I also prefer adding a -mabi=auto option rather than change existing behavior.
On Wed, Jun 8, 2022 at 5:06 PM pc.wang via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Thanks for your opinion! I did these just because LLVM has already done the > same thing and I wanted to make GCC with the same behavior of LLVM. The only > difference is that LLVM has no handling for ilp32f and lp64f and I have sent > a patch to do it (sees https://reviews.llvm.org/D125947). > As for RISC-V specs, there are some descriptions in > https://github.com/riscv-non-isa/riscv-toolchain-conventions#specifying-the-target-isa-with--march: > > A target -march which includes floating point instructions implies a > > hardfloat calling convention, but can be overridden using the -mabi flag > > (see the next section). > But I think we can make it clearer. > ------------------------------------------------------------------ > Sender:Palmer Dabbelt <pal...@dabbelt.com> > Sent At:2022 Jun. 8 (Wed.) 02:45 > Recipient:gcc-patches <gcc-patches@gcc.gnu.org> > Cc:pc.wang <pc.w...@linux.alibaba.com> > Subject:Re: [PATCH] RISC-V: Compute default ABI from -mcpu or -march > > On Mon, 06 Jun 2022 19:51:20 PDT (-0700), gcc-patches@gcc.gnu.org wrote: > > If -mcpu or -march is specified and there is no -mabi, we will calculate > > default ABI from arch string provided by -march or defined in CPU info. > > IMO this is generally a good idea and we've talked about it before, but > just setting the ABI from the ISA isn't quite the right way to go. IIRC > we came up with something slightly more complicated, like picking the > closest supported multilib. That's probably more in line with what > users are asking for, which IIUC is sort of just "I don't care that much > about ABI, just make my stuff build". > > Whatever we do here, we should document in the RISC-V specs as we'll > want to make sure LLVM does the same thing. We probably also want some > sort of "-mabi=auto" argument, as it's always best to have an argument > that changes back to the no-argument behavior. > > > > > > gcc/ChangeLog: > > > > * common/config/riscv/riscv-common.cc (compute_default_abi): > > Implementation > > to calculate -mabi from arch string. > > (riscv_expand_abi_from_arch): New spec function to calcalute -mabi > > from arch > > string provided by -march option. > > (riscv_expand_abi_from_cpu): New spec function to find CPU info and > > calculate > > -mabi from arch string defined in CPU info. > > * config/riscv/riscv.h (EXTRA_SPEC_FUNCTIONS): Add above spec > > functions. > > (OPTION_DEFAULT_SPECS): Use new spec functions to calculate -mabi > > and -march > > has higher priority than -mcpu. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.target/riscv/mabi-1.c: ilp32e test. > > * gcc.target/riscv/mabi-2.c: ilp32 test. > > * gcc.target/riscv/mabi-3.c: ilp32f test. > > * gcc.target/riscv/mabi-4.c: ilp32d test. > > * gcc.target/riscv/mabi-5.c: lp64 test. > > * gcc.target/riscv/mabi-6.c: lp64f test. > > * gcc.target/riscv/mabi-7.c: lp64d test. > > * gcc.target/riscv/mabi-8.c: -march override -mcpu. > > --- > > gcc/common/config/riscv/riscv-common.cc | 66 +++++++++++++++++++++++++ > > gcc/config/riscv/riscv.h | 15 ++++-- > > gcc/testsuite/gcc.target/riscv/mabi-1.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-2.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-3.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-4.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-5.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-6.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-7.c | 7 +++ > > gcc/testsuite/gcc.target/riscv/mabi-8.c | 7 +++ > > 10 files changed, 134 insertions(+), 3 deletions(-) > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-1.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-2.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-3.