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* [InstCombine] Use SimplifyFMulInst to simplify multiply in fma.Florian Hahn2019-09-101-3/+5
| | | | | | | | | | | | | | This allows us to fold fma's that multiply with 0.0. Also, the multiply by 1.0 case is handled there as well. The fneg/fabs cases are not handled by SimplifyFMulInst, so we need to keep them. Reviewers: spatel, anemet, lebedev.ri Reviewed By: spatel Differential Revision: https://reviews.llvm.org/D67351 llvm-svn: 371518
* [InstCombine] fold extract+insert into identity shuffleSanjay Patel2019-09-081-0/+52
| | | | | | | | | | | | | | | This is similar to the existing fold for splats added with: rL365379 If we can adjust the shuffle mask to include another element in an identity mask (if it changes vector length, that's an extract/insert subvector operation in the backend), then that can eliminate extractelement/insertelement pairs in IR. All targets are expected to lower shuffles with identity masks efficiently. llvm-svn: 371340
* Change TargetLibraryInfo analysis passes to always require FunctionTeresa Johnson2019-09-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This is the first change to enable the TLI to be built per-function so that -fno-builtin* handling can be migrated to use function attributes. See discussion on D61634 for background. This is an enabler for fixing handling of these options for LTO, for example. This change should not affect behavior, as the provided function is not yet used to build a specifically per-function TLI, but rather enables that migration. Most of the changes were very mechanical, e.g. passing a Function to the legacy analysis pass's getTLI interface, or in Module level cases, adding a callback. This is similar to the way the per-function TTI analysis works. There was one place where we were looking for builtins but not in the context of a specific function. See FindCXAAtExit in lib/Transforms/IPO/GlobalOpt.cpp. I'm somewhat concerned my workaround could provide the wrong behavior in some corner cases. Suggestions welcome. Reviewers: chandlerc, hfinkel Subscribers: arsenm, dschuff, jvesely, nhaehnle, mehdi_amini, javed.absar, sbc100, jgravelle-google, eraman, aheejin, steven_wu, george.burgess.iv, dexonsmith, jfb, asbirlea, gchatelet, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66428 llvm-svn: 371284
* InstCombine: Fix crash on icmp of gep with addrspacecasted nullMatt Arsenault2019-09-051-2/+2
| | | | llvm-svn: 371146
* [InstCombine] foldICmpBinOp(): consider inverted check in 'unsigned sub ↵Roman Lebedev2019-09-051-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | overflow' check A follow-up for r329011. This may be changed to produce @llvm.sub.with.overflow in a later patch, but for now just make things more consistent overall. A few observations stem from this: * There does not seem to be a similar one-instruction fold for uadd-overflow * I'm not sure we'll want to canonicalize `B u> A` as `usub.with.overflow`, so since the `icmp` here no longer refers to `sub`, reconstructing `usub.with.overflow` will be problematic, and will likely require standalone pass (similar to DivRemPairs). https://rise4fun.com/Alive/Zqs Name: (A - B) u> A --> B u> A %t0 = sub i8 %A, %B %r = icmp ugt i8 %t0, %A => %r = icmp ugt i8 %B, %A Name: (A - B) u<= A --> B u<= A %t0 = sub i8 %A, %B %r = icmp ule i8 %t0, %A => %r = icmp ule i8 %B, %A Name: C u< (C - D) --> C u< D %t0 = sub i8 %C, %D %r = icmp ult i8 %C, %t0 => %r = icmp ult i8 %C, %D Name: C u>= (C - D) --> C u>= D %t0 = sub i8 %C, %D %r = icmp uge i8 %C, %t0 => %r = icmp uge i8 %C, %D llvm-svn: 371101
