Make early if conversion dependent upon the subtarget and add
a subtarget hook to enable. Unconditionally add to the pass pipeline
for targets that might want to use it. No functional change.

llvm-svn: 209340
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index b94bd71..a6ad386 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -35,6 +35,13 @@
 #define GET_SUBTARGETINFO_CTOR
 #include "X86GenSubtargetInfo.inc"
 
+// Temporary option to control early if-conversion for x86 while adding machine
+// models.
+static cl::opt<bool>
+X86EarlyIfConv("x86-early-ifcvt", cl::Hidden,
+               cl::desc("Enable early if-conversion on X86"));
+
+
 /// ClassifyBlockAddressReference - Classify a blockaddress reference for the
 /// current subtarget according to how we should reference it in a non-pcrel
 /// context.
@@ -310,3 +317,8 @@
   CriticalPathRCs.clear();
   return PostRAScheduler && OptLevel >= CodeGenOpt::Default;
 }
+
+bool
+X86Subtarget::enableEarlyIfConversion() const override {
+  return hasCMOV() && X86EarlyIfConv;
+}