[llvm-commits] Please review: make bugpoint aware of blockaddress constant in global initializers

[Eli Friedman]

On Tue, Feb 7, 2012 at 5:21 PM, Daniel Reynaud <dreynaud at apple.com> wrote:
> Even better with the actual patch.
>
>
>
> On Feb 7, 2012, at 5:20 PM, Daniel Reynaud wrote:
>
> This is a patch for http://llvm.org/bugs/show_bug.cgi?id=11919
>
> It seems to do the trick for me. When this particular configuration (a
> global initializer references a blockaddress from a function that has been
> sent to a different module) is not encountered, it should produce the same
> initializer pattern as usual (i.e., everything in the safe module).
>
> thanks,
> daniel

+  bool globalInitUsesExternalBA(GlobalVariable* GV) {
+      if (!GV->hasInitializer())
+          return false;
+
+      Constant *I = GV->getInitializer();
+
+      // walk the values used by the initializer
+      // (and recurse into things like ConstantExpr)
+      std::vector<Constant*> Worklist;
+      Worklist.push_back(I);
+      while(!Worklist.empty()) {
+        Constant* V = Worklist.back();
+        Worklist.pop_back();
+
+        if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) {
+          Function *F = BA->getFunction();
+          if (F->isDeclaration())
+            return true;
+        }
+
+        for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i)
+          if (Constant *C = dyn_cast<Constant>(*i))
+            Worklist.push_back(C);
+      }
+
+    return false;
+  }

You need to make sure not to recurse into GlobalValues.  You also
probably want a hashtable so you don't run into bad performance
characteristics with ConstantExprs.

Also, weird indentation.


+  // Try to split the global initializers evenly
+  for (Module::global_iterator I = M->global_begin(), E = M->global_end();
+       I != E; ++I) {
+    GlobalVariable *GV = cast<GlobalVariable>(NewVMap[I]);
+    if (globalInitUsesExternalBA(I)) {
+      assert(!globalInitUsesExternalBA(GV) && "A global initializer references"
+          "functions in both the safe and the test module");

I don't see what prevents this assertion from triggering...

-Eli