vsk added a comment.
Sorry for the delay here.
================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:793
Opts.EnableDebugEntryValues = Args.hasArg(OPT_femit_debug_entry_values);
+ Opts.EmitCallSiteInfo = true;
+ }
----------------
djtodoro wrote:
> vsk wrote:
> > I don't understand how Opts.EnableDebugEntryValues and
> > Opts.EmitCallSiteInfo are different. What is the second option supposed to
> > control, that the first option does not? I thought we could already
> > suppress entry values in llvm at -O0 + -g.
> >
> > Is `EmitCallSiteInfo = false` supposed to disable TAG_call_site emission?
> I'll try to describe the difference between Call Site Info and entry values.
>
> Entry values (call-site-params and dbg-values with dw_op_entry_val) are
> features from debug info. The call-site-params are extension of the call-site
> (`TAG_call_site`) debug info. Since the emission of the `TAG_call_site` was
> already restricted to `-O>0 + -g` in the `constructCallSiteEntryDIEs()`
> (there is a code checking the existence of the `AllCallsDescribed`), that
> implies the `collectCallSiteParameters()` will be called for that combination
> only (since it is being called in the `constructCallSiteEntryDIEs()`).
> Further on, the `collectCallSiteParameters()` will call the
> `describeLoadedValue()`, which is target-dependent method, and it is
> implemented only for x86, arm and aarch64 targets at the moment, so we need
> to restrict the emission of call-site-params only to the targets.
>
> The Call Site Info is utility helping us implementing the entry values. We
> did not have the information about arguments forwarding (necessary for
> implementing the `describeLoadedValue()` by searching for the values loaded
> into the forwarding registers), so the conclusion was to add such info as
> `MF` attribute (callSites:). In addition, there were thoughts the attribute
> could be used by other places in LLVM, but currently it is being used only by
> Debug Entry Values feature. My understanding is the `MF` attribute is
> different thing to the Debug Entry Values, and we can not restrict the
> production of such attribute by looking at the Debug Info Metadata (for
> example by looking at the `AllCallsDescribed` flag), so that is why I added
> the additional flag.
>
>
> > Is EmitCallSiteInfo = false supposed to disable TAG_call_site emission?
> No, it should restrict only the `callSites` `MF` attribute.
>
Thanks for explaining, this sgtm.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D75175/new/
https://reviews.llvm.org/D75175
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