allow passing jit option to superpmi.py replay

[AndyAyersMS]

No description provided.

[AndyAyersMS]

@BruceForstall PTAL
cc @dotnet/jit-contrib

I am using this to enable extra checking with my locally collected PGO MCH files, as part of tracking down where profiles become inconsistent:

superpmi.py replay -mch_files d:\bugs\spmi-pgo\tiered-pgo-9.mch --jitoption JitProfileChecks=2

[AndyAyersMS]

@kunalspathak maybe you can take a look?

[kunalspathak]

LGTM

[BruceForstall]

I guess you prefer this to setting an environment variable before invoking the python script? Seems like this feature might be more convenient in some scripting.

For consistency, though, I think the option should only have a single leading - : my understanding of the convention is that a single - switch takes an argument; a double -- does not.

[AndyAyersMS]

Ah, did not realize that was the convention, thought maybe -- was for more obscure options.

Do we document in superpmi.py that ambient COMPlus env vars are hoovered up and passed along as jitoption ?

I wasn't sure I could/should count on this.

[BruceForstall]

Do we document in superpmi.py that ambient COMPlus env vars are hoovered up and passed along as jitoption ?

superpmi.exe (implementing the host interface) itself reads the environment:

runtime/src/coreclr/ToolBox/superpmi/superpmi/jithost.cpp

Line 140 in a3ed2e2

const WCHAR* JitHost::getStringConfigValue(const WCHAR* key)

. It looks in this order:

1. -jitoption force
2. stored value in collection
3. -jitoption
4. environment

I also realized you only changed replay. You also want to set these for asmdiffs, in which case you need to add them to target_flags (probably):

runtime/src/coreclr/scripts/superpmi.py

Line 1570 in a3ed2e2

target_flags = []

. There are a set of flags that get passed to both the "determine asm diffs" command and each "generated textual asm", and you want these to be set for both. Currently, this is only the target and altjit-related commands, so the variable name is a bit specific to altjit, as complus vars are handled separately.