* [InstCombine] foldICmpBinOp(): consider inverted check in 'unsigned add ↵Roman Lebedev2019-09-051-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | overflow' check A follow-up for r342004. This will be changed to produce @llvm.add.with.overflow in a later patch, but for now just make things more consistent overall. https://rise4fun.com/Alive/qxE Name: (Op1 + X) u< Op1 --> ~Op1 u< X %t0 = add i8 %Op1, %X %r = icmp ult i8 %t0, %Op1 => %n = xor i8 %Op1, -1 %r = icmp ult i8 %n, %X Name: (Op1 + X) u>= Op1 --> ~Op1 u>= X %t0 = add i8 %Op1, %X %r = icmp uge i8 %t0, %Op1 => %n = xor i8 %Op1, -1 %r = icmp uge i8 %n, %X ;------------------------------------------------------------------------------- Name: Op0 u> (Op0 + X) --> X u> ~Op0 %t0 = add i8 %Op0, %X %r = icmp ugt i8 %Op0, %t0 => %n = xor i8 %Op0, -1 %r = icmp ugt i8 %X, %n Name: Op0 u<= (Op0 + X) --> X u<= ~Op0 %t0 = add i8 %Op0, %X %r = icmp ule i8 %Op0, %t0 => %n = xor i8 %Op0, -1 %r = icmp ule i8 %X, %n llvm-svn: 371100
* [InstCombine] sub(xor(x, y), or(x, y)) -> neg(and(x, y))David Bolvansky2019-09-041-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: ``` Name: sub(xor(x, y), or(x, y)) -> neg(and(x, y)) %or = or i32 %y, %x %xor = xor i32 %x, %y %sub = sub i32 %xor, %or => %sub1 = and i32 %x, %y %sub = sub i32 0, %sub1 Optimization: sub(xor(x, y), or(x, y)) -> neg(and(x, y)) Done: 1 Optimization is correct! ``` https://rise4fun.com/Alive/8OI Reviewers: lebedev.ri Reviewed By: lebedev.ri Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67188 llvm-svn: 370945
* [InstCombine] Fold sub (and A, B) (or A, B)) to neg (xor A, B)David Bolvansky2019-09-041-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: ``` Name: sub(and(x, y), or(x, y)) -> neg(xor(x, y)) %or = or i32 %y, %x %and = and i32 %x, %y %sub = sub i32 %and, %or => %sub1 = xor i32 %x, %y %sub = sub i32 0, %sub1 Optimization: sub(and(x, y), or(x, y)) -> neg(xor(x, y)) Done: 1 Optimization is correct! ``` https://rise4fun.com/Alive/VI6 Found by @lebedev.ri. Also author of the proof. Reviewers: lebedev.ri, spatel Reviewed By: lebedev.ri Subscribers: llvm-commits, lebedev.ri Tags: #llvm Differential Revision: https://reviews.llvm.org/D67155 llvm-svn: 370934
* [InstCombine] Fold sub (or A, B) (and A, B) to (xor A, B)David Bolvansky2019-09-041-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: ``` Name: sub or and to xor %or = or i32 %y, %x %and = and i32 %x, %y %sub = sub i32 %or, %and => %sub = xor i32 %x, %y Optimization: sub or and to xor Done: 1 Optimization is correct! ``` https://rise4fun.com/Alive/eJu Reviewers: spatel, lebedev.ri Reviewed By: lebedev.ri Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67153 llvm-svn: 370883
* [InstCombine] recognize bswap disguised as shufflevectorSanjay Patel2019-09-021-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | bitcast <N x i8> (shuf X, undef, <N, N-1,...0>) to i{N*8} --> bswap (bitcast X to i{N*8}) In PR43146: https://bugs.llvm.org/show_bug.cgi?id=43146 ...we have a more complicated case where SLP is making a mess of bswap. This patch won't do anything for that currently, but we need to improve bswap recognition in instcombine, SLP, and/or a standalone pass to avoid that problem. This is limited using the data-layout so we don't try to do this transform with actual vector types. The backend does not appear to have folds to convert in either direction, so we don't want to mess up something that is actually better lowered as a shuffle. On x86, we're trading something like this: vmovd %edi, %xmm0 vpshufb LCPI0_0(%rip), %xmm0, %xmm0 ## xmm0 = xmm0[3,2,1,0,u,u,u,u,u,u,u,u,u,u,u,u] vmovd %xmm0, %eax For: movl %edi, %eax bswapl %eax Differential Revision: https://reviews.llvm.org/D66965 llvm-svn: 370659
* [InstCombine][AMDGPU] Simplify tbuffer loadsPiotr Sobczak2019-08-301-0/+3
| | | | | | | | | | | | | | | | Summary: Add missing tbuffer loads intrinsics in SimplifyDemandedVectorElts. Reviewers: arsenm, nhaehnle Reviewed By: arsenm Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66926 llvm-svn: 370475
