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Handle some additonal cases of external weak globals.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71717 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2009-05-13 20:55:30 +00:00
parent f3cc96e1f3
commit 556d0a0d15
1 changed files with 22 additions and 4 deletions
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26
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -348,6 +348,20 @@ static Value *GetIfCondition(BasicBlock *BB,
return 0;
}
/// findGlobalVariableBase - Recurse into a ConstantExpr to find the underlying
/// GlobalVariable, if there is one.
static GlobalVariable* findGlobalVariableBase(ConstantExpr* CE) {
if (isa<GlobalVariable>(CE))
return dyn_cast<GlobalVariable>(CE);
if (CE->getOpcode()==Instruction::GetElementPtr ||
CE->getOpcode()==Instruction::BitCast) {
if (isa<GlobalVariable>(CE->getOperand(0)))
return dyn_cast<GlobalVariable>(CE->getOperand(0));
if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(CE->getOperand(0)))
return findGlobalVariableBase(CE2);
}
return NULL;
}
/// DominatesMergePoint - If we have a merge point of an "if condition" as
/// accepted above, return true if the specified value dominates the block. We
@ -395,10 +409,14 @@ static bool DominatesMergePoint(Value *V, BasicBlock *BB,
!isa<Constant>(I->getOperand(0)))
return false;
// External weak globals may have address 0, so we can't load them.
if (GlobalVariable* GV= dyn_cast<GlobalVariable>(I->getOperand(0))) {
if (GV->hasExternalWeakLinkage())
return false;
}
GlobalVariable* GV = dyn_cast<GlobalVariable>(I->getOperand(0));
if (GV && GV->hasExternalWeakLinkage())
return false;
// The global may be buried within a ConstantExpr.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I->getOperand(0)))
GV = findGlobalVariableBase(CE);
if (GV && GV->hasExternalWeakLinkage())
return false;
// Finally, we have to check to make sure there are no instructions
// before the load in its basic block, as we are going to hoist the loop