[PATCH] D152924: [libLTO][AIX] Respect `-f[no]-integrated-as` on AIX

[Qiongsi Wu via Phabricator via cfe-commits]

qiongsiwu1 added inline comments.


================
Comment at: clang/lib/Driver/ToolChains/CommonArgs.cpp:700
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine(PluginOptPrefix) + "-no-integrated-as=" + NoIntegratedAs));
+  else if (!UseIntegratedAs) {
----------------
shchenz wrote:
> qiongsiwu1 wrote:
> > shchenz wrote:
> > > Seems other options leverage the default value in the back end, for example the default value for `DisableIntegratedAS` in backend is false, so when the front end requires integrated-as, maybe we can save the option here?
> > Ah thanks for the comment! 
> > 
> > > maybe we can save the option here?
> > 
> > Could you help me understand what we mean by "the option"? Do we mean saving (or using?) the value of `-f[no]-integrated-as` explicitly here somehow instead of relying on `ToolChain.useIntegratedAs()`? How do we intend to use the saved option value? My understanding is that `DisableIntegratedAS` takes its value from the option `-no-integrated-as` if `-no-integrated-as` is specified. As pointed out eariler, `DisableIntegratedAS` is false by default. This code explicitly sets `-no-integrated-as` to `0` or `1`, so for the LTO use case, we overwrite the back end default since the option is always present. 
> For example, if front-end requires to use integrated-assembler which is same with back-end's default value, we don't need to pass `-no-integrated-as=0`? We only pass the option `-no-integrated-as=1` when `if (IsOSAIX && !UseIntegratedAs)`.
Ah I see! Thanks for the clarification! 

@w2yehia and I discussed this and we preferred setting the option explicitly regardless of the backend's default. The reason was that we did not want to leave a hanging case where the option was not passed to the backend, a case in which we would rely on a non-local option(`DisableIntegratedAS`)'s default value to control the backend. In other words, always passing in the option allowed us to reason about this code locally within this file. @w2yehia feel free to chime in if I am not describing our discussion correctly. 

Could you help me understand the benefit of not passing in the option for the default case? 


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  https://reviews.llvm.org/D152924/new/

https://reviews.llvm.org/D152924