Clean up ARM tail calls a bit. They're pseudo-instructions for normal branches.

Also more cleanly separate the ARM vs. Thumb functionality. Previously, the
encoding would be incorrect for some Thumb instructions (the indirect calls).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127637 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 43 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMAsmPrinter.cpp b/lib/Target/ARM/ARMAsmPrinter.cpp
index 4c9ab3c..784a661 100644
--- a/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -1707,6 +1707,49 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     }
     return;
   }
+  // Tail jump branches are really just branch instructions with additional
+  // code-gen attributes. Convert them to the cannonical form here.
+  case ARM::TAILJMPd:
+  case ARM::TAILJMPdND: {
+    MCInst TmpInst, TmpInst2;
+    // Lower the instruction as-is to get the operands properly converted.
+    LowerARMMachineInstrToMCInst(MI, TmpInst2, *this);
+    TmpInst.setOpcode(ARM::Bcc);
+    TmpInst.addOperand(TmpInst2.getOperand(0));
+    // Add predicate operands.
+    TmpInst.addOperand(MCOperand::CreateImm(ARMCC::AL));
+    TmpInst.addOperand(MCOperand::CreateReg(0));
+    OutStreamer.AddComment("TAILCALL");
+    OutStreamer.EmitInstruction(TmpInst);
+    return;
+  }
+  case ARM::tTAILJMPd:
+  case ARM::tTAILJMPdND: {
+    MCInst TmpInst, TmpInst2;
+    LowerARMMachineInstrToMCInst(MI, TmpInst2, *this);
+    TmpInst.setOpcode(ARM::tB);
+    TmpInst.addOperand(TmpInst2.getOperand(0));
+    OutStreamer.AddComment("TAILCALL");
+    OutStreamer.EmitInstruction(TmpInst);
+    return;
+  }
+  case ARM::TAILJMPrND:
+  case ARM::tTAILJMPrND:
+  case ARM::TAILJMPr:
+  case ARM::tTAILJMPr: {
+    unsigned newOpc = (Opc == ARM::TAILJMPr || Opc == ARM::TAILJMPrND)
+      ? ARM::BX : ARM::tBX;
+    MCInst TmpInst;
+    TmpInst.setOpcode(newOpc);
+    TmpInst.addOperand(MCOperand::CreateReg(MI->getOperand(0).getReg()));
+    // Predicate.
+    TmpInst.addOperand(MCOperand::CreateImm(ARMCC::AL));
+    TmpInst.addOperand(MCOperand::CreateReg(0));
+    OutStreamer.AddComment("TAILCALL");
+    OutStreamer.EmitInstruction(TmpInst);
+    return;
+  }
+
   // These are the pseudos created to comply with stricter operand restrictions
   // on ARMv5. Lower them now to "normal" instructions, since all the
   // restrictions are already satisfied.