Fix PR7174, a couple o Mips fixes:

- Fix a typo for PIC check during jmp table lowering
- Also fix the "first jump table basic block is not
considered only reachable by fall through" problem, use this
ad-hoc solution until I come up with something better.

Patch by stetorvs@gmail.com

llvm-svn: 108820

2 files changed, 21 insertions, 1 deletions

diff --git a/llvm/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp b/llvm/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
index 8ae05b75e91..6660f6b6243 100644
--- a/llvm/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
+++ b/llvm/lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp
@@ -18,6 +18,8 @@
 #include "MipsInstrInfo.h"
 #include "MipsTargetMachine.h"
 #include "MipsMachineFunction.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Instructions.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
@@ -75,6 +77,7 @@ namespace {
     }
     virtual void EmitFunctionBodyStart();
     virtual void EmitFunctionBodyEnd();
+    virtual bool isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
     static const char *getRegisterName(unsigned RegNo);
 
     virtual void EmitFunctionEntryLabel();
@@ -227,6 +230,23 @@ void MipsAsmPrinter::EmitFunctionBodyEnd() {
 }
 
 
+/// 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.
+bool MipsAsmPrinter::isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) 
+    const {
+  // The predecessor has to be immediately before this block.
+  const MachineBasicBlock *Pred = *MBB->pred_begin();
+
+  // If the predecessor is a switch statement, assume a jump table
+  // implementation, so it is not a fall through.
+  if (const BasicBlock *bb = Pred->getBasicBlock())
+    if (isa<SwitchInst>(bb->getTerminator()))
+      return false;
+  
+  return AsmPrinter::isBlockOnlyReachableByFallthrough(MBB);
+}
+
 // Print out an operand for an inline asm expression.
 bool MipsAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo, 
                                      unsigned AsmVariant,const char *ExtraCode,
diff --git a/llvm/lib/Target/Mips/MipsISelLowering.cpp b/llvm/lib/Target/Mips/MipsISelLowering.cpp
index f67572e8041..b0b99bad160 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsISelLowering.cpp
@@ -542,7 +542,7 @@ LowerJumpTable(SDValue Op, SelectionDAG &DAG) const
 
   SDValue JTI = DAG.getTargetJumpTable(JT->getIndex(), PtrVT, OpFlag);
 
-  if (IsPIC) {
+  if (!IsPIC) {
     SDValue Ops[] = { JTI };
     HiPart = DAG.getNode(MipsISD::Hi, dl, DAG.getVTList(MVT::i32), Ops, 1);
   } else // Emit Load from Global Pointer