[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

3 files changed, 12 insertions, 13 deletions

diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index 1dafff60921..cea97b5fa53 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -154,6 +154,10 @@ def FeatureLongCalls : SubtargetFeature<"long-calls", "GenLongCalls", "true",
                                         "Generate calls via indirect call "
                                         "instructions">;
 
+def FeatureReserveR9 : SubtargetFeature<"reserve-r9", "ReserveR9", "true",
+                                        "Reserve R9, making it unavailable as "
+                                        "GPR">;
+
 def FeatureNoMovt : SubtargetFeature<"no-movt", "NoMovt", "true",
                                      "Don't use movt/movw pairs for 32-bit "
                                      "imms">;
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 3180480986d..9d2f0291076 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.
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;