8285378: Remove unnecessary nop for C1 exception and deopt handler

Reviewed-by: kvn, dlong

src/hotspot/cpu/aarch64/c1_LIRAssembler_aarch64.cpp

@@ -378,13 +378,6 @@ int LIR_Assembler::initial_frame_size_in_bytes() const {
 
 
 int LIR_Assembler::emit_exception_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(exception_handler_size());
   if (handler_base == NULL) {
@@ -403,7 +396,8 @@ int LIR_Assembler::emit_exception_handler() {
   __ verify_not_null_oop(r0);
 
   // search an exception handler (r0: exception oop, r3: throwing pc)
-  __ far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::handle_exception_from_callee_id)));  __ should_not_reach_here();
+  __ far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::handle_exception_from_callee_id)));
+  __ should_not_reach_here();
   guarantee(code_offset() - offset <= exception_handler_size(), "overflow");
   __ end_a_stub();
 
@@ -471,13 +465,6 @@ int LIR_Assembler::emit_unwind_handler() {
 
 
 int LIR_Assembler::emit_deopt_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(deopt_handler_size());
   if (handler_base == NULL) {

src/hotspot/cpu/arm/c1_LIRAssembler_arm.cpp

@@ -199,9 +199,6 @@ int LIR_Assembler::initial_frame_size_in_bytes() const {
 
 
 int LIR_Assembler::emit_exception_handler() {
-  // TODO: ARM
-  __ nop(); // See comments in other ports
-
   address handler_base = __ start_a_stub(exception_handler_size());
   if (handler_base == NULL) {
     bailout("exception handler overflow");

src/hotspot/cpu/ppc/c1_LIRAssembler_ppc.cpp

@@ -167,13 +167,6 @@ void LIR_Assembler::osr_entry() {
 
 
 int LIR_Assembler::emit_exception_handler() {
-  // If the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri).
-  __ nop();
-
   // Generate code for the exception handler.
   address handler_base = __ start_a_stub(exception_handler_size());
 
@@ -247,13 +240,6 @@ int LIR_Assembler::emit_unwind_handler() {
 
 
 int LIR_Assembler::emit_deopt_handler() {
-  // If the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri).
-  __ nop();
-
   // Generate code for deopt handler.
   address handler_base = __ start_a_stub(deopt_handler_size());
 

src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp

@@ -307,13 +307,6 @@ int LIR_Assembler::initial_frame_size_in_bytes() const {
 }
 
 int LIR_Assembler::emit_exception_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci ==> add a nop
-  // (was bug 5/14/1999 -gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(exception_handler_size());
   if (handler_base == NULL) {
@@ -399,13 +392,6 @@ int LIR_Assembler::emit_unwind_handler() {
 }
 
 int LIR_Assembler::emit_deopt_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bck => add a nop
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(deopt_handler_size());
   if (handler_base == NULL) {

src/hotspot/cpu/s390/c1_LIRAssembler_s390.cpp

@@ -165,13 +165,6 @@ address LIR_Assembler::emit_call_c(address a) {
 }
 
 int LIR_Assembler::emit_exception_handler() {
-  // If the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci. => Add a nop.
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // Generate code for exception handler.
   address handler_base = __ start_a_stub(exception_handler_size());
   if (handler_base == NULL) {
@@ -263,13 +256,6 @@ int LIR_Assembler::emit_unwind_handler() {
 }
 
 int LIR_Assembler::emit_deopt_handler() {
-  // If the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci. => Add a nop.
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // Generate code for exception handler.
   address handler_base = __ start_a_stub(deopt_handler_size());
   if (handler_base == NULL) {

src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp

@@ -398,13 +398,6 @@ int LIR_Assembler::initial_frame_size_in_bytes() const {
 
 
 int LIR_Assembler::emit_exception_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(exception_handler_size());
   if (handler_base == NULL) {
@@ -499,13 +492,6 @@ int LIR_Assembler::emit_unwind_handler() {
 
 
 int LIR_Assembler::emit_deopt_handler() {
-  // if the last instruction is a call (typically to do a throw which
-  // is coming at the end after block reordering) the return address
-  // must still point into the code area in order to avoid assertion
-  // failures when searching for the corresponding bci => add a nop
-  // (was bug 5/14/1999 - gri)
-  __ nop();
-
   // generate code for exception handler
   address handler_base = __ start_a_stub(deopt_handler_size());
   if (handler_base == NULL) {