Add a pass to lower is.constant and objectsize intrinsics
This pass lowers is.constant and objectsize intrinsics not simplified by
earlier constant folding, i.e. if the object given is not constant or if
not using the optimized pass chain. The result is recursively simplified
and constant conditionals are pruned, so that dead blocks are removed
even for -O0. This allows inline asm blocks with operand constraints to
work all the time.
The new pass replaces the existing lowering in the codegen-prepare pass
and fallbacks in SDAG/GlobalISEL and FastISel. The latter now assert
on the intrinsics.
Differential Revision: https://reviews.llvm.org/D65280
llvm-svn: 374784
This pass lowers is.constant and objectsize intrinsics not simplified by
earlier constant folding, i.e. if the object given is not constant or if
not using the optimized pass chain. The result is recursively simplified
and constant conditionals are pruned, so that dead blocks are removed
even for -O0. This allows inline asm blocks with operand constraints to
work all the time.
The new pass replaces the existing lowering in the codegen-prepare pass
and fallbacks in SDAG/GlobalISEL and FastISel. The latter now assert
on the intrinsics.
Differential Revision: https://reviews.llvm.org/D65280
llvm-svn: 374743
In MVE, as of rL371218, we are attempting to sink chains of instructions such as:
%l1 = insertelement <8 x i8> undef, i8 %l0, i32 0
%broadcast.splat26 = shufflevector <8 x i8> %l1, <8 x i8> undef, <8 x i32> zeroinitializer
In certain situations though, we can end up breaking the dominance relations of
instructions. This happens when we sink the instruction into a loop, but cannot
remove the originals. The Use is updated, which might in fact be a Use from the
second instruction to the first.
This attempts to fix that by reversing the order of instruction that are sunk,
and ensuring that we update the uses on new instructions if they have already
been sunk, not the old ones.
Differential Revision: https://reviews.llvm.org/D67366
llvm-svn: 371743
This patch sinks add/mul(shufflevector(insertelement())) into the basic block in which they are used so that they can then be selected together.
This is useful for various MVE instructions, such as vmla and others that take R registers.
Loop tests have been added to the vmla test file to make sure vmlas are generated in loops.
Differential revision: https://reviews.llvm.org/D66295
llvm-svn: 371218
If OptimizeExtractBits() encountered a shift instruction with no operands at all,
it would erase the instruction, but still return false.
This previously didn’t matter because its caller would always return after
processing the instruction, but https://reviews.llvm.org/D63233 changed the
function’s caller to fall through if it returned false, which would then cause
a use-after-free detectable by ASAN.
This change makes OptimizeExtractBits return true if it removes a shift
instruction with no users, terminating processing of the instruction.
Patch by: @brentdax (Brent Royal-Gordon)
Differential Revision: https://reviews.llvm.org/D66330
llvm-svn: 369168
This is based on the example/discussion in PR37428:
https://bugs.llvm.org/show_bug.cgi?id=37428
Proper vector shift instructions don't appear until AVX2, so we may generate several
extra instructions within a loop trying to compensate for that. It's difficult to
recover from that shift expansion later than this, so use the existing TLI hook and
splat analysis to enable better codegen.
This extends CGP functionality introduced with:
rL201655
Differential Revision: https://reviews.llvm.org/D63233
llvm-svn: 363511
This is a subset of the original commit from rL359879
which was reverted because it could crash when using the 'RemovedInstructions'
structure that enables delayed deletion of dead instructions. The motivating
compile-time win does not require that change though. We should get most of
that win from this change alone.
Using/updating a dominator tree to match math overflow patterns may be very
expensive in compile-time (because of the way CGP uses a DT), so just handle
the single-block case.
See post-commit thread for rL354298 for more details:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190422/646276.html
Differential Revision: https://reviews.llvm.org/D61075
llvm-svn: 359969
Using/updating a dominator tree to match math overflow patterns may be very
expensive in compile-time (because of the way CGP uses a DT), so just handle
the single-block case.
Also, we were restarting the iterator loops when doing the overflow intrinsic
transforms by marking the dominator tree for update. That was done to prevent
iterating over a removed instruction. But we can postpone the deletion using
the existing "RemovedInsts" structure, and that means we don't need to update
the DT.
