From 8ead88dca1a54f3d36d1f484cc35600180abfa04 Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Tue, 19 Apr 2016 22:25:02 +0000
Subject: [PATCH] ARM: fix assertion failure on -O0 cmpxchg.

Because lowering of CMP_SWAP_64 occurs during type legalization, there can be
i64 types produced by more than just a BUILD_PAIR or similar. My initial tests
used just incoming function args.

llvm-svn: 266828
---
 lib/Target/ARM/ARMISelLowering.cpp | 16 +++++++++-------
 test/CodeGen/ARM/cmpxchg-O0.ll     | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index f240dca1b07..febe58b8fa7 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -6971,13 +6971,17 @@ static void ReplaceREADCYCLECOUNTER(SDNode *N,
   Results.push_back(Cycles32.getValue(1));
 }
 
-static SDValue createGPRPairNode(SelectionDAG &DAG, SDValue V0, SDValue V1) {
-  SDLoc dl(V0.getNode());
+static SDValue createGPRPairNode(SelectionDAG &DAG, SDValue V) {
+  SDLoc dl(V.getNode());
+  SDValue VLo = DAG.getAnyExtOrTrunc(V, dl, MVT::i32);
+  SDValue VHi = DAG.getAnyExtOrTrunc(
+      DAG.getNode(ISD::SRL, dl, MVT::i64, V, DAG.getConstant(32, dl, MVT::i32)),
+      dl, MVT::i32);
   SDValue RegClass =
       DAG.getTargetConstant(ARM::GPRPairRegClassID, dl, MVT::i32);
   SDValue SubReg0 = DAG.getTargetConstant(ARM::gsub_0, dl, MVT::i32);
   SDValue SubReg1 = DAG.getTargetConstant(ARM::gsub_1, dl, MVT::i32);
-  const SDValue Ops[] = { RegClass, V0, SubReg0, V1, SubReg1 };
+  const SDValue Ops[] = { RegClass, VLo, SubReg0, VHi, SubReg1 };
   return SDValue(
       DAG.getMachineNode(TargetOpcode::REG_SEQUENCE, dl, MVT::Untyped, Ops), 0);
 }
@@ -6988,10 +6992,8 @@ static void ReplaceCMP_SWAP_64Results(SDNode *N,
   assert(N->getValueType(0) == MVT::i64 &&
          "AtomicCmpSwap on types less than 64 should be legal");
   SDValue Ops[] = {N->getOperand(1),
-                   createGPRPairNode(DAG, N->getOperand(2)->getOperand(0),
-                                     N->getOperand(2)->getOperand(1)),
-                   createGPRPairNode(DAG, N->getOperand(3)->getOperand(0),
-                                     N->getOperand(3)->getOperand(1)),
+                   createGPRPairNode(DAG, N->getOperand(2)),
+                   createGPRPairNode(DAG, N->getOperand(3)),
                    N->getOperand(0)};
   SDNode *CmpSwap = DAG.getMachineNode(
       ARM::CMP_SWAP_64, SDLoc(N),
diff --git a/test/CodeGen/ARM/cmpxchg-O0.ll b/test/CodeGen/ARM/cmpxchg-O0.ll
index 0bf22b05a76..c29050ed680 100644
--- a/test/CodeGen/ARM/cmpxchg-O0.ll
+++ b/test/CodeGen/ARM/cmpxchg-O0.ll
@@ -79,3 +79,24 @@ define { i64, i1 } @test_cmpxchg_64(i64* %addr, i64 %desired, i64 %new) nounwind
   %res = cmpxchg i64* %addr, i64 %desired, i64 %new seq_cst monotonic
   ret { i64, i1 } %res
 }
+
+define { i64, i1 } @test_nontrivial_args(i64* %addr, i64 %desired, i64 %new) {
+; CHECK-LABEL: test_nontrivial_args:
+; CHECK:     dmb ish
+; CHECK-NOT: uxt
+; CHECK: [[RETRY:.LBB[0-9]+_[0-9]+]]:
+; CHECK:     ldrexd [[OLDLO:r[0-9]+]], [[OLDHI:r[0-9]+]], [r0]
+; CHECK:     cmp [[OLDLO]], {{r[0-9]+}}
+; CHECK:     sbcs{{(\.w)?}} [[STATUS:r[0-9]+]], [[OLDHI]], {{r[0-9]+}}
+; CHECK:     bne [[DONE:.LBB[0-9]+_[0-9]+]]
+; CHECK:     strexd [[STATUS]], {{r[0-9]+}}, {{r[0-9]+}}, [r0]
+; CHECK:     cmp{{(\.w)?}} [[STATUS]], #0
+; CHECK:     bne [[RETRY]]
+; CHECK: [[DONE]]:
+; CHECK:     dmb ish
+
+  %desired1 = add i64 %desired, 1
+  %new1 = add i64 %new, 1
+  %res = cmpxchg i64* %addr, i64 %desired1, i64 %new1 seq_cst seq_cst
+  ret { i64, i1 } %res
+}