Fix integer undefined behavior due to signed left shift overflow in LLVM.

Reviewed offline by chandlerc.

llvm-svn: 162623

2 files changed, 5 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 375bd7eb88d..aa5d140e9f6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1475,10 +1475,9 @@ static const MCExpr *LowerConstant(const Constant *CV, AsmPrinter &AP) {
       return Base;
 
     // Truncate/sext the offset to the pointer size.
-    if (TD.getPointerSizeInBits() != 64) {
-      int SExtAmount = 64-TD.getPointerSizeInBits();
-      Offset = (Offset << SExtAmount) >> SExtAmount;
-    }
+    unsigned Width = TD.getPointerSizeInBits();
+    if (Width < 64)
+      Offset = SignExtend64(Offset, Width);
 
     return MCBinaryExpr::CreateAdd(Base, MCConstantExpr::Create(Offset, Ctx),
                                    Ctx);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f4fe8927f69..3ab0b46def8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1097,10 +1097,9 @@ SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV, DebugLoc DL,
          "Cannot set target flags on target-independent globals");
 
   // Truncate (with sign-extension) the offset value to the pointer size.
-  EVT PTy = TLI.getPointerTy();
-  unsigned BitWidth = PTy.getSizeInBits();
+  unsigned BitWidth = TLI.getPointerTy().getSizeInBits();
   if (BitWidth < 64)
-    Offset = (Offset << (64 - BitWidth) >> (64 - BitWidth));
+    Offset = SignExtend64(Offset, BitWidth);
 
   const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
   if (!GVar) {