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When propagating equalities, eg replacing A with B in every basic block

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dominated by Root, check that B is available throughout the scope.  This
is obviously true (famous last words?) given the current logic, but the
check may be helpful if more complicated reasoning is added one day.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153323 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands
2012-03-23 08:45:52 +00:00
parent 01b305f94c
commit e959f7e17f
1 changed files with 3 additions and 0 deletions
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3
lib/Transforms/Scalar/GVN.cpp
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@ -2001,6 +2001,9 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, BasicBlock *Root) {
LVN = RVN; LVN = RVN;
} }
} }
assert((!isa<Instruction>(RHS) ||
DT->properlyDominates(cast<Instruction>(RHS)->getParent(), Root)) &&
"Instruction doesn't dominate scope!");
// If value numbering later deduces that an instruction in the scope is equal // If value numbering later deduces that an instruction in the scope is equal
// to 'LHS' then ensure it will be turned into 'RHS'. // to 'LHS' then ensure it will be turned into 'RHS'.