r226915 - Process the -fno-signed-zeros optimization flag (PR20870)
Tom Stellard
tom at stellard.net
Tue Apr 7 17:59:05 PDT 2015
On Tue, Apr 07, 2015 at 05:45:20PM -0700, Richard Smith wrote:
> On Tue, Apr 7, 2015 at 4:36 PM, Tom Stellard <tom at stellard.net> wrote:
>
> > On Tue, Apr 07, 2015 at 03:11:44PM -0700, Richard Smith wrote:
> > > On Tue, Apr 7, 2015 at 3:05 PM, Tom Stellard <tom at stellard.net> wrote:
> > >
> > > > On Fri, Jan 23, 2015 at 04:40:50PM -0000, Sanjay Patel wrote:
> > > > > Author: spatel
> > > > > Date: Fri Jan 23 10:40:50 2015
> > > > > New Revision: 226915
> > > > >
> > > > > URL: http://llvm.org/viewvc/llvm-project?rev=226915&view=rev
> > > > > Log:
> > > > > Process the -fno-signed-zeros optimization flag (PR20870)
> > > > >
> > > > > The driver currently accepts but ignores the -fno-signed-zeros flag.
> > > > > This patch passes the flag through and enables 'nsz' fast-math-flag
> > > > > generation in IR.
> > > > >
> > > > > The existing OpenCL flag for the same functionality is made into an
> > > > > alias here. It may be removed in a subsequent patch.
> > > > >
> > > >
> > > > What is the reason for removing this option? This will break OpenCL
> > > > implementations that use clang.
> > >
> > >
> > > We do not provide any stability guarantees for Clang's -cc1 interface in
> > > general. Are these implementations running -cc1 directly, or passing this
> > > flag via -Xclang? If the latter, we should add a proper (stable)
> > > driver-level flag for it.
> > >
> >
> > I understand there are no stability guarantees, but regardless I feel
> > like it's useful to keep it around as an alias since it is part of
> > the OpenCL spec. Is there a high cost involved in keeping it?
> >
>
> It's not really reasonable to expect Clang's -cc1 to implement the flags
> required by the OpenCL spec. Your OpenCL driver should be recognizing those
> flags and handling them in whatever manner is appropriate.
>
What's the difference between -cc1 flags and 'proper driver-level flags' ?
> In the OpenCL implementation I'm working on (clover), we are using the
> > C++ API, so the argument is being passed via:
> > clang::CompilerInvocation::CreateFromArgs()
>
>
> Could you instead set NoSignedZeros directly on the CodeGenOptions of the
> CompilerInvocation after calling CreateFromArgs?
I could do this, but I'm wondering if there still might be a way to add
the OpenCL flags to clang. It is still useful if you want to do offline
compilation.
-Tom
>
> -Tom
> >
> >
> >
> > > -Tom
> > > >
> > > > > This should resolve bug 20870 (
> > > > http://llvm.org/bugs/show_bug.cgi?id=20870 );
> > > > > patches for the optimizer were checked in at:
> > > > > http://llvm.org/viewvc/llvm-project?view=revision&revision=225050
> > > > > http://llvm.org/viewvc/llvm-project?view=revision&revision=224583
> > > > >
> > > > > Differential Revision: http://reviews.llvm.org/D6873
> > > > >
> > > > >
> > > > > Modified:
> > > > > cfe/trunk/include/clang/Driver/CC1Options.td
> > > > > cfe/trunk/include/clang/Driver/Options.td
> > > > > cfe/trunk/lib/Driver/Tools.cpp
> > > > > cfe/trunk/lib/Frontend/CompilerInvocation.cpp
> > > > > cfe/trunk/test/CodeGen/finite-math.c
> > > > > cfe/trunk/test/Driver/fast-math.c
> > > > >
> > > > > Modified: cfe/trunk/include/clang/Driver/CC1Options.td
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/CC1Options.td?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/include/clang/Driver/CC1Options.td (original)
> > > > > +++ cfe/trunk/include/clang/Driver/CC1Options.td Fri Jan 23 10:40:50
> > 2015
> > > > > @@ -580,7 +580,7 @@ def cl_finite_math_only : Flag<["-"], "c
> > > > > HelpText<"OpenCL only. Allow floating-point optimizations that
> > assume
> > > > arguments and results are not NaNs or +-Inf.">;
> > > > > def cl_kernel_arg_info : Flag<["-"], "cl-kernel-arg-info">,
> > > > > HelpText<"OpenCL only. Generate kernel argument metadata.">;
> > > > > -def cl_no_signed_zeros : Flag<["-"], "cl-no-signed-zeros">,
> > > > > +def : Flag<["-"], "cl-no-signed-zeros">, Alias<fno_signed_zeros>,
> > > > > HelpText<"OpenCL only. Allow optimizations to ignore the
> > signedness
> > > > of the floating-point zero.">;
> > > > > def cl_unsafe_math_optimizations : Flag<["-"],
> > > > "cl-unsafe-math-optimizations">,
> > > > > HelpText<"OpenCL only. Allow unsafe floating-point optimizations.
