[llvm-commits] [llvm] r98550 - /llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp

[Chris Lattner]

Author: lattner
Date: Mon Mar 15 11:37:42 2010
New Revision: 98550

URL: http://llvm.org/viewvc/llvm-project?rev=98550&view=rev
Log:
don't eliminate address-taken blocks here.

Modified:
    llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp

Modified: llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp?rev=98550&r1=98549&r2=98550&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp (original)
+++ llvm/trunk/lib/CodeGen/UnreachableBlockElim.cpp Mon Mar 15 11:37:42 2010
@@ -58,13 +58,25 @@
   return new UnreachableBlockElim();
 }
 
+static void MarkReachableFrom(BasicBlock *BB, 
+                              SmallPtrSet<BasicBlock*, 8> &Reachable) {
+  for (df_ext_iterator<BasicBlock*, SmallPtrSet<BasicBlock*, 8> > I =
+       df_ext_begin(BB, Reachable), E = df_ext_end(BB, Reachable); I != E; ++I)
+    ; // Mark all reachable blocks.
+}
+
 bool UnreachableBlockElim::runOnFunction(Function &F) {
   SmallPtrSet<BasicBlock*, 8> Reachable;
 
   // Mark all reachable blocks.
-  for (df_ext_iterator<Function*, SmallPtrSet<BasicBlock*, 8> > I =
-       df_ext_begin(&F, Reachable), E = df_ext_end(&F, Reachable); I != E; ++I)
-    /* Mark all reachable blocks */;
+  MarkReachableFrom(&F.getEntryBlock(), Reachable);
+  
+  // Mark any address-taken blocks.  We don't want codegen to delete these
+  // because the address may already be referenced by another function and the
+  // label may be referenced.
+  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+    if (I->hasAddressTaken() && !Reachable.count(I))
+      MarkReachableFrom(I, Reachable);
 
   // Loop over all dead blocks, remembering them and deleting all instructions
   // in them.