[ARM] Define a subtarget feature and use it to decide whether long calls should

be emitted.

This is needed to enable ARM long calls for LTO and enable and disable it on a
per-function basis.

Out-of-tree projects currently using EnableARMLongCalls to emit long calls
should start passing "+long-calls" to the feature string (see the changes made
to clang in r241565).

rdar://problem/21529937

Differential Revision: http://reviews.llvm.org/D9364

llvm-svn: 241566

5 files changed, 14 insertions, 12 deletions

diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index 96b4742da2b..ef609a66d03 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -150,6 +150,10 @@ def FeatureAClass : SubtargetFeature<"aclass", "ARMProcClass", "AClass",
 def FeatureNaClTrap : SubtargetFeature<"nacl-trap", "UseNaClTrap", "true",
                                        "NaCl trap">;
 
+def FeatureLongCalls : SubtargetFeature<"long-calls", "GenLongCalls", "true",
+                                        "Generate calls via indirect call "
+                                        "instructions">;
+
 // ARM ISAs.
 def HasV4TOps   : SubtargetFeature<"v4t", "HasV4TOps", "true",
                                    "Support ARM v4T instructions">;
diff --git a/llvm/lib/Target/ARM/ARMFastISel.cpp b/llvm/lib/Target/ARM/ARMFastISel.cpp
index 4175b4af86e..3a36d462799 100644
--- a/llvm/lib/Target/ARM/ARMFastISel.cpp
+++ b/llvm/lib/Target/ARM/ARMFastISel.cpp
@@ -49,8 +49,6 @@
 #include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
-extern cl::opt<bool> EnableARMLongCalls;
-
 namespace {
 
   // All possible address modes, plus some.
@@ -2246,19 +2244,19 @@ bool ARMFastISel::ARMEmitLibcall(const Instruction *I, RTLIB::Libcall Call) {
     return false;
 
   unsigned CalleeReg = 0;
-  if (EnableARMLongCalls) {
+  if (Subtarget->genLongCalls()) {
     CalleeReg = getLibcallReg(TLI.getLibcallName(Call));
     if (CalleeReg == 0) return false;
   }
 
   // Issue the call.
-  unsigned CallOpc = ARMSelectCallOp(EnableARMLongCalls);
+  unsigned CallOpc = ARMSelectCallOp(Subtarget->genLongCalls());
   MachineInstrBuilder MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt,
                                     DbgLoc, TII.get(CallOpc));
   // BL / BLX don't take a predicate, but tBL / tBLX do.
   if (isThumb2)
     AddDefaultPred(MIB);
-  if (EnableARMLongCalls)
+  if (Subtarget->genLongCalls())
     MIB.addReg(CalleeReg);
   else
     MIB.addExternalSymbol(TLI.getLibcallName(Call));
@@ -2380,7 +2378,7 @@ bool ARMFastISel::SelectCall(const Instruction *I,
 
   bool UseReg = false;
   const GlobalValue *GV = dyn_cast<GlobalValue>(Callee);
-  if (!GV || EnableARMLongCalls) UseReg = true;
+  if (!GV || Subtarget->genLongCalls()) UseReg = true;
 
   unsigned CalleeReg = 0;
   if (UseReg) {
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 607ce767be2..9d25e2cf182 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -60,11 +60,6 @@ STATISTIC(NumTailCalls, "Number of tail calls");
 STATISTIC(NumMovwMovt, "Number of GAs materialized with movw + movt");
 STATISTIC(NumLoopByVals, "Number of loops generated for byval arguments");
 
-cl::opt<bool>
-EnableARMLongCalls("arm-long-calls", cl::Hidden,
-  cl::desc("Generate calls via indirect call instructions"),
-  cl::init(false));
-
 static cl::opt<bool>
 ARMInterworking("arm-interworking", cl::Hidden,
   cl::desc("Enable / disable ARM interworking (for debugging only)"),
@@ -1694,7 +1689,7 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   bool isLocalARMFunc = false;
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
 
-  if (EnableARMLongCalls) {
+  if (Subtarget->genLongCalls()) {
     assert((Subtarget->isTargetWindows() ||
             getTargetMachine().getRelocationModel() == Reloc::Static) &&
            "long-calls with non-static relocation model!");
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index af18eeabf0e..fe9743d09b5 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -172,6 +172,7 @@ void ARMSubtarget::initializeEnvironment() {
   AllowsUnalignedMem = false;
   Thumb2DSP = false;
   UseNaClTrap = false;
+  GenLongCalls = false;
   UnsafeFPMath = false;
 }
 
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index 9909a6a6d19..dd101df9b63 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -206,6 +206,9 @@ protected:
   /// NaCl TRAP instruction is generated instead of the regular TRAP.
   bool UseNaClTrap;
 
+  /// Generate calls via indirect call instructions.
+  bool GenLongCalls;
+
   /// Target machine allowed unsafe FP math (such as use of NEON fp)
   bool UnsafeFPMath;
 
@@ -342,6 +345,7 @@ public:
   bool hasMPExtension() const { return HasMPExtension; }
   bool hasThumb2DSP() const { return Thumb2DSP; }
   bool useNaClTrap() const { return UseNaClTrap; }
+  bool genLongCalls() const { return GenLongCalls; }
 
   bool hasFP16() const { return HasFP16; }
   bool hasD16() const { return HasD16; }