llvm/InstCombine at cb7b458c96a9b880cfaa55d6e9b53733ea966b51 - llvm

RPCS3/llvm

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History

Roman Lebedev ebc98fa7a0 [InstCombine] foldUnsignedUnderflowCheck(): handle last few cases (PR43251)

Summary:
I don't have a direct motivational case for this,
but it would be good to have this for completeness/symmetry.

This pattern is basically the motivational pattern from
https://bugs.llvm.org/show_bug.cgi?id=43251
but with different predicate that requires that the offset is non-zero.

The completeness bit comes from the fact that a similar pattern (offset != zero)
will be needed for https://bugs.llvm.org/show_bug.cgi?id=43259,
so it'd seem to be good to not overlook very similar patterns..

Proofs: https://rise4fun.com/Alive/21b

Also, there is something odd with `isKnownNonZero()`, if the non-zero
knowledge was specified as an assumption, it didn't pick it up (PR43267)

With this, i see no other missing folds for
https://bugs.llvm.org/show_bug.cgi?id=43251

Reviewers: spatel, nikic, xbolva00

Reviewed By: spatel

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67412

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372257 91177308-0d34-0410-b5e6-96231b3b80d8

2019-09-18 20:10:07 +00:00

CMakeLists.txt

[InstCombine] Optimize atomicrmw <op>, 0 into load atomic when possible

2019-02-07 21:27:23 +00:00

InstCombineAddSub.cpp

[InstCombine] sub(xor(x, y), or(x, y)) -> neg(and(x, y))

2019-09-04 18:03:21 +00:00

InstCombineAndOrXor.cpp

[InstCombine] foldUnsignedUnderflowCheck(): handle last few cases (PR43251)

2019-09-18 20:10:07 +00:00

InstCombineAtomicRMW.cpp

[InstCombine] Extend saturating idempotent atomicrmw transform to FP