michele.scandale added inline comments.
================
Comment at: clang/include/clang/Basic/LangOptions.h:396-401
+ allow_reassoc(LangOpts.FastMath || LangOpts.AllowFPReassoc),
+ no_nans(LangOpts.FastMath || LangOpts.NoHonorNaNs),
+ no_infs(LangOpts.FastMath || LangOpts.NoHonorInfs),
+ no_signed_zeros(LangOpts.FastMath || LangOpts.NoSignedZero),
+ allow_reciprocal(LangOpts.FastMath || LangOpts.AllowRecip),
+ approx_func(LangOpts.FastMath || LangOpts.ApproxFunc) {}
----------------
Same comment on `LangOpts.FastMath || ` as the one for `CompilerInvocation.cpp`.
================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:3190-3196
+ Opts.AllowFPReassoc = Opts.FastMath || CGOpts.Reassociate;
+ Opts.NoHonorNaNs =
+ Opts.FastMath || CGOpts.NoNaNsFPMath || Opts.FiniteMathOnly;
+ Opts.NoHonorInfs =
+ Opts.FastMath || CGOpts.NoInfsFPMath || Opts.FiniteMathOnly;
+ Opts.NoSignedZero = Opts.FastMath || CGOpts.NoSignedZeros;
+ Opts.AllowRecip = Opts.FastMath || CGOpts.ReciprocalMath;
----------------
Why do we need `Opts.FastMath || ` here? The code in the compiler driver
`clang/lib/Driver/ToolChains/Clang.cpp`
(https://github.com/llvm/llvm-project/blob/master/clang/lib/Driver/ToolChains/Clang.cpp#L2510)
already takes care of generating the right flags for the CC1 to configure the
floating point rules.
Moreover, if we ignore what the compiler driver does, the fact that
`Args.hasArg(OPT_ffast_math)` is not considered in the definition of the
codegen options such as `NoInfsFPMath`, `NoNaNsFPMath`, `NoSignedZeros`,
`Reassociate`, so the you have already two distinct options for the same
abstract property that might not match.
I think that at the CC1 level the reasoning should be done in terms of the fine
grain options, and let the compiler driver makes life easy for the users --
i.e. `LangOpts.FastMath` should just control whether the macro `__FAST_MATH__`
is defined or not.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D72841/new/
https://reviews.llvm.org/D72841
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