[PATCH] Allow opt to run pass that needs target machine.

[Andrew Trick]

On Jan 15, 2014, at 12:18 PM, Quentin Colombet <qcolombet at apple.com> wrote:

> Hi,
> 
> The attached patch adds the machinery into opt to enable testing passes that use target machine information.
> Thanks for your review.
> 
> ** Context **
> 
> opt is a great tool to test/play with IR to IR passes. However, opt is not able to feed a pass with target machine information (like TargetLowering) and this prevents the testing (or an easy testing) of the meaty part of some passes (e.g., codegenprepare). 
> 
> 
> ** Proposed Solution **
> 
> When registering a pass, a pass can now specify a second construct that takes as argument a pointer to TargetMachine.
> The PassInfo class has been updated to reflect that possibility.
> If such a constructor exists opt will use it instead of the default constructor when instantiating the pass.
> 
> A pass can specify that it supports the second constructor by using the new INITIALIZE_PASSxxx_WITH_TM as illustrated in codegenprepare.
> 
> A subsequent patch will make use of this feature to better test codegenprepare on something I am currently working.

I agree, we need to be able to test codegenprepare. We don’t want to expose this interface to other passes though. IR passes should go through TTI instead.

Hardcoding a check for codegenprepare within opt.cpp isn’t great either. As we discussed in person, a good compromise would be to directly call setTargetMachineCtor from CodeGenPrepare so we don’t need the INITIALIZE_PASS…WITH_TM macros.

-Andy