[llvm-commits] [llvm] r71717 - /llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp

[Dale Johannesen]

Author: johannes
Date: Wed May 13 15:55:30 2009
New Revision: 71717

URL: http://llvm.org/viewvc/llvm-project?rev=71717&view=rev
Log:
Handle some additonal cases of external weak globals.


Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=71717&r1=71716&r2=71717&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Wed May 13 15:55:30 2009
@@ -348,6 +348,20 @@
   return 0;
 }
 
+/// findGlobalVariableBase - Recurse into a ConstantExpr to find the underlying
+/// GlobalVariable, if there is one.
+static GlobalVariable* findGlobalVariableBase(ConstantExpr* CE) {
+  if (isa<GlobalVariable>(CE))
+    return dyn_cast<GlobalVariable>(CE);
+  if (CE->getOpcode()==Instruction::GetElementPtr ||
+      CE->getOpcode()==Instruction::BitCast) {
+    if (isa<GlobalVariable>(CE->getOperand(0)))
+      return dyn_cast<GlobalVariable>(CE->getOperand(0));
+    if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(CE->getOperand(0)))
+      return findGlobalVariableBase(CE2);
+  }
+  return NULL;
+}
 
 /// DominatesMergePoint - If we have a merge point of an "if condition" as
 /// accepted above, return true if the specified value dominates the block.  We
@@ -395,10 +409,14 @@
             !isa<Constant>(I->getOperand(0)))
           return false;
         // External weak globals may have address 0, so we can't load them.
-        if (GlobalVariable* GV= dyn_cast<GlobalVariable>(I->getOperand(0))) {
-          if (GV->hasExternalWeakLinkage())
-            return false;
-        }
+        GlobalVariable* GV = dyn_cast<GlobalVariable>(I->getOperand(0));
+        if (GV && GV->hasExternalWeakLinkage())
+          return false;
+        // The global may be buried within a ConstantExpr.
+        if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I->getOperand(0)))
+          GV = findGlobalVariableBase(CE);
+        if (GV && GV->hasExternalWeakLinkage())
+          return false;
 
         // Finally, we have to check to make sure there are no instructions
         // before the load in its basic block, as we are going to hoist the loop