.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203862 91177308-0d34-0410-b5e6-96231b3b80d8
On ELF and COFF an alias is just another name for a position in the file.
There is no way to refer to a position in another file, so an alias to
undefined is meaningless.
MachO currently doesn't support aliases. The spec has a N_INDR, which when
implemented will have a different set of restrictions. Adding support for
it shouldn't be harder than any other IR extension.
For now, having the IR represent what is actually possible with current
tools makes it easier to fix the design of GlobalAlias.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203705 91177308-0d34-0410-b5e6-96231b3b80d8
optimize a call to a llvm intrinsic to something that invovles a call to a C
library call, make sure it sets the right calling convention on the call.
e.g.
extern double pow(double, double);
double t(double x) {
return pow(10, x);
}
Compiles to something like this for AAPCS-VFP:
define arm_aapcs_vfpcc double @t(double %x) #0 {
entry:
%0 = call double @llvm.pow.f64(double 1.000000e+01, double %x)
ret double %0
}
declare double @llvm.pow.f64(double, double) #1
Simplify libcall (part of instcombine) will turn the above into:
define arm_aapcs_vfpcc double @t(double %x) #0 {
entry:
%__exp10 = call double @__exp10(double %x) #1
ret double %__exp10
}
declare double @__exp10(double)
The pre-instcombine code works because calls to LLVM builtins are special.
Instruction selection will chose the right calling convention for the call.
However, the code after instcombine is wrong. The call to __exp10 will use
the C calling convention.
I can think of 3 options to fix this.
1. Make "C" calling convention just work since the target should know what CC
is being used.
This doesn't work because each function can use different CC with the "pcs"
attribute.
2. Have Clang add the right CC keyword on the calls to LLVM builtin.
This will work but it doesn't match the LLVM IR specification which states
these are "Standard C Library Intrinsics".
3. Fix simplify libcall so the resulting calls to the C routines will have the
proper CC keyword. e.g.
%__exp10 = call arm_aapcs_vfpcc double @__exp10(double %x) #1
This works and is the solution I implemented here.
Both solutions #2 and #3 would work. After carefully considering the pros and
cons, I decided to implement #3 for the following reasons.
1. It doesn't change the "spec" of the intrinsics.
2. It's a self-contained fix.
There are a couple of potential downsides.
1. There could be other places in the optimizer that is broken in the same way
that's not addressed by this.
2. There could be other calling conventions that need to be propagated by
simplify-libcall that's not handled.
But for now, this is the fix that I'm most comfortable with.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203488 91177308-0d34-0410-b5e6-96231b3b80d8
Sequences of insertelement/extractelements are sometimes used to build
vectorsr; this code tries to put them back together into shuffles, but
could only produce a completely uniform shuffle types (<N x T> from two
<N x T> sources).
This should allow shuffles with different numbers of elements on the
input and output sides as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203229 91177308-0d34-0410-b5e6-96231b3b80d8
are operations that do not access memory but may be sensitive
to floating-point environment changes. LLVM does not attempt
to model FP environment changes, so this was unnecessarily conservative
and was getting on the way of some optimizations, in particular
SLP vectorization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203037 91177308-0d34-0410-b5e6-96231b3b80d8
