[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

1 files changed, 4 insertions, 6 deletions

diff --git a/llvm/lib/Target/ARM/ARMFastISel.cpp b/llvm/lib/Target/ARM/ARMFastISel.cpp
index 4175b4a..3a36d46 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) {