Commit Graph

113 Commits

Author SHA1 Message Date
Craig Topper f7b86728fa [InstCombine] Simplify binops that are only used by a select and are fed by a select with the same condition.
Summary:
This patch optimizes a binop sandwiched between 2 selects with the same condition. Since we know its only used by the select we can propagate the appropriate input value from the earlier select.

As I'm writing this I realize I may need to avoid doing this for division in case the select was protecting a divide by zero?

Reviewers: spatel, majnemer

Reviewed By: majnemer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D39999

llvm-svn: 318267
2017-11-15 05:23:02 +00:00
Matt Arsenault 90e4f719e1 Fix some misc. -enable-var-scope violations
llvm-svn: 318006
2017-11-13 01:47:52 +00:00
Sanjay Patel 4eb046172f [InstCombine] auto-generate complete checks; NFC
llvm-svn: 314712
2017-10-02 20:16:59 +00:00
Craig Topper 516e39cd38 [InstCombine] Teach select01 helper of foldSelectIntoOp to handle vector splats
We were handling some vectors in foldSelectIntoOp, but not if the operand of the bin op was any kind of vector constant. This patch fixes it to treat vector splats the same as scalars.

Differential Revision: https://reviews.llvm.org/D37232

llvm-svn: 311940
2017-08-28 22:00:27 +00:00
Craig Topper 882f29630b [InstCombine] Make folding (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1 support splat vectors
This also uses decomposeBitTestICmp to decode the compare.

Differential Revision: https://reviews.llvm.org/D36781

llvm-svn: 311044
2017-08-16 21:52:07 +00:00
Craig Topper a36eae0b2b [InstCombine] Add test case for PR33721.
llvm-svn: 307621
2017-07-11 05:12:52 +00:00
Sanjay Patel 7227276d41 [InstCombine] canonicalize icmp predicate feeding select
This canonicalization was suggested in D33172 as a way to make InstCombine behavior more uniform. 
We have this transform for icmp+br, so unless there's some reason that icmp+select should be 
treated differently, we should do the same thing here.

The benefit comes from increasing the chances of creating identical instructions. This is shown in
the tests in logical-select.ll (PR32791). InstCombine doesn't fold those directly, but EarlyCSE 
can simplify the identical cmps, and then InstCombine can fold the selects together.

The possible regression for the tests in select.ll raises questions about poison/undef:
http://lists.llvm.org/pipermail/llvm-dev/2017-May/113261.html

...but that transform is just as likely to be triggered by this canonicalization as it is to be 
missed, so we're just pointing out a commutation deficiency in the pattern matching:
https://reviews.llvm.org/rL228409

Differential Revision: https://reviews.llvm.org/D34242

llvm-svn: 306435
2017-06-27 17:53:22 +00:00
Hiroshi Inoue b300824ee7 fix trivial typos in comment, NFC
dereferencable -> dereferenceable

llvm-svn: 306210
2017-06-24 15:43:33 +00:00
Sanjay Patel 6e41018942 [InstCombine] fix wrong undef handling when converting select to shuffle
As discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32486
...the canonicalization of vector select to shufflevector does not hold up
when undef elements are present in the condition vector. 

Try to make the undef handling clear in the code and the LangRef.

Differential Revision: https://reviews.llvm.org/D31980

llvm-svn: 300092
2017-04-12 18:39:53 +00:00
Sanjay Patel cb731f1538 [InstCombine] canonicalize non-obivous forms of integer min/max
This is part of trying to clean up our handling of min/max patterns in IR.
By converting these to canonical form, we're more likely to recognize them
because there are various places in InstCombine that don't use 
matchSelectPattern or m_SMax and friends.

The backend fixups referenced in the now deleted TODO comment were added with:
https://reviews.llvm.org/rL291392
https://reviews.llvm.org/rL289738

If there's any codegen fallout from this change, we should be able to address
it in DAGCombiner or target-specific lowering. 

llvm-svn: 295758
2017-02-21 19:33:53 +00:00
Sanjay Patel 73fc8ddb06 [InstCombine] fix operand-complexity-based canonicalization (PR28296)
The code comments didn't match the code logic, and we didn't actually distinguish the fake unary (not/neg/fneg) 
operators from arguments. Adding another level to the weighting scheme provides more structure and can help 
simplify the pattern matching in InstCombine and other places.

