tblah added inline comments.
================ Comment at: flang/include/flang/Frontend/LangOptions.h:29 + + // Enable the floating point pragma + FPM_On, ---------------- vzakhari wrote: > tblah wrote: > > awarzynski wrote: > > > What are these pragmas? Perhaps you can add a test that would include > > > them? > > I copied this comment from clang. I believe the pragma is > > ``` > > #pragma clang fp contract(fast) > > ``` > > > > See > > https://clang.llvm.org/docs/LanguageExtensions.html#extensions-to-specify-floating-point-flags > > > > This patch only adds support for argument processing, so I can't test for > > the pragmas. > I do not think we should blindly copy this from clang. I believe > `-ffp-contract=on` is there to do the contraction complying to the language > standard - but Fortran standard says nothing about contraction. I am also > not aware about a Fortran compiler that supports directives related to > contraction, so `fast-honor-pragmas` does not seem to be applicable as well. > Basically, we end up with just `off` and `fast`. > > Now, it may be reasonable to support the same `-ffp-contract=` arguments so > that users can apply the same options sets for C/C++ and Fortran > compilations. If we want to do this, we need to map `on` and > `fast-honor-pragmas` to something, e.g. `fast`. A driver warning (not an > error) may be useful to make the option's behavior clear when `on` and > `fast-honor-pragmas` are passed. From the clang help text: ``` Form fused FP ops (e.g. FMAs): fast (fuses across statements disregarding pragmas) | on (only fuses in the same statement unless dictated by pragmas) | off (never fuses) Default is 'on' ``` So if we removed `on` and set the default to `off` we would no longer fuse within the same statement by default. Classic-flang seems to support `on`, `off` and `fast`: https://github.com/flang-compiler/flang/blob/master/test/llvm_ir_correct/fma.f90 ================ Comment at: flang/test/Driver/driver-help-hidden.f90:34 ! CHECK-NEXT: Use <value> as character line width in fixed mode +! CHECK-NEXT: -ffp-contract=<value> Form fused FP ops (e.g. FMAs): fast (fuses across statements disregarding pragmas) | on (only fuses in the same statement unless dictated by pragmas) | off (never fuses) | fast-honor-pragmas (fuses across statements unless diectated by pragmas). Default is 'fast' for CUDA, 'fast-honor-pragmas' for HIP, and 'on' otherwise. ! CHECK-NEXT: -ffree-form Process source files in free form ---------------- vzakhari wrote: > Is it easy to emit a different help message for Flang to say that there are > only two modes for Fortran? @awarzynski tells me there is no way to do this short of having separate `Options.td` for flang and clang. Once we have settled on which arguments to support, I will update the shared help text to mention flang. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D136080/new/ https://reviews.llvm.org/D136080 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
