Just because a GlobalVariable's initializer is [N x { i32, void ()* }] doesn't

mean that it has to be ConstantArray of ConstantStruct. We might have
ConstantAggregateZero, at either level, so don't crash on that.

Also, semi-deprecate the sentinal value. The linker isn't aware of sentinals so
we end up with the two lists appended, each with their "sentinals" on them.
Different parts of LLVM treated sentinals differently, so make them all just
ignore the single entry and continue on with the rest of the list.

llvm-svn: 129307

3 files changed, 20 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/ELFWriter.cpp b/llvm/lib/CodeGen/ELFWriter.cpp
index 25c2e02599e..b321a15addd 100644
--- a/llvm/lib/CodeGen/ELFWriter.cpp
+++ b/llvm/lib/CodeGen/ELFWriter.cpp
@@ -662,12 +662,16 @@ bool ELFWriter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
 void ELFWriter::EmitXXStructorList(Constant *List, ELFSection &Xtor) {
   // Should be an array of '{ i32, void ()* }' structs.  The first value is the
   // init priority, which we ignore.
+  if (List->isNullValue()) return;
   ConstantArray *InitList = cast<ConstantArray>(List);
   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
+    if (InitList->getOperand(i)->isNullValue())
+      continue;
     ConstantStruct *CS = cast<ConstantStruct>(InitList->getOperand(i));
 
     if (CS->getOperand(1)->isNullValue())
-      return;  // Found a null terminator, exit printing.
+      continue;
+
     // Emit the function pointer.
     EmitGlobalConstant(CS->getOperand(1), Xtor);
   }
diff --git a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
index 13e07acc151..6d767be492b 100644
--- a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -313,13 +313,17 @@ void ExecutionEngine::runStaticConstructorsDestructors(Module *module,
 
   // Should be an array of '{ i32, void ()* }' structs.  The first value is
   // the init priority, which we ignore.
+  if (isa<ConstantAggregateZero>(GV->getInitializer()))
+    return;
   ConstantArray *InitList = cast<ConstantArray>(GV->getInitializer());
   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
+    if (isa<ConstantAggregateZero>(InitList->getOperand(i)))
+      continue;
     ConstantStruct *CS = cast<ConstantStruct>(InitList->getOperand(i));
 
     Constant *FP = CS->getOperand(1);
     if (FP->isNullValue())
-      break;  // Found a null terminator, exit.
+      continue;  // Found a sentinal value, ignore.
 
     // Strip off constant expression casts.
     if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index ca4ea5c5857..ded58aca75f 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1954,14 +1954,15 @@ GlobalVariable *GlobalOpt::FindGlobalCtors(Module &M) {
   // Verify that the initializer is simple enough for us to handle. We are
   // only allowed to optimize the initializer if it is unique.
   if (!GV->hasUniqueInitializer()) return 0;
-  
-  ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
-  if (!CA) return 0;
 
-  for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
-    ConstantStruct *CS = dyn_cast<ConstantStruct>(*i);
-    if (!CS) return 0;
+  if (isa<ConstantAggregateZero>(GV->getInitializer()))
+    return GV;
+  ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
 
+  for (User::op_iterator i = CA->op_begin(), e = CA->op_end(); i != e; ++i) {
+    if (isa<ConstantAggregateZero>(*i))
+      continue;
+    ConstantStruct *CS = cast<ConstantStruct>(*i);
     if (isa<ConstantPointerNull>(CS->getOperand(1)))
       continue;
 
@@ -1981,6 +1982,8 @@ GlobalVariable *GlobalOpt::FindGlobalCtors(Module &M) {
 /// ParseGlobalCtors - Given a llvm.global_ctors list that we can understand,
 /// return a list of the functions and null terminator as a vector.
 static std::vector<Function*> ParseGlobalCtors(GlobalVariable *GV) {
+  if (GV->getInitializer()->isNullValue())
+    return std::vector<Function*>();
   ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
   std::vector<Function*> Result;
   Result.reserve(CA->getNumOperands());
@@ -2011,7 +2014,7 @@ static GlobalVariable *InstallGlobalCtors(GlobalVariable *GCL,
       const PointerType *PFTy = PointerType::getUnqual(FTy);
       CSVals[1] = Constant::getNullValue(PFTy);
       CSVals[0] = ConstantInt::get(Type::getInt32Ty(GCL->getContext()),
-                                   2147483647);
+                                   0x7fffffff);
     }
     CAList.push_back(ConstantStruct::get(GCL->getContext(), CSVals, false));
   }