move isOnlyReachableByFallthrough out of MachineBasicBlock into AsmPrinter,
and add a sparc implementation that knows about delay slots. Patch by
Nathan Keynes!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96492 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp b/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
index 9a2ce6b..ecb8b00 100644
--- a/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
+++ b/lib/Target/Sparc/AsmPrinter/SparcAsmPrinter.cpp
@@ -56,6 +56,9 @@
unsigned AsmVariant, const char *ExtraCode);
bool printGetPCX(const MachineInstr *MI, unsigned OpNo);
+
+ virtual bool isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB)
+ const;
};
} // end of anonymous namespace
@@ -197,6 +200,38 @@
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.
+/// Override AsmPrinter 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)->getDesc().isTerminator() )
+ ; /* Noop */
+ return I == Pred->end() || !I->getDesc().isBarrier();
+}
+
+
+
// Force static initialization.
extern "C" void LLVMInitializeSparcAsmPrinter() {
RegisterAsmPrinter<SparcAsmPrinter> X(TheSparcTarget);