* [InstCombine] reduce duplicated code; NFCSanjay Patel2019-08-291-10/+13
| | | | llvm-svn: 370399
* [InstCombine] Fold '((%x * %y) u/ %x) != %y' to '@llvm.umul.with.overflow' + ↵Roman Lebedev2019-08-292-5/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | overflow bit extraction Summary: `((%x * %y) u/ %x) != %y` is one of (3?) common ways to check that some unsigned multiplication (will not) overflow. Currently, we don't catch it. We could: ``` $ /repositories/alive2/build-Clang-unknown/alive -root-only ~/llvm-patch1.ll Processing /home/lebedevri/llvm-patch1.ll.. ---------------------------------------- Name: no overflow %o0 = mul i4 %y, %x %o1 = udiv i4 %o0, %x %r = icmp ne i4 %o1, %y ret i1 %r => %n0 = umul_overflow i4 %x, %y %o0 = extractvalue {i4, i1} %n0, 0 %o1 = udiv %o0, %x %r = extractvalue {i4, i1} %n0, 1 ret %r Done: 1 Optimization is correct! ---------------------------------------- Name: no overflow %o0 = mul i4 %y, %x %o1 = udiv i4 %o0, %x %r = icmp eq i4 %o1, %y ret i1 %r => %n0 = umul_overflow i4 %x, %y %o0 = extractvalue {i4, i1} %n0, 0 %o1 = udiv %o0, %x %n1 = extractvalue {i4, i1} %n0, 1 %r = xor %n1, -1 ret i1 %r Done: 1 Optimization is correct! ``` Reviewers: nikic, spatel, efriedma, xbolva00, RKSimon Reviewed By: nikic Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D65144 llvm-svn: 370348
* [InstCombine] Fold '(-1 u/ %x) u< %y' to '@llvm.umul.with.overflow' + ↵Roman Lebedev2019-08-291-0/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | overflow bit extraction Summary: `(-1 u/ %x) u< %y` is one of (3?) common ways to check that some unsigned multiplication (will not) overflow. Currently, we don't catch it. We could: ``` ---------------------------------------- Name: no overflow %o0 = udiv i4 -1, %x %r = icmp ult i4 %o0, %y => %o0 = udiv i4 -1, %x %n0 = umul_overflow i4 %x, %y %r = extractvalue {i4, i1} %n0, 1 Done: 1 Optimization is correct! ---------------------------------------- Name: no overflow, swapped %o0 = udiv i4 -1, %x %r = icmp ugt i4 %y, %o0 => %o0 = udiv i4 -1, %x %n0 = umul_overflow i4 %x, %y %r = extractvalue {i4, i1} %n0, 1 Done: 1 Optimization is correct! ---------------------------------------- Name: overflow %o0 = udiv i4 -1, %x %r = icmp uge i4 %o0, %y => %o0 = udiv i4 -1, %x %n0 = umul_overflow i4 %x, %y %n1 = extractvalue {i4, i1} %n0, 1 %r = xor %n1, -1 Done: 1 Optimization is correct! ---------------------------------------- Name: overflow %o0 = udiv i4 -1, %x %r = icmp ule i4 %y, %o0 => %o0 = udiv i4 -1, %x %n0 = umul_overflow i4 %x, %y %n1 = extractvalue {i4, i1} %n0, 1 %r = xor %n1, -1 Done: 1 Optimization is correct! ``` As it can be observed from tests, while simply forming the `@llvm.umul.with.overflow` is easy, if we were looking for the inverted answer, then more work needs to be done to cleanup the now-pointless control-flow that was guarding against division-by-zero. This is being addressed in follow-up patches. Reviewers: nikic, spatel, efriedma, xbolva00, RKSimon Reviewed By: nikic, xbolva00 Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D65143 llvm-svn: 370347
* [InstCombine] Shift amount reassociation in bittest: trunc-of-lshr (PR42399)Roman Lebedev2019-08-291-14/+58
