Currently, when using COMPlus_JitGCDump/COMPlus_NgenGCDump, GC info is displayed in a block at the end of compilation.

Create options that allow the information to be interleaved into the asm dumped with COMPlus_JitDisasm/COMPlus_NgenDisasm. These options would be in addition to the current ones, which are still useful.

Interleaved output allows us to always add GC info into our asm diffs process. Currently, adding GC info into asm diffs requires enabling adding (back) instruction offsets into the asm output, because GC info is based on asm offsets. But adding these means that as soon as there is a single new instruction, or change in encoding size of an instruction, then all subsequent instructions in the function show up as a diff. This is really noisy. Thus, we rarely if ever pay attention to GC info diffs, which we should.

Note that the JIT dump does emit interleaved GC info as part of the "Instructions as they come out of the scheduler" phase. It would be better if the interleaved GC info dump suggested here come from decoding the fully generated GC info, the way the SOS !u -gcinfo command does it. Perhaps the code for !u -gcinfo could be borrowed for this (see dotnet/diagnostics#403).

Changes should be made to jit-diff and possibly jit-analyze (https://github.com/dotnet/jitutils), and to superpmi.py, to use these new options.

category:implementation
theme:asmdiffs
skill-level:beginner
cost:small
impact:small