Distinguish early clobber output operands from clobbered registers.

Both become <earlyclobber> defs on the INLINEASM MachineInstr, but we
now use two different asm operand kinds.

The new Kind_Clobber is treated identically to the old
Kind_RegDefEarlyClobber for now, but x87 floating point stack inline
assembly does care about the difference.

This will pop a register off the stack:

  asm("fstp %st" : : "t"(x) : "st");

While this will pop the input and push an output:

  asm("fst %st" : "=&t"(r) : "t"(x));

We need to know if ST0 was a clobber or an output operand, and we can't
depend on <dead> flags for that.

llvm-svn: 133902

llvm/include/llvm/InlineAsm.h

@@ -188,24 +188,31 @@ public:
   // in the backend.
   
   enum {
+    // Fixed operands on an INLINEASM SDNode.
     Op_InputChain = 0,
     Op_AsmString = 1,
     Op_MDNode = 2,
     Op_ExtraInfo = 3,    // HasSideEffects, IsAlignStack
     Op_FirstOperand = 4,
 
+    // Fixed operands on an INLINEASM MachineInstr.
     MIOp_AsmString = 0,
     MIOp_ExtraInfo = 1,    // HasSideEffects, IsAlignStack
     MIOp_FirstOperand = 2,
 
+    // Interpretation of the MIOp_ExtraInfo bit field.
     Extra_HasSideEffects = 1,
     Extra_IsAlignStack = 2,
 
-    Kind_RegUse = 1,
-    Kind_RegDef = 2,
-    Kind_Imm = 3,
-    Kind_Mem = 4,
-    Kind_RegDefEarlyClobber = 6,
+    // Inline asm operands map to multiple SDNode / MachineInstr operands.
+    // The first operand is an immediate describing the asm operand, the low
+    // bits is the kind:
+    Kind_RegUse = 1,             // Input register, "r".
+    Kind_RegDef = 2,             // Output register, "=r".
+    Kind_RegDefEarlyClobber = 3, // Early-clobber output register, "=&r".
+    Kind_Clobber = 4,            // Clobbered register, "~r".
+    Kind_Imm = 5,                // Immediate.
+    Kind_Mem = 6,                // Memory operand, "m".
 
     Flag_MatchingOperand = 0x80000000
   };
@@ -233,6 +240,9 @@ public:
   static bool isRegDefEarlyClobberKind(unsigned Flag) {
     return getKind(Flag) == Kind_RegDefEarlyClobber;
   }
+  static bool isClobberKind(unsigned Flag) {
+    return getKind(Flag) == Kind_Clobber;
+  }
 
   /// getNumOperandRegisters - Extract the number of registers field from the
   /// inline asm operand flag.

llvm/lib/CodeGen/MachineInstr.cpp

@@ -1443,9 +1443,10 @@ void MachineInstr::print(raw_ostream &OS, const TargetMachine *TM) const {
       switch (InlineAsm::getKind(Flag)) {
       case InlineAsm::Kind_RegUse:             OS << ":[reguse]"; break;
       case InlineAsm::Kind_RegDef:             OS << ":[regdef]"; break;
+      case InlineAsm::Kind_RegDefEarlyClobber: OS << ":[regdef-ec]"; break;
+      case InlineAsm::Kind_Clobber:            OS << ":[clobber]"; break;
       case InlineAsm::Kind_Imm:                OS << ":[imm]"; break;
       case InlineAsm::Kind_Mem:                OS << ":[mem]"; break;
-      case InlineAsm::Kind_RegDefEarlyClobber: OS << ":[regdef-ec]"; break;
       default: OS << ":[??" << InlineAsm::getKind(Flag) << ']'; break;
       }
 

llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

@@ -851,6 +851,7 @@ EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned,
         }
         break;
       case InlineAsm::Kind_RegDefEarlyClobber:
+      case InlineAsm::Kind_Clobber:
         for (; NumVals; --NumVals, ++i) {
           unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
           MI->addOperand(MachineOperand::CreateReg(Reg, /*isDef=*/ true,

llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp

@@ -490,7 +490,8 @@ bool ScheduleDAGFast::DelayForLiveRegsBottomUp(SUnit *SU,
 
         ++i; // Skip the ID value.
         if (InlineAsm::isRegDefKind(Flags) ||
-            InlineAsm::isRegDefEarlyClobberKind(Flags)) {
+            InlineAsm::isRegDefEarlyClobberKind(Flags) ||
+            InlineAsm::isClobberKind(Flags)) {
           // Check for def of register or earlyclobber register.
           for (; NumVals; --NumVals, ++i) {
             unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();

llvm/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp

@@ -1092,7 +1092,8 @@ DelayForLiveRegsBottomUp(SUnit *SU, SmallVector<unsigned, 4> &LRegs) {
 
         ++i; // Skip the ID value.
         if (InlineAsm::isRegDefKind(Flags) ||
-            InlineAsm::isRegDefEarlyClobberKind(Flags)) {
+            InlineAsm::isRegDefEarlyClobberKind(Flags) ||
+            InlineAsm::isClobberKind(Flags)) {
           // Check for def of register or earlyclobber register.
           for (; NumVals; --NumVals, ++i) {
             unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -6051,8 +6051,7 @@ void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
       // Add the clobbered value to the operand list, so that the register
       // allocator is aware that the physreg got clobbered.
       if (!OpInfo.AssignedRegs.Regs.empty())
-        OpInfo.AssignedRegs.AddInlineAsmOperands(
-                                            InlineAsm::Kind_RegDefEarlyClobber,
+        OpInfo.AssignedRegs.AddInlineAsmOperands(InlineAsm::Kind_Clobber,
                                                  false, 0, DAG,
                                                  AsmNodeOperands);
       break;