arsenm added inline comments.
================
Comment at: clang/lib/CodeGen/CGCall.cpp:2030-2031
+ bool EnabledForTarget = TEntry->second;
+ if (EnabledForTarget != EnabledForFunc)
+ return;
+ }
----------------
jmmartinez wrote:
> arsenm wrote:
> > Early return breaks the other features
> I did not understand this remark.
>
> If the features are not compatible, we do not add a "target-features" entry
> in the new "FuncAttrs". Then, the old "target-features" entry is kept in the
> Function coming from the builtin.
>
> If you think it would be better to set the target-features in FuncAttrs to
> the old value in any case. If that's the case I've added the following code:
>
> if (EnabledForTarget != EnabledForFunc) {
> FuncAttr.addAttribute(FFeatures);
> return;
> }
You find an incompatible feature and then discontinue processing any further
features by early exiting. I expect this to act like an append to any features
already present. The incompatibility is at an individual feature level, not the
group
================
Comment at: clang/lib/CodeGen/CGCall.cpp:2034
+ }
+
+ FuncAttr.addAttribute("target-features", llvm::join(MergedFeatures, ","));
----------------
jmmartinez wrote:
> arsenm wrote:
> > Really it would be less bad if the incompatible functions were not imported
> > rather than the backend pass
> I thought it was possible to have functions with incompatible features in the
> same module.
> e.g. one function compiled with some instruction set support, one without,
> and an ifunc that resolves to one or the other.
>
> Maybe it's not the case in the context of `-mlink-builtin-bitcode`?
The truth is this system isn't really well considered. We don't have real ifunc
support and we probably shouldn't be using subtargets for cases with
incompatible encodings
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D159206/new/
https://reviews.llvm.org/D159206
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