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| author | Philip Reames <listmail@philipreames.com> | 2021-04-05 19:21:38 -0700 |
|---|---|---|
| committer | Philip Reames <listmail@philipreames.com> | 2021-04-05 19:22:36 -0700 |
| commit | 13deb6aac723e5694d404f21ee136e9773eb27a6 (patch) | |
| tree | 8121f759f8d8c389dd2fe8aae087fbf5b833c463 /llvm/lib/Analysis/ValueTracking.cpp | |
| parent | 812ce7f9beb2b828032ddbd01d3aba4c1f9d76da (diff) | |
| download | llvm-13deb6aac723e5694d404f21ee136e9773eb27a6.zip llvm-13deb6aac723e5694d404f21ee136e9773eb27a6.tar.gz llvm-13deb6aac723e5694d404f21ee136e9773eb27a6.tar.bz2 | |
Exact ashr/lshr don't loose any set bits and are thus trivially invertible
Use that fact to improve isKnownNonEqual.
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 93c628b..4732a1f 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -2588,6 +2588,17 @@ static Optional<unsigned> getInvertibleOperand(const Operator *Op1, return 0; break; } + case Instruction::AShr: + case Instruction::LShr: { + auto *PEO1 = cast<PossiblyExactOperator>(Op1); + auto *PEO2 = cast<PossiblyExactOperator>(Op2); + if (!PEO1->isExact() || !PEO2->isExact()) + break; + + if (Op1->getOperand(1) == Op2->getOperand(1)) + return 0; + break; + } case Instruction::SExt: case Instruction::ZExt: if (Op1->getOperand(0)->getType() == Op2->getOperand(0)->getType()) |