From 967570f2ecdbedeae80bcc19744cf111c3e112e1 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Wed, 22 Feb 2012 01:43:47 +0000
Subject: Improve handling of blockaddresses in bugpoint when splitting a
 module.  Patch by Daniel Reynaud.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151115 91177308-0d34-0410-b5e6-96231b3b80d8
---
 tools/bugpoint/ExtractFunction.cpp | 60 ++++++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 6 deletions(-)

diff --git a/tools/bugpoint/ExtractFunction.cpp b/tools/bugpoint/ExtractFunction.cpp
index f2e61f8b5d..ac8e159711 100644
--- a/tools/bugpoint/ExtractFunction.cpp
+++ b/tools/bugpoint/ExtractFunction.cpp
@@ -47,7 +47,39 @@ namespace {
   cl::opt<bool, true>
   NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
          cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
-}
+
+  Function* globalInitUsesExternalBA(GlobalVariable* GV) {
+    if (!GV->hasInitializer())
+      return 0;
+
+    Constant *I = GV->getInitializer();
+
+    // walk the values used by the initializer
+    // (and recurse into things like ConstantExpr)
+    std::vector<Constant*> Todo;
+    std::set<Constant*> Done;
+    Todo.push_back(I);
+
+    while (!Todo.empty()) {
+      Constant* V = Todo.back();
+      Todo.pop_back();
+      Done.insert(V);
+
+      if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) {
+        Function *F = BA->getFunction();
+        if (F->isDeclaration())
+          return F;
+      }
+
+      for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i) {
+        Constant *C = dyn_cast<Constant>(*i);
+        if (C && !isa<GlobalValue>(C) && !Done.count(C))
+          Todo.push_back(C);
+      }
+    }
+    return 0;
+  }
+}  // end anonymous namespace
 
 /// deleteInstructionFromProgram - This method clones the current Program and
 /// deletes the specified instruction from the cloned module.  It then runs a
@@ -272,11 +304,6 @@ llvm::SplitFunctionsOutOfModule(Module *M,
   ValueToValueMapTy NewVMap;
   Module *New = CloneModule(M, NewVMap);
 
-  // Make sure global initializers exist only in the safe module (CBE->.so)
-  for (Module::global_iterator I = New->global_begin(), E = New->global_end();
-       I != E; ++I)
-    I->setInitializer(0);  // Delete the initializer to make it external
-
   // Remove the Test functions from the Safe module
   std::set<Function *> TestFunctions;
   for (unsigned i = 0, e = F.size(); i != e; ++i) {
@@ -295,6 +322,27 @@ llvm::SplitFunctionsOutOfModule(Module *M,
       DeleteFunctionBody(I);
   
 
+  // 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 (Function *TestFn = globalInitUsesExternalBA(I)) {
+      if (Function *SafeFn = globalInitUsesExternalBA(GV)) {
+        errs() << "*** Error: when reducing functions, encountered "
+                  "the global '";
+        WriteAsOperand(errs(), GV, false);
+        errs() << "' with an initializer that references blockaddresses "
+                  "from safe function '" << SafeFn->getName()
+               << "' and from test function '" << TestFn->getName() << "'.\n";
+        exit(1);
+      }
+      I->setInitializer(0);  // Delete the initializer to make it external
+    } else {
+      // If we keep it in the safe module, then delete it in the test module
+      GV->setInitializer(0);
+    }
+  }
+
   // Make sure that there is a global ctor/dtor array in both halves of the
   // module if they both have static ctor/dtor functions.
   SplitStaticCtorDtor("llvm.global_ctors", M, New, NewVMap);
-- 
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