1 files changed, 9 insertions, 2 deletions
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index b153b68..7b40868 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -667,8 +667,14 @@ bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
 }
 
 bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
   const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-  return (RealignStack && !AFI->isThumb1OnlyFunction());
+  // We can't realign the stack if:
+  // 1. Dynamic stack realignment is explicitly disabled,
+  // 2. This is a Thumb1 function (it's not useful, so we don't bother), or
+  // 3. There are VLAs in the function and the base pointer is disabled.
+  return (RealignStack && !AFI->isThumb1OnlyFunction() &&
+          (!MFI->hasVarSizedObjects() || EnableBasePointer));
 }
 
 bool ARMBaseRegisterInfo::
@@ -1890,7 +1896,8 @@ emitPrologue(MachineFunction &MF) const {
   AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
   AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
 
-  // If we need dynamic stack realignment, do it here.
+  // If we need dynamic stack realignment, do it here. Be paranoid and make
+  // sure if we also have VLAs, we have a base pointer for frame access.
   if (needsStackRealignment(MF)) {
     unsigned MaxAlign = MFI->getMaxAlignment();
     assert (!AFI->isThumb1OnlyFunction());