Allow FEATURE_INTERPRETER to be enabled by command-line option

[parjong]

No description provided.

[BruceForstall]

Who is going to define the cmake FEATURE_INTERPRETER variable? What platforms/configurations do you expect to enable the interpreter?

[BruceForstall]

cc @dotnet/jit-contrib

[parjong]

@BruceForstall I would like to take a look it just for fun.

[parjong]

To be more specific, I recently read this article, and have interested in the interpreter internal.

[BruceForstall]

Presumably you could just add the

add_definitions(-DFEATURE_INTERPRETER)

in a private branch. Why do you need to merge this change? I'm no cmake expert: how does merging this change make it easier?

Bottom-line: I don't want there to be any chance the interpreter is accidentally compiled in by default.

[parjong]

This PR allows users to enable FEATURE_INTERPERTER using the following command-line:

$ ./build.sh cmakeargs "-DFEATURE_INTERPRETER=1" ...

I want to build and test this feature without additional patch, but I also do not want to turn it default. I updated PR not to turn on this feature accidentally. FEATURE_INTERPRETER will be turned on only when users provide the additional command-line option mentioned above.

[mattwarren]

@parjong glad your found the blog post useful, it was fun to write!

BTW if you want to get all the statistics printed out at the end of a program run, you also need to make the following changes in interpreter.h, I didn't cover that in the post

// If this is set, we keep track of extra information about IL instructions executed per-method.
-#define INTERP_PROFILE 0
+#define INTERP_PROFILE 1

// If this is set, we track the distribution of IL instructions.
-#define INTERP_ILINSTR_PROFILE 0
+#define INTERP_ILINSTR_PROFILE 1

[parjong]

@mattwarren Thanks you for comment 👍 I'll try.