Fix 64-bit atomic operations in Thumb mode.

The ARM and Thumb variants of LDREXD and STREXD have different constraints and
take different operands. Previously the code expanding atomic operations didn't
take this into account and asserted in Thumb mode.

llvm-svn: 173780

1 files changed, 46 insertions, 74 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 3d283a5ac95..6beb1abd222 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -5969,9 +5969,6 @@ ARMTargetLowering::EmitAtomicBinary64(MachineInstr *MI, MachineBasicBlock *BB,
     MRI.constrainRegClass(ptr, &ARM::rGPRRegClass);
   }
 
-  unsigned ldrOpc = isThumb2 ? ARM::t2LDREXD : ARM::LDREXD;
-  unsigned strOpc = isThumb2 ? ARM::t2STREXD : ARM::STREXD;
-
   MachineBasicBlock *loopMBB = MF->CreateMachineBasicBlock(LLVM_BB);
   MachineBasicBlock *contBB = 0, *cont2BB = 0;
   if (IsCmpxchg || IsMinMax)
@@ -6009,42 +6006,26 @@ ARMTargetLowering::EmitAtomicBinary64(MachineInstr *MI, MachineBasicBlock *BB,
   //   cmp storesuccess, #0
   //   bne- loopMBB
   //   fallthrough --> exitMBB
-  //
-  // Note that the registers are explicitly specified because there is not any
-  // way to force the register allocator to allocate a register pair.
-  //
-  // FIXME: The hardcoded registers are not necessary for Thumb2, but we
-  // need to properly enforce the restriction that the two output registers
-  // for ldrexd must be different.
   BB = loopMBB;
+
   // Load
-  unsigned GPRPair0 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-  unsigned GPRPair1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-  unsigned GPRPair2;
-  if (IsMinMax) {
-    //We need an extra double register for doing min/max.
-    unsigned undef = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    unsigned r1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    GPRPair2 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    BuildMI(BB, dl, TII->get(TargetOpcode::IMPLICIT_DEF), undef);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), r1)
-      .addReg(undef)
-      .addReg(vallo)
-      .addImm(ARM::gsub_0);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), GPRPair2)
-      .addReg(r1)
-      .addReg(valhi)
-      .addImm(ARM::gsub_1);
+  if (isThumb2) {
+    AddDefaultPred(BuildMI(BB, dl, TII->get(ARM::t2LDREXD))
+                   .addReg(destlo, RegState::Define)
+                   .addReg(desthi, RegState::Define)
+                   .addReg(ptr));
+  } else {
+    unsigned GPRPair0 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
+    AddDefaultPred(BuildMI(BB, dl, TII->get(ARM::LDREXD))
+                   .addReg(GPRPair0, RegState::Define).addReg(ptr));
+    // Copy r2/r3 into dest.  (This copy will normally be coalesced.)
+    BuildMI(BB, dl, TII->get(TargetOpcode::COPY), destlo)
+      .addReg(GPRPair0, 0, ARM::gsub_0);
+    BuildMI(BB, dl, TII->get(TargetOpcode::COPY), desthi)
+      .addReg(GPRPair0, 0, ARM::gsub_1);
   }
 
-  AddDefaultPred(BuildMI(BB, dl, TII->get(ldrOpc))
-                 .addReg(GPRPair0, RegState::Define).addReg(ptr));
-  // Copy r2/r3 into dest.  (This copy will normally be coalesced.)
-  BuildMI(BB, dl, TII->get(TargetOpcode::COPY), destlo)
-    .addReg(GPRPair0, 0, ARM::gsub_0);
-  BuildMI(BB, dl, TII->get(TargetOpcode::COPY), desthi)
-    .addReg(GPRPair0, 0, ARM::gsub_1);
-
+  unsigned StoreLo, StoreHi;
   if (IsCmpxchg) {
     // Add early exit
     for (unsigned i = 0; i < 2; i++) {
@@ -6060,19 +6041,8 @@ ARMTargetLowering::EmitAtomicBinary64(MachineInstr *MI, MachineBasicBlock *BB,
     }
 
