https://gcc.gnu.org/g:8b0e157f65e0e2f70fcc9a8f9dd7f1f426c05bcb
commit 8b0e157f65e0e2f70fcc9a8f9dd7f1f426c05bcb Author: Michael Meissner <[email protected]> Date: Fri Feb 13 00:16:36 2026 -0500 Add wD constraint. This patch adds a new constraint ('wD') that matches the accumulator registers that overlap with VSX registers 0..31 on power10. Future patches will add the support for a separate accumulator register class that will be used when the support for dense math registes is added. In this patch, I have removed using the wD constriant in mma.md. A later patch will move to using wA instead of a d constraint. The patches have been tested on both little and big endian systems. Can I check it into the master branch? 2026-02-12 Michael Meissner <[email protected]> * config/rs6000/constraints.md (wD): New constraint. * config/rs6000/predicates.md (accumulator_operand): New predicate. * config/rs6000/rs6000.cc (rs6000_debug_reg_global): Print the register class for the 'wD' constraint. (rs6000_init_hard_regno_mode_ok): Set up the 'wD' register constraint class. * config/rs6000/rs6000.h (enum r6000_reg_class_enum): Add element for the 'wD' constraint. * doc/md.texi (PowerPC constraints): Document the 'wD' constraint. Diff: --- gcc/config/rs6000/constraints.md | 3 +++ gcc/config/rs6000/predicates.md | 18 ++++++++++++++++++ gcc/config/rs6000/rs6000.cc | 7 ++++++- gcc/config/rs6000/rs6000.h | 1 + gcc/doc/md.texi | 5 +++++ 5 files changed, 33 insertions(+), 1 deletion(-) diff --git a/gcc/config/rs6000/constraints.md b/gcc/config/rs6000/constraints.md index d0ed47faab84..0d1cde5bd4de 100644 --- a/gcc/config/rs6000/constraints.md +++ b/gcc/config/rs6000/constraints.md @@ -107,6 +107,9 @@ (match_test "TARGET_P8_VECTOR") (match_operand 0 "s5bit_cint_operand"))) +(define_register_constraint "wD" "rs6000_constraints[RS6000_CONSTRAINT_wD]" + "Accumulator register.") + (define_constraint "wE" "@internal Vector constant that can be loaded with the XXSPLTIB instruction." (match_test "xxspltib_constant_nosplit (op, mode)")) diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md index 54dbc8bcc952..682fd2dc6e85 100644 --- a/gcc/config/rs6000/predicates.md +++ b/gcc/config/rs6000/predicates.md @@ -186,6 +186,24 @@ return VLOGICAL_REGNO_P (REGNO (op)); }) +;; Return 1 if op is an accumulator. On power10 systems, the accumulators +;; overlap with the FPRs. +(define_predicate "accumulator_operand" + (match_operand 0 "register_operand") +{ + if (SUBREG_P (op)) + op = SUBREG_REG (op); + + if (!REG_P (op)) + return 0; + + if (!HARD_REGISTER_P (op)) + return 1; + + int r = REGNO (op); + return FP_REGNO_P (r) && (r & 3) == 0; +}) + ;; Return 1 if op is the carry register. (define_predicate "ca_operand" (match_operand 0 "register_operand") diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc index 11fd61f2e8da..68d5e95179f7 100644 --- a/gcc/config/rs6000/rs6000.cc +++ b/gcc/config/rs6000/rs6000.cc @@ -2328,6 +2328,7 @@ rs6000_debug_reg_global (void) "wr reg_class = %s\n" "wx reg_class = %s\n" "wA reg_class = %s\n" + "wD reg_class = %s\n" "\n", reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_d]], reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_v]], @@ -2335,7 +2336,8 @@ rs6000_debug_reg_global (void) reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_we]], reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_wr]], reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_wx]], - reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_wA]]); + reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_wA]], + reg_class_names[rs6000_constraints[RS6000_CONSTRAINT_wD]]); nl = "\n"; for (m = 0; m < NUM_MACHINE_MODES; ++m) @@ -2992,6 +2994,9 @@ rs6000_init_hard_regno_mode_ok (bool global_init_p) if (TARGET_DIRECT_MOVE_128) rs6000_constraints[RS6000_CONSTRAINT_we] = VSX_REGS; + if (TARGET_MMA) + rs6000_constraints[RS6000_CONSTRAINT_wD] = FLOAT_REGS; + /* Set up the reload helper and direct move functions. */ if (TARGET_VSX || TARGET_ALTIVEC) { diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h index 2d3016db5135..04709f0dcd6e 100644 --- a/gcc/config/rs6000/rs6000.h +++ b/gcc/config/rs6000/rs6000.h @@ -1183,6 +1183,7 @@ enum r6000_reg_class_enum { RS6000_CONSTRAINT_wr, /* GPR register if 64-bit */ RS6000_CONSTRAINT_wx, /* FPR register for STFIWX */ RS6000_CONSTRAINT_wA, /* BASE_REGS if 64-bit. */ + RS6000_CONSTRAINT_wD, /* Accumulator regs if MMA/Dense Math. */ RS6000_CONSTRAINT_MAX }; diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index edbdb1d50f1a..2b7f90ce5370 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -3415,6 +3415,11 @@ Like @code{d}, if @option{-mpowerpc-gfxopt} is used; otherwise, @code{NO_REGS}. @item wA Like @code{b}, if @option{-mpowerpc64} is used; otherwise, @code{NO_REGS}. +@item wD +Accumulator register if @option{-mma} is used; otherwise, +@code{NO_REGS}. For @option{-mcpu=power10} the accumulator registers +overlap with VSX vector registers 0..31. + @item wB Signed 5-bit constant integer that can be loaded into an Altivec register.
