CTLZ idiom recognition (r303102).
Summary:
The following case:
i = 1;
if(n)
while (n >>= 1)
i++;
use(i);
Was converted to:
i = 1;
if(n)
i += builtin_ctlz(n >> 1, false);
use(i);
Which is not correct. The patch make it:
i = 1;
if(n)
i += builtin_ctlz(n >> 1, true);
use(i);
From: Evgeny Stupachenko <evstupac@gmail.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303212 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
RewritePHIs algorithm used in building of CoroFrame inserts a placeholder
```
%placeholder = phi [%val]
```
on every edge leading to a block starting with PHI node with multiple incoming edges,
so that if one of the incoming values was spilled and need to be reloaded, we have a
place to insert a reload. We use SplitEdge helper function to split the incoming edge.
SplitEdge function does not deal with unwind edges comping into a block with an EHPad.
This patch adds an ehAwareSplitEdge function that can correctly split the unwind edge.
For landing pads, we clone the landing pad into every edge block and replace the original
landing pad with a PHI collection the values from all incoming landing pads.
For WinEH pads, we keep the original EHPad in place and insert cleanuppad/cleapret in the
edge blocks.
Reviewers: majnemer, rnk
Reviewed By: majnemer
Subscribers: EricWF, llvm-commits
Differential Revision: https://reviews.llvm.org/D31845
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303172 91177308-0d34-0410-b5e6-96231b3b80d8
This function gives the wrong answer on some non-ELF platforms in some
cases. The function that does the right thing lives in Mangler.h. To try to
discourage people from using this function, give it a different name.
Differential Revision: https://reviews.llvm.org/D33162
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303134 91177308-0d34-0410-b5e6-96231b3b80d8
ARM Neon has native support for half-sized vector registers (64 bits). This
is beneficial for example for 2D and 3D graphics. This patch adds the option
to lower MinVecRegSize from 128 via a TTI in the SLP Vectorizer.
*** Performance Analysis
This change was motivated by some internal benchmarks but it is also
beneficial on SPEC and the LLVM testsuite.
The results are with -O3 and PGO. A negative percentage is an improvement.
The testsuite was run with a sample size of 4.
** SPEC
* CFP2006/482.sphinx3 -3.34%
A pretty hot loop is SLP vectorized resulting in nice instruction reduction.
This used to be a +22% regression before rL299482.
* CFP2000/177.mesa -3.34%
* CINT2000/256.bzip2 +6.97%
My current plan is to extend the fix in rL299482 to i16 which brings the
regression down to +2.5%. There are also other problems with the codegen in
this loop so there is further room for improvement.
** LLVM testsuite
* SingleSource/Benchmarks/Misc/ReedSolomon -10.75%
There are multiple small SLP vectorizations outside the hot code. It's a bit
surprising that it adds up to 10%. Some of this may be code-layout noise.
* MultiSource/Benchmarks/VersaBench/beamformer/beamformer -8.40%
The opt-viewer screenshot can be seen at F3218284. We start at a colder store
but the tree leads us into the hottest loop.
* MultiSource/Applications/lambda-0.1.3/lambda -2.68%
* MultiSource/Benchmarks/Bullet/bullet -2.18%
This is using 3D vectors.
* SingleSource/Benchmarks/Shootout-C++/Shootout-C++-lists +6.67%
Noise, binary is unchanged.
* MultiSource/Benchmarks/Ptrdist/anagram/anagram +4.90%
There is an additional SLP in the cold code. The test runs for ~1sec and
prints out over 2000 lines. This is most likely noise.
* MultiSource/Applications/aha/aha +1.63%
* MultiSource/Applications/JM/lencod/lencod +1.41%
* SingleSource/Benchmarks/Misc/richards_benchmark +1.15%
Differential Revision: https://reviews.llvm.org/D31965
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303116 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The following loops should be recognized:
i = 0;
while (n) {
n = n >> 1;
i++;
body();
}
use(i);
And replaced with builtin_ctlz(n) if body() is empty or
for CPUs that have CTLZ instruction converted to countable:
for (j = 0; j < builtin_ctlz(n); j++) {
n = n >> 1;
i++;
body();
}
use(builtin_ctlz(n));
Reviewers: rengolin, joerg
Differential Revision: http://reviews.llvm.org/D32605
From: Evgeny Stupachenko <evstupac@gmail.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303102 91177308-0d34-0410-b5e6-96231b3b80d8
verifyMemoryCongruency() filters out trivially dead MemoryDef(s),
as we find them immediately dead, before moving from TOP to a new
congruence class.
This fixes the same problem for PHI(s) skipping MemoryPhis if all
the operands are dead.
Differential Revision: https://reviews.llvm.org/D33044
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303100 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Merge overflow computation for signed add,
appearing both in InstCombine and ValueTracking.
As part of the merge,
cleanup the interface for overflow checks in InstCombine.
Patch by Yoav Ben-Shalom.
Reviewers: craig.topper, majnemer
Reviewed By: craig.topper
Subscribers: takuto.ikuta, llvm-commits
Differential Revision: https://reviews.llvm.org/D32946
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303029 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
If the Worklist build causes an IR change this change flag currently factors into the flag for running another iteration of the iteration loop. But only changes during processing should trigger another loop.
This patch captures the worklist creation change flag into the outside the loop flag currently used for DbgDeclares and only sends that flag up to the caller. Rerunning the loop only depends on IC.run() now.
This uses the debug output of InstCombine to determine if one or two iterations run. I couldn't think of a better way to detect it since the second spurious iteration shoudn't make any visible changes. Just wasted computation.
I can do a pre-commit of the test case with the CHECK-NOT as a CHECK if this is an ok way to check this.
