[llvm-branch-commits] [llvm-branch] r71719 - in /llvm/branches/Apple/Dib: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/2009-05-12-externweak.ll

[Bill Wendling]

Author: void
Date: Wed May 13 16:11:15 2009
New Revision: 71719

URL: http://llvm.org/viewvc/llvm-project?rev=71719&view=rev
Log:
--- Merging r71688 into '.':
U    lib/Transforms/Utils/SimplifyCFG.cpp
--- Merging r71717 into '.':
G    lib/Transforms/Utils/SimplifyCFG.cpp
--- Merging r71691 into '.':
A    test/Transforms/SimplifyCFG/2009-05-12-externweak.ll

Added:
    llvm/branches/Apple/Dib/test/Transforms/SimplifyCFG/2009-05-12-externweak.ll
      - copied unchanged from r71691, llvm/trunk/test/Transforms/SimplifyCFG/2009-05-12-externweak.ll
Modified:
    llvm/branches/Apple/Dib/lib/Transforms/Utils/SimplifyCFG.cpp

Modified: llvm/branches/Apple/Dib/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/Dib/lib/Transforms/Utils/SimplifyCFG.cpp?rev=71719&r1=71718&r2=71719&view=diff

==============================================================================
--- llvm/branches/Apple/Dib/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/branches/Apple/Dib/lib/Transforms/Utils/SimplifyCFG.cpp Wed May 13 16:11:15 2009
@@ -18,6 +18,7 @@
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Type.h"
 #include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Analysis/ConstantFolding.h"
@@ -347,6 +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
@@ -393,6 +408,15 @@
         if (!isa<AllocaInst>(I->getOperand(0)) &&
             !isa<Constant>(I->getOperand(0)))
           return false;
+        // External weak globals may have address 0, so we can't load them.
+        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