Handle some additonal cases of external weak globals.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71717 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 4834591..79b92ea 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -348,6 +348,20 @@
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 @@
!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