dylanmckay added inline comments.
================
Comment at: llvm/lib/IR/AutoUpgrade.cpp:4297
+ // address space of 1.
+ if (T.isAMDGPU() && !DL.contains("-G") && !DL.startswith("G")) {
+ return DL.empty() ? std::string("G1") : (DL + "-G1").str();
----------------
arichardson wrote:
> akhuang wrote:
> > arichardson wrote:
> > > arsenm wrote:
> > > > I would expect datalayout upgrades to work by parsing the old string,
> > > > and checking the field values inside. I guess directly checking the
> > > > string isn't a new problem here
> > > I agree that would be less error prone. I wonder if there are cases where
> > > the old string may fail to parse so you have to do the textual upgrade
> > > first. I'm happy to make this change.
> > >
> > > @akhuang is there a reason you used string parsing in D67631? Any
> > > objections to changing the code to parse the datalayout and add missing
> > > attributes?
> > I don't think so; parsing the datalayout sounds better to me too.
> I just looked into parsing the DataLayout instead. Unfortunately the
> resulting code is more complicated since there are no setters in DataLayout
> and no way to create a normalized representation.
> There's also no way to differentiate between no `-G ` passed and `-G0` so
> something like `e-p:64:64-G0` will be converted to `e-p:64:64-G0-G1`
>
I suspect it would be possible to use the existing `DataLayout(StringRef)`
constructor on the string, then call `getDefaultGlobalsAddressSpace()` on it,
explicitly ignoring modifying the datalayout for the special case of an
explicit `-G0`.
For example,
```cpp
DataLayout ParsedDL = DataLayout(DL);
if (T.isAMDGPU() && !DL.contains("-G0")
&&ParsedDL.getDefaultGlobalsAddressSpace() != 1) {
return DL.empty() ? std::string("G1") : (DL + "-G1").str();
}
```
As I understand it, this would cover the fact that we cannot distinguish
between an explicit default globals space of zero, and a datalayout without a
default globals space (also `DL::getDefaultGlobalsAddressSpace() == 0`) by
explicitly excluding the special case `-G0`
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D84345/new/
https://reviews.llvm.org/D84345
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