Don't load values out of global constants with weak
linkage: the value may be replaced with something
different at link time. (Frontends that want to
allow values to be loaded out of weak constants can
give their constants weak_odr linkage).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67407 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 4a7f4c7..10671cd 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -11215,14 +11215,15 @@
// Instcombine load (constant global) into the value loaded.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
- if (GV->isConstant() && !GV->isDeclaration())
+ if (GV->isConstant() && !GV->isDeclaration() && !GV->mayBeOverridden())
return ReplaceInstUsesWith(LI, GV->getInitializer());
// Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
- if (GV->isConstant() && !GV->isDeclaration())
+ if (GV->isConstant() && !GV->isDeclaration() &&
+ !GV->mayBeOverridden())
if (Constant *V =
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
return ReplaceInstUsesWith(LI, V);
@@ -11246,7 +11247,7 @@
// If this load comes from anywhere in a constant global, and if the global
// is all undef or zero, we know what it loads.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){
- if (GV->isConstant() && GV->hasInitializer()) {
+ if (GV->isConstant() && GV->hasInitializer() && !GV->mayBeOverridden()) {
if (GV->getInitializer()->isNullValue())
return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
else if (isa<UndefValue>(GV->getInitializer()))