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

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index dc2fa8c1049130dae3fa76c72ab399196b86d457..5a8e8cc2f02ff4fb8e3297b5aded4379958d873c 100644 (file)
--- 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 f24415796f4ede61e1f5c4096172eb43749e3908..5ebddb596e3b04d80c7b29b34db5260d453b46a0 100644 (file)
--- 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);

diff --git a/test/CodeGen/SPARC/missinglabel.ll b/test/CodeGen/SPARC/missinglabel.ll
new file mode 100644 (file)
index 0000000..bcf384b
--- /dev/null
+++ b/test/CodeGen/SPARC/missinglabel.ll
@@ -0,0 +1,23 @@
+; RUN: llc < %s -verify-machineinstrs | FileCheck %s
+target datalayout = "E-m:e-i64:64-n32:64-S128"
+target triple = "sparc64-unknown-linux-gnu"
+
+define void @f() align 2 {
+entry:
+; CHECK: %xcc, .LBB0_1
+  %cmp = icmp eq i64 undef, 0
+  br i1 %cmp, label %targetblock, label %cond.false
+
+cond.false:
+  unreachable
+
+; CHECK: .LBB0_1: ! %targetblock
+targetblock:
+  br i1 undef, label %cond.false.i83, label %exit.i85
+
+cond.false.i83:
+  unreachable
+
+exit.i85:
+  unreachable
+}