> > > > Also implies -cl-no-signed-zeros and -cl-mad-enable">;
> > > > >
> > > > > Modified: cfe/trunk/include/clang/Driver/Options.td
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/include/clang/Driver/Options.td (original)
> > > > > +++ cfe/trunk/include/clang/Driver/Options.td Fri Jan 23 10:40:50
> > 2015
> > > > > @@ -566,7 +566,9 @@ def fno_reciprocal_math : Flag<["-"], "f
> > > > > def ffinite_math_only : Flag<["-"], "ffinite-math-only">,
> > > > Group<f_Group>, Flags<[CC1Option]>;
> > > > > def fno_finite_math_only : Flag<["-"], "fno-finite-math-only">,
> > > > Group<f_Group>;
> > > > > def fsigned_zeros : Flag<["-"], "fsigned-zeros">, Group<f_Group>;
> > > > > -def fno_signed_zeros : Flag<["-"], "fno-signed-zeros">,
> > Group<f_Group>;
> > > > > +def fno_signed_zeros :
> > > > > + Flag<["-"], "fno-signed-zeros">, Group<f_Group>,
> > Flags<[CC1Option]>,
> > > > > + HelpText<"Allow optimizations that ignore the sign of floating
> > point
> > > > zeros">;
> > > > > def fhonor_nans : Flag<["-"], "fhonor-nans">, Group<f_Group>;
> > > > > def fno_honor_nans : Flag<["-"], "fno-honor-nans">, Group<f_Group>;
> > > > > def fhonor_infinities : Flag<["-"], "fhonor-infinities">,
> > > > Group<f_Group>;
> > > > >
> > > > > Modified: cfe/trunk/lib/Driver/Tools.cpp
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/lib/Driver/Tools.cpp (original)
> > > > > +++ cfe/trunk/lib/Driver/Tools.cpp Fri Jan 23 10:40:50 2015
> > > > > @@ -2955,6 +2955,8 @@ void Clang::ConstructJob(Compilation &C,
> > > > > !TrappingMath)
> > > > > CmdArgs.push_back("-menable-unsafe-fp-math");
> > > > >
> > > > > + if (!SignedZeros)
> > > > > + CmdArgs.push_back("-fno-signed-zeros");
> > > > >
> > > > > // Validate and pass through -fp-contract option.
