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CodeGen: it turns out that NAND is not the same thing as BIC. At all.

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We've been performing the wrong operation on ARM for "atomicrmw nand" for
years, since "a NAND b" is "~(a & b)" rather than ARM's very tempting "a & ~b".
This bled over into the generic expansion pass.

So I assume no-one has ever actually tried to do an atomic nand in the real
world. Oh well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212443 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover
2014-07-07 09:06:35 +00:00
parent 682e019983
commit 3e16b022be
5 changed files with 13 additions and 9 deletions
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2
lib/CodeGen/AtomicExpandLoadLinkedPass.cpp
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@ -186,7 +186,7 @@ bool AtomicExpandLoadLinked::expandAtomicRMW(AtomicRMWInst *AI) {
NewVal = Builder.CreateAnd(Loaded, AI->getValOperand(), "new");
break;
case AtomicRMWInst::Nand:
NewVal = Builder.CreateAnd(Loaded, Builder.CreateNot(AI->getValOperand()),
NewVal = Builder.CreateNot(Builder.CreateAnd(Loaded, AI->getValOperand()),
"new");
break;
case AtomicRMWInst::Or: