[PATCH] D77231: [lld] Support -emit-asm with LTO

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a subscriber: pcc.
MaskRay added inline comments.


================
Comment at: lld/ELF/Driver.cpp:890
   config->emitLLVM = args.hasArg(OPT_plugin_opt_emit_llvm, false);
+  config->emitAsm = args.hasArg(OPT_lto_emit_asm, false);
   config->emitRelocs = args.hasArg(OPT_emit_relocs);
----------------
hoyFB wrote:
> hoyFB wrote:
> > grimar wrote:
> > > It looks inconsistent with another `OPT_lto*` options we have:
> > > 
> > > ```
> > >   config->ltoAAPipeline = args.getLastArgValue(OPT_lto_aa_pipeline);
> > >   config->ltoCSProfileGenerate = args.hasArg(OPT_lto_cs_profile_generate);
> > >   config->ltoCSProfileFile = args.getLastArgValue(OPT_lto_cs_profile_file);
> > > ...
> > > ```
> > > 
> > > Should it be called `config->ltoEmitAsm` to be consistent?
> > > 
> > > Or, instead, it could be `args.hasArg(OPT_plugin_opt_emit_asm, false)`, what also would make sense it seems.
> > > 
> > > What do other reviewers think?
> > Naming it ```config->ltoEmitAsm``` sounds good to me. If you look at the relationship between ```OPT_lto*``` and ```OPT_plugin_opt_*``` in lld, the later is always an alias of the former.
> Well, on the second thought, I'm thinking maybe just removing the `--lto-emit-asm` switch and only having `--plugin-opt=emit-asm`, since it is not lld-exclusive. What do you think?
`--plugin-opt=*` is for compatibility with gold. gold uses LLVMgold.so and the plugin interface does not allow insert arbitrary option on the fly. @pcc started to use `--lto-*` in D18667

Maybe he has some thoughts here.


================
Comment at: lld/ELF/Driver.cpp:1937
+  if (config->emitAsm)
+    return;
+
----------------
hoyFB wrote:
> grimar wrote:
> > grimar wrote:
> > > That the last 2 comments have a large common part. Also it seems that if `thinLTOIndexOnly`, `emitLLVM` and `emitAsm` were added at once and not separatelly, we would not split them. I think it might be better to rewrite these 3 comments into a single one and do:
> > > 
> > > ```
> > > // <A shorter and nicer comment here>
> > > if (config->thinLTOIndexOnly || config->emitLLVM || config->emitAsm)
> > >   return;
> > > ```
> > "That the last 2..." -> "Last 2..."
> Sounds good.
> `if (config->thinLTOIndexOnly || config->emitLLVM || config->emitAsm) return;`

+1


================
Comment at: lld/ELF/LTO.cpp:312
+    for (unsigned i = 1; i != maxTasks; ++i)
+      saveBuffer(buf[i], config->outputFile + Twine(i));
+    return {};
----------------
To be honest, the output file naming (--save-temps and the new emit-asm) here also looks strange to me. Why is 1 special cased? @pcc @tejohnson 


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77231/new/

https://reviews.llvm.org/D77231