1 files changed, 32 insertions, 4 deletions
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 02bf97cacb8..5d5caa2e9a7 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -807,10 +807,38 @@ Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned BuiltinID,
   }
   case X86::BI__builtin_ia32_palignr128:
   case X86::BI__builtin_ia32_palignr: {
-    Function *F = CGM.getIntrinsic(BuiltinID == X86::BI__builtin_ia32_palignr128 ?
-				   Intrinsic::x86_ssse3_palign_r_128 :
-				   Intrinsic::x86_ssse3_palign_r);
-    return Builder.CreateCall(F, &Ops[0], &Ops[0] + Ops.size());
+    unsigned shiftVal = cast<llvm::ConstantInt>(Ops[2])->getZExtValue();
+    
+    // If palignr is shifting the pair of input vectors less than 17 bytes,
+    // emit a shuffle instruction.
+    if (shiftVal <= 16) {
+      const llvm::Type *IntTy = llvm::Type::getInt32Ty(VMContext);
+
+      llvm::SmallVector<llvm::Constant*, 16> Indices;
+      for (unsigned i = 0; i != 16; ++i)
+        Indices.push_back(llvm::ConstantInt::get(IntTy, shiftVal + i));
+      
+      Value* SV = llvm::ConstantVector::get(Indices.begin(), Indices.size());
+      return Builder.CreateShuffleVector(Ops[1], Ops[0], SV, "palignr");
+    }
+    
+    // If palignr is shifting the pair of input vectors more than 16 but less
+    // than 32 bytes, emit a logical right shift of the destination.
+    if (shiftVal < 32) {
+      const llvm::Type *EltTy = llvm::Type::getInt64Ty(VMContext);
+      const llvm::Type *VecTy = llvm::VectorType::get(EltTy, 2);
+      const llvm::Type *IntTy = llvm::Type::getInt32Ty(VMContext);
+      
+      Ops[0] = Builder.CreateBitCast(Ops[0], VecTy, "cast");
+      Ops[1] = llvm::ConstantInt::get(IntTy, (shiftVal-16) * 8);
+      
+      // create i32 constant
+      llvm::Function *F = CGM.getIntrinsic(Intrinsic::x86_sse2_psrl_dq);
+      return Builder.CreateCall(F, &Ops[0], &Ops[0] + 2, "palignr");
+    }
+    
+    // If palignr is shifting the pair of vectors more than 32 bytes, emit zero.
+    return llvm::Constant::getNullValue(ConvertType(E->getType()));
   }
   }
 }