[M68k] implement move to and from sr (#111145)

This PR enables the use of the status register in inline assembly.
This is necessary to, for example, set and retrieve the current
interrupt mask.

---------

Co-authored-by: kirk <[email protected]>

Author: TechnoElf

llvm/lib/Target/M68k/AsmParser/M68kAsmParser.cpp

@@ -258,6 +258,7 @@ static inline unsigned getRegisterIndex(unsigned Register) {
   // We don't care about the indices of these registers.
   case M68k::PC:
   case M68k::CCR:
+  case M68k::SR:
   case M68k::FPC:
   case M68k::FPS:
   case M68k::FPIAR:
@@ -636,10 +637,13 @@ bool M68kAsmParser::parseRegisterName(MCRegister &RegNo, SMLoc Loc,
                                       StringRef RegisterName) {
   auto RegisterNameLower = RegisterName.lower();
 
-  // CCR register
+  // CCR and SR register
   if (RegisterNameLower == "ccr") {
     RegNo = M68k::CCR;
     return true;
+  } else if (RegisterNameLower == "sr") {
+    RegNo = M68k::SR;
+    return true;
   }
 
   // Parse simple general-purpose registers.

llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp

@@ -117,6 +117,12 @@ static DecodeStatus DecodeCCRCRegisterClass(MCInst &Inst, APInt &Insn,
   llvm_unreachable("unimplemented");
 }
 
+static DecodeStatus DecodeSRCRegisterClass(MCInst &Inst, APInt &Insn,
+                                           uint64_t Address,
+                                           const void *Decoder) {
+  llvm_unreachable("unimplemented");
+}
+
 static DecodeStatus DecodeImm32(MCInst &Inst, uint64_t Imm, uint64_t Address,
                                 const void *Decoder) {
   Inst.addOperand(MCOperand::createImm(M68k::swapWord<uint32_t>(Imm)));

llvm/lib/Target/M68k/M68kInstrData.td

@@ -365,13 +365,14 @@ def MOVM32mp_P : MxMOVEM_RM_Pseudo<MxType32r, MxType32.POp>;
 // ons that will be resolved sometime after RA pass.
 //===----------------------------------------------------------------------===//
 
+/// Move to CCR
 /// --------------------------------------------------
 ///  F  E  D  C  B  A  9  8  7  6 | 5  4  3 | 2  1  0
 /// --------------------------------------------------
 ///                               | EFFECTIVE ADDRESS
 ///  0  1  0  0  0  1  0  0  1  1 |   MODE  |   REG
 /// --------------------------------------------------
-let Defs = [CCR] in
+let Defs = [CCR] in {
 class MxMoveToCCR<MxOperand MEMOp, MxEncMemOp SRC_ENC>
     : MxInst<(outs CCRC:$dst), (ins MEMOp:$src), "move.w\t$src, $dst", []> {
   let Inst = (ascend
@@ -382,6 +383,7 @@ class MxMoveToCCR<MxOperand MEMOp, MxEncMemOp SRC_ENC>
 
 class MxMoveToCCRPseudo<MxOperand MEMOp>
     : MxPseudo<(outs CCRC:$dst), (ins MEMOp:$src)>;
+} // let Defs = [CCR]
 
 let mayLoad = 1 in
 foreach AM = MxMoveSupportedAMs in {
@@ -436,6 +438,64 @@ foreach AM = MxMoveSupportedAMs in {
 def MOV16dc : MxMoveFromCCR_R;
 def MOV8dc  : MxMoveFromCCR_RPseudo<MxOp8AddrMode_d.Op>;
 
+/// Move to SR
+/// --------------------------------------------------
+///  F  E  D  C  B  A  9  8  7  6 | 5  4  3 | 2  1  0
+/// --------------------------------------------------
+///                               | EFFECTIVE ADDRESS
+///  0  1  0  0  0  1  1  0  1  1 |   MODE  |   REG
+/// --------------------------------------------------
+let Defs = [SR] in {
+class MxMoveToSR<MxOperand MEMOp, MxEncMemOp SRC_ENC>
+    : MxInst<(outs SRC:$dst), (ins MEMOp:$src), "move.w\t$src, $dst", []> {
+  let Inst = (ascend
+    (descend 0b0100011011, SRC_ENC.EA),
+    SRC_ENC.Supplement
+  );
+}
+} // let Defs = [SR]
+
+let mayLoad = 1 in
+foreach AM = MxMoveSupportedAMs in {
+  def MOV16s # AM : MxMoveToSR<!cast<MxOpBundle>("MxOp16AddrMode_"#AM).Op,
+                                !cast<MxEncMemOp>("MxMoveSrcOpEnc_"#AM)>;
+} // foreach AM
+
+def MOV16sd : MxMoveToSR<MxOp16AddrMode_d.Op, MxMoveSrcOpEnc_d>;
+
+/// Move from SR
+/// --------------------------------------------------
+///  F  E  D  C  B  A  9  8  7  6 | 5  4  3 | 2  1  0
+/// --------------------------------------------------
+///                               | EFFECTIVE ADDRESS
+///  0  1  0  0  0  0  0  0  1  1 |   MODE  |   REG
+/// --------------------------------------------------
+let Uses = [SR] in {
+class MxMoveFromSR_R
+    : MxInst<(outs MxDRD16:$dst), (ins SRC:$src), "move.w\t$src, $dst", []>,
+      Requires<[ AtLeastM68010 ]> {
+  let Inst = (descend 0b0100000011, MxEncAddrMode_d<"dst">.EA);
+}
+
+class MxMoveFromSR_M<MxOperand MEMOp, MxEncMemOp DST_ENC>
+    : MxInst<(outs), (ins MEMOp:$dst, SRC:$src), "move.w\t$src, $dst", []>,
+      Requires<[ AtLeastM68010 ]> {
+  let Inst = (ascend
+    (descend 0b0100000011, DST_ENC.EA),
+    DST_ENC.Supplement
+  );
+}
+} // let Uses = [SR]
+
+let mayStore = 1 in
+foreach AM = MxMoveSupportedAMs in {
+  def MOV16 # AM # s
+    : MxMoveFromSR_M<!cast<MxOpBundle>("MxOp16AddrMode_"#AM).Op,
+                      !cast<MxEncMemOp>("MxMoveDstOpEnc_"#AM)>;
+} // foreach AM
+
+def MOV16ds : MxMoveFromSR_R;
+
 //===----------------------------------------------------------------------===//
 // LEA
 //===----------------------------------------------------------------------===//

llvm/test/MC/M68k/Data/Classes/MxMoveSR.s

@@ -0,0 +1,9 @@
+; RUN: llvm-mc -triple=m68k -mcpu=M68000 -show-encoding %s | FileCheck %s
+
+; CHECK:      move.w  %d1, %sr
+; CHECK-SAME: encoding: [0x46,0xc1]
+move.w	%d1, %sr
+
+; CHECK:      move.w  %sr, %d1
+; CHECK-SAME: encoding: [0x40,0xc1]
+move.w	%sr, %d1