1 files changed, 26 insertions, 45 deletions

diff --git a/lib/Transforms/Utils/CtorUtils.cpp b/lib/Transforms/Utils/CtorUtils.cpp
index a359424..26875e8 100644
--- a/lib/Transforms/Utils/CtorUtils.cpp
+++ b/lib/Transforms/Utils/CtorUtils.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/BitVector.h"
 #include "llvm/Transforms/Utils/CtorUtils.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
@@ -24,41 +25,22 @@
 namespace llvm {
 
 namespace {
-/// Given a specified llvm.global_ctors list, install the
-/// specified array.
-void installGlobalCtors(GlobalVariable *GCL,
-                        const std::vector<Function *> &Ctors) {
-  // If we made a change, reassemble the initializer list.
-  Constant *CSVals[3];
-
-  StructType *StructTy =
-      cast<StructType>(GCL->getType()->getElementType()->getArrayElementType());
-
-  // Create the new init list.
-  std::vector<Constant *> CAList;
-  for (Function *F : Ctors) {
-    Type *Int32Ty = Type::getInt32Ty(GCL->getContext());
-    if (F) {
-      CSVals[0] = ConstantInt::get(Int32Ty, 65535);
-      CSVals[1] = F;
-    } else {
-      CSVals[0] = ConstantInt::get(Int32Ty, 0x7fffffff);
-      CSVals[1] = Constant::getNullValue(StructTy->getElementType(1));
-    }
-    // FIXME: Only allow the 3-field form in LLVM 4.0.
-    size_t NumElts = StructTy->getNumElements();
-    if (NumElts > 2)
-      CSVals[2] = Constant::getNullValue(StructTy->getElementType(2));
-    CAList.push_back(
-        ConstantStruct::get(StructTy, makeArrayRef(CSVals, NumElts)));
-  }
-
-  // Create the array initializer.
-  Constant *CA =
-      ConstantArray::get(ArrayType::get(StructTy, CAList.size()), CAList);
+/// Given a specified llvm.global_ctors list, remove the listed elements.
+void removeGlobalCtors(GlobalVariable *GCL, const BitVector &CtorsToRemove) {
+  // Filter out the initializer elements to remove.
+  ConstantArray *OldCA = cast<ConstantArray>(GCL->getInitializer());
+  SmallVector<Constant *, 10> CAList;
+  for (unsigned I = 0, E = OldCA->getNumOperands(); I < E; ++I)
+    if (!CtorsToRemove.test(I))
+      CAList.push_back(OldCA->getOperand(I));
+
+  // Create the new array initializer.
+  ArrayType *ATy =
+      ArrayType::get(OldCA->getType()->getElementType(), CAList.size());
+  Constant *CA = ConstantArray::get(ATy, CAList);
 
   // If we didn't change the number of elements, don't create a new GV.
-  if (CA->getType() == GCL->getInitializer()->getType()) {
+  if (CA->getType() == OldCA->getType()) {
     GCL->setInitializer(CA);
     return;
   }
@@ -82,7 +64,7 @@ void installGlobalCtors(GlobalVariable *GCL,
 
 /// Given a llvm.global_ctors list that we can understand,
 /// return a list of the functions and null terminator as a vector.
-std::vector<Function*> parseGlobalCtors(GlobalVariable *GV) {
+std::vector<Function *> parseGlobalCtors(GlobalVariable *GV) {
   if (GV->getInitializer()->isNullValue())
     return std::vector<Function *>();
   ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
@@ -147,17 +129,15 @@ bool optimizeGlobalCtorsList(Module &M,
   bool MadeChange = false;
 
   // Loop over global ctors, optimizing them when we can.
-  for (unsigned i = 0; i != Ctors.size(); ++i) {
+  unsigned NumCtors = Ctors.size();
+  BitVector CtorsToRemove(NumCtors);
+  for (unsigned i = 0; i != Ctors.size() && NumCtors > 0; ++i) {
     Function *F = Ctors[i];
     // Found a null terminator in the middle of the list, prune off the rest of
     // the list.
-    if (!F) {
-      if (i != Ctors.size() - 1) {
-        Ctors.resize(i + 1);
-        MadeChange = true;
-      }
-      break;
-    }
+    if (!F)
+      continue;
+
     DEBUG(dbgs() << "Optimizing Global Constructor: " << *F << "\n");
 
     // We cannot simplify external ctor functions.
@@ -166,9 +146,10 @@ bool optimizeGlobalCtorsList(Module &M,
 
     // If we can evaluate the ctor at compile time, do.
     if (ShouldRemove(F)) {
-      Ctors.erase(Ctors.begin() + i);
+      Ctors[i] = nullptr;
+      CtorsToRemove.set(i);
+      NumCtors--;
       MadeChange = true;
-      --i;
       continue;
     }
   }
@@ -176,7 +157,7 @@ bool optimizeGlobalCtorsList(Module &M,
   if (!MadeChange)
     return false;
 
-  installGlobalCtors(GlobalCtors, Ctors);
+  removeGlobalCtors(GlobalCtors, CtorsToRemove);
   return true;
 }