From e64054552385aced493969af6f8341d944e150a8 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 1 May 2024 22:44:10 -0700 Subject: [PATCH] target/s390x: Simplify help_branch Always use a tcg branch, instead of movcond. The movcond was not a bad idea before PER was added, but since then we have either 2 or 3 actions to perform on each leg of the branch, and multiple movcond is inefficient. Reorder the taken branch to be fallthrough of the tcg branch. Reviewed-by: Ilya Leoshkevich Signed-off-by: Richard Henderson Message-ID: <20240502054417.234340-8-richard.henderson@linaro.org> Signed-off-by: Thomas Huth --- target/s390x/tcg/translate.c | 164 ++++++++++++----------------------- 1 file changed, 56 insertions(+), 108 deletions(-) diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c index 7ae928c3b0..78066aaf84 100644 --- a/target/s390x/tcg/translate.c +++ b/target/s390x/tcg/translate.c @@ -353,25 +353,6 @@ static void per_branch(DisasContext *s, bool to_next) #endif } -static void per_branch_cond(DisasContext *s, TCGCond cond, - TCGv_i64 arg1, TCGv_i64 arg2) -{ -#ifndef CONFIG_USER_ONLY - if (s->base.tb->flags & FLAG_MASK_PER_BRANCH) { - TCGLabel *lab = gen_new_label(); - tcg_gen_brcond_i64(tcg_invert_cond(cond), arg1, arg2, lab); - - tcg_gen_movi_i64(gbea, s->base.pc_next); - gen_helper_per_branch(tcg_env, gbea, psw_addr); - - gen_set_label(lab); - } else { - TCGv_i64 pc = tcg_constant_i64(s->base.pc_next); - tcg_gen_movcond_i64(cond, gbea, arg1, arg2, gbea, pc); - } -#endif -} - static void per_breaking_event(DisasContext *s) { tcg_gen_movi_i64(gbea, s->base.pc_next); @@ -1128,14 +1109,12 @@ static DisasJumpType help_goto_indirect(DisasContext *s, TCGv_i64 dest) static DisasJumpType help_branch(DisasContext *s, DisasCompare *c, bool is_imm, int imm, TCGv_i64 cdest) { - DisasJumpType ret; uint64_t dest = s->base.pc_next + (int64_t)imm * 2; - TCGLabel *lab; + TCGLabel *lab, *over; /* Take care of the special cases first. */ if (c->cond == TCG_COND_NEVER) { - ret = DISAS_NEXT; - goto egress; + return DISAS_NEXT; } if (is_imm) { /* @@ -1145,104 +1124,73 @@ static DisasJumpType help_branch(DisasContext *s, DisasCompare *c, if (c->cond == TCG_COND_ALWAYS || (dest == s->pc_tmp && !(s->base.tb->flags & FLAG_MASK_PER_BRANCH))) { - ret = help_goto_direct(s, dest); - goto egress; + return help_goto_direct(s, dest); } } else { if (!cdest) { /* E.g. bcr %r0 -> no branch. */ - ret = DISAS_NEXT; - goto egress; + return DISAS_NEXT; } if (c->cond == TCG_COND_ALWAYS) { - ret = help_goto_indirect(s, cdest); - goto egress; + return help_goto_indirect(s, cdest); } } - if (use_goto_tb(s, s->pc_tmp)) { - if (is_imm && use_goto_tb(s, dest)) { - /* Both exits can use goto_tb. */ - update_cc_op(s); + update_cc_op(s); - lab = gen_new_label(); - if (c->is_64) { - tcg_gen_brcond_i64(c->cond, c->u.s64.a, c->u.s64.b, lab); - } else { - tcg_gen_brcond_i32(c->cond, c->u.s32.a, c->u.s32.b, lab); - } - - /* Branch not taken. */ - tcg_gen_goto_tb(0); - tcg_gen_movi_i64(psw_addr, s->pc_tmp); - tcg_gen_exit_tb(s->base.tb, 