8022574: remove HaltNode code after uncommon trap calls

Reviewed-by: thartmann, mdoerr, simonis

src/hotspot/cpu/aarch64/aarch64.ad

@@ -15285,9 +15285,9 @@ instruct ShouldNotReachHere() %{
   format %{ "ShouldNotReachHere" %}
 
   ins_encode %{
-    // +1 so NativeInstruction::is_sigill_zombie_not_entrant() doesn't
-    // return true
-    __ dpcs1(0xdead + 1);
+    if (is_reachable()) {
+      __ dpcs1(0xdead + 1);
+    }
   %}
 
   ins_pipe(pipe_class_default);

src/hotspot/cpu/arm/arm.ad

@@ -8959,11 +8959,12 @@ instruct ShouldNotReachHere( )
   match(Halt);
   ins_cost(CALL_COST);
 
-  size(4);
   // Use the following format syntax
   format %{ "ShouldNotReachHere" %}
   ins_encode %{
-    __ udf(0xdead);
+    if (is_reachable()) {
+      __ udf(0xdead);
+    }
   %}
   ins_pipe(tail_call);
 %}

src/hotspot/cpu/ppc/ppc.ad

@@ -15136,10 +15136,11 @@ instruct ShouldNotReachHere() %{
   ins_cost(CALL_COST);
 
   format %{ "ShouldNotReachHere" %}
-  size(4);
   ins_encode %{
-    // TODO: PPC port $archOpcode(ppc64Opcode_tdi);
-    __ trap_should_not_reach_here();
+    if (is_reachable()) {
+      // TODO: PPC port $archOpcode(ppc64Opcode_tdi);
+      __ trap_should_not_reach_here();
+    }
   %}
   ins_pipe(pipe_class_default);
 %}

src/hotspot/cpu/s390/s390.ad

@@ -9886,9 +9886,12 @@ instruct RethrowException() %{
 instruct ShouldNotReachHere() %{
   match(Halt);
   ins_cost(CALL_COST);
-  size(2);
   format %{ "ILLTRAP; ShouldNotReachHere" %}
-  ins_encode %{ __ z_illtrap(); %}
+  ins_encode %{
+    if (is_reachable()) {
+      __ z_illtrap();
+    }
+  %}
   ins_pipe(pipe_class_dummy);
 %}
 

src/hotspot/cpu/x86/x86.ad

@@ -2341,9 +2341,11 @@ operand cmpOp_vcmppd() %{
 
 instruct ShouldNotReachHere() %{
   match(Halt);
-  format %{ "ud2\t# ShouldNotReachHere" %}
+  format %{ "stop\t# ShouldNotReachHere" %}
   ins_encode %{
-    __ stop(_halt_reason);
+    if (is_reachable()) {
+      __ stop(_halt_reason);
+    }
   %}
   ins_pipe(pipe_slow);
 %}

src/hotspot/share/adlc/output_c.cpp

@@ -3941,6 +3941,7 @@ void ArchDesc::buildMachNode(FILE *fp_cpp, InstructForm *inst, const char *inden
   }
   if (inst->is_ideal_halt()) {
     fprintf(fp_cpp, "%s node->_halt_reason = _leaf->as_Halt()->_halt_reason;\n", indent);
+    fprintf(fp_cpp, "%s node->_reachable   = _leaf->as_Halt()->_reachable;\n", indent);
   }
   if (inst->is_ideal_jump()) {
     fprintf(fp_cpp, "%s node->_probs = _leaf->as_Jump()->_probs;\n", indent);

src/hotspot/share/opto/graphKit.cpp

@@ -2113,7 +2113,8 @@ void GraphKit::uncommon_trap(int trap_request,
   // The debug info is the only real input to this call.
 
   // Halt-and-catch fire here.  The above call should never return!
-  HaltNode* halt = new HaltNode(control(), frameptr(), "uncommon trap returned which should never happen");
+  HaltNode* halt = new HaltNode(control(), frameptr(), "uncommon trap returned which should never happen"
+                                                       PRODUCT_ONLY(COMMA /*reachable*/false));
   _gvn.set_type_bottom(halt);
   root()->add_req(halt);
 

src/hotspot/share/opto/machnode.hpp

@@ -1010,8 +1010,12 @@ public:
 // Machine-specific versions of halt nodes
 class MachHaltNode : public MachReturnNode {
 public:
+  bool _reachable;
   const char* _halt_reason;
   virtual JVMState* jvms() const;
+  bool is_reachable() const {
+    return _reachable;
+  }
 };
 
 class MachMemBarNode : public MachNode {

src/hotspot/share/opto/rootnode.cpp

@@ -62,7 +62,8 @@ Node *RootNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 }
 
 //=============================================================================
-HaltNode::HaltNode(Node* ctrl, Node* frameptr, const char* halt_reason) : Node(TypeFunc::Parms), _halt_reason(halt_reason) {
+HaltNode::HaltNode(Node* ctrl, Node* frameptr, const char* halt_reason, bool reachable)
+                        : Node(TypeFunc::Parms), _halt_reason(halt_reason), _reachable(reachable) {
   init_class_id(Class_Halt);
   Node* top = Compile::current()->top();
   init_req(TypeFunc::Control,  ctrl        );

src/hotspot/share/opto/rootnode.hpp

@@ -52,7 +52,8 @@ public:
 class HaltNode : public Node {
 public:
   const char* _halt_reason;
-  HaltNode(Node* ctrl, Node* frameptr, const char* halt_reason);
+  bool        _reachable;
+  HaltNode(Node* ctrl, Node* frameptr, const char* halt_reason, bool reachable = true);
   virtual int Opcode() const;
   virtual bool  pinned() const { return true; };
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);