[AArch64] Don't force MVT::Untyped when selecting LD1LANEpost.

The result is either an Untyped reg sequence, on ldN with N > 1, or
just the type of the input vector, on ld1.  Don't force Untyped.
Instead, just use the type of the reg sequence.

This mirrors the behavior of createTuple, which feeds the LD1*_POST.

The narrow code path wasn't actually covered by tests, because V64
insert_vector_elt are widened to V128 before the LD1LANEpost combine
has the chance to run, usually.

The only case where it does run on V64 vectors is if the vector ops
legalizer ran.  So, tickle the code with a ctpop.

Fixes PR23265.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235243 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
index f75700d..610e7cf 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ b/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -1234,7 +1234,7 @@ SDNode *AArch64DAGToDAGISel::SelectPostLoadLane(SDNode *N, unsigned NumVecs,
   SDValue RegSeq = createQTuple(Regs);
 
   const EVT ResTys[] = {MVT::i64, // Type of the write back register
-                        MVT::Untyped, MVT::Other};
+                        RegSeq->getValueType(0), MVT::Other};
 
   unsigned LaneNo =
       cast<ConstantSDNode>(N->getOperand(NumVecs + 1))->getZExtValue();

diff --git a/test/CodeGen/AArch64/arm64-indexed-vector-ldst.ll b/test/CodeGen/AArch64/arm64-indexed-vector-ldst.ll
index 3cfbb14..ba31513 100644 (file)
--- a/test/CodeGen/AArch64/arm64-indexed-vector-ldst.ll
+++ b/test/CodeGen/AArch64/arm64-indexed-vector-ldst.ll
@@ -6193,3 +6193,25 @@ define <4 x float> @test_v4f32_post_reg_ld1lane_dep_vec_on_load(float* %bar, flo
   store float* %tmp3, float** %ptr
   ret <4 x float> %tmp2
 }
+
+; Make sure that we test the narrow V64 code path.
+; The tests above don't, because there, 64-bit insert_vector_elt nodes will be
+; widened to 128-bit before the LD1LANEpost combine has the chance to run,
+; making it avoid narrow vector types.
+; One way to trick that combine into running early is to force the vector ops
+; legalizer to run.  We achieve that using the ctpop.
+; PR23265
+define <4 x i16> @test_v4i16_post_reg_ld1lane_forced_narrow(i16* %bar, i16** %ptr, i64 %inc, <4 x i16> %A, <2 x i32>* %d) {
+; CHECK-LABEL: test_v4i16_post_reg_ld1lane_forced_narrow:
+; CHECK: ld1.h  { v0 }[1], [x0], x{{[0-9]+}}
+  %tmp1 = load i16, i16* %bar
+  %tmp2 = insertelement <4 x i16> %A, i16 %tmp1, i32 1
+  %tmp3 = getelementptr i16, i16* %bar, i64 %inc
+  store i16* %tmp3, i16** %ptr
+  %dl =  load <2 x i32>,  <2 x i32>* %d
+  %dr = call <2 x i32> @llvm.ctpop.v2i32(<2 x i32> %dl)
+  store <2 x i32> %dr, <2 x i32>* %d
+  ret <4 x i16> %tmp2
+}
+
+declare <2 x i32> @llvm.ctpop.v2i32(<2 x i32>)