[code-reflection] RFR: OpWriter block naming align with block indexes

[Adam Sotona]

I propose to change OpWriter block naming conventions to be aligned with block indexes.

It is very hard to debug when there is no connection between debugged body and available prints provided by OpWriter.
This patch composes block name as composition of block indexes from super-parent-body block index down the actual block index. With fallback to the `block__<counter>` In case the block is not a part of a body.

This is and example of such print:

    %0 : java.util.function.IntUnaryOperator = lambda @loc="88:31" (%1 : int)int -> {
        %2 : Var<int> = var %1 @"i" @loc="88:31";
        %3 : int = var.load %2 @loc="89:17";
        %4 : int = constant @"0" @loc="89:21";
        %5 : boolean = gt %3 %4 @loc="89:17";
        cbranch %5 ^block_0_1 ^block_0_2;
      
      ^block_0_1:
        %6 : java.util.function.IntUnaryOperator = lambda @loc="90:38" (%7 : int)int -> {
            %8 : Var<int> = var %7 @"ii" @loc="90:38";
            %9 : int = var.load %8 @loc="91:25";
            %10 : int = constant @"0" @loc="91:30";
            %11 : boolean = lt %9 %10 @loc="91:25";
            cbranch %11 ^block_0_1_1 ^block_0_1_2;
          
          ^block_0_1_1:
            %12 : int = constant @"2" @loc="92:32";
            %13 : int = var.load %8 @loc="92:36";
            %14 : int = mul %12 %13 @loc="92:32";
            %15 : int = constant @"1" @loc="92:41";
            %16 : int = sub %14 %15 @loc="92:32";
            return %16 @loc="92:25";
          
          ^block_0_1_2:
            %17 : int = var.load %8 @loc="94:32";
            return %17 @loc="94:25";
          
          ^block_0_1_3:
            return @loc="90:38";
        };
        %18 : Var<java.util.function.IntUnaryOperator> = var %6 @"o" @loc="90:17";
        %19 : java.util.function.IntUnaryOperator = var.load %18 @loc="97:24";
        %20 : int = constant @"2" @loc="97:37";
        %21 : int = var.load %2 @loc="97:41";
        %22 : int = mul %20 %21 @loc="97:37";
        %23 : int = invoke %19 %22 @"java.util.function.IntUnaryOperator::applyAsInt(int)int" @loc="97:24";
        return %23 @loc="97:17";
      
      ^block_0_2:
        %24 : java.util.function.IntUnaryOperator = lambda @loc="99:38" (%25 : int)int -> {
            %26 : Var<int> = var %25 @"ii" @loc="99:38";
            %27 : int = var.load %26 @loc="100:25";
            %28 : int = constant @"0" @loc="100:30";
            %29 : boolean = lt %27 %28 @loc="100:25";
            cbranch %29 ^block_0_2_1 ^block_0_2_2;
          
          ^block_0_2_1:
            %30 : int = constant @"2" @loc="101:32";
            %31 : int = var.load %26 @loc="101:36";
            %32 : int = mul %30 %31 @loc="101:32";
            %33 : int = constant @"1" @loc="101:41";
            %34 : int = sub %32 %33 @loc="101:32";
            return %34 @loc="101:25";
          
          ^block_0_2_2:
            %35 : int = var.load %26 @loc="103:32";
            return %35 @loc="103:25";
          
          ^block_0_2_3:
            return @loc="99:38";
        };
        %36 : Var<java.util.function.IntUnaryOperator> = var %24 @"o" @loc="99:17";
        %37 : java.util.function.IntUnaryOperator = var.load %36 @loc="106:24";
        %38 : int = constant @"3" @loc="106:37";
        %39 : int = var.load %2 @loc="106:41";
        %40 : int = mul %38 %39 @loc="106:37";
        %41 : int = invoke %37 %40 @"java.util.function.IntUnaryOperator::applyAsInt(int)int" @loc="106:24";
        return %41 @loc="106:17";
      
      ^block_0_3:
        return @loc="88:31";
    };
    %42 : Var<java.util.function.IntUnaryOperator> = var %0 @"o1" @loc="88:9";
    %43 : java.io.PrintStream = field.load @"java.lang.System::out()java.io.PrintStream" @loc="109:9";
    %44 : java.util.function.IntUnaryOperator = var.load %42 @loc="109:28";
    %45 : int = constant @"10" @loc="109:42";
    %46 : int = invoke %44 %45 @"java.util.function.IntUnaryOperator::applyAsInt(int)int" @loc="109:28";
    invoke %43 %46 @"java.io.PrintStream::println(int)void" @loc="109:9";
    return @loc="86:5";

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

Commit messages:
 - OpWriter block naming alligned with block indexes

Changes: https://git.openjdk.org/babylon/pull/91/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=91&range=00
  Stats: 10 lines in 1 file changed: 9 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/babylon/pull/91.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/91/head:pull/91

PR: https://git.openjdk.org/babylon/pull/91