See post-commit thread for rL354298 for more details:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190422/646276.html
Differential Revision: https://reviews.llvm.org/D61075
llvm-svn: 359879
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
This is probably a bigger limitation than necessary, but since we don't have any evidence yet
that this transform led to real-world perf improvements rather than regressions, I'm making a
quick, blunt fix.
In the motivating x86 example from:
https://bugs.llvm.org/show_bug.cgi?id=41129
...and shown in the regression test, we want to avoid an extra instruction in the dominating
block because that could be costly.
The x86 LSR test diff is reversing the changes from D57789. There's no evidence that 1 version
is any better than the other yet.
Differential Revision: https://reviews.llvm.org/D59602
llvm-svn: 356665
This is almost the same as:
rL355345
...and should prevent any potential crashing from examples like:
https://bugs.llvm.org/show_bug.cgi?id=41064
...although the bug was masked by:
rL355823
...and I'm not sure how to repro the problem after that change.
llvm-svn: 356218
Targets can potentially emit more efficient code if they know address
computations never overflow. For example ILP32 code on AArch64 (which only has
64-bit address computation) can ignore the possibility of overflow with this
extra information.
llvm-svn: 355926
Inserting an overflowing arithmetic intrinsic can increase register
pressure by producing two values at a point where only one is needed,
while the second use maybe several blocks away. This increase in
pressure is likely to be more detrimental on performance than
rematerialising one of the original instructions.
So, check that the arithmetic and compare instructions are no further
apart than their immediate successor/predecessor.
Differential Revision: https://reviews.llvm.org/D59024
llvm-svn: 355823
r44412 fixed a huge compile time regression but it needed ModifiedDT flag to be
maintained correctly in optimizations in optimizeBlock() and optimizeInst().
Function optimizeSelectInst() does not update the flag.
This patch propagates the flag in optimizeSelectInst() back to
optimizeBlock().
This patch also removes ModifiedDT in CodeGenPrepare class (which is not used).
The property of ModifiedDT is now recorded in a ref parameter.
Differential Revision: https://reviews.llvm.org/D59139
llvm-svn: 355751
This uses the infrastructure added in rL353152 to sink zext and sexts to
sub/add users, to enable vsubl/vaddl generation when NEON is available.
See https://bugs.llvm.org/show_bug.cgi?id=40025.
Reviewers: SjoerdMeijer, t.p.northover, samparker, efriedma
Reviewed By: samparker
Differential Revision: https://reviews.llvm.org/D58063
llvm-svn: 355460
The test is reduced from an example in the post-commit thread for:
rL354746
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190304/632396.html
While we must avoid dying here, the real question should be:
Why is non-canonical and/or degenerate code making it to CGP when
using the new pass manager?
llvm-svn: 355345
There's likely a missed IR canonicalization for at least 1 of these
patterns. Otherwise, we wouldn't have needed the pattern-matching
enhancement in D57516.
Note that -- unlike usubo added with D57789 -- the TLI hook for
this transform defaults to 'on'. So if there's any perf fallout
from this, targets should look at how they're lowering the uaddo
node in SDAG and/or override that hook.
The x86 diffs suggest that there's some missing pattern-matching
for forming inc/dec.
This should fix the remaining known problems in:
https://bugs.llvm.org/show_bug.cgi?id=40486https://bugs.llvm.org/show_bug.cgi?id=31754
llvm-svn: 354746
The motivating x86 cases for forming the intrinsic are shown in PR31754 and PR40487:
https://bugs.llvm.org/show_bug.cgi?id=31754https://bugs.llvm.org/show_bug.cgi?id=40487
..and those are shown in the IR test file and x86 codegen file.
Matching the usubo pattern is harder than uaddo because we have 2 independent values rather than a def-use.
This adds a TLI hook that should preserve the existing behavior for uaddo formation, but disables usubo
formation by default. Only x86 overrides that setting for now although other targets will likely benefit
by forming usbuo too.
Differential Revision: https://reviews.llvm.org/D57789
llvm-svn: 354298
This patch improves code generation for some AArch64 ACLE intrinsics. It adds
support to CGP to duplicate and sink operands to their user, if they can be
folded into a target instruction, like zexts and sub into usubl. It adds a
TargetLowering hook shouldSinkOperands, which looks at the operands of
instructions to see if sinking is profitable.
