[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, 3 insertions, 10 deletions

diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 3180480..9d2f029 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -40,10 +40,6 @@ using namespace llvm;
 #include "ARMGenSubtargetInfo.inc"
 
 static cl::opt<bool>
-ReserveR9("arm-reserve-r9", cl::Hidden,
-          cl::desc("Reserve R9, making it unavailable as GPR"));
-
-static cl::opt<bool>
 UseFusedMulOps("arm-use-mulops",
                cl::init(true), cl::Hidden);
 
@@ -144,7 +140,7 @@ void ARMSubtarget::initializeEnvironment() {
   UseSoftFloat = false;
   HasThumb2 = false;
   NoARM = false;
-  IsR9Reserved = ReserveR9;
+  ReserveR9 = false;
   NoMovt = false;
   SupportsTailCall = false;
   HasFP16 = false;
@@ -212,13 +208,10 @@ void ARMSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
   if (isTargetNaCl())
     stackAlignment = 16;
 
-  if (isTargetMachO()) {
-    IsR9Reserved = ReserveR9 || !HasV6Ops;
+  if (isTargetMachO())
     SupportsTailCall = !isTargetIOS() || !getTargetTriple().isOSVersionLT(5, 0);
-  } else {
-    IsR9Reserved = ReserveR9;
+  else
     SupportsTailCall = !isThumb1Only();
-  }
 
   if (Align == DefaultAlign) {
     // Assume pre-ARMv6 doesn't support unaligned accesses.