3 files changed, 19 insertions, 3 deletions
diff --git a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
index 429c2a582bb..382dc44ad03 100644
--- a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -1647,6 +1647,9 @@ ARMConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
   if (!isThumb1)
     llvm_unreachable("fixupUnconditionalBr is Thumb1 only!");
 
+  if (!AFI->isLRSpilled())
+    report_fatal_error("underestimated function size");
+
   // Use BL to implement far jump.
   Br.MaxDisp = (1 << 21) * 2;
   MI->setDesc(TII->get(ARM::tBfar));
diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index cee6f867526..0e5740f55ea 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -29,6 +29,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -1475,13 +1476,17 @@ bool ARMFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
 }
 
 // FIXME: Make generic?
-static unsigned GetFunctionSizeInBytes(const MachineFunction &MF,
-                                       const ARMBaseInstrInfo &TII) {
+static unsigned EstimateFunctionSizeInBytes(const MachineFunction &MF,
+                                            const ARMBaseInstrInfo &TII) {
   unsigned FnSize = 0;
   for (auto &MBB : MF) {
     for (auto &MI : MBB)
       FnSize += TII.getInstSizeInBytes(MI);
   }
+  if (MF.getJumpTableInfo())
+    for (auto &Table: MF.getJumpTableInfo()->getJumpTables())
+      FnSize += Table.MBBs.size() * 4;
+  FnSize += MF.getConstantPool()->getConstants().size() * 4;
   return FnSize;
 }
 
@@ -1725,7 +1730,7 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
 
   bool ForceLRSpill = false;
   if (!LRSpilled && AFI->isThumb1OnlyFunction()) {
-    unsigned FnSize = GetFunctionSizeInBytes(MF, TII);
+    unsigned FnSize = EstimateFunctionSizeInBytes(MF, TII);
     // Force LR to be spilled if the Thumb function size is > 2048. This enables
     // use of BL to implement far jump. If it turns out that it's not needed
     // then the branch fix up path will undo it.
@@ -2027,6 +2032,7 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
     SavedRegs.set(ARM::LR);
     AFI->setLRIsSpilledForFarJump(true);
   }
+  AFI->setLRIsSpilled(SavedRegs.test(ARM::LR));
 }
 
 MachineBasicBlock::iterator ARMFrameLowering::eliminateCallFramePseudoInstr(
diff --git a/llvm/lib/Target/ARM/ARMMachineFunctionInfo.h b/llvm/lib/Target/ARM/ARMMachineFunctionInfo.h
index cad6e8e3825..f96124e10f3 100644
--- a/llvm/lib/Target/ARM/ARMMachineFunctionInfo.h
+++ b/llvm/lib/Target/ARM/ARMMachineFunctionInfo.h
@@ -61,6 +61,10 @@ class ARMFunctionInfo : public MachineFunctionInfo {
   /// enable far jump.
   bool LRSpilledForFarJump = false;
 
+  /// LRSpilled - True if the LR register has been for spilled for
+  /// any reason, so it's legal to emit an ARM::tBfar (i.e. "bl").
+  bool LRSpilled = false;
+
   /// FramePtrSpillOffset - If HasStackFrame, this records the frame pointer
   /// spill stack offset.
   unsigned FramePtrSpillOffset = 0;
@@ -150,6 +154,9 @@ public:
   bool shouldRestoreSPFromFP() const { return RestoreSPFromFP; }
   void setShouldRestoreSPFromFP(bool s) { RestoreSPFromFP = s; }
 
+  bool isLRSpilled() const { return LRSpilled; }
+  void setLRIsSpilled(bool s) { LRSpilled = s; }
+
   bool isLRSpilledForFarJump() const { return LRSpilledForFarJump; }
   void setLRIsSpilledForFarJump(bool s) { LRSpilledForFarJump = s; }