[llvm] [PGO]add bitcode-use-sample-profile (PR #66178)

[Teresa Johnson via llvm-commits]

teresajohnson wrote:

> > Also, if you are going to use an internal attribute, how about using the existing -mllvm -force-attribute=use-sample-profile. The ForceFunctionAttrs pass runs early in the ThinLTO pre-link pipeline, before sample pgo.
> 
> `-force-attribute` needs a function name, like ` -force-attribute=foo:use-sample-profile`, so it is unfeasible to apply it to every function in the IR. Although it is quite easy to add support for wildcard like ` -force-attribute=*:use-sample-profile` and I think this sounds like an elegant solution

I haven't personally tried this option, but the documentation of the option indicates that if no function name is given the attribute gets applied to all functions in the module:

static cl::list<std::string> ForceAttributes(
    "force-attribute", cl::Hidden,
    cl::desc(
        "Add an attribute to a function. This can be a "
        "pair of 'function-name:attribute-name', to apply an attribute to a "
        "specific function. For "
        "example -force-attribute=foo:noinline. Specifying only an attribute "
        "will apply the attribute to every function in the module. This "
        "option can be specified multiple times."));

https://github.com/llvm/llvm-project/pull/66178