0); - - /* Branch taken. */ - gen_set_label(lab); - per_breaking_event(s); - tcg_gen_goto_tb(1); - tcg_gen_movi_i64(psw_addr, dest); - tcg_gen_exit_tb(s->base.tb, 1); - - ret = DISAS_NORETURN; - } else { - /* Fallthru can use goto_tb, but taken branch cannot. */ - /* Store taken branch destination before the brcond. This - avoids having to allocate a new local temp to hold it. - We'll overwrite this in the not taken case anyway. */ - if (!is_imm) { - tcg_gen_mov_i64(psw_addr, cdest); - } - - lab = gen_new_label(); - if (c->is_64) { - tcg_gen_brcond_i64(c->cond, c->u.s64.a, c->u.s64.b, lab); - } else { - tcg_gen_brcond_i32(c->cond, c->u.s32.a, c->u.s32.b, lab); - } - - /* Branch not taken. */ - update_cc_op(s); - tcg_gen_goto_tb(0); - tcg_gen_movi_i64(psw_addr, s->pc_tmp); - tcg_gen_exit_tb(s->base.tb, 0); - - gen_set_label(lab); - if (is_imm) { - tcg_gen_movi_i64(psw_addr, dest); - } - per_breaking_event(s); - ret = DISAS_PC_UPDATED; - } + /* + * Ensure the taken branch is fall-through of the tcg branch. + * This keeps @cdest usage within the extended basic block, + * which avoids an otherwise unnecessary spill to the stack. + */ + lab = gen_new_label(); + if (s->base.tb->flags & FLAG_MASK_PER_BRANCH) { + over = gen_new_label(); } else { - /* Fallthru cannot use goto_tb. This by itself is vanishingly rare. - Most commonly we're single-stepping or some other condition that - disables all use of goto_tb. Just update the PC and exit. */ - - TCGv_i64 next = tcg_constant_i64(s->pc_tmp); - if (is_imm) { - cdest = tcg_constant_i64(dest); - } - - if (c->is_64) { - tcg_gen_movcond_i64(c->cond, psw_addr, c->u.s64.a, c->u.s64.b, - cdest, next); - per_branch_cond(s, c->cond, c->u.s64.a, c->u.s64.b); - } else { - TCGv_i32 t0 = tcg_temp_new_i32(); - TCGv_i64 t1 = tcg_temp_new_i64(); - TCGv_i64 z = tcg_constant_i64(0); - tcg_gen_setcond_i32(c->cond, t0, c->u.s32.a, c->u.s32.b); - tcg_gen_extu_i32_i64(t1, t0); - tcg_gen_movcond_i64(TCG_COND_NE, psw_addr, t1, z, cdest, next); - per_branch_cond(s, TCG_COND_NE, t1, z); - } - - ret = DISAS_PC_UPDATED; + over = NULL; } - egress: - return ret; + if (c->is_64) { + tcg_gen_brcond_i64(tcg_invert_cond(c->cond), + c->u.s64.a, c->u.s64.b, lab); + } else { + tcg_gen_brcond_i32(tcg_invert_cond(c->cond), + c->u.s32.a, c->u.s32.b, lab); + } + + /* Branch taken. */ + if (is_imm) { + tcg_gen_movi_i64(psw_addr, dest); + } else { + tcg_gen_mov_i64(psw_addr, cdest); + } + per_branch(s, false); + + if (is_imm && use_goto_tb(s, dest)) { + tcg_gen_goto_tb(0); + tcg_gen_exit_tb(s->base.tb, 0); + } else if (over) { + tcg_gen_br(over); + } else { + tcg_gen_lookup_and_goto_ptr(); + } + + gen_set_label(lab); + + /* Branch not taken. */ + tcg_gen_movi_i64(psw_addr, s->pc_tmp); + if (use_goto_tb(s, s->pc_tmp)) { + tcg_gen_goto_tb(1); + tcg_gen_exit_tb(s->base.tb, 1); + } + + if (over) { + gen_set_label(over); + return DISAS_PC_UPDATED; + } + + tcg_gen_lookup_and_goto_ptr(); + return DISAS_NORETURN; } /* ====================================================================== */