From a5defd33eab2139cfd42a48576b25b26e26f80cf Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Thu, 7 Feb 2019 10:35:34 +0000
Subject: [PATCH] AArch64: implement copy for paired GPR registers.

When doing 128-bit atomics using CASP we might need to copy a GPRPair to a
different register, but that was unimplemented up to now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353383 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/AArch64/AArch64InstrInfo.cpp | 41 +++++++++++++++++++++++++
 lib/Target/AArch64/AArch64InstrInfo.h   |  4 +++
 test/CodeGen/AArch64/seqpaircopy.mir    | 23 ++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100644 test/CodeGen/AArch64/seqpaircopy.mir

diff --git a/lib/Target/AArch64/AArch64InstrInfo.cpp b/lib/Target/AArch64/AArch64InstrInfo.cpp
index e2018ab7578..f5d86c2e54a 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -2291,6 +2291,31 @@ void AArch64InstrInfo::copyPhysRegTuple(MachineBasicBlock &MBB,
   }
 }
 
+void AArch64InstrInfo::copyGPRRegTuple(MachineBasicBlock &MBB,
+                                       MachineBasicBlock::iterator I,
+                                       DebugLoc DL, unsigned DestReg,
+                                       unsigned SrcReg, bool KillSrc,
+                                       unsigned Opcode, unsigned ZeroReg,
+                                       llvm::ArrayRef<unsigned> Indices) const {
+  const TargetRegisterInfo *TRI = &getRegisterInfo();
+  unsigned NumRegs = Indices.size();
+
+#ifndef NDEBUG
+  uint16_t DestEncoding = TRI->getEncodingValue(DestReg);
+  uint16_t SrcEncoding = TRI->getEncodingValue(SrcReg);
+  assert(DestEncoding % NumRegs == 0 && SrcEncoding % NumRegs == 0 &&
+         "GPR reg sequences should not be able to overlap");
+#endif
+
+  for (unsigned SubReg = 0; SubReg != NumRegs; ++SubReg) {
+    const MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(Opcode));
+    AddSubReg(MIB, DestReg, Indices[SubReg], RegState::Define, TRI);
+    MIB.addReg(ZeroReg);
+    AddSubReg(MIB, SrcReg, Indices[SubReg], getKillRegState(KillSrc), TRI);
+    MIB.addImm(0);
+  }
+}
+
 void AArch64InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
                                    MachineBasicBlock::iterator I,
                                    const DebugLoc &DL, unsigned DestReg,
@@ -2430,6 +2455,22 @@ void AArch64InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     return;
   }
 
+  if (AArch64::XSeqPairsClassRegClass.contains(DestReg) &&
+      AArch64::XSeqPairsClassRegClass.contains(SrcReg)) {
+    static const unsigned Indices[] = {AArch64::sube64, AArch64::subo64};
+    copyGPRRegTuple(MBB, I, DL, DestReg, SrcReg, KillSrc, AArch64::ORRXrs,
+                    AArch64::XZR, Indices);
+    return;
+  }
+
+  if (AArch64::WSeqPairsClassRegClass.contains(DestReg) &&
+      AArch64::WSeqPairsClassRegClass.contains(SrcReg)) {
+    static const unsigned Indices[] = {AArch64::sube32, AArch64::subo32};
+    copyGPRRegTuple(MBB, I, DL, DestReg, SrcReg, KillSrc, AArch64::ORRWrs,
+                    AArch64::WZR, Indices);
+    return;
+  }
+
   if (AArch64::FPR128RegClass.contains(DestReg) &&
       AArch64::FPR128RegClass.contains(SrcReg)) {
     if (Subtarget.hasNEON()) {
diff --git a/lib/Target/AArch64/AArch64InstrInfo.h b/lib/Target/AArch64/AArch64InstrInfo.h
index f9e37845a45..537a812264a 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.h
+++ b/lib/Target/AArch64/AArch64InstrInfo.h
@@ -121,6 +121,10 @@ public:
                         const DebugLoc &DL, unsigned DestReg, unsigned SrcReg,
                         bool KillSrc, unsigned Opcode,
                         llvm::ArrayRef<unsigned> Indices) const;
+  void copyGPRRegTuple(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
+                       DebugLoc DL, unsigned DestReg, unsigned SrcReg,
+                       bool KillSrc, unsigned Opcode, unsigned ZeroReg,
+                       llvm::ArrayRef<unsigned> Indices) const;
   void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                    const DebugLoc &DL, unsigned DestReg, unsigned SrcReg,
                    bool KillSrc) const override;
diff --git a/test/CodeGen/AArch64/seqpaircopy.mir b/test/CodeGen/AArch64/seqpaircopy.mir
new file mode 100644
index 00000000000..89511cbf726
--- /dev/null
+++ b/test/CodeGen/AArch64/seqpaircopy.mir
@@ -0,0 +1,23 @@
+# RUN: llc -o - %s -mtriple=aarch64-- -mattr=+v8.1a -run-pass=postrapseudos | FileCheck %s
+---
+# CHECK-LABEL: name: copy_xseqpairs
+name: copy_xseqpairs
+body: |
+  bb.0:
+    ; CHECK: $x4_x5 = CASPALX $x4_x5, $x2_x3, $x0
+    ; CHECK: $x0 = ORRXrs $xzr, $x4, 0
+    ; CHECK: $x1 = ORRXrs $xzr, $x5, 0
+    $x4_x5 = CASPALX $x4_x5, $x2_x3, $x0
+    $x0_x1 = COPY $x4_x5
+...
+---
+# CHECK-LABEL: name: copy_wseqpairs
+name: copy_wseqpairs
+body: |
+  bb.0:
+    ; CHECK: $w4_w5 = CASPALW $w4_w5, $w2_w3, $x0
+    ; CHECK: $w0 = ORRWrs $wzr, $w4, 0
+    ; CHECK: $w1 = ORRWrs $wzr, $w5, 0
+    $w4_w5 = CASPALW $w4_w5, $w2_w3, $x0
+    $w0_w1 = COPY $w4_w5
+...
-- 
2.40.0