This is a subset of D31678 as I'm still not sure how to verify the analysis behavior for that.
Reviewers: davide, majnemer, spatel, chandlerc
Reviewed By: davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32453
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302982 91177308-0d34-0410-b5e6-96231b3b80d8
This patch adds min/max population count, leading/trailing zero/one bit counting methods.
The min methods return answers based on bits that are known without considering unknown bits. The max methods give answers taking into account the largest count that unknown bits could give.
Differential Revision: https://reviews.llvm.org/D32931
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302925 91177308-0d34-0410-b5e6-96231b3b80d8
While debugging a predicate info problem, I noticed this was missing
a newline, making the debug output slightly less readable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302908 91177308-0d34-0410-b5e6-96231b3b80d8
invariant PHI inputs and to rewrite PHI nodes during the actual
unswitching.
The checking is quite easy, but rewriting the PHI nodes is somewhat
surprisingly challenging. This should handle both branches and switches.
I think this is now a full featured trivial unswitcher, and more full
featured than the trivial cases in the old pass while still being (IMO)
somewhat simpler in how it works.
Next up is to verify its correctness in more widespread testing, and
then to add non-trivial unswitching.
Thanks to Davide and Sanjoy for the excellent review. There is one
remaining question that I may address in a follow-up patch (see the
review thread for details) but it isn't related to the functionality
specifically.
Differential Revision: https://reviews.llvm.org/D32699
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302867 91177308-0d34-0410-b5e6-96231b3b80d8
The approach I followed was to emit the remark after getTreeCost concludes
that SLP is profitable. I initially tried emitting them after the
vectorizeRootInstruction calls in vectorizeChainsInBlock but I vaguely
remember missing a few cases for example in HorizontalReduction::tryToReduce.
ORE is placed in BoUpSLP so that it's available from everywhere (notably
HorizontalReduction::tryToReduce).
We use the first instruction in the root bundle as the locator for the remark.
In order to get a sense how far the tree is spanning I've include the size of
the tree in the remark. This is not perfect of course but it gives you at
least a rough idea about the tree. Then you can follow up with -view-slp-tree
to really see the actual tree.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302811 91177308-0d34-0410-b5e6-96231b3b80d8
Introduce LoopVectorizationPlanner.executePlan(), replacing ILV.vectorize() and
refactoring ILV.vectorizeLoop(). Method collectDeadInstructions() is moved from
ILV to LVP. These changes facilitate building VPlans and using them to generate
code, following https://reviews.llvm.org/D28975 and its tentative breakdown.
Method ILV.createEmptyLoop() is renamed ILV.createVectorizedLoopSkeleton() to
improve clarity; it's contents remain intact.
Differential Revision: https://reviews.llvm.org/D32200
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302790 91177308-0d34-0410-b5e6-96231b3b80d8
It turned out that MSan was incorrectly calculating the shadow for int comparisons: it was done by truncating the result of (Shadow1 OR Shadow2) to i1, effectively rendering all bits except LSB useless.
This approach doesn't work e.g. in the case where the values being compared are even (i.e. have the LSB of the shadow equal to zero).
Instead, if CreateShadowCast() has to cast a bigger int to i1, we replace the truncation with an ICMP to 0.
This patch doesn't affect the code generated for SPEC 2006 binaries, i.e. there's no performance impact.
For the test case reported in PR32842 MSan with the patch generates a slightly more efficient code:
orq %rcx, %rax
jne .LBB0_6
, instead of:
orl %ecx, %eax
testb $1, %al
jne .LBB0_6
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302787 91177308-0d34-0410-b5e6-96231b3b80d8
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
This canonicalization was added at:
https://reviews.llvm.org/rL7264
By moving xors out/down, we can more easily combine constants. I'm adding
tests that do not change with this patch, so we can verify that those kinds
of transforms are still happening.
This is no-functional-change-intended because there's a later fold:
// (X^C)|Y -> (X|Y)^C iff Y&C == 0
...and demanded-bits appears to guarantee that any fold that would have
hit the fold we're removing here would be caught by that 2nd fold.
Similar reasoning was used in:
https://reviews.llvm.org/rL299384
The larger motivation for removing this code is that it could interfere with
the fix for PR32706:
https://bugs.llvm.org/show_bug.cgi?id=32706
Ie, we're not checking if the 'xor' is actually a 'not', so we could reverse
a 'not' optimization and cause an infinite loop by altering an 'xor X, -1'.
Differential Revision: https://reviews.llvm.org/D33050
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302733 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes a ubsan bot failure after r302597, which made getProfileCount
non-static, but ended up invoking it on a null ProfileSummaryInfo object
in some cases from buildModuleSummaryIndex.
Most testing passed because the non-static getProfileCount currently
doesn't access any member variables, but I found this when testing a
follow on patch (D32877) that adds a member variable access.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302705 91177308-0d34-0410-b5e6-96231b3b80d8
This is another step towards favoring 'not' ops over random 'xor' in IR:
https://bugs.llvm.org/show_bug.cgi?id=32706
This transformation may have occurred in longer IR sequences using computeKnownBits,
but that could be much more expensive to calculate.
As the scalar result shows, we do not currently favor 'not' in all cases. The 'not'
created by the transform is transformed again (unnecessarily). Vectors don't have
this problem because vectors are (wrongly) excluded from several other combines.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302659 91177308-0d34-0410-b5e6-96231b3b80d8
This pass doesn't correctly handle testing for when it is legal to hoist
arbitrary instructions. The whitelist happens to make it safe, so before
it is removed the pass's legality checks will need to be enhanced.
Details have been added to the code review thread for the patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302640 91177308-0d34-0410-b5e6-96231b3b80d8
