Abu 1078a1dabd

Lowering ~x | (x - 1) to ~blsi(x) (#186722) ...

Alive2 proof: 
https://alive2.llvm.org/ce/z/bK93Cn

I've implemented a fold in `InstCombineAndOrXor.cpp` to canonicalize `~x
| (x - 1)` to `~(x & -x)` which enables the CodeGen to emit the `blsi`
instruction.

I've also added a test in `CodeGen/X86`.

Fixes #184055

---------

Co-authored-by: Tim Gymnich <tim@gymni.ch>

2026-03-19 20:45:56 +08:00

..

CMakeLists.txt

…

InstCombineAddSub.cpp

[InstCombine] Support disjoint or in add-sub reassociation fold (#186827)

2026-03-16 17:43:20 +00:00

InstCombineAndOrXor.cpp

Lowering ~x | (x - 1) to ~blsi(x) (#186722)

2026-03-19 20:45:56 +08:00

InstCombineAtomicRMW.cpp

[NFC][InstCombine] Fix namespace usage in InstCombine (#161902)

2025-10-04 05:28:24 -07:00

InstCombineCalls.cpp

[InstCombine] Fix crash in foldReversedIntrinsicOperands for struct-return intrinsics (#186339)

2026-03-13 10:28:21 +00:00

InstCombineCasts.cpp

[InstCombine] Fold trunc (usub.sat 1, x) to i1 -> icmp eq x, 0 (#185524)

2026-03-10 18:46:20 +00:00

InstCombineCompares.cpp

[IPO][InstCombine][Vectorize][NFCI] Drop uses of BranchInst (#186596)

2026-03-14 17:49:00 +00:00

InstCombineInternal.h

[Analysis][NFC] Drop use of BranchInst (#186374)

2026-03-13 13:42:19 +00:00

InstCombineLoadStoreAlloca.cpp

[InstCombine] RAUW for proven zero-indexed GEPs rather than cloning for a specific user (#185053)

2026-03-18 09:47:51 -05:00

InstCombineMulDivRem.cpp

InstCombine: Use SimplifyDemandedFPClass on fmul (#177490)

2026-02-10 09:49:31 +00:00

InstCombineNegator.cpp

[InstCombine] Optimize sub(sext(add(x,y)),sext(add(x,z))). (#144174)

2025-06-19 10:13:58 -07:00

InstCombinePHI.cpp

[IPO][InstCombine][Vectorize][NFCI] Drop uses of BranchInst (#186596)

2026-03-14 17:49:00 +00:00

InstCombineSelect.cpp

[InstCombine] Fix profile metadata propagation in InstCombine select folding (#179743)

2026-03-11 09:01:57 -07:00

InstCombineShifts.cpp

[InstCombine] Fix crash on large integers in visitShl (#176723)

2026-01-19 12:07:03 +01:00

InstCombineSimplifyDemanded.cpp

[InstCombine] Fix comment in SimplifyDemandedUseBits (NFC) (#187126)

2026-03-18 18:45:56 +00:00

InstCombineVectorOps.cpp

[IPO][InstCombine][Vectorize][NFCI] Drop uses of BranchInst (#186596)

2026-03-14 17:49:00 +00:00

InstructionCombining.cpp

[IR][NFCI] Remove *WithoutDebug (#187240)

2026-03-18 15:08:41 +00:00