[PATCH] D46315: [RegUsageInfoCollector] Fix handling of callee saved registers with CSR optimization.

[Jonas Paulsson via Phabricator via llvm-commits]

jonpa requested review of this revision.
jonpa added inline comments.


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Comment at: lib/CodeGen/RegUsageInfoCollector.cpp:149
+          << " function optimized for not having CSR.\n");
   }
 
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qcolombet wrote:
> jonpa wrote:
> > qcolombet wrote:
> > > This logging is not very useful now. I would get rid of it.
> > Do you want to remove this entire clause of just the dbgs() output?
> > 
> > I might object a little to removing this, since I have made SystemZ tests that checks for this, for instance to check that the return register is saved even on such a function:
> > 
> > ```
> > ; DBG: fun3 function optimized for not having CSR
> > ; CHECK-LABEL: fun3
> > ​; CHECK: stmg    %r14, %r15, 112(%r15)
> > ​; CHECK: lr      %r14
> > ​; CHECK: a       %r14
> > ​; CHECK: lmg     %r14, %r15, 112(%r15)
> > ​; CHECK: br      %r14
> > 
> > ```
> > It also seems useful to IPRA to have the statistic around...
> > 
> To me the logging is not useful anymore because there is no change of behavior in the past itself based on isSafeForNoCSROpt.
> It looks to me that we are printing this because we expect determineCalleeSaved to do the right thing with it, but that's a big assumption :).
Unless you object, I'll keep it there, since I think this should be reported in the logs at least somewhere (and not by every backend).



https://reviews.llvm.org/D46315