dang added inline comments.

================
Comment at: clang/test/CodeGen/fp-function-attrs.cpp:2
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -ffast-math -ffinite-math-only 
-menable-unsafe-fp-math \
+// RUN:   -menable-no-infs -menable-no-nans -fno-signed-zeros 
-freciprocal-math \
+// RUN:   -fapprox-func -mreassociate -ffp-contract=fast -emit-llvm -o - %s | 
FileCheck %s
----------------
Anastasia wrote:
> dang wrote:
> > Anastasia wrote:
> > > dang wrote:
> > > > Anastasia wrote:
> > > > > Not clear why do you need to pass these extra flags now?
> > > > Previously passing -ffast-math to CC1 implied all these other flags. I 
> > > > am trying to make CC1 option parsing as simple as possible, so that we 
> > > > can then make it easy to generate a command line from a 
> > > > CompilerInvocation instance. You can refer to [[ 
> > > > http://lists.llvm.org/pipermail/cfe-dev/2020-May/065421.html | 
> > > > http://lists.llvm.org/pipermail/cfe-dev/2020-May/065421.html ]] for 
> > > > more details on why we want to be able to do this
> > > Just to understand, there used to be implied flags and it made the manual 
> > > command line use of clang more compact and easy... Is the idea now to 
> > > change those compound flags such that individul flags always need to be 
> > > passed?
> > > 
> > > Although I thought you are still adding the implicit flags:
> > > 
> > >           {options::OPT_cl_fast_relaxed_math,
> > >            [&](const Arg *Arg) {
> > >              RenderArg(Arg);
> > > 
> > >              CmdArgs.push_back(GetArgString(options::OPT_cl_mad_enable));
> > >              CmdArgs.push_back(GetArgString(options::OPT_ffast_math));
> > >              
> > > CmdArgs.push_back(GetArgString(options::OPT_ffinite_math_only));
> > >              CmdArgs.push_back(
> > >                  GetArgString(options::OPT_menable_unsafe_fp_math));
> > >              CmdArgs.push_back(GetArgString(options::OPT_mreassociate));
> > >              
> > > CmdArgs.push_back(GetArgString(options::OPT_menable_no_nans));
> > >              CmdArgs.push_back(
> > >                  GetArgString(options::OPT_menable_no_infinities));
> > >              
> > > CmdArgs.push_back(GetArgString(options::OPT_fno_signed_zeros));
> > >              
> > > CmdArgs.push_back(GetArgString(options::OPT_freciprocal_math));
> > >              CmdArgs.push_back(GetArgString(options::OPT_fapprox_func));
> > >            }}
> > > 
> > > Do I just misunderstand something?
> > The command line of the driver doesn't change. This patch only affects what 
> > CC1 understands, now CC1 doesn't know anymore that `-cl-fast-relaxed-math` 
> > implies all these other options so the driver is responsible for specifying 
> > them when it constructs the CC1 command line.
> > 
> > To summarize, the clang driver command line isn't affected by this patch 
> > and it shouldn't be so let me know if something is wrong there. However, 
> > manually constructed `clang -cc1` invocations need to specify the all the 
> > implied flags manually now.
> Yes I understand, however, I am wondering whether this is intuitive because 
> it seems the behavior of clang with `-cc1` and without will be different if 
> the same `-cl-fast-relaxed-math` flag is passed.
> 
> I also find adding all the flags manually is too verbode if 
> `-cl-fast-relaxed-math` assumes to enable all the extra setting.
My understanding is that `-cc1` is an internal interface, so end-users should 
never use `-cc1` directly and/or rely on itss interface. It is already the case 
that flags mean very different things to the driver and `-cc1` for example 
"--target=" and "-triple". Furthermore, this impacted very few tests which 
leads me to believe that few compiler developers actually rely on this behavior.

Do you think this would be a major inconvenience to compiler developers to have 
to manually expand it out?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82756/new/

https://reviews.llvm.org/D82756

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