[PATCH] D157451: [AMDGPU] Do not deduce access qualifiers from IR attributes

[Changpeng Fang via Phabricator via llvm-commits]

cfang added inline comments.


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Comment at: llvm/test/CodeGen/AMDGPU/hsa-metadata-deduce-ro-arg-v3.ll:26
 }
 
 !0 = !{i32 1, i32 1}
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rampitec wrote:
> arsenm wrote:
> > cfang wrote:
> > > arsenm wrote:
> > > > cfang wrote:
> > > > > arsenm wrote:
> > > > > > This looks like lost test coverage, need to test the access of the metadata
> > > > > Under V3, if the access is default, it won't print out "default", (will not print out the access qualifier at all).
> > > > > 
> > > > > But I am curious because "noalias readonly %in", why the access is not "readonly"? Does it mean the original access qualifier got lost? 
> > > > the point of this is introspection of the source program, not the actual properties. if someone defines something as readwrite but is only ever read, the optimizer can conclude it's readonly even though it wasn't declared that way
> > > Under V3 or above, it is designed NOT to print out the access qualifier if it is "default". 
> > > Do you want to CHECK-NOT for :access" for the default?
> > > 
> > > 
> > > 
> > -NEXT checks are safer than -NOT
> Right, this can be deduced and had quite positive performance impact on some kernels.
It seems we are using the same AccQual field for two purposes: 1) optimization, 2) get_kernel_arg_info.AccessQualifier, and 
the second one is expected from  getMetadata("kernel_arg_access_qual")


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https://reviews.llvm.org/D157451