func reorderGlobalConstructors(m llvm.Module) error {
ctors := m.NamedGlobal("llvm.global_ctors")
if ctors.IsNil() {
// No global constructors.
return nil
}
init := ctors.Initializer()
arraylength := init.Type().ArrayLength()
zeroindex := []uint32{0}
// The constructors are ordered within each package, but the packages
// are in reverse order. We must go backwards through the constructors,
// reassigning priorities.
ceiling, npackagectors := -1, -1
for i := arraylength - 1; i >= 0; i-- {
indices := []uint32{uint32(i)}
ctor := llvm.ConstExtractValue(init, indices)
priority := int(llvm.ConstExtractValue(ctor, zeroindex).ZExtValue())
if npackagectors == -1 {
ceiling = arraylength - (i + 1) + priority
npackagectors = priority
}
newpriority := ceiling - (npackagectors - priority)
newpriorityvalue := llvm.ConstInt(llvm.Int32Type(), uint64(newpriority), false)
ctor = llvm.ConstInsertValue(ctor, newpriorityvalue, zeroindex)
if priority == 1 {
npackagectors = -1
}
init = llvm.ConstInsertValue(init, ctor, indices)
}
ctors.SetInitializer(init)
return nil
}
