[ARM] Define subtarget feature "reserve-r9", which is used to decide

whether register r9 should be reserved.

This change is needed because we cannot use a backend option to set
cl::opt "arm-reserve-r9" when doing LTO.

Out-of-tree projects currently using cl::opt option "-arm-reserve-r9" to
reserve r9 should make changes to add subtarget feature "reserve-r9" to
the IR.

rdar://problem/21529937

Differential Revision: http://reviews.llvm.org/D11320

llvm-svn: 242737

1 files changed, 5 insertions, 3 deletions

diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index 4f9bc372e4b..b80dc7051f1 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -109,8 +109,8 @@ protected:
   /// NoARM - True if subtarget does not support ARM mode execution.
   bool NoARM;
 
-  /// IsR9Reserved - True if R9 is a not available as general purpose register.
-  bool IsR9Reserved;
+  /// ReserveR9 - True if R9 is not available as a general purpose register.
+  bool ReserveR9;
 
   /// NoMovt - True if MOVT / MOVW pairs are not used for materialization of
   /// 32-bit imms (including global addresses).
@@ -413,7 +413,9 @@ public:
     return isThumb1Only() && isMClass();
   }
 
-  bool isR9Reserved() const { return IsR9Reserved; }
+  bool isR9Reserved() const {
+    return isTargetMachO() ? (ReserveR9 || !HasV6Ops) : ReserveR9;
+  }
 
   bool useMovt(const MachineFunction &MF) const;