I decided to add a new target hook, as for the sinking to be profitable,
at least on AArch64, we have to look at multiple operands of an
instruction, instead of looking at the users of a zext for example.
The sinking is done in CGP, because it works around an instruction
selection limitation. If instruction selection is not limited to a
single basic block, this patch should not be needed any longer.
Alternatively this could be done in the LoopSink pass, which tries to
undo LICM for instructions in blocks that are not executed frequently.
Note that we do not force the operands to sink to have a single user,
because we duplicate them before sinking. Therefore this is only
desirable if they really can be done for free. Additionally we could
consider the impact on live ranges later on.
This should fix https://bugs.llvm.org/show_bug.cgi?id=40025.
As for performance, we have internal code that uses intrinsics and can
be speed up by 10% by this change.
Reviewers: SjoerdMeijer, t.p.northover, samparker, efriedma, RKSimon, spatel
Reviewed By: samparker
Differential Revision: https://reviews.llvm.org/D57377
llvm-svn: 353152
This is no-functional-change-intended although there could
be intermediate variations caused by a difference in the
debug info produced by setting that from the builder's
insertion point.
I'm updating the IR test file associated with this code just
to show that the naming differences from using the builder
are visible.
The motivation for adding a helper function is that we are
likely to extend this code to deal with other overflow ops.
llvm-svn: 353056
There are 2 changes visible here:
1. There's no reason to limit this transform based on number
of condition registers. That diff allows PPC to produce
slightly better (dot-instructions should be generally good)
code.
Note: someone that cares about PPC codegen might want to
look closer at that output because it seems like we could
still improve this.
2. We (probably?) should not bother trying to form uaddo (or
other overflow ops) when there's no target support for such
an op. This goes beyond checking whether the op is expanded
because both PPC and AArch64 show better codegen for standard
types regardless of whether the op is legal/custom.
llvm-svn: 353001
This is the most important uaddo problem mentioned in PR31754:
https://bugs.llvm.org/show_bug.cgi?id=31754
...but that was overcome in x86 codegen with D57637.
That patch also corrects the inc vs. add regressions seen with the previous attempt at this.
Still, we want to make this matcher complete, so we can potentially canonicalize the pattern
even if it's an 'add 1' operation.
Pattern matching, however, shouldn't assume that we have canonicalized IR, so we match 4
commuted variants of uaddo.
There's also a test with a crazy type to show that the existing CGP transform based on this
matcher is not limited by target legality checks.
I'm not sure if the Hexagon diff means the test is no longer testing what it intended to
test, but that should be solvable in a follow-up.
Differential Revision: https://reviews.llvm.org/D57516
llvm-svn: 352998
This ensures that if we make it to the backend w/o lowering widenable_conditions first, that we generate correct code. Doing it in CGP - instead of isel - let's us fold control flow before hitting block local instruction selection.
Differential Revision: https://reviews.llvm.org/D57473
llvm-svn: 352779
This is the most important uaddo problem mentioned in PR31754:
https://bugs.llvm.org/show_bug.cgi?id=31754
We were failing to match the canonicalized pattern when it's an 'add 1' operation.
Pattern matching, however, shouldn't assume that we have canonicalized IR, so we
match 4 commuted variants of uaddo.
There's also a test with a crazy type to show that the existing CGP transform
based on this matcher is not limited by target legality checks, but that's a
different problem.
Differential Revision: https://reviews.llvm.org/D57516
llvm-svn: 352766
This change reverts r351626.
The changes in r351626 cause quadratic work in several cases. (See r351626 thread on llvm-commits for details.)
llvm-svn: 352722
This is meant to be used with clang's __builtin_dynamic_object_size.
When 'true' is passed to this parameter, the intrinsic has the
potential to be folded into instructions that will be evaluated
at run time. When 'false', the objectsize intrinsic behaviour is
unchanged.
rdar://32212419
Differential revision: https://reviews.llvm.org/D56761
llvm-svn: 352664
This reverts commit r351618.
Compiler RT + ASAN tests are failing for PowerPC. Not sure
how would I reproduce these on macOS, so reverting (again)
until I do.
llvm-svn: 351619
Fangrui Song