8357434: x86: Simplify Interpreter::profile_taken_branch

Reviewed-by: kvn, vlivanov

Author: shipilev

src/hotspot/cpu/x86/interp_masm_x86.cpp

@@ -1355,25 +1355,15 @@ void InterpreterMacroAssembler::update_mdp_for_ret(Register return_bci) {
 }
 
 
-void InterpreterMacroAssembler::profile_taken_branch(Register mdp,
-                                                     Register bumped_count) {
+void InterpreterMacroAssembler::profile_taken_branch(Register mdp) {
   if (ProfileInterpreter) {
     Label profile_continue;
 
     // If no method data exists, go to profile_continue.
-    // Otherwise, assign to mdp
     test_method_data_pointer(mdp, profile_continue);
 
     // We are taking a branch.  Increment the taken count.
-    // We inline increment_mdp_data_at to return bumped_count in a register
-    //increment_mdp_data_at(mdp, in_bytes(JumpData::taken_offset()));
-    Address data(mdp, in_bytes(JumpData::taken_offset()));
-    movptr(bumped_count, data);
-    assert(DataLayout::counter_increment == 1,
-            "flow-free idiom only works with 1");
-    addptr(bumped_count, DataLayout::counter_increment);
-    sbbptr(bumped_count, 0);
-    movptr(data, bumped_count); // Store back out
+    increment_mdp_data_at(mdp, in_bytes(JumpData::taken_offset()));
 
     // The method data pointer needs to be updated to reflect the new target.
     update_mdp_by_offset(mdp, in_bytes(JumpData::displacement_offset()));
@@ -1389,7 +1379,7 @@ void InterpreterMacroAssembler::profile_not_taken_branch(Register mdp) {
     // If no method data exists, go to profile_continue.
     test_method_data_pointer(mdp, profile_continue);
 
-    // We are taking a branch.  Increment the not taken count.
+    // We are not taking a branch.  Increment the not taken count.
     increment_mdp_data_at(mdp, in_bytes(BranchData::not_taken_offset()));
 
     // The method data pointer needs to be updated to correspond to

src/hotspot/cpu/x86/interp_masm_x86.hpp

@@ -236,7 +236,7 @@ class InterpreterMacroAssembler: public MacroAssembler {
   void update_mdp_by_constant(Register mdp_in, int constant);
   void update_mdp_for_ret(Register return_bci);
 
-  void profile_taken_branch(Register mdp, Register bumped_count);
+  void profile_taken_branch(Register mdp);
   void profile_not_taken_branch(Register mdp);
   void profile_call(Register mdp);
   void profile_final_call(Register mdp);

src/hotspot/cpu/x86/templateTable_x86.cpp

@@ -1687,8 +1687,7 @@ void TemplateTable::float_cmp(bool is_float, int unordered_result) {
 
 void TemplateTable::branch(bool is_jsr, bool is_wide) {
   __ get_method(rcx); // rcx holds method
-  __ profile_taken_branch(rax, rbx); // rax holds updated MDP, rbx
-                                     // holds bumped taken count
+  __ profile_taken_branch(rax); // rax holds updated MDP
 
   const ByteSize be_offset = MethodCounters::backedge_counter_offset() +
                              InvocationCounter::counter_offset();
@@ -1739,7 +1738,6 @@ void TemplateTable::branch(bool is_jsr, bool is_wide) {
   if (UseLoopCounter) {
     // increment backedge counter for backward branches
     // rax: MDO
-    // rbx: MDO bumped taken-count
     // rcx: method
     // rdx: target offset
     // r13: target bcp