I fixed regressions that would have shown up from this change in:
rL290067
rL290127

But that doesn't mean there are no pattern-matching logic holes left; some combines may just be missing regression tests.

Should fix:
https://llvm.org/bugs/show_bug.cgi?id=28296

Differential Revision: https://reviews.llvm.org/D27933

llvm-svn: 294049
2017-02-03 21:43:34 +00:00
Sanjay Patel 9666996563 [ValueTracking] recognize a 'not' of an assumed condition as false
Also, add the corresponding match to the AssumptionCache's 'Affected Values' list.

Differential Revision: https://reviews.llvm.org/D28485

llvm-svn: 292239
2017-01-17 18:15:49 +00:00
Sanjay Patel 5178363687 [InstCombine] if the condition of a select may be known via assumes, eliminate the select
This is a limited solution for PR31512:
https://llvm.org/bugs/show_bug.cgi?id=31512

The motivation is that we will need to increase usage of llvm.assume and/or metadata to solve PR28430:
https://llvm.org/bugs/show_bug.cgi?id=28430

...and this kind of simplification is needed to take advantage of that extra information.

The 'not' test case would be handled by:
https://reviews.llvm.org/D28485

Differential Revision:
https://reviews.llvm.org/D28337

llvm-svn: 291915
2017-01-13 17:02:42 +00:00
Sanjay Patel 2419d670c2 [InstCombine] auto-generate checks for select+bitwise logic tests; NFC
llvm-svn: 288254
2016-11-30 17:07:21 +00:00
Sanjay Patel 8625c43662 [InstCombine] move min/max tests to min/max test file; NFC
llvm-svn: 286256
2016-11-08 18:12:19 +00:00
Sanjay Patel 586aeee341 [InstCombine] move/fix tests for adjusted min/max
I think the former 'test50' had a typo making it functionally equivalent
to the former 'test49'; changed the predicate to provide more coverage.

llvm-svn: 285706
2016-11-01 16:39:30 +00:00
Sanjay Patel 36eeb6d6f6 [ValueTracking] recognize more variants of smin/smax
Try harder to detect obfuscated min/max patterns: the initial pattern was added with D9352 / rL236202. 
There was a bug fix for PR27137 at rL264996, but I think we can do better by folding the corresponding
smax pattern and commuted variants.

The codegen tests demonstrate the effect of ValueTracking on the backend via SelectionDAGBuilder. We
can't expose these differences minimally in IR because we don't have smin/smax intrinsics for IR.

Differential Revision: https://reviews.llvm.org/D26091

llvm-svn: 285499
2016-10-29 16:21:19 +00:00
Sanjay Patel 19ace1d548 [InstCombine] move/add tests for smin/smax folds
llvm-svn: 285414
2016-10-28 16:54:03 +00:00
Sanjay Patel c0de9c9e40 [InstCombine] fix foldSPFofSPF() to handle vector splats
llvm-svn: 285345
2016-10-27 21:19:40 +00:00
Sanjay Patel 923f74b27c [InstCombine] add vector tests for foldSPFofSPF to show missing folds
llvm-svn: 285340
2016-10-27 20:51:03 +00:00
Sanjay Patel cc8e0af3e5 [InstCombine] auto-generate checks for min/max tests
llvm-svn: 285336
2016-10-27 19:54:15 +00:00
Sanjay Patel e372aecb8a [ValueTracking] fix matchSelectPattern to allow vector splat folds of min/max/abs/nabs
llvm-svn: 285303
2016-10-27 15:26:10 +00:00
Sanjay Patel d5b8d64d4b [InstCombine] add tests for missing folds of vector abs/nabs/min/max
llvm-svn: 285299
2016-10-27 15:02:45 +00:00
Sanjay Patel 60f80d7a8b [InstCombine] regenerate some checks
llvm-svn: 285036
2016-10-24 22:50:26 +00:00
Sanjay Patel f26710d97d [InstCombine] canonicalize vector select with constant vector condition to shuffle
As discussed on llvm-dev ( http://lists.llvm.org/pipermail/llvm-dev/2016-August/104210.html ): 
turn a vector select with constant condition operand into a shuffle as a canonicalization step.
Shuffles may be easier to reason about in conjunction with other shuffles and insert/extract.

