Rewrite handling of 64-bit palignr intrinsics to be vector shuffles.

Stop multiplying constant by 8 accordingly in the header and change
intrinsic definition for what types we expect.

Add to existing palignr test to check that we're emitting the correct things.

llvm-svn: 101332

1 files changed, 32 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 85ab1dceba9..95c41db86e0 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -982,8 +982,38 @@ Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned BuiltinID,
     return Builder.CreateStore(Ops[1], Ops[0]);
   }
   case X86::BI__builtin_ia32_palignr: {
-    Function *F = CGM.getIntrinsic(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 9 bytes,
+    // emit a shuffle instruction.
+    if (shiftVal <= 8) {
+      const llvm::Type *IntTy = llvm::Type::getInt32Ty(VMContext);
+
+      llvm::SmallVector<llvm::Constant*, 8> Indices;
+      for (unsigned i = 0; i != 8; ++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 8 but less
+    // than 16 bytes, emit a logical right shift of the destination.
+    if (shiftVal < 16) {
+      // MMX has these as 1 x i64 vectors for some odd optimization reasons.
+      const llvm::Type *EltTy = llvm::Type::getInt64Ty(VMContext);
+      const llvm::Type *VecTy = llvm::VectorType::get(EltTy, 1);
+      
+      Ops[0] = Builder.CreateBitCast(Ops[0], VecTy, "cast");
+      Ops[1] = llvm::ConstantInt::get(VecTy, (shiftVal-8) * 8);
+      
+      // create i32 constant
+      llvm::Function *F = CGM.getIntrinsic(Intrinsic::x86_mmx_psrl_q);
+      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()));
   }
   case X86::BI__builtin_ia32_palignr128: {
     unsigned shiftVal = cast<llvm::ConstantInt>(Ops[2])->getZExtValue();