src/hotspot/share/opto/callGenerator.cpp

*** 294,313 ****
  }
  
  // Allow inlining decisions to be delayed
  class LateInlineCallGenerator : public DirectCallGenerator {
   private:
!   // unique id for log compilation
!   jlong _unique_id;
  
   protected:
    CallGenerator* _inline_cg;
    virtual bool do_late_inline_check(JVMState* jvms) { return true; }
  
   public:
!   LateInlineCallGenerator(ciMethod* method, CallGenerator* inline_cg) :
!     DirectCallGenerator(method, true), _unique_id(0), _inline_cg(inline_cg) {}
  
    virtual bool is_late_inline() const { return true; }
  
    // Convert the CallStaticJava into an inline
    virtual void do_late_inline();
--- 294,313 ----
  }
  
  // Allow inlining decisions to be delayed
  class LateInlineCallGenerator : public DirectCallGenerator {
   private:
!   jlong _unique_id;   // unique id for log compilation
!   bool _is_pure_call; // a hint that the call doesn't have important side effects to care about
  
   protected:
    CallGenerator* _inline_cg;
    virtual bool do_late_inline_check(JVMState* jvms) { return true; }
  
   public:
!   LateInlineCallGenerator(ciMethod* method, CallGenerator* inline_cg, bool is_pure_call = false) :
!     DirectCallGenerator(method, true), _unique_id(0), _is_pure_call(is_pure_call), _inline_cg(inline_cg) {}
  
    virtual bool is_late_inline() const { return true; }
  
    // Convert the CallStaticJava into an inline
    virtual void do_late_inline();
*** 387,396 ****
--- 387,403 ----
    // Remove inlined methods from Compiler's lists.
    if (call->is_macro()) {
      C->remove_macro_node(call);
    }
  
+   bool result_not_used = (callprojs.resproj == NULL || callprojs.resproj->outcnt() == 0);
+   if (_is_pure_call && result_not_used) {
+     // The call is marked as pure (no important side effects), but result isn't used.
+     // It's safe to remove the call.
+     GraphKit kit(call->jvms());
+     kit.replace_call(call, C->top(), true);
+   } else {
      // Make a clone of the JVMState that appropriate to use for driving a parse
      JVMState* old_jvms = call->jvms();
      JVMState* jvms = old_jvms->clone_shallow(C);
      uint size = call->req();
      SafePointNode* map = new SafePointNode(size, jvms);
*** 459,468 ****
--- 466,476 ----
      C->set_has_loops(C->has_loops() || _inline_cg->method()->has_loops());
      C->env()->notice_inlined_method(_inline_cg->method());
      C->set_inlining_progress(true);
      C->set_do_cleanup(kit.stopped()); // path is dead; needs cleanup
      kit.replace_call(call, result, true);
+   }
  }
  
  
  CallGenerator* CallGenerator::for_late_inline(ciMethod* method, CallGenerator* inline_cg) {
    return new LateInlineCallGenerator(method, inline_cg);
*** 549,559 ****
  
  class LateInlineBoxingCallGenerator : public LateInlineCallGenerator {
  
   public:
    LateInlineBoxingCallGenerator(ciMethod* method, CallGenerator* inline_cg) :
!     LateInlineCallGenerator(method, inline_cg) {}
  
    virtual JVMState* generate(JVMState* jvms) {
      Compile *C = Compile::current();
  
      C->log_inline_id(this);
--- 557,567 ----
  
  class LateInlineBoxingCallGenerator : public LateInlineCallGenerator {
  
   public:
    LateInlineBoxingCallGenerator(ciMethod* method, CallGenerator* inline_cg) :
!     LateInlineCallGenerator(method, inline_cg, /*is_pure=*/true) {}
  
    virtual JVMState* generate(JVMState* jvms) {
      Compile *C = Compile::current();
  
      C->log_inline_id(this);