Possible known (minor?) regressions from this change are filed as:
https://llvm.org/bugs/show_bug.cgi?id=28530 
https://llvm.org/bugs/show_bug.cgi?id=28531 
https://llvm.org/bugs/show_bug.cgi?id=30371

If something terrible happens to perf after this commit, feel free to revert until a backend
fix is in place.

Differential Revision: https://reviews.llvm.org/D24279

llvm-svn: 281787
2016-09-16 22:16:18 +00:00
Sanjay Patel 0753c06d9c [InstCombine] LogicOpc (zext X), C --> zext (LogicOpc X, C) (PR28476)
The benefits of this change include:
1. Remove DeMorgan-matching code that was added specifically to work-around 
   the missing transform in http://reviews.llvm.org/rL248634.
2. Makes the DeMorgan transform work for vectors too.
3. Fix PR28476: https://llvm.org/bugs/show_bug.cgi?id=28476

Extending this transform to other casts and other associative operators may
be useful too. See https://reviews.llvm.org/D22421 for a prerequisite for
doing that though.

Differential Revision: https://reviews.llvm.org/D22271

llvm-svn: 276221
2016-07-21 00:24:18 +00:00
Sanjay Patel 5f3c70307d [InstSimplify][InstCombine] don't crash when folding vector selects of icmp
Differential Revision: https://reviews.llvm.org/D22602

llvm-svn: 276209
2016-07-20 23:40:01 +00:00
Sanjay Patel d4ea94eb94 regenerate checks
llvm-svn: 276042
2016-07-19 22:32:15 +00:00
Sanjay Patel cbaac41856 [InstCombine] enable vector select of bools -> logic folds
llvm-svn: 274465
2016-07-03 14:34:39 +00:00
Sanjay Patel 42396ae0ea add vector bool select tests and regenerate checks for scalar bool select tests
llvm-svn: 274460
2016-07-03 13:26:02 +00:00
Sanjay Patel 216d8cf720 [InstCombine] allow more than one use for vector bitcast folding with selects
The motivating example for this transform is similar to D20774 where bitcasts interfere
with a single cmp/select sequence, but in this case we have 2 uses of each bitcast to 
produce min and max ops:

define void @minmax_bc_store(<4 x float> %a, <4 x float> %b, <4 x float>* %ptr1, <4 x float>* %ptr2) {
  %cmp = fcmp olt <4 x float> %a, %b
  %bc1 = bitcast <4 x float> %a to <4 x i32>
  %bc2 = bitcast <4 x float> %b to <4 x i32>
  %sel1 = select <4 x i1> %cmp, <4 x i32> %bc1, <4 x i32> %bc2
  %sel2 = select <4 x i1> %cmp, <4 x i32> %bc2, <4 x i32> %bc1
  %bc3 = bitcast <4 x float>* %ptr1 to <4 x i32>*
  store <4 x i32> %sel1, <4 x i32>* %bc3
  %bc4 = bitcast <4 x float>* %ptr2 to <4 x i32>*
  store <4 x i32> %sel2, <4 x i32>* %bc4
  ret void
}

With this patch, we move the selects up to use the input args which allows getting rid of
all of the bitcasts:

define void @minmax_bc_store(<4 x float> %a, <4 x float> %b, <4 x float>* %ptr1, <4 x float>* %ptr2) {
  %cmp = fcmp olt <4 x float> %a, %b
  %sel1.v = select <4 x i1> %cmp, <4 x float> %a, <4 x float> %b
  %sel2.v = select <4 x i1> %cmp, <4 x float> %b, <4 x float> %a
  store <4 x float> %sel1.v, <4 x float>* %ptr1, align 16
  store <4 x float> %sel2.v, <4 x float>* %ptr2, align 16
  ret void
}

The asm for x86 SSE then improves from:

movaps  %xmm0, %xmm2
cmpltps %xmm1, %xmm2
movaps  %xmm2, %xmm3
andnps  %xmm1, %xmm3
movaps  %xmm2, %xmm4
andnps  %xmm0, %xmm4
andps %xmm2, %xmm0
orps  %xmm3, %xmm0
andps %xmm1, %xmm2
orps  %xmm4, %xmm2
movaps  %xmm0, (%rdi)
movaps  %xmm2, (%rsi)

To:

movaps  %xmm0, %xmm2
minps %xmm1, %xmm2
maxps %xmm0, %xmm1
movaps  %xmm2, (%rdi)
movaps  %xmm1, (%rsi)

The TODO comments show that we're limiting this transform only to vectors and only to bitcasts
because we need to improve other transforms or risk creating worse codegen.