     // Copy to physregs for strexd
-    unsigned setlo = MI->getOperand(5).getReg();
-    unsigned sethi = MI->getOperand(6).getReg();
-    unsigned undef = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    unsigned r1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    BuildMI(BB, dl, TII->get(TargetOpcode::IMPLICIT_DEF), undef);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), r1)
-      .addReg(undef)
-      .addReg(setlo)
-      .addImm(ARM::gsub_0);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), GPRPair1)
-      .addReg(r1)
-      .addReg(sethi)
-      .addImm(ARM::gsub_1);
+    StoreLo = MI->getOperand(5).getReg();
+    StoreHi = MI->getOperand(6).getReg();
   } else if (Op1) {
     // Perform binary operation
     unsigned tmpRegLo = MRI.createVirtualRegister(TRC);
@@ -6084,32 +6054,13 @@ ARMTargetLowering::EmitAtomicBinary64(MachineInstr *MI, MachineBasicBlock *BB,
                    .addReg(desthi).addReg(valhi))
         .addReg(IsMinMax ? ARM::CPSR : 0, getDefRegState(IsMinMax));
 
-    unsigned UndefPair = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    BuildMI(BB, dl, TII->get(TargetOpcode::IMPLICIT_DEF), UndefPair);
-    unsigned r1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), r1)
-      .addReg(UndefPair)
-      .addReg(tmpRegLo)
-      .addImm(ARM::gsub_0);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), GPRPair1)
-      .addReg(r1)
-      .addReg(tmpRegHi)
-      .addImm(ARM::gsub_1);
+    StoreLo = tmpRegLo;
+    StoreHi = tmpRegHi;
   } else {
     // Copy to physregs for strexd
-    unsigned UndefPair = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    unsigned r1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
-    BuildMI(BB, dl, TII->get(TargetOpcode::IMPLICIT_DEF), UndefPair);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), r1)
-      .addReg(UndefPair)
-      .addReg(vallo)
-      .addImm(ARM::gsub_0);
-    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), GPRPair1)
-      .addReg(r1)
-      .addReg(valhi)
-      .addImm(ARM::gsub_1);
+    StoreLo = vallo;
+    StoreHi = valhi;
   }
-  unsigned GPRPairStore = GPRPair1;
   if (IsMinMax) {
     // Compare and branch to exit block.
     BuildMI(BB, dl, TII->get(isThumb2 ? ARM::t2Bcc : ARM::Bcc))
@@ -6117,12 +6068,33 @@ ARMTargetLowering::EmitAtomicBinary64(MachineInstr *MI, MachineBasicBlock *BB,
     BB->addSuccessor(exitMBB);
     BB->addSuccessor(contBB);
     BB = contBB;
-    GPRPairStore = GPRPair2;
+    StoreLo = vallo;
+    StoreHi = valhi;
   }
 
   // Store
-  AddDefaultPred(BuildMI(BB, dl, TII->get(strOpc), storesuccess)
-                 .addReg(GPRPairStore).addReg(ptr));
+  if (isThumb2) {
+    AddDefaultPred(BuildMI(BB, dl, TII->get(ARM::t2STREXD), storesuccess)
+                   .addReg(StoreLo).addReg(StoreHi).addReg(ptr));
+  } else {
+    // Marshal a pair...
+    unsigned StorePair = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
+    unsigned UndefPair = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
+    unsigned r1 = MRI.createVirtualRegister(&ARM::GPRPairRegClass);
+    BuildMI(BB, dl, TII->get(TargetOpcode::IMPLICIT_DEF), UndefPair);
+    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), r1)
+      .addReg(UndefPair)
+      .addReg(StoreLo)
+      .addImm(ARM::gsub_0);
+    BuildMI(BB, dl, TII->get(TargetOpcode::INSERT_SUBREG), StorePair)
+      .addReg(r1)
+      .addReg(StoreHi)
+      .addImm(ARM::gsub_1);
+
+    // ...and store it
+    AddDefaultPred(BuildMI(BB, dl, TII->get(ARM::STREXD), storesuccess)
+                   .addReg(StorePair).addReg(ptr));
+  }
   // Cmp+jump
   AddDefaultPred(BuildMI(BB, dl, TII->get(isThumb2 ? ARM::t2CMPri : ARM::CMPri))
                  .addReg(storesuccess).addImm(0));