Fix fat call transform for x86

[MichalStrehovsky]

AddArgumentToTail with a null first argument will AV.

I think this also works with methods that take a return buffer (methods that return large structs), but might require a pair of eyes more experienced in this codebase.

[sandreenko]

I think this also works with methods that take a return buffer (methods that return large structs), but might require a pair of eyes more experienced in this codebase.

Could you please explain that to me? What is special about methods with a return buffer in the context of this change?

[MichalStrehovsky]

I think this also works with methods that take a return buffer (methods that return large structs), but might require a pair of eyes more experienced in this codebase.

Could you please explain that to me? What is special about methods with a return buffer in the context of this change?

The #if branch for the #else that I'm touching here is handling fatCall->HasRetBufArg(). I was wondering if I need to handle it in the #else too, but things seem to work without that.

[sandreenko]

The #if branch for the #else that I'm touching here is handling fatCall->HasRetBufArg(). I was wondering if I need to handle it in the #else too, but things seem to work without that.

Got it, yes, I have checked that and it is correct, gtPrependNewCallArg can handle args = nullptr.

[sandreenko]

LGTM, thank you.

[mikedn]

Shouldn't this check actually be in AddArgumentToTail?

[MichalStrehovsky]

We would have to change the signature of the method and either pass fatCall->gtCallArgs by reference or have it return a Use* that we can assign. Doable, but I already merged this and I really dislike dealing with the JIT code formatter (which I'm sure would moan about something).

[AndyAyersMS]

@MichalStrehovsky if you use jitutils then jit code formatting is pretty simple

• clone jitutils repo
• run bootstrap.cmd from repo root
• cd to your runtime repo
• run jit-format --fix --untidy --runtime src\coreclr

[MichalStrehovsky]

@AndyAyersMS thanks! I'm bookmarking your comment