Differential Revision: http://reviews.llvm.org/D21190

llvm-svn: 273011
2016-06-17 16:46:50 +00:00
Sanjoy Das 56df0ec610 [InstCombine] Fix incorrect rule from rL236202
The rule for SMIN introduced in rL236202 doesn't work as advertised: the
check for Pred == ICmpInst::ICMP_SGT was missing.

llvm-svn: 264996
2016-03-31 05:14:34 +00:00
Artur Pilipenko f84dc06e5b Push isDereferenceableAndAlignedPointer down into isSafeToLoadUnconditionally
Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D16226

llvm-svn: 258010
2016-01-17 12:35:29 +00:00
Artur Pilipenko 0e21d54b51 Take alignment into account in isSafeToLoadUnconditionally
Reviewed By: hfinkel

Differential Revision: http://reviews.llvm.org/D10475

llvm-svn: 240636
2015-06-25 12:18:43 +00:00
Philip Reames c25df11614 Reapply 239795 - [InstCombine] Propagate non-null facts to call parameters
The original change broke clang side tests.  I will be submitting those momentarily.  This change includes post commit feedback on the original change from from Pete Cooper.

Original Submission comments:
If a parameter to a function is known non-null, use the existing parameter attributes to record that fact at the call site. This has no optimization benefit by itself - that I know of - but is an enabling change for http://reviews.llvm.org/D9129.

Differential Revision: http://reviews.llvm.org/D9132

llvm-svn: 239849
2015-06-16 20:24:25 +00:00
Philip Reames 1a6305f313 Revert 239795
I forgot to update some clang test cases.  I'll fix and resubmit tomorrow.

llvm-svn: 239800
2015-06-16 01:20:53 +00:00
Philip Reames dfc29fba60 [InstCombine] Propagate non-null facts to call parameters
If a parameter to a function is known non-null, use the existing parameter attributes to record that fact at the call site. This has no optimization benefit by itself - that I know of - but is an enabling change for http://reviews.llvm.org/D9129.

Differential Revision: http://reviews.llvm.org/D9132

llvm-svn: 239795
2015-06-16 00:43:54 +00:00
David Majnemer 468f670021 [InstCombine] Don't miscompile select to poison
If we have (select a, b, c), it is sometimes valid to simplify this to a
single select operand.  However, doing so is only valid if the
computation doesn't inject poison into the computation.

It might be helpful to consider the following example:
  (select (icmp ne %i, INT_MAX), (add nsw %i, 1), INT_MIN)

The select is equivalent to (add %i, 1) but not (add nsw %i, 1).

Self hosting on x86_64 revealed that this occurs very, very rarely so
bailing out is hopefully pretty reasonable.

llvm-svn: 239215
2015-06-06 02:30:43 +00:00
Renato Golin 3dabb23384 Revert "[InstCombine] Rephrase fix to SimplifyWithOpReplaced"
This reverts commit r239141. This commit was an attempt to reintroduce
a previous patch that broke many self-hosting bots with clang timeouts,
but it still has slowdown issues, at least  on ARM, increasing the
compilation time (stage 2, clang's) by 5x.

llvm-svn: 239175
2015-06-05 18:24:12 +00:00
David Majnemer 6d8081835d [InstCombine] Rephrase fix to SimplifyWithOpReplaced
I don't have the IR which is causing the build bot breakage but I can
postulate as to why they are timing out:
1. SimplifyWithOpReplaced was stripping flags from the simplified value.
2. visitSelectInstWithICmp was overriding SimplifyWithOpReplaced because
   it's simplification wasn't correct.
3. InstCombine would revisit the add instruction and note that it can
   rederive the flags.
4. By modifying the value, we chose to revisit instructions which reuse
   the value.  One of the instructions is the original select, causing
   LLVM to never reach fixpoint.

Instead, strip the flags only when we are sure we are going to perform
the simplification.

llvm-svn: 239141
2015-06-05 09:57:57 +00:00
Daniel Jasper 917fa5ee66 Revert "[InstCombine] Don't miscompile safe increment idiom"
This is breaking a lot of build bots and is causing very long-running
compiles (infinite loops)?

