[AVR] No cli for SPWRITE on XMEGA

Author: tomtor

llvm/lib/Target/AVR/AVRExpandPseudoInsts.cpp

@@ -2531,27 +2531,42 @@ bool AVRExpandPseudo::expand<AVR::SPWRITE>(Block &MBB, BlockIt MBBI) {
   unsigned Flags = MI.getFlags();
   TRI->splitReg(SrcReg, SrcLoReg, SrcHiReg);
 
-  buildMI(MBB, MBBI, AVR::INRdA)
+  // From the XMEGA series manual:
+  // To prevent corruption when updating the stack pointer from software,
+  // a write to SPL will automatically disable interrupts
+  // for up to four instructions or until the next I/O memory write.
+  if (STI.getELFArch() >= 102) { // An XMEGA device
+    buildMI(MBB, MBBI, AVR::OUTARr)
+      .addImm(0x3d)
+      .addReg(SrcLoReg, getKillRegState(SrcIsKill))
+      .setMIFlags(Flags);
+    buildMI(MBB, MBBI, AVR::OUTARr)
+      .addImm(0x3e)
+      .addReg(SrcHiReg, getKillRegState(SrcIsKill))
+      .setMIFlags(Flags);
+  } else { // Disable interrupts for older devices (3 extra instructions)
+    buildMI(MBB, MBBI, AVR::INRdA)
       .addReg(STI.getTmpRegister(), RegState::Define)
       .addImm(STI.getIORegSREG())
       .setMIFlags(Flags);
 
-  buildMI(MBB, MBBI, AVR::BCLRs).addImm(0x07).setMIFlags(Flags);
+    buildMI(MBB, MBBI, AVR::BCLRs).addImm(0x07).setMIFlags(Flags);
 
-  buildMI(MBB, MBBI, AVR::OUTARr)
+    buildMI(MBB, MBBI, AVR::OUTARr)
       .addImm(0x3e)
       .addReg(SrcHiReg, getKillRegState(SrcIsKill))
       .setMIFlags(Flags);
 
-  buildMI(MBB, MBBI, AVR::OUTARr)
+    buildMI(MBB, MBBI, AVR::OUTARr)
       .addImm(STI.getIORegSREG())
       .addReg(STI.getTmpRegister(), RegState::Kill)
       .setMIFlags(Flags);
 
-  buildMI(MBB, MBBI, AVR::OUTARr)
+    buildMI(MBB, MBBI, AVR::OUTARr)
       .addImm(0x3d)
       .addReg(SrcLoReg, getKillRegState(SrcIsKill))
       .setMIFlags(Flags);
+  }
 
   MI.eraseFromParent();
   return true;