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Finally, the fold i was looking forward to :) The legality check is muddy, i doubt i've groked the full generalization, but it handles all the cases i care about, and can come up with: https://rise4fun.com/Alive/26j I.e. we can perform the fold if **any** of the following is true: * The shift amount is either zero or one less than widest bitwidth * Either of the values being shifted has at most lowest bit set * The value that is being shifted by `shl` (which is not truncated) should have no less leading zeros than the total shift amount; * The value that is being shifted by `lshr` (which **is** truncated) should have no less leading zeros than the widest bit width minus total shift amount minus one I strongly suspect there is some better generalization, but i'm not aware of it as of right now. For now i also avoided using actual `computeKnownBits()`, but restricted it to constants. Reviewers: spatel, nikic, xbolva00 Reviewed By: spatel Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66383 llvm-svn: 370324
* Fix variable set but no used warning on NDEBUG builds. NFCI.Simon Pilgrim2019-08-291-2/+2
| | | | llvm-svn: 370317
* [InstCombine] clean up wrap propagation for reassociated ops; NFCISanjay Patel2019-08-281-11/+15
| | | | | | | | | | Always true/false checks were flagged by static analysis; https://bugs.llvm.org/show_bug.cgi?id=43143 I have not confirmed the logic difference in propagating nsw vs. nuw, but presumably we would have noticed a bug by now if that was wrong. llvm-svn: 370248
* Reduce scope of variable only used in a local pattern match. NFCI.Simon Pilgrim2019-08-281-1/+1
| | | | llvm-svn: 370224
* [InstCombine] Disable recursion in foldGEPICmp for vector pointer GEPsCraig Topper2019-08-281-2/+4
| | | | | | | Due to missing vector support in this function, recursion can generate worse code in some cases. llvm-svn: 370221
* Fix uninitialized variable warning in cppcheck. NFCI.Simon Pilgrim2019-08-281-1/+1
| | | | | | InstCombiner::MaxArraySizeForCombine is set outside the constructor so we need to ensure it has a default initialization value. llvm-svn: 370220
* [NFC] Added a comment to avoid possible confusionDavid Bolvansky2019-08-281-0/+2
| | | | llvm-svn: 370217
* Remove duplicate 'BitWidth' variable. NFCI.Simon Pilgrim2019-08-281-1/+0
| | | | llvm-svn: 370212
* InstCombiner::visitSelectInst - rename Pred to MinMaxPred to stop shadow ↵Simon Pilgrim2019-08-281-5/+6
| | | | | | | | variable warning. NFCI. We have a lot of Predicate variables, all similarly named.... llvm-svn: 370207
* Annotate return values of allocation functions with dereferenceable_or_nullDavid Bolvansky2019-08-281-0/+33
| | | | | | | | | | | | | | | | | | | | | | | Summary: Example define dso_local noalias i8* @_Z6maixxnv() local_unnamed_addr #0 { entry: %call = tail call noalias dereferenceable_or_null(64) i8* @malloc(i64 64) #6 ret i8* %call } Reviewers: jdoerfert Reviewed By: jdoerfert Subscribers: aaron.ballman, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66651 llvm-svn: 370168
* [InstCombine] Disable some portions of foldGEPICmp for GEPs that return a ↵Craig Topper2019-08-271-11/+26
| | | | | | vector of pointers. Fix other portions. llvm-svn: 370114
* [InstCombine] Fold select with ctlz to cttzDavid Bolvansky2019-08-271-0/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Handle pattern [0]: int ctz(unsigned int a) { int c = __clz(a & -a); return a ? 31 - c : c; } In reality, the compiler can generate much better code for cttz, so fold away this pattern. https://godbolt.org/z/c5kPtV [0] https://community.arm.com/community-help/f/discussions/2114/count-trailing-zeros Reviewers: spatel, nikic, lebedev.ri, dmgreen, hfinkel Reviewed By: hfinkel Subscribers: hfinkel, javed.absar, kristof.beyls, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66308 llvm-svn: 370037
* msan, codegen, instcombine: Keep more lifetime markers used for msanVitaly Buka2019-08-261-0/+1
| | | | | | | | | | | | Reviewers: eugenis Subscribers: hiraditya, cfe-commits, #sanitizers, llvm-commits Tags: #clang, #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D66695 llvm-svn: 369979
* [InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null ↵Philip Reames2019-08-261-1/+6
