Currently we have no stats for anything regarding the tier 2 optimizer.
Without them we are making too many guesses about what we should be doing.

The performance numbers tell us that things aren't working as well as they should, although not too badly either.
However, performance numbers tell us nothing about why that is, or what is happening.

For example, #109038 should have increased the important ratio of (number of uops executed)/(traces started) but we have no idea if it actually did.

We need the following stats soon:

• Total micro-ops executed
• Total number of traces started
• Total number of traces created
• Optimization attempts

The following stats would also be nice, but are less urgent:

• Per uop execution counts, like we have for tier 1 instructions.
• Exit reason counts: polymorphism vs branch mis-prediction
• A histogram of uops executed per trace

Linked PRs

• gh-109329: Support for basic pystats for Tier 2 #109913
• gh-109329: Add stat for "trace too short" #110402
• gh-109329: Count tier2 miss opcodes #110561