[PATCH] D102742: [IR] make stack-protector-guard-* flags into module attrs

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson added inline comments.


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Comment at: clang/include/clang/Driver/Options.td:3429
   HelpText<"Use the given reg for addressing the stack-protector guard">,
-  MarshallingInfoString<CodeGenOpts<"StackProtectorGuardReg">, [{"none"}]>;
+  MarshallingInfoString<CodeGenOpts<"StackProtectorGuardReg">>;
 def mfentry : Flag<["-"], "mfentry">, HelpText<"Insert calls to fentry at function entry (x86/SystemZ only)">,
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nickdesaulniers wrote:
> tejohnson wrote:
> > nickdesaulniers wrote:
> > > tejohnson wrote:
> > > > What's the effect of or reason for this change?
> > > Of the 3 options added in D88631 (`mstack_protector_guard_EQ`, `mstack_protector_guard_offset_EQ`, `mstack_protector_guard_reg_EQ`) 2 are strings (`mstack_protector_guard_EQ` and `mstack_protector_guard_reg_EQ`).  It was inconsistent that one could be unspecified, where as the other could be unspecified or `"none"` (but those 2 values were equivalent).
> > > 
> > > Without this change, in clang/lib/CodeGen/CodeGenModule.cpp I'd need to check that `StackProtectorGuardReg != "none"` rather than `!StackProtectorGuardReg.empty()` below.
> > > 
> > > I can change it back, but I think the asymmetry between `mstack_protector_guard_EQ` and `mstack_protector_guard_reg_EQ` in D88631, and I missed that in code review.
> > > 
> > > I don't think there would be any other observers of such a change.
> > I see. Does unspecified mean something like just "-mstack-protector-guard-reg=" with nothing after the =? I didn't realize that was supported.
> It looks like we validate for that case in the front end already. Specifically, `RenderAnalyzerOptions` in clang/lib/Driver/ToolChains/Clang.cpp.
> 
>     $ clang -mstack-protector-guard-reg= ...
>     clang-13: error: invalid value '' in 'mstack-protector-guard-reg='
Does that mean that without the "none" handling there is no way to disable? I.e. overriding an earlier value. Not sure how important this is.


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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102742/new/

https://reviews.llvm.org/D102742