Likely, we shouldn't return nullptr?

llvm-svn: 239139
2015-06-05 09:31:20 +00:00
David Majnemer 00f7d9ecc8 [InstCombine] Don't miscompile safe increment idiom
We cleverly handle cases where computation done in one argument of a select
instruction is suitable for the other operand, thus obviating the need
of the select and the comparison.  However, the other operand cannot
have flags.

This fixes PR23757.

llvm-svn: 239115
2015-06-04 23:11:30 +00:00
Sanjoy Das a8c178f280 [InstCombine] Add a new formula for SMIN.
Summary:
After this change `MatchSelectPattern` recognizes the following form
of SMIN:

  Y >s C ? ~Y : ~C == ~Y <s ~C ? ~Y : ~C = SMIN(~Y, ~C)

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9352

llvm-svn: 236202
2015-04-30 04:56:00 +00:00
Duncan P. N. Exon Smith 49e6a70fe3 Verifier: Call verifyModule() from llc and opt
Change `llc` and `opt` to run `verifyModule()`.  This ensures that we
check the full module before `FunctionPass::doInitialization()` ever
gets called (I was getting crashes in `DwarfDebug` instead of verifier
failures when testing a WIP patch that checks operands of compile
units).  In `opt`, also move up debug-info-stripping so that it still
runs before verification.

There was a fair bit of broken code that was sitting in tree.
Interestingly, some were cases of a `select` that referred to itself in
`-instcombine` tests (apparently an intermediate result).  I split them
off to `*-noverify.ll` tests with RUN lines like this:

    opt < %s -S -disable-verify -instcombine | opt -S | FileCheck %s

This avoids verifying the input file (so we can get the broken code into
`-instcombine), but still verifies the output with a second call to
`opt` (to verify that `-instcombine` will clean it up like it should).

llvm-svn: 233432
2015-03-27 22:04:28 +00:00
David Blaikie a79ac14fa6 [opaque pointer type] Add textual IR support for explicit type parameter to load instruction
Essentially the same as the GEP change in r230786.

A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)

import fileinput
import sys
import re

pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")

for line in sys.stdin:
  sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7649

llvm-svn: 230794
2015-02-27 21:17:42 +00:00
Matthias Braun 2e404597f4 InstCombine: Combine select sequences into a single select
Normalize
select(C0, select(C1, a, b), b) -> select((C0 & C1), a, b)
select(C0, a, select(C1, a, b)) -> select((C0 | C1), a, b)

This normal form may enable further combines on the And/Or and shortens
paths for the values. Many targets prefer the other but can go back
easily in CodeGen.

Differential Revision: http://reviews.llvm.org/D7399

llvm-svn: 228409
2015-02-06 17:49:36 +00:00
Philip Reames 5ad26c353c Loading from null is valid outside of addrspace 0
This patches fixes a miscompile where we were assuming that loading from null is undefined and thus we could assume it doesn't happen.  This transform is perfectly legal in address space 0, but is not neccessarily legal in other address spaces.

We really should introduce a hook to control this property on a per target per address space basis.  We may be loosing valuable optimizations in some address spaces by being too conservative.

Original patch by Thomas P Raoux (submitted to llvm-commits), tests and formatting fixes by me.

llvm-svn: 224961
2014-12-29 22:46:21 +00:00
David Majnemer 6eed0e0d20 This should have been part of r224676.
llvm-svn: 224677
2014-12-20 04:48:34 +00:00
David Majnemer b0362e4ee6 InstCombine: Squash an icmp+select into bitwise arithmetic
(X & INT_MIN) == 0 ? X ^ INT_MIN : X  into  X | INT_MIN
(X & INT_MIN) != 0 ? X ^ INT_MIN : X  into  X & INT_MAX

This fixes PR21993.

llvm-svn: 224676
2014-12-20 04:45:35 +00:00
David Majnemer 40157d5c4d InstCombine: Restore optimizations lost in r210006
This restores our ability to optimize:
(X & C) == 0 ? X ^ C : X  into  X | C
(X & C) != 0 ? X ^ C : X  into  X & ~C

llvm-svn: 222871
2014-11-27 07:25:21 +00:00