> > > > > if (Arg *A = Args.getLastArg(options::OPT_ffast_math,
> > > > FastMathAliasOption,
> > > > >
> > > > > Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
> > > > > +++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Fri Jan 23 10:40:50
> > > > 2015
> > > > > @@ -441,7 +441,7 @@ static bool ParseCodeGenArgs(CodeGenOpti
> > > > >
> > Args.hasArg(OPT_cl_unsafe_math_optimizations) ||
> > > > > Args.hasArg(OPT_cl_finite_math_only) ||
> > > > > Args.hasArg(OPT_cl_fast_relaxed_math));
> > > > > - Opts.NoSignedZeros = Args.hasArg(OPT_cl_no_signed_zeros);
> > > > > + Opts.NoSignedZeros = Args.hasArg(OPT_fno_signed_zeros);
> > > > > Opts.NoZeroInitializedInBSS =
> > > > Args.hasArg(OPT_mno_zero_initialized_in_bss);
> > > > > Opts.BackendOptions = Args.getAllArgValues(OPT_backend_option);
> > > > > Opts.NumRegisterParameters = getLastArgIntValue(Args,
> > OPT_mregparm,
> > > > 0, Diags);
> > > > >
> > > > > Modified: cfe/trunk/test/CodeGen/finite-math.c
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/finite-math.c?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/test/CodeGen/finite-math.c (original)
> > > > > +++ cfe/trunk/test/CodeGen/finite-math.c Fri Jan 23 10:40:50 2015
> > > > > @@ -1,11 +1,15 @@
> > > > > -// RUN: %clang_cc1 -ffinite-math-only -emit-llvm -o - %s |
> > FileCheck %s
> > > > > +// RUN: %clang_cc1 -ffinite-math-only -emit-llvm -o - %s |
> > FileCheck %s
> > > > -check-prefix=CHECK -check-prefix=FINITE
> > > > > +// RUN: %clang_cc1 -fno-signed-zeros -emit-llvm -o - %s | FileCheck
> > %s
> > > > -check-prefix=CHECK -check-prefix=NSZ
> > > > > +
> > > > > float f0, f1, f2;
> > > > >
> > > > > void foo(void) {
> > > > > // CHECK-LABEL: define void @foo()
> > > > >
> > > > > - // CHECK: fadd nnan ninf
> > > > > + // FINITE: fadd nnan ninf
> > > > > + // NSZ: fadd nsz
> > > > > f0 = f1 + f2;
> > > > >
> > > > > // CHECK: ret
> > > > > }
> > > > > +
> > > > >
> > > > > Modified: cfe/trunk/test/Driver/fast-math.c
> > > > > URL:
> > > >
> > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/fast-math.c?rev=226915&r1=226914&r2=226915&view=diff
> > > > >
> > > >
> > ==============================================================================
> > > > > --- cfe/trunk/test/Driver/fast-math.c (original)
> > > > > +++ cfe/trunk/test/Driver/fast-math.c Fri Jan 23 10:40:50 2015
> > > > > @@ -25,6 +25,21 @@
> > > > > // CHECK-NO-INFS-NO-FAST-MATH: "-cc1"
> > > > > // CHECK-NO-INFS-NO-FAST-MATH-NOT: "-menable-no-infs"
> > > > > //
> > > > > +// RUN: %clang -### -fno-signed-zeros -c %s 2>&1 \
> > > > > +// RUN: | FileCheck --check-prefix=CHECK-NO-SIGNED-ZEROS %s
> > > > > +// CHECK-NO-SIGNED-ZEROS: "-cc1"
> > > > > +// CHECK-NO-SIGNED-ZEROS: "-fno-signed-zeros"
> > > > > +//
> > > > > +// RUN: %clang -### -fno-fast-math -fno-signed-zeros -c %s 2>&1 \
> > > > > +// RUN: | FileCheck
> > --check-prefix=CHECK-NO-FAST-MATH-NO-SIGNED-ZEROS
> > > > %s
> > > > > +// CHECK-NO-FAST-MATH-NO-SIGNED-ZEROS: "-cc1"
> > > > > +// CHECK-NO-FAST-MATH-NO-SIGNED-ZEROS: "-fno-signed-zeros"
> > > > > +//
> > > > > +// RUN: %clang -### -fno-signed-zeros -fno-fast-math -c %s 2>&1 \
> > > > > +// RUN: | FileCheck
> > --check-prefix=CHECK-NO-SIGNED-ZEROS-NO-FAST-MATH
> > > > %s
> > > > > +// CHECK-NO-SIGNED-ZEROS-NO-FAST-MATH: "-cc1"
> > > > > +// CHECK-NO-SIGNED-ZEROS-NO-FAST-MATH-NOT: "-fno-signed-zeros"
> > > > > +//
> > > > > // RUN: %clang -### -fno-honor-nans -c %s 2>&1 \
> > > > > // RUN: | FileCheck --check-prefix=CHECK-NO-NANS %s
> > > > > // CHECK-NO-NANS: "-cc1"
> > > > >
> > > > >
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