Handle bundled terminators in isBlockOnlyReachableByFallthrough.

Targets like SPARC and MIPS have delay slots and normally bundle the
delay slot instruction with the corresponding terminator.

Teach isBlockOnlyReachableByFallthrough to find any MBB operands on
bundled terminators so SPARC doesn't need to specialize this function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199061 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 42 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index dc2fa8c104..5a8e8cc2f0 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -22,6 +22,7 @@
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBundle.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
@@ -2216,14 +2217,13 @@ isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
     if (!MI.isBranch() || MI.isIndirectBranch())
       return false;
 
-    // If we are the operands of one of the branches, this is not
-    // a fall through.
-    for (MachineInstr::mop_iterator OI = MI.operands_begin(),
-           OE = MI.operands_end(); OI != OE; ++OI) {
-      const MachineOperand& OP = *OI;
-      if (OP.isJTI())
+    // If we are the operands of one of the branches, this is not a fall
+    // through. Note that targets with delay slots will usually bundle
+    // terminators with the delay slot instruction.
+    for (ConstMIBundleOperands OP(&MI); OP.isValid(); ++OP) {
+      if (OP->isJTI())
         return false;
-      if (OP.isMBB() && OP.getMBB() == MBB)
+      if (OP->isMBB() && OP->getMBB() == MBB)
         return false;
     }
   }
diff --git a/lib/Target/Sparc/SparcAsmPrinter.cpp b/lib/Target/Sparc/SparcAsmPrinter.cpp
index f24415796f..5ebddb596e 100644
--- a/lib/Target/Sparc/SparcAsmPrinter.cpp
+++ b/lib/Target/Sparc/SparcAsmPrinter.cpp
@@ -65,10 +65,6 @@ namespace {
     bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                                unsigned AsmVariant, const char *ExtraCode,
                                raw_ostream &O);
-
-    virtual bool isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB)
-                       const;
-
   };
 } // end of anonymous namespace
 
@@ -391,37 +387,6 @@ bool SparcAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
   return false;
 }
 
-/// isBlockOnlyReachableByFallthough - Return true if the basic block has
-/// exactly one predecessor and the control transfer mechanism between
-/// the predecessor and this block is a fall-through.
-///
-/// This overrides AsmPrinter's implementation to handle delay slots.
-bool SparcAsmPrinter::
-isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
-  // If this is a landing pad, it isn't a fall through.  If it has no preds,
-  // then nothing falls through to it.
-  if (MBB->isLandingPad() || MBB->pred_empty())
-    return false;
-
-  // If there isn't exactly one predecessor, it can't be a fall through.
-  MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), PI2 = PI;
-  ++PI2;
-  if (PI2 != MBB->pred_end())
-    return false;
-
-  // The predecessor has to be immediately before this block.
-  const MachineBasicBlock *Pred = *PI;
-
-  if (!Pred->isLayoutSuccessor(MBB))
-    return false;
-
-  // Check if the last terminator is an unconditional branch.
-  MachineBasicBlock::const_iterator I = Pred->end();
-  while (I != Pred->begin() && !(--I)->isTerminator())
-    ; // Noop
-  return I == Pred->end() || !I->isBarrier();
-}
-
 // Force static initialization.
 extern "C" void LLVMInitializeSparcAsmPrinter() {
   RegisterAsmPrinter<SparcAsmPrinter> X(TheSparcTarget);