| | | | | | | | | | for vectors Extend the transform introduced in https://reviews.llvm.org/D66608 to work for vector geps as well. Differential Revision: https://reviews.llvm.org/D66671 llvm-svn: 369949
* [Constant] Add 'isElementWiseEqual()' methodRoman Lebedev2019-08-241-16/+2
| | | | | | | | | | | Promoting it from InstCombine's tryToReuseConstantFromSelectInComparison(). Return true if this constant and a constant 'Y' are element-wise equal. This is identical to just comparing the pointers, with the exception that for vectors, if only one of the constants has an `undef` element in some lane, the constants still match. llvm-svn: 369842
* [InstCombine] matchThreeWayIntCompare(): commutativity awarenessRoman Lebedev2019-08-241-13/+42
| | | | | | | | | | | | | | | | | | | | | | | | | Summary: `matchThreeWayIntCompare()` looks for ``` select i1 (a == b), i32 Equal, i32 (select i1 (a < b), i32 Less, i32 Greater) ``` but both of these selects/compares can be in it's commuted form, so out of 8 variants, only the two most basic ones is handled. This fixes regression being introduced in D66232. Reviewers: spatel, nikic, efriedma, xbolva00 Reviewed By: spatel Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66607 llvm-svn: 369841
* [InstCombine] Try to reuse constant from select in leading comparisonRoman Lebedev2019-08-242-12/+112
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: If we have e.g.: ``` %t = icmp ult i32 %x, 65536 %r = select i1 %t, i32 %y, i32 65535 ``` the constants `65535` and `65536` are suspiciously close. We could perform a transformation to deduplicate them: ``` Name: ult %t = icmp ult i32 %x, 65536 %r = select i1 %t, i32 %y, i32 65535 => %t.inv = icmp ugt i32 %x, 65535 %r = select i1 %t.inv, i32 65535, i32 %y ``` https://rise4fun.com/Alive/avb While this may seem esoteric, this should certainly be good for vectors (less constant pool usage) and for opt-for-size - need to have only one constant. But the real fun part here is that it allows further transformation, in particular it finishes cleaning up the `clamp` folding, see e.g. `canonicalize-clamp-with-select-of-constant-threshold-pattern.ll`. We start with e.g. ``` %dont_need_to_clamp_positive = icmp sle i32 %X, 32767 %dont_need_to_clamp_negative = icmp sge i32 %X, -32768 %clamp_limit = select i1 %dont_need_to_clamp_positive, i32 -32768, i32 32767 %dont_need_to_clamp = and i1 %dont_need_to_clamp_positive, %dont_need_to_clamp_negative %R = select i1 %dont_need_to_clamp, i32 %X, i32 %clamp_limit ``` without this patch we currently produce ``` %1 = icmp slt i32 %X, 32768 %2 = icmp sgt i32 %X, -32768 %3 = select i1 %2, i32 %X, i32 -32768 %R = select i1 %1, i32 %3, i32 32767 ``` which isn't really a `clamp` - both comparisons are performed on the original value, this patch changes it into ``` %1.inv = icmp sgt i32 %X, 32767 %2 = icmp sgt i32 %X, -32768 %3 = select i1 %2, i32 %X, i32 -32768 %R = select i1 %1.inv, i32 32767, i32 %3 ``` and then the magic happens! Some further transform finishes polishing it and we finally get: ``` %t1 = icmp sgt i32 %X, -32768 %t2 = select i1 %t1, i32 %X, i32 -32768 %t3 = icmp slt i32 %t2, 32767 %R = select i1 %t3, i32 %t2, i32 32767 ``` which is beautiful and just what we want. Proofs for `getFlippedStrictnessPredicateAndConstant()` for de-canonicalization: https://rise4fun.com/Alive/THl Proofs for the fold itself: https://rise4fun.com/Alive/THl Reviewers: spatel, dmgreen, nikic, xbolva00 Reviewed By: spatel Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66232 llvm-svn: 369840
* Fix a bug in just submitted rL369789Philip Reames2019-08-231-1/+4
| | | | | | | | Started implementing the vector case and realized the scalar case hadn't handled the GEP producing a different type than the base correctly. It's entertaining seeing what slips through review when we're focused on the 'hard' parts. :( Also adding an extra vector test as it happened to be in workspace and wasn't worth separating. llvm-svn: 369795
