Add support for fast isel of zext.

llvm-svn: 55396

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index b0369b32e0a..99ffc3f7817 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -330,6 +330,35 @@ FastISel::SelectInstructions(BasicBlock::iterator Begin,
         // or attempt constant folding.
         return I;
 
+    case Instruction::ZExt:
+      if (!isa<ConstantInt>(I->getOperand(0))) {
+        MVT SrcVT = MVT::getMVT(I->getOperand(0)->getType());
+        MVT DstVT = MVT::getMVT(I->getType());
+        
+        if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
+            DstVT == MVT::Other || !DstVT.isSimple() ||
+            !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
+          // Unhandled type. Halt "fast" selection and bail.
+          return I;
+        
+        unsigned InputReg = ValueMap[I->getOperand(0)];
+        if (!InputReg)
+          // Unhandled operand.  Halt "fast" selection and bail.
+          return I;
+        
+        unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(),
+                                        DstVT.getSimpleVT(),
+                                        ISD::ZERO_EXTEND,
+                                        InputReg);
+        if (!ResultReg)
+          return I;
+        
+        ValueMap[I] = ResultReg;
+        break;
+      } else
+        // TODO: Support constant operands
+        return I;
+
     case Instruction::SIToFP:
       if (!isa<ConstantInt>(I->getOperand(0))) {
         MVT SrcVT = MVT::getMVT(I->getOperand(0)->getType());