Add custom encoder for the 's' bit denoting whether an ARM arithmetic

instruction should set the processor status flags or not. Remove the now
unnecessary special handling for the bit from the MCCodeEmitter.

llvm-svn: 116360

llvm/lib/Target/ARM/ARMCodeEmitter.cpp

@@ -156,6 +156,17 @@ namespace {
       return getMachineOpValue(MI, MI.getOperand(OpIdx));
     }
 
+    // FIXME: The legacy JIT ARMCodeEmitter doesn't rely on the the
+    //  TableGen'erated getBinaryCodeForInstr() function to encode any
+    //  operand values, instead querying getMachineOpValue() directly for
+    //  each operand it needs to encode. Thus, any of the new encoder
+    //  helper functions can simply return 0 as the values the return
+    //  are already handled elsewhere. They are placeholders to allow this
+    //  encoder to continue to function until the MC encoder is sufficiently
+    //  far along that this one can be eliminated entirely.
+    unsigned getCCOutOpValue(const MachineInstr &MI, unsigned Op)
+      const { return 0; }
+
     /// getMovi32Value - Return binary encoding of operand for movw/movt. If the
     /// machine operand requires relocation, record the relocation and return
     /// zero.

llvm/lib/Target/ARM/ARMInstrFormats.td

@@ -153,11 +153,13 @@ def pred : PredicateOperand<OtherVT, (ops i32imm, CCR),
 
 // Conditional code result for instructions whose 's' bit is set, e.g. subs.
 def cc_out : OptionalDefOperand<OtherVT, (ops CCR), (ops (i32 zero_reg))> {
+  string EncoderMethod = "getCCOutOpValue";
   let PrintMethod = "printSBitModifierOperand";
 }
 
 // Same as cc_out except it defaults to setting CPSR.
 def s_cc_out : OptionalDefOperand<OtherVT, (ops CCR), (ops (i32 CPSR))> {
+  string EncoderMethod = "getCCOutOpValue";
   let PrintMethod = "printSBitModifierOperand";
 }
 
@@ -273,9 +275,9 @@ class sI<dag oops, dag iops, AddrMode am, SizeFlagVal sz,
          list<dag> pattern>
   : InstARM<am, sz, im, f, GenericDomain, cstr, itin> {
   bits<4> p; // Predicate operand
+  bits<1> s; // condition-code set flag ('1' if the insn should set the flags)
   let Inst{31-28} = p;
-  // FIXME: The 's' operand needs to be handled, but the current generic
-  //        get-value handlers don't know how to deal with it.
+  let Inst{20} = s;
 
   let OutOperandList = oops;
   let InOperandList = !con(iops, (ins pred:$p, cc_out:$s));

llvm/lib/Target/ARM/ARMMCCodeEmitter.cpp

@@ -49,6 +49,13 @@ public:
   /// operand requires relocation, record the relocation and return zero.
   unsigned getMachineOpValue(const MCInst &MI,const MCOperand &MO) const;
 
+  /// getCCOutOpValue - Return encoding of the 's' bit.
+  unsigned getCCOutOpValue(const MCInst &MI, unsigned Op) const {
+    // The operand is either reg0 or CPSR. The 's' bit is encoded as '0' or
+    // '1' respectively.
+    return MI.getOperand(Op).getReg() == ARM::CPSR;
+  }
+
   unsigned getNumFixupKinds() const {
     assert(0 && "ARMMCCodeEmitter::getNumFixupKinds() not yet implemented.");
     return 0;
@@ -151,9 +158,6 @@ EncodeInstruction(const MCInst &MI, raw_ostream &OS,
   switch (Opcode) {
   default: break;
   case ARM::MOVi:
-    // The 's' bit.
-    if (MI.getOperand(4).getReg() == ARM::CPSR)
-      Value |= 1 << ARMII::S_BitShift;
     // The shifted immediate value.
     Value |= getMachineSoImmOpValue((unsigned)MI.getOperand(1).getImm());
     break;
@@ -163,9 +167,6 @@ EncodeInstruction(const MCInst &MI, raw_ostream &OS,
   case ARM::EORri:
   case ARM::ORRri:
   case ARM::SUBri:
-    // The 's' bit.
-    if (MI.getOperand(5).getReg() == ARM::CPSR)
-      Value |= 1 << ARMII::S_BitShift;
     // The shifted immediate value.
     Value |= getMachineSoImmOpValue((unsigned)MI.getOperand(2).getImm());
     break;
@@ -175,9 +176,6 @@ EncodeInstruction(const MCInst &MI, raw_ostream &OS,
   case ARM::EORrs:
   case ARM::ORRrs:
   case ARM::SUBrs: {
-    // The 's' bit.
-    if (MI.getOperand(7).getReg() == ARM::CPSR)
-      Value |= 1 << ARMII::S_BitShift;
     // The so_reg operand needs the shift ammount encoded.
     unsigned ShVal = MI.getOperand(4).getImm();
     unsigned ShType = ARM_AM::getShiftOpcEncoding(ARM_AM::getSORegShOp(ShVal));