* [InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, nullPhilip Reames2019-08-231-0/+21
| | | | | | | | | | This generalizes the isGEPKnownNonNull rule from ValueTracking to apply when we do not know if the base is non-null, and thus need to replace one condition with another. The core notion is that since an inbounds GEP can only form null if the base pointer is null and the offset is zero. However, if the offset is non-zero, the the "inbounds" marker makes the result poison. Thus, we're free to ignore the case where the offset is non-zero. Similarly, there's no case under which a non-null base can result in a null result without generating poison. Differential Revision: https://reviews.llvm.org/D66608 llvm-svn: 369789
* [instcombine] icmp eq/ne (sub C, Y), C -> icmp eq/ne Y, 0Philip Reames2019-08-211-0/+5
| | | | | | Noticed while looking at pr43028. llvm-svn: 369541
* [InstCombine] narrow icmp with extended operands of different widthsSanjay Patel2019-08-211-6/+17
| | | | | | | | | | | An intermediate extend is used to widen the narrow operand to the width of the other (wider) operand. At that point, we have the same logic as the existing transform that was restricted to folds of equal width zext/sext. This mostly solves PR42700: https://bugs.llvm.org/show_bug.cgi?id=42700 llvm-svn: 369519
* [InstCombine] add helper function for icmp+zext/sext; NFCSanjay Patel2019-08-201-69/+75
| | | | llvm-svn: 369421
* [InstCombine] make fold for icmp with sext more efficient; NFCSanjay Patel2019-08-201-13/+7
| | | | | | | We were creating 2 instructions and relying on a subsequent fold to invert a not(icmp). Create the final icmp directly instead. llvm-svn: 369411
* [InstCombine] improve readability for icmp with cast folds; NFCSanjay Patel2019-08-202-47/+42
| | | | | | | | 1. Update function name and stale code comments. 2. Use variable names that are less ambiguous. 3. Move operand checks into the function as early exits. llvm-svn: 369390
* [InstCombine] simplify min/max of min/max with same operands (PR35607)Sanjay Patel2019-08-201-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the original integer variant requested in: https://bugs.llvm.org/show_bug.cgi?id=35607 As noted in the TODO and several similar TODOs around this block, we could do this in instsimplify, but then it would cost more because we would be trying to match min/max via ValueTracking in 2 different places. There are 4 commuted variants for each of smin/smax/umin/umax that are not matched here. There are also icmp predicate variants that are not included in the affected test file because they are already handled by instsimplify by folding the final icmp to true/false. https://rise4fun.com/Alive/3KVc Name: smax(smax, smin) %c1 = icmp slt i32 %x, %y %c2 = icmp slt i32 %y, %x %min = select i1 %c1, i32 %x, i32 %y %max = select i1 %c2, i32 %x, i32 %y %c3 = icmp sgt i32 %max, %min %r = select i1 %c3, i32 %max, i32 %min => %r = %max Name: smin(smax, smin) %c1 = icmp slt i32 %x, %y %c2 = icmp slt i32 %y, %x %min = select i1 %c1, i32 %x, i32 %y %max = select i1 %c2, i32 %x, i32 %y %c3 = icmp sgt i32 %max, %min %r = select i1 %c3, i32 %min, i32 %max => %r = %min Name: umax(umax, umin) %c1 = icmp ult i32 %x, %y %c2 = icmp ult i32 %y, %x %min = select i1 %c1, i32 %x, i32 %y %max = select i1 %c2, i32 %x, i32 %y %c3 = icmp ult i32 %min, %max %r = select i1 %c3, i32 %max, i32 %min => %r = %max Name: umin(umax, umin) %c1 = icmp ult i32 %x, %y %c2 = icmp ult i32 %y, %x %min = select i1 %c1, i32 %x, i32 %y %max = select i1 %c2, i32 %x, i32 %y %c3 = icmp ult i32 %min, %max %r = select i1 %c3, i32 %min, i32 %max => %r = %min llvm-svn: 369386