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-4.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-5.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-6.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-7.c > > create mode 100644 gcc/testsuite/gcc.target/riscv/mabi-8.c > > > > diff --git a/gcc/common/config/riscv/riscv-common.cc > > b/gcc/common/config/riscv/riscv-common.cc > > index 0e5be2ce105..f8e40549d18 100644 > > --- a/gcc/common/config/riscv/riscv-common.cc > > +++ b/gcc/common/config/riscv/riscv-common.cc > > @@ -1266,6 +1266,72 @@ riscv_default_mtune (int argc, const char **argv) > > return default_mtune; > > } > > > > +/* Compute default -mabi option from arch string. */ > > + > > +static const char * > > +compute_default_abi (const char* arch_str) > > +{ > > + location_t loc = UNKNOWN_LOCATION; > > + > > + riscv_parse_arch_string (arch_str, NULL, loc); > > + > > + if (current_subset_list->xlen () == 64) > > + { > > + if (current_subset_list->lookup ("d", RISCV_DONT_CARE_VERSION, > > + RISCV_DONT_CARE_VERSION)) > > + return "lp64d"; > > + if (current_subset_list->lookup ("f", RISCV_DONT_CARE_VERSION, > > + RISCV_DONT_CARE_VERSION)) > > + return "lp64f"; > > + return "lp64"; > > + } > > + else > > + { > > + if (current_subset_list->lookup ("e", RISCV_DONT_CARE_VERSION, > > + RISCV_DONT_CARE_VERSION)) > > + return "ilp32e"; > > + if (current_subset_list->lookup ("d", RISCV_DONT_CARE_VERSION, > > + RISCV_DONT_CARE_VERSION)) > > + return "ilp32d"; > > + if (current_subset_list->lookup ("f", RISCV_DONT_CARE_VERSION, > > + RISCV_DONT_CARE_VERSION)) > > + return "ilp32f"; > > + return "ilp32"; > > + } > > +} > > + > > +/* Expand default -mabi option from -march option. */ > > + > > +const char * > > +riscv_expand_abi_from_arch (int argc, const char **argv) > > +{ > > + gcc_assert (argc == 1); > > + return xasprintf ("-mabi=%s", compute_default_abi (argv[0])); > > +} > > + > > +/* Expand default -mabi option from -mcpu option. */ > > + > > +const char * > > +riscv_expand_abi_from_cpu (int argc, const char **argv) > > +{ > > + gcc_assert (argc > 0 && argc <= 2); > > + const char *default_abi_str = NULL; > > + if (argc >= 2) > > + default_abi_str = argv[1]; > > + > > + const riscv_cpu_info *cpu = riscv_find_cpu (argv[0]); > > + > > + if (cpu == NULL) > > + { > > + if (default_abi_str == NULL) > > + return ""; > > + else > > + return xasprintf ("-mabi=%s", default_abi_str); > > + } > > + else > > + return xasprintf ("-mabi=%s", compute_default_abi (cpu->arch)); > > +} > > + > > /* Expand arch string with implied extensions from -mcpu option. */ > > > > const char * > > diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h > > index 6f7f4d3fbdc..14cd695f37f 100644 > > --- a/gcc/config/riscv/riscv.h > > +++ b/gcc/config/riscv/riscv.h > > @@ -50,15 +50,20 @@ along with GCC; see the file COPYING3. If not see > > extern const char *riscv_expand_arch (int argc, const char **argv); > > extern const char *riscv_expand_arch_from_cpu (int argc, const char > > **argv); > > extern const char *riscv_default_mtune (int argc, const char **argv); > > +extern const char *riscv_expand_abi_from_arch (int argc, const char > > **argv); > > +extern const char *riscv_expand_abi_from_cpu (int argc, const char **argv); > > > > # define EXTRA_SPEC_FUNCTIONS \ > > { "riscv_expand_arch", riscv_expand_arch }, \ > > { "riscv_expand_arch_from_cpu", riscv_expand_arch_from_cpu }, \ > > - { "riscv_default_mtune", riscv_default_mtune }, > > + { "riscv_default_mtune", riscv_default_mtune }, \ > > + { "riscv_expand_abi_from_arch", riscv_expand_abi_from_arch }, \ > > + { "riscv_expand_abi_from_cpu", riscv_expand_abi_from_cpu }, > > > > /* Support for a compile-time default CPU, et cetera. The rules are: > > --with-arch is ignored if -march or -mcpu is specified. > > - --with-abi is ignored if -mabi is specified. > > + --with-abi is ignored if -mabi is specified. If -mcpu or -march is > > + specified, suitable -mabi will be selected from arch string. > > --with-tune is ignored if -mtune or -mcpu is specified. > > --with-isa-spec is ignored if -misa-spec is specified. > > > > @@ -70,7 +75,11 @@ extern const char *riscv_default_mtune (int argc, const > > char **argv); > > {"arch", "%{!march=*:" \ > > " %{!mcpu=*:-march=%(VALUE)}" \ > > " %{mcpu=*:%:riscv_expand_arch_from_cpu(%* %(VALUE))}}" }, \ > > - {"abi", "%{!mabi=*:-mabi=%(VALUE)}" }, \ > > + {"abi", "%{!mabi=*:" \ > > + " %{!march=*:" \ > > + " %{!mcpu=*:-mabi=%(VALUE)}" \ > > + " %{mcpu=*:%:riscv_expand_abi_from_cpu(%* %(VALUE))}}" \ > > + " %{march=*:%:riscv_expand_abi_from_arch(%*)}}" }, \ > > {"isa_spec", "%{!misa-spec=*:-misa-spec=%(VALUE)}" }, \ > > > > #ifdef IN_LIBGCC2 > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-1.c > > b/gcc/testsuite/gcc.target/riscv/mabi-1.c > > new file mode 100644 > > index 00000000000..83bc343f8d8 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-1.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv32e" } */ > > + > > +#if !((__riscv_xlen == 32) && defined(__riscv_abi_rve)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-2.c > > b/gcc/testsuite/gcc.target/riscv/mabi-2.c > > new file mode 100644 > > index 00000000000..6a97c2ae2a3 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-2.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv32ima" } */ > > + > > +#if !((__riscv_xlen == 32) && defined(__riscv_float_abi_soft)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-3.c > > b/gcc/testsuite/gcc.target/riscv/mabi-3.c > > new file mode 100644 > > index 00000000000..cef04313e19 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-3.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv32imaf" } */ > > + > > +#if !((__riscv_xlen == 32) && defined(__riscv_float_abi_single)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-4.c > > b/gcc/testsuite/gcc.target/riscv/mabi-4.c > > new file mode 100644 > > index 00000000000..d62dcf6ed75 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-4.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv32imafd" } */ > > + > > +#if !((__riscv_xlen == 32) && defined(__riscv_float_abi_double)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-5.c > > b/gcc/testsuite/gcc.target/riscv/mabi-5.c > > new file mode 100644 > > index 00000000000..000e5e282c2 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-5.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv64ima" } */ > > + > > +#if !((__riscv_xlen == 64) && defined(__riscv_float_abi_soft)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-6.c > > b/gcc/testsuite/gcc.target/riscv/mabi-6.c > > new file mode 100644 > > index 00000000000..ed1458d4158 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-6.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv64imaf" } */ > > + > > +#if !((__riscv_xlen == 64) && defined(__riscv_float_abi_single)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-7.c > > b/gcc/testsuite/gcc.target/riscv/mabi-7.c > > new file mode 100644 > > index 00000000000..675fe359cfd > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-7.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-march=rv64imafd" } */ > > + > > +#if !((__riscv_xlen == 64) && defined(__riscv_float_abi_double)) > > +#error "unexpected abi" > > +#endif > > diff --git a/gcc/testsuite/gcc.target/riscv/mabi-8.c > > b/gcc/testsuite/gcc.target/riscv/mabi-8.c > > new file mode 100644 > > index 00000000000..8c7e08e4289 > > --- /dev/null > > +++ b/gcc/testsuite/gcc.target/riscv/mabi-8.c > > @@ -0,0 +1,7 @@ > > +/* { dg-do compile } */ > > +/* { dg-skip-if "-mabi given" { *-*-* } { "-mabi=*" } } */ > > +/* { dg-options "-mcpu=sifive-s21 -march=rv64imafd" } */ > > + > > +#if !((__riscv_xlen == 64) && defined(__riscv_float_abi_double)) > > +#error "unexpected abi" > > +#endif
