release/20.x: [AArch64] Handle XAR with v1i64 operand types (#141754)

[nikic]

Backport of 32837f3.

[llvmbot]

@llvm/pr-subscribers-backend-aarch64

Author: Nikita Popov (nikic)

Changes

Backport of 32837f3.

---

Full diff: https://github.com/llvm/llvm-project/pull/143163.diff

2 Files Affected:

• (modified) llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp (+23-1)
• (modified) llvm/test/CodeGen/AArch64/xar.ll (+20)

diff --git a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
index 1387a224fa660..0aad7665f6216 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -4608,9 +4608,31 @@ bool AArch64DAGToDAGISel::trySelectXAR(SDNode *N) {
   if (ShAmt + HsAmt != 64)
     return false;
 
+  // If the input is a v1i64, widen to a v2i64 to use XAR.
+  assert((VT == MVT::v1i64 || VT == MVT::v2i64) && "Unexpected XAR type!");
+  if (VT == MVT::v1i64) {
+    EVT SVT = MVT::v2i64;
+    SDValue Undef =
+        SDValue(CurDAG->getMachineNode(AArch64::IMPLICIT_DEF, DL, SVT), 0);
+    SDValue DSub = CurDAG->getTargetConstant(AArch64::dsub, DL, MVT::i32);
+    R1 = SDValue(CurDAG->getMachineNode(AArch64::INSERT_SUBREG, DL, SVT, Undef,
+                                        R1, DSub),
+                 0);
+    if (R2.getValueType() == MVT::v1i64)
+      R2 = SDValue(CurDAG->getMachineNode(AArch64::INSERT_SUBREG, DL, SVT,
+                                          Undef, R2, DSub),
+                   0);
+  }
+
   SDValue Ops[] = {R1, R2, Imm};
-  CurDAG->SelectNodeTo(N, AArch64::XAR, N0.getValueType(), Ops);
+  SDNode *XAR = CurDAG->getMachineNode(AArch64::XAR, DL, MVT::v2i64, Ops);
 
+  if (VT == MVT::v1i64) {
+    SDValue DSub = CurDAG->getTargetConstant(AArch64::dsub, DL, MVT::i32);
+    XAR = CurDAG->getMachineNode(AArch64::EXTRACT_SUBREG, DL, VT,
+                                 SDValue(XAR, 0), DSub);
+  }
+  ReplaceNode(N, XAR);
   return true;
 }
 
diff --git a/llvm/test/CodeGen/AArch64/xar.ll b/llvm/test/CodeGen/AArch64/xar.ll
index d050eaf6646de..5666ab35cde48 100644
--- a/llvm/test/CodeGen/AArch64/xar.ll
+++ b/llvm/test/CodeGen/AArch64/xar.ll
@@ -19,4 +19,24 @@ define <2 x i64> @xar(<2 x i64> %x, <2 x i64> %y) {
     ret <2 x i64> %b
 }
 
+define <1 x i64> @xar_v1i64(<1 x i64> %a, <1 x i64> %b) {
+; SHA3-LABEL: xar_v1i64:
+; SHA3:       // %bb.0:
+; SHA3-NEXT:    // kill: def $d0 killed $d0 def $q0
+; SHA3-NEXT:    // kill: def $d1 killed $d1 def $q1
+; SHA3-NEXT:    xar v0.2d, v0.2d, v1.2d, #63
+; SHA3-NEXT:    // kill: def $d0 killed $d0 killed $q0
+; SHA3-NEXT:    ret
+;
+; NOSHA3-LABEL: xar_v1i64:
+; NOSHA3:       // %bb.0:
+; NOSHA3-NEXT:    eor v1.8b, v0.8b, v1.8b
+; NOSHA3-NEXT:    shl d0, d1, #1
+; NOSHA3-NEXT:    usra d0, d1, #63
+; NOSHA3-NEXT:    ret
+  %v.val = xor <1 x i64> %a, %b
+  %fshl = tail call <1 x i64> @llvm.fshl.v1i64(<1 x i64> %v.val, <1 x i64> %v.val, <1 x i64> splat (i64 1))
+  ret <1 x i64> %fshl
+}
+
 declare <2 x i64> @llvm.fshl.v2i64(<2 x i64>, <2 x i64>, <2 x i64>)

[davemgreen]

LGTM. If you wanted something super-safe for a backport, it could just do if (VT == v1i64) return false;, but either way this looks OK to me.

[tstellar]

Merged: 22a3e6b