https://gcc.gnu.org/g:ac6f0edba0fe0a5525d9348fde4d7f4191f6611c
commit ac6f0edba0fe0a5525d9348fde4d7f4191f6611c Author: Michael Meissner <[email protected]> Date: Tue Mar 3 20:09:02 2026 -0500 Add the -mdense-math option. This patch adds the -mdense-math option for -mcpu=future. The next set of patches will support for using dense math registers with the MMA instructions. All this patch does is add the option. A future patch will implement support for dense math registers, and another patch will then switch the MMA instructions to use dense math registers. The patches have been tested on both little and big endian systems. Can I check it into the master branch? This is version 4 of the patches. The previous patches were: * https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707452.html * https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707453.html * https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707454.html * https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707455.html * https://gcc.gnu.org/pipermail/gcc-patches/2026-February/707456.html gcc/ 2026-03-03 Michael Meissner <[email protected]> * config/rs6000/rs6000-c.cc (rs6000_define_or_undefine_macro): Define __DENSE_MATH__ if we have dense math registers. * config/rs6000/rs6000.cc (rs6000_option_override_internal): Do not allow -mdense-math unless -mcpu=future is used. (rs6000_opt_masks): Add -mdense-math support. * config/rs6000/rs6000.opt (-mdense-math): New option. * doc/invoke.texi (RS/6000 and PowerPC Options): Add -mdense-math. Diff: --- gcc/config/rs6000/rs6000-c.cc | 4 ++++ gcc/config/rs6000/rs6000.cc | 10 ++++++++++ gcc/config/rs6000/rs6000.opt | 4 ++++ gcc/doc/invoke.texi | 7 +++++++ 4 files changed, 25 insertions(+) diff --git a/gcc/config/rs6000/rs6000-c.cc b/gcc/config/rs6000/rs6000-c.cc index eb6a881aa9bd..a7eb951b014d 100644 --- a/gcc/config/rs6000/rs6000-c.cc +++ b/gcc/config/rs6000/rs6000-c.cc @@ -590,6 +590,10 @@ rs6000_target_modify_macros (bool define_p, HOST_WIDE_INT flags) /* Tell the user if we support the MMA instructions. */ if ((flags & OPTION_MASK_MMA) != 0) rs6000_define_or_undefine_macro (define_p, "__MMA__"); + /* Tell the user if we support the dense math registers for use with MMA and + cryptography. */ + if ((flags & OPTION_MASK_DENSE_MATH) != 0) + rs6000_define_or_undefine_macro (define_p, "__DENSE_MATH__"); /* Whether pc-relative code is being generated. */ if ((flags & OPTION_MASK_PCREL) != 0) rs6000_define_or_undefine_macro (define_p, "__PCREL__"); diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc index 3454a090dbc2..68d5e95179f7 100644 --- a/gcc/config/rs6000/rs6000.cc +++ b/gcc/config/rs6000/rs6000.cc @@ -4410,6 +4410,15 @@ rs6000_option_override_internal (bool global_init_p) if (!TARGET_PCREL && TARGET_PCREL_OPT) rs6000_isa_flags &= ~OPTION_MASK_PCREL_OPT; + /* Turn off dense math register support on non-future systems. */ + if (TARGET_DENSE_MATH && !TARGET_FUTURE) + { + if ((rs6000_isa_flags_explicit & OPTION_MASK_DENSE_MATH) != 0) + error ("%qs requires %qs", "-mdense-math", "-mcpu=future"); + + rs6000_isa_flags &= ~OPTION_MASK_DENSE_MATH; + } + if (TARGET_DEBUG_REG || TARGET_DEBUG_TARGET) rs6000_print_isa_options (stderr, 0, "after subtarget", rs6000_isa_flags); @@ -24463,6 +24472,7 @@ static struct rs6000_opt_mask const rs6000_opt_masks[] = false, true }, { "cmpb", OPTION_MASK_CMPB, false, true }, { "crypto", OPTION_MASK_CRYPTO, false, true }, + { "dense-math", OPTION_MASK_DENSE_MATH, false, true }, { "direct-move", 0, false, true }, { "dlmzb", OPTION_MASK_DLMZB, false, true }, { "efficient-unaligned-vsx", OPTION_MASK_EFFICIENT_UNALIGNED_VSX, diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt index 9f3519da77b2..f836d1982877 100644 --- a/gcc/config/rs6000/rs6000.opt +++ b/gcc/config/rs6000/rs6000.opt @@ -639,6 +639,10 @@ mieee128-constant Target Var(TARGET_IEEE128_CONSTANT) Init(1) Save Generate (do not generate) code that uses the LXVKQ instruction. +mdense-math +Target Mask(DENSE_MATH) Var(rs6000_isa_flags) +Generate (do not generate) instructions that use dense math registers. + ; Documented parameters -param=rs6000-vect-unroll-limit= diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 56bd4b35e9ae..eb774b0c622f 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -32675,6 +32675,13 @@ This option is enabled by default. Enable or disable warnings about deprecated @samp{vector long ...} Altivec type usage. This option is enabled by default. +@opindex mdense-math +@opindex mno-dense-math +@item -mdense-math +@itemx -mno-dense-math +Generate (do not generate) code that uses the dense math registers. +This option is enabled by default. + @end table @node RX Options