* [InstCombine] Cherry-pick NFC cleanups of ↵Roman Lebedev2019-08-181-5/+8
| | | | | | foldShiftIntoShiftInAnotherHandOfAndInICmp() from D66383 llvm-svn: 369207
* Revert r367891 - "[InstCombine] combine mul+shl separated by zext"Sanjay Patel2019-08-161-13/+2
| | | | | | | | | | | | | This reverts commit 5dbb90bfe14ace30224239cac7c61a1422fa5144. As noted in the post-commit thread for r367891, this can create a multiply that is lowered to a libcall that may not exist. We need to improve the backend decomposition for integer multiply before trying to re-land this (if it's still worthwhile after doing the backend work). llvm-svn: 369174
* [InstCombine] canonicalize a scalar-select-of-vectors to vector selectSanjay Patel2019-08-161-0/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This pattern may arise more frequently with an enhancement to SLP vectorization suggested in PR42755: https://bugs.llvm.org/show_bug.cgi?id=42755 ...but we should handle this pattern to make things easier for the backend either way. For all in-tree targets that I looked at, codegen for typical vector sizes looks better when we change to a vector select, so this is safe to do without a cost model (in other words, as a target-independent canonicalization). For example, if the condition of the select is a scalar, we end up with something like this on x86: vpcmpgtd %xmm0, %xmm1, %xmm0 vpextrb $12, %xmm0, %eax testb $1, %al jne LBB0_2 ## %bb.1: vmovaps %xmm3, %xmm2 LBB0_2: vmovaps %xmm2, %xmm0 Rather than the splat-condition variant: vpcmpgtd %xmm0, %xmm1, %xmm0 vpshufd $255, %xmm0, %xmm0 ## xmm0 = xmm0[3,3,3,3] vblendvps %xmm0, %xmm2, %xmm3, %xmm0 Differential Revision: https://reviews.llvm.org/D66095 llvm-svn: 369140
* [InstCombine] Shift amount reassociation in bittest: trunc-of-shl (PR42399)Roman Lebedev2019-08-161-19/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This is continuation of D63829 / https://bugs.llvm.org/show_bug.cgi?id=42399 I thought naive pattern would solve my issue, but nope, it involved truncation, thus more folds needed.. This isn't really the fold i'm interested in, i need trunc-of-lshr, but i'we decided to start with `shl` because it's simpler. In this case, no extra legality checks are needed: https://rise4fun.com/Alive/CAb We should be careful about not increasing instruction count, since we need to produce `zext` because `and` is done in wider type. Reviewers: spatel, nikic, xbolva00 Reviewed By: spatel Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66057 llvm-svn: 369117
* [InstCombine] Refactor getFlippedStrictnessPredicateAndConstant() out of ↵Roman Lebedev2019-08-142-32/+50
| | | | | | | | | canonicalizeCmpWithConstant(), NFCI I'd like to use it elsewhere, hopefully without reinventing the wheel. No functional change intended so far. llvm-svn: 368820
* [InstCombine] Non-canonical clamp-like pattern handlingRoman Lebedev2019-08-131-0/+146
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Given a pattern like: ``` %old_cmp1 = icmp slt i32 %x, C2 %old_replacement = select i1 %old_cmp1, i32 %target_low, i32 %target_high %old_x_offseted = add i32 %x, C1 %old_cmp0 = icmp ult i32 %old_x_offseted, C0 %r = select i1 %old_cmp0, i32 %x, i32 %old_replacement ``` it can be rewritten as more canonical pattern: ``` %new_cmp1 = icmp slt i32 %x, -C1 %new_cmp2 = icmp sge i32 %x, C0-C1 %new_clamped_low = select i1 %new_cmp1, i32 %target_low, i32 %x %r = select i1 %new_cmp2, i32 %target_high, i32 %new_clamped_low ``` Iff `-C1 s<= C2 s<= C0-C1` Also, `ULT` predicate can also be `UGE`; or `UGT` iff `C0 != -1` (+invert result) Also, `SLT` predicate can also be `SGE`; or `SGT` iff `C2 != INT_MAX` (+invert result) If `C1 == 0`, then all 3 instructions must be one-use; else at most either `%old_cmp1` or `%old_x_offseted` can have extra uses. NOTE: if we could reuse `%old_cmp1` as one of the comparisons we'll have to build, this could be less limiting. So there are two icmp's, each one with 3 predicate variants, so there are 9 fold variants: | | ULT | UGE | UGT | | SLT | https://rise4fun.com/Alive/yIJ | https://rise4fun.com/Alive/5BfN | https://rise4fun.com/Alive/INH | | SGE | https://rise4fun.com/Alive/hd8 | https://rise4fun.com/Alive/Abk | https://rise4fun.com/Alive/PlzS | | SGT | https://rise4fun.com/Alive/VYG | https://rise4fun.com/Alive/oMY | https://rise4fun.com/Alive/KrzC | {F9730206} This fold was brought up in https://reviews.llvm.org/D65148#1603922 by @dmgreen, and is needed to unblock that patch. This patch requires D65530. Reviewers: spatel, nikic, xbolva00, dmgreen Reviewed By: spatel Subscribers: hiraditya, llvm-commits, dmgreen Tags: #llvm Differential Revision: https://reviews.llvm.org/D65765 llvm-svn: 368687
* [InstCombine][NFC] Rename IsFreeToInvert() -> isFreeToInvert() for consistencyRoman Lebedev2019-08-134-18/+18
| | | | | | As per https://reviews.llvm.org/D65530#inline-592325 llvm-svn: 368686
* [InstCombine] foldXorOfICmps(): don't give up on non-single-use ICmp's if ↵Roman Lebedev2019-08-132-10/+63
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | all users are freely invertible Summary: This is rather unconventional.. As the comment there says, we don't have much folds for xor-of-icmps, we try to turn them into an and-of-icmps, for which we have plenty of folds. But if the ICmp we need to invert is not single-use - we give up. As discussed in https://reviews.llvm.org/D65148#1603922, we may have a non-canonical CLAMP pattern, with bit match and select-of-threshold that we'll potentially clamp. As it can be seen in `canonicalize-clamp-with-select-of-constant-threshold-pattern.ll`, out of all 8 variations of the pattern, only two are **not** canonicalized into the variant with and+icmp instead of bit math. The reason is because the ICmp we need to invert is not single-use - we give up. We indeed can't perform this fold at will, the general rule is that we should not increase instruction count in InstCombine, But we wouldn't end up increasing instruction count if we can adapt every other user to the inverted value. This way the `not` we create **will** get folded, and in the end the instruction count did not increase. For that, of course, we need to look at the users of a Value, which is again rather unconventional for InstCombine :S Thus i'm proposing to be a little bit more insistive in `foldXorOfICmps()`. The alternatives would be to not create that `not`, but add duplicate code to manually invert all users; or to add some even less general combine to handle some more specific pattern[s]. Reviewers: spatel, nikic, RKSimon, craig.topper Reviewed By: spatel Subscribers: hiraditya, jdoerfert, dmgreen, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D65530 llvm-svn: 368685
* [InstCombine] x /c fabs(x) -> copysign(1.0, x)David Bolvansky2019-08-121-0/+11
| | | | | | | | | | | | | | | | | | Summary: x / fabs(x) -> copysign(1.0, x) fabs(x) / x -> copysign(1.0, x) Reviewers: spatel, foad, RKSimon, efriedma Reviewed By: spatel Subscribers: lebedev.ri, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D65898 llvm-svn: 368570
* [InstCombine] foldShiftIntoShiftInAnotherHandOfAndInICmp(): avoid ↵Roman Lebedev2019-08-121-6/+5
| | | | | | | | | | | constantexpr pitfail (PR42962) Instead of matching value and then blindly casting to BinaryOperator just to get the opcode, just match instruction and do no cast. Fixes https://bugs.llvm.org/show_bug.cgi?id=42962 llvm-svn: 368554
* [InstCombine][NFC] Use SimplifyAddInst() instead of ↵Roman Lebedev2019-08-101-2/+2
| | | | | | SimplifyBinOp(Instruction::BinaryOps::Add, ) llvm-svn: 368521
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