RFR: JDK-8241503: C2: Share MacroAssembler between mach nodes during code emission [v11]

[Boris Ulasevich]

On Tue, 26 Mar 2024 19:02:42 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

>> # Description
>> 
>> Please review this PR with a patch to re-use the same C2_MacroAssembler object to emit all instructions in the same compilation unit.
>> 
>> Overall, the change is pretty simple. However, due to the renaming of the variable to access C2_MacroAssembler, from `_masm.` to `masm->`, and also some method prototype changes, the patch became quite large.
>> 
>> # Help Needed for Testing
>> 
>> I don't have access to all platforms necessary to test this. I hope some other folks can help with testing on `S390`, `RISC-V` and `PPC`.
>
> Cesar Soares Lucas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
> 
>  - Merge remote-tracking branch 'origin/master' into reuse-macroasm
>  - Fix AArch64 build & improve comment about InstructionMark
>  - Catching up with changes in master
>  - Catching up with origin/master
>  - Catch up with origin/master
>  - Merge with origin/master
>  - Fix build, copyright dates, m4 files.
>  - Fix merge
>  - Catch up with master branch.
>    
>    Merge remote-tracking branch 'origin/master' into reuse-macroasm
>  - Some inst_mark fixes; Catch up with master.
>  - ... and 2 more: https://git.openjdk.org/jdk/compare/89e0889a...b4d73c98

Do you need help understanding the problem? The crash occurred because you removed the line `fprintf(fp, "  cbuf.set_insts_mark();\n");` from the generator of AD nodes ::emit() methods. That is why emit_call_reloc finds cbuf.insts->_mark unitialized.


// Call Runtime Instruction
instruct CallRuntimeDirect(method meth) %{
  match(CallRuntime);
  effect(USE meth);
  ins_cost(CALL_COST);
  format %{ "CALL,runtime" %}
  ins_encode( Java_To_Runtime( meth ),
              call_epilog );
  ins_pipe(simple_call);
%}

-->

void CallRuntimeDirectNode::emit(CodeBuffer& cbuf, PhaseRegAlloc* ra_) const {
  cbuf.set_insts_mark();
  // Start at oper_input_base() and count operands
  unsigned idx0 = 1;
  unsigned idx1 = 1;    //
  {
#line 1217 "/home/boris/jdk-bulasevich/src/hotspot/cpu/arm/arm.ad"
    // CALL directly to the runtime
    emit_call_reloc(cbuf, as_MachCall(), opnd_array(1), runtime_call_Relocation::spec());
#line 999999
  }
  {
#line 1213 "/home/boris/jdk-bulasevich/src/hotspot/cpu/arm/arm.ad"
    // nothing
#line 999999
  }
}